THE RELATIONSHIP BETWEEN STANDING POSTURE, FUNCTIONAL HIP RANGE OF MOTION, AND POSTURAL CONTROL IN FEMALE COLLEGIATE

VOLLEYBALL PLAYERS

THESIS

A THESIS Submitted to the Faculty of the School of Graduate Studies

and Research of California University of Pennsylvania in partial fulfillment of the requirements for the degree of

Master of Science

BY

CATHERINE L. DOUGHERTY

Research Adviser, Dr. Rebecca A. Hess

California, Pennsylvania

2005

ii

iii

Acknowledgements

Firstly, I want to thank God for waking me up this morning, for granting me the grace and perseverance with which I could accomplish this prestigious achievement. If it were not for the ability he has bestowed upon me, both mentally and physically, this feat may not have been possible.

Thanks to my parents, Bob and Judy Dougherty, for the many sacrifices they have made in order for me to obtain such a dignified education. Their constant encouragement, reassurance, and devotion have promoted the diligence necessary to complete this degree of success. Thank you, also, for instilling in me the firm, Catholic belief that God will provide for me and protect me on my journey through life. I will offer up all my accomplishments, tribulations, and defeats to gain his grace.

Thank you to my committee, Dr. Hess, Dr. Reuter, and Jeff Hatton, for the professional advice and the determination to make this endeavor a hopeful success. You have proven that nothing is merely handed to the undeserved; but with the proper amount of persistence (and loss of sleep), even the worst of researchers can develop a fundamental competence for the researching, and re-researching, process. I assure you that if I had commenced this program at the intended time, this would have been done two months ago. Instead it seems I have learned the necessary material after-the-fact.

Thanks to my fabulous boyfriend, Dave, who helped me maintain composure when this thesis-writing procedure had me at my whit’s end. If it were not for him, I would probably be bald in the loony-bin right now. Thank you to my classmates for the stress-relieving nights at Lagerhead’s and the many memories. Thank you to my Aunt JoAnne and Uncle Will for donating me a ’94 Acura Integra with 220,000 miles to get me to school daily. It still runs like a dream! And lastly, thanks to Lisa and Amber for allowing me to shack-up in their spare room on my air mattress to save me the excess mileage on my car and un-necessary sleep-deprivation.

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TABLE OF CONTENTS

Page SIGNATURE PAGE . . . . . . . . . . . . . . . . ii

ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . iii

TABLE OF CONTENTS . . . . . . . . . . . . . . . iv

LIST OF TABLES . . . . . . . . . . . . . . . . vii

INTRODUCTION . . . . . . . . . . . . . . . . . 1

METHODS . . . . . . . . . . . . . . . . . . 11

Research Design. . . . . . . . . . . . . . . 11

Subjects. . . . . . . . . . . . . . . . . . . 12

Preliminary Research. . . . . . . . . . . 13

Instrumentation. . . . . . . . . . . . . . . 13

Static Postural and Flexibility Assessment . . 14

Dynamic and Functional Assessment. . . . . . 16

Procedures . . . . . . . . . . . . . . . . . 18

Hypotheses . . . . . . . . . . . . . . . . 23

Data Analysis . . . . . . . . . . . . . . . 23

RESULTS . . . . . . . . . . . . . . . . . . . 25

Demographic Data . . . . . . . . . . . . . . 25

Hypotheses Testing . . . . . . . . . . . . . 25

Additional Findings . . . . . . . . . . . . . 32

DISCUSSION . . . . . . . . . . . . . . . . . 37

Discussion of Results . . . . . . . . . . . . 37

Conclusions . . . . . . . . . . . . . . . . 43

v

Recommendations . . . . . . . . . . . . . . . . 44

REFERENCES . . . . . . . . . . . . . . . . . 46

APPENDICES . . . . . . . . . . . . . . . . . 49

A. Review of the Literature . . . . . . . . . . . . 49

Introduction. . . . . . . . . . . . . 50

Core Stability. . . . . . . . . . . . . . . 52

Composition of the Core. . . . . . . . . . 52

Importance of Core Strengthening . . . . . . 54

Assessment of Core Strength and Stability. . . 55

Testing for Core Stability. . . . . . .56

Testing for Core Power. . . . . . . . 57

Strengthening strategies. . . . . . . . . 58

Postural Deviations. . . . . . . . . . . . 62

Functional Range of Motion in Lower Extremity. . 66

Knee Injuries in Female Athletes. . . . . . . 69

ACL Injury. . . . . . . . . . . . . . . 70

Patellar Maltracking and Subluxation. . . . . 76

Patellar Tendonitis. . . . . . . . . . . 77

Summary. . . . . . . . . . . . . . .78

B. The Problem. . . . . . . . . . . . . . . . . 80

Statement of the Problem . . . . . . . . . . 81

Definition of Terms . . . . . . . . . . . . 81

Basic Assumptions . . . . . . . . . . . . . 84

Limitation of the Study . . . . . . . . . . 84

vi

Significance of the Study. . . . . . . . . . 85

C. Additional Methods. . . . . . . . . . . . . . 86

Informed Consent (C1). . . . . . . . . . . . 87

Institutional Review Board (C2). . . . . . . . 90

General Demographic Information (C3). . . . . . 95

Evaluation Form (C4). . . . . . . . . . . . 97

Active Hip Range of Motion Measurements (C5). . 100

Overhead Squat Assessment (C6). . . . . . . .102

REFERENCES . . . . . . . . . . . . . . . . . 104

ABSTRACT . . . . . . . . . . . . . . . . . . 108

vii

LIST OF TABLES

Table Title Page

1 Q-angle Compared to Standing Posture, 28 Overhead Squat, and Jump Recovery

2 Active Hip ROM Compared to Standing Posture, 30 Overhead Squat, and Jump Recovery

3 Knee Pathology Compared to Standing Posture, 34 Overhead Squat, and Jump Recovery

4 Vertical Jump Heights for 10 Division II 36 Female Volleyball Athletes

1

INTRODUCTION

The prevalence of knee injuries is a serious problem

for athletic trainers, particularly those working with

female athletes. Knee injuries have been traced back to

defects such as lack of core strength, postural deficits,

increased Q-angle, tibial valgus, subtalar pronation, and

associated imbalances in flexibility and functional range

of motion.1,2 While core stability and postural control are

necessary components of every athlete’s training regimen,

the beneficial effects on power and function have often

been ignored.2 If more athletic trainers and coaches were

aware of their role in optimal performance, core stability

and postural control might be incorporated more readily

into every athlete’s conditioning program, potentially

lessening the stress and workload of certain avoidable

overuse injuries.

The core supplies the entire kinetic chain with

neuromuscular control and efficiency.2 Core muscle groups,

namely the lumbar extensors, abdominals (rectus abdominis,

external and internal obliques, and transverses abdominis),

and hip musculature (psoas, gluteus medius and maximus, and

hamstrings), create stabilization and force-couple

relationships that normal function is dependent upon. When

2

normal length-tension relationships are established, the

body is provided with an environment that will allow

optimal arthrokinematics during functional kinetic chain

movements.2

Overuse injuries, such as medial tibial stress

syndrome and tendonitis, are often caused by abnormal

biomechanics of the lower extremity.3,4 While we as

clinicians may feel more informed about the effect that

lower extremity biomechanics can have on pathologies

ranging from the foot to the hip, it is also important to

consider the effect of lower extremity biomechanics on the

pelvis and lumbar spine. Abnormal biomechanics, beginning

as low as the subtalar joint, may cause compensatory

movements that lead to pathology of the pelvis and lumbar

spine. Resulting imbalances of the hip and/or lower

extremity musculature may contribute to the onset of low

back pain.3 Therefore, a comprehensive evaluation for low

back pain should include assessment of the lower extremity

for such abnormalities.3

Overuse injuries develop when repetitive stress to

bone and musculotendinous structures damages tissue at a

greater rate than that at which the body can repair

itself.5 A combination of extrinsic factors, such as

training errors and environmental factors, and intrinsic

3

or anatomical factors, such as bony alignment of the

extremities, flexibility deficits, and ligamentous

laxity, predispose athletes to develop overuse injuries.

Malalignment of the lower extremity, including excessive

femoral anteversion, increased Q angle, tibial vara

(internal rotation of tibia), genu varum or valgum (“bow-

legged” or “knock-kneed”, respectively), subtalar varus

and pronation (flattening of the medial longitudinal

arch) are frequently cited as predisposing to knee

extensor mechanism overuse injuries, namely tendonitis.5

These and other forms of malalignment have also been

implicated in iliotibial band syndrome, medial tibial

stress syndrome, lower extremity stress fractures and

plantar fasciitis.5

The kinetic chain works synergistically to produce

force concentrically, reduce force eccentrically, and

dynamically stabilize against abnormal forces. When

functionally efficient, each component of the core

disperses weight, absorbs force, and transfers ground

reaction forces. Core strength is also mandatory,

specifically in lower extremity dominant sports, to

provide proximal stability during competition.2,6 If the

distal musculature is strong but the core is weak, there

will not be enough force created to produce or control

4

efficient movements. Again, a weak core is a typical

cause of inefficient movements that could lead to

injury.2,6

Neuromuscular efficiency is promoted by the

appropriate combination of postural alignment (static and

dynamic) and stability, which allows the body to absorb

momentum at the correct joint, in the correct plane, and at

the correct time.3 As this efficiency decreases, so does the

body’s ability to react accordingly to abnormal forces.

This could potentially lead to compensation and

substitution patterns, as well as poor posture during

functional activities.3,5 Pathology of structures within the

neuromusculoskeletal system can result from skeletal

malalignment, which has been defined as either abnormal

joint alignment or deformity within a bone. Pathology can

also result from correlated or compensatory motions or

postures, which may accompany skeletal malalignment.3,4

Consequently, mechanical stress is placed on the static

(ligaments and bones) and dynamic (muscles and tendons)

tissues causing repetitive microtrauma, incorrect

mechanics, and injury.5 Sometimes this overloading of joints

and small muscles is due to the core not sufficiently

contributing to the effort. Therefore, stability and

movement are critically dependent on the coordination of

5

all the muscles surrounding the lumbo-pelvic hip complex.3

It is imperative to link common lower limb skeletal

malalignments to their correlated and compensatory motions

and postures.3,4

Unfortunately, lower extremity malalignment is less

amenable to intervention since it is congenital.

Orthotics are often prescribed to improve lower extremity

alignment. However, studies have not shown that orthotics

have any effect on knee alignment and, while they can

alter subtalar joint alignment, the clinical benefit of

this remains unclear.5 Awareness of anatomical factors

that may predispose athletes to overuse injuries allows

the athletic trainer to develop individual rehabilitation

programs designed to decrease the risk of overuse injury.

In addition, the clinician can advise the athlete on the

importance of avoiding extrinsic factors that may result

in overuse injury.5

Muscle inflexibility also predisposes athletes to the

development of a variety of overuse injuries.5 Flexibility

deficits may be improved by an appropriate stretching

program. Range of motion throughout the entire lower

extremity must be within normal limits to ensure standard

length-tension relationships and ultimately produce regular

arthrokinematics.5 If one muscle, or group of muscles, is

6

incapable of proper lengthening, it can create imbalances

throughout the entire kinetic chain. Without normal length-

tension relationships, an athlete is more prone to injury

due to improper passive lengthening and faulty eccentric

contraction of the musculature to absorb the force.5 These

imbalances and functional adaptations need to be corrected

to avoid problematic situations for the athlete,

particularly the female athlete, that may be predisposed to

such situations, as well as for the athletic trainer, whose

role is to treat and rehabilitate athletes’ injuries, if

not prevent them altogether.

Female participation in athletics has increased

dramatically over the last decade. Accompanying the

increase in sports participation is the increase incidence

of injury.7 Anterior cruciate ligament (ACL) sprains and

tears, patellar tendonitis, and subluxing patella are just

a few of the typical knee injuries seen regularly in the

jumping, female athletic population. Many of these

occurrences are due to valgus motion of the knee during

jump recovery as a result of muscular imbalances.7,8

Women appear to suffer four to eight times the number

of ACL injuries for the same sports as men.9 A greater Q-

angle (normal for females is ~ 180), anterior pelvic tilt,

anteverted hips, genu valgum, genu recurvatum, and subtalar

7

pronation are some of the anatomical differences that may

predispose a female to knee injury.7 Education about proper

dynamic stabilization of the muscles acting on the knee, as

well as hip joint, is vital.

Both intrinsic and extrinsic factors have been

proposed to contribute to the greater knee injury rate in

female athletes compared with their male counterparts.10,11

Specifically, intrinsic factors refer to lower extremity

skeletal malalignments, including excessive Q-angle, genu

valgum, femoral anteversion, and general joint laxity.

However, most of the skeletal variations between males and

females develop only after the rapid growth associated with

puberty. Not surprisingly then, post-pubescent females

suffer the highest rate of lower-limb injury when compared

with both the prepubescent female and male athletes.10-12

Some of the extrinsic factors associated with ACL

injury include motor control strategies, coordination of

movement patterns, the level of conditioning and muscular

strength, and possibly even menstrual factors affecting

ligamentous laxity.13 Only recently have extrinsic factors,

such as jumping and landing strategies, related to ACL

injuries been studied.13 Most of this research has focused

on kinetics, neuromuscular activity, and kinematics in the

sagittal plane without regard to maturation and frontal

8

plane motion. The kinematics of high-risk landing patterns

have been identified and many components of these parallel

the variations in female structural alignment with altered

motion occurring in the frontal plane.10,12 Recent research

in college-aged participants identified gender differences

in lower extremity kinematics and kinetics during landing

activities, indicating that female athletes may possess

altered motor control strategies that result in knee

positions in which an ACL injury may occur.10,13 However,

there is a scarcity of information on the landing control

strategies in young pre-adolescent female sport

participants. Perhaps the reduced injury rate in this

population is a result of using landing strategies that are

“safer” than older female participants. Conversely, these

older female athletes may be utilizing landing strategies

that become injurious when changes in the skeletal

architecture are influenced by the onset of

menstruation.10,13,14

The menstrual cycle may be one of the leading

explanations for differences between males and females with

regards to lower extremity injuries.9,14,15 The basis for this

cycle is the endocrine coordination between the

hypothalamus, the pituitary gland, and the ovaries. The

coordination among these centers occurs through the

9

circulatory system via hormones. During the course of this

cycle, the absolute levels of estrogen, progesterone, and

relaxin (thought to drastically diminish collagen tension),

and the ratio of these hormone concentrations, change over

the mean cycle duration of 28 days.9,14 This could entail a

difference in joint stability due to an increase in

ligamentous laxity.

In summary, biomechanical interaction of the entire

lower extremity, as well as the core, may be important

contributors to the risk of knee injury. Understanding the

interaction between trunk motion and those of the lower

limb joints during functional activity may provide further

insight into the resultant injury mechanism.16 For instance,

trunk accelerations at contact will have a significant

impact on coupled hip and knee flexion, and more than

likely, on alternative planar loading at the knee joint.

Thus, the lumbo-pelvic-hip complex, as well as the knee

stabilizers, must have efficient functioning to withstand

these multi-planar impacts.16 The athletic trainer is

responsible for recognizing muscular imbalances to ensure

optimal performance and possible prevention of injuries

altogether.

The purpose of this study was to evaluate the

relationship between a female jumping athlete’s tri-planar

10

active hip range of motion, and static, dynamic, and

functional postural control of the knee and ankle. The

following research questions were addressed:

(1) Does an increased Q-angle past the normal average value

(180 for females) coincide and negatively correlate with

tibial valgus and subtalar pronation in static standing

posture, as well as lead to the same observed dynamic and

functional postural discrepancies?

(2) Do discrepancies in hip active range of motion,

specifically decreased hip abduction, extension, and/or

external rotation, and increased hip adduction, flexion,

and/or internal rotation, result in tibial valgus and

subtalar pronation, as well as lead to the same observed

dynamic and functional postural discrepancies?

11

METHODS

The following sections will be addressed in the methods:

(1) Research Design, (2) Subjects, (3) Preliminary Research,

(4) Instrumentation, (5) Procedures, (6) Hypotheses, and

(7) Data Analysis.

Research Design

A descriptive correlational design was used for this

study. The independent variables were Q-angle reported in

degrees, presence of tibial valgus in standing posture,

presence of subtalar pronation in standing posture, and

active hip range of motion (AROM reported in degrees) in

all three planes.17,18 The dependent variables were measures

of core stability and neuromuscular efficiency as measured

by performance of the Overhead Squat according to the

National Academy of Sports Medicine (NASM)19, and functional

ability as measured by performance of a simulated jump

recovery. Standing tibial valgus and subtalar pronation

served as static measures, the Overhead Squat as a dynamic

measure, and jump recovery as a functional measure for

subjects’ postural control. The group used for testing was

comprised of volunteer female volleyball athletes from

California University of Pennsylvania, with and without a

12

history of lower extremity injuries. Results were limited

to those female athletes participating in collegiate

volleyball at the Division II level. The descriptive

design was useful in examining the relationship between hip

AROM and static, dynamic, and functional posture in the

female collegiate jumping athlete, which could potentially

serve as a diagnostic profile for possible injury.

Subjects

Ten (N = 10) female volunteers from the California

University of Pennsylvania’s Volleyball team completed this

study. The subjects were a mixture of uninjured and

chronically injured athletes; however, the athletes must

have been actively participating in spring training in

order to participate. Subjects were asked to volunteer

without any coercion from the coach. Data collection was

performed May 2005 (post-season). Each subject was tested

individually in one testing session. Informed consent

(Appendix C1) was obtained from each volunteer, and the

project was presented to the Institutional Review Board

(Appendix C2) prior to data collection.

13

Preliminary Research

The researcher collected results of the lower

extremity postural assessment (Q-angle measurements and

presence of tibial valgus and/or subtalar pronation), hip

flexibility assessment, and the performance of Overhead

Squat and jump recovery from three female test subjects.

This pilot work was performed to familiarize the researcher

with performance of the tests and procedures, and provide a

more accurate time frame for subjects’ participation. No

changes were made as a result of this preliminary

investigation.

Instrumentation

The following instruments were used to collect data

for the study: a demographic information form, scale, tape

measure, evaluation forms (documenting Q-angle

measurements, hip AROM, and results of static, dynamic, and

functional assessments), hip range of motion assessment,17

foot posture and tibiofemoral alignment observation,

universal goniometer, NASM Overhead Squat assessment,19 and

video camera.

14

General demographic information (Appendix C3)

documenting the age, recorded height and weight, history of

knee injury, menstrual patterns, and first day of the last

menstruation for each subject was recorded by the

researcher. The subjects’ weight was measured on a scale

(Detecto, Cardinal Scale Manufacturing Co., Webb City, MO),

and subjects’ height was measured with a tape measure

affixed to the wall at the appropriate height.

Static Postural and Flexibility Assessments

Subjects’ Q-angle was measured with a universal

goniometer and recorded in degrees by using the angle from

the anterior superior iliac spine (ASIS) through the

midpoint of the patella and to the tibial tuberosity.8 The

researcher then analyzed and compared the measurements with

normal values according to Starkey (>180 is considered

excessive for females).8 The goniometer is a protractor-like

instrument that measures range of motion of articulations

in degrees. Investigators have found good inter-tester

reliability (r = .91) and validity for the goniometer as an

instrument to efficiently measure joint angles.17

Flexibility of the hip was also measured with a

universal goniometer and recorded in degrees on the eval-

uation form (Appendix C4). All goniometric measurements

15

were taken actively (AROM) to assess the participants’

functional ranges of motion. These measurements were

recorded in degrees as differences from the normal values

documented by Kendall, et al, and Roach and Miles (Appendix

C5) to further validate postural dysfunctions.18,20 The

following ranges were analyzed: hip flexion (supine with

measuring knee flexed, other leg flat on table, pelvis

neutral), hip extension (prone with both knees extended),

hip abduction/ adduction (supine with both knees extended),

and hip internal/external rotation (seated with hips and

knees flexed at 900).17,21,22

Dysfunction in the tibiofemoral joint and subtalar

joint typically stems from hip ROM discrepancies.5 Lower-

crossed syndrome (anteriorly tilted pelvis with associated

increased lumbar lordosis), and pronation-distortion

syndrome (flattened arches with pronated feet) are common

postural deviations that may occur as a result of these ROM

discrepancies.5 Muscular imbalances found in these

deviations, such as tight hip flexors, adductors, erector

spinae, peroneals, and gastrocnemius muscles, and weakened

gluteus maximus and medius, abdominals, and anterior and

posterior tibialis muscles, are the source of faulty static

posture, and furthermore, faulty dynamic and functional

16

mechanics that may potentially lead to preventable

injuries.5

The subjects’ standing posture was then evaluated for

the static anomalies of tibial valgus and subtalar

pronation and compared with normal posture as dictated by

Starkey.8 A check was placed on the evaluation form in the

appropriate box to indicate presence of valgus or

pronation. The subjects were then requested to perform the

NASM Overhead Squat test19 with minimal instruction and the

jump recovery test.

Dynamic and Functional Assessments

The Overhead Squat assessment was observed closely for

dynamic compensations, specifically at the feet/ankles

(pronation, externally rotated feet), knees (alignment of

knee-to-toe), and lumbo-pelvic-hip complex (weight

shifting). Score sheets from the NASM manual (Appendix

C6)19 were used to rate the subjects’ performance based on

these observations, and compared to static/postural

flexibility assessments. Reliability and validity of the

NASM Overhead Squat assessment is still undergoing review

and analysis. The assessment is currently used as a

comparative tool. A check was placed on the evaluation

form in the appropriate box to indicate presence of valgus

17

or pronation. Performance was video-taped by a graduate

athletic training student for optimal analysis at a later

time.

To efficiently assess the athletes’ functional jump

recovery, a vertical jump test was administered employing

the VertecTM (Questtek Corp, Northridge, CA), a device with

colored plastic swivel vanes that displace as the athlete

jumps and hits them at their maximum height. The VertecTM

measures vertical jump heights from 6- to 12ft, and each

vane is ½ inch apart. The reliability of the VertecTM

vertical jump test has been reported to be quite high (r =

.93).23 According to the manufacturer’s suggested

measurement instructions, the bottom vane of the VertecTM

was placed at the athlete’s standing reach height (single

arm).24 The subject was then asked to jump as high as

possible and displace the vanes at the maximum height. The

athlete was allowed to squat as low as desired, but no

initial step is permitted, and the athlete must land on

both legs simultaneously. The jump height was then

measured in inches by counting the number of vanes

displaced between the athlete’s standing reach height and

jumping reach height and dividing by two (each is ½ inch

apart). This measure was then converted into centimeters.

18

To adequately examine the athletes’ mechanics upon

landing, the athlete was asked to perform three trials with

maximal effort and displace the vane at the maximal height.

One warm-up jump and three actual jumps for maximum height

were permitted for each individual with 30 second rest

intervals between each jump.24,25 Again, the jump recovery

was video-taped for proper analysis and resultant

functional compensations of tibial valgus and subtalar

pronation were thoroughly checked and recorded on the

evaluation form (Appendix C4). If the position of the

knees upon landing was viewed to be fully extended, a “/”

was also recorded in the appropriate column of the

evaluation form.

Procedures

Institutional Review Board (IRB) approval, subject

selection, and preliminary research were done prior to data

collection. A graduate athletic training student’s

assistance was also sought, and he was informed of the

intent and correct procedures for the study. The

researcher then approached the Volleyball team as a group,

explained the requirements and benefits of participation in

the study, and asked for volunteers. Thereafter, the

19

subjects were asked to complete the consent form and were

assigned a subject number with which to preserve subject

confidentiality.

The subjects’ general demographic information was

requested from the subject and documented by the

researcher. The researcher then obtained the athletes’

weight on a scale. The subjects were then advised to warm-

up on the Life FitnessTM 9500 HR stationary bicycle for five

minutes (level 5, approximately 90 RPM, seat height set to

point at which extended knee has approximately 50 of

flexion) to promote tissue warming25 and to prepare for

flexibility testing, performance of the Overhead Squat, and

simulated jump recovery. Next, the subject was asked to

remove their shoes and instructed to lie supine on the

table to allow for their Q-angle to be measured and

recorded on the evaluation form. The goniometer axis was

placed in the center of the patella, with the stationary

arm aligned with the ASIS and movement arm aligned with the

tibial tuberosity.

Each participant’s hip AROM was then measured with a

goniometer and was recorded in degrees on the evaluation

form. The subject was positioned accordingly and asked to

actively move her leg into the desired range to be measured

while the researcher palpated the corresponding anterior

20

superior iliac spine (ASIS) to ensure that neutral pelvis

was sustained. A trial movement was permitted to determine

if the motion can occur pain-free. The second AROM was

measured and recorded when the subject could no longer move

within the desired proper position of neutral pelvis.

Hip flexion was measured with the subject lying supine with

measuring knee flexed, other leg flat on table, pelvis

neutral; and hip extension was measured with the subject

lying prone with both knees extended. The goniometer’s

stationary arm was in line with the trunk, axis at greater

trochanter, and movement arm in line with the longitudinal

axis of the femur for both the flexion and extension

measurements. Hip abduction and adduction was measured

with the subject lying supine with both knees extended.

The goniometer’s stationary arm was positioned horizontally

at ASIS level, axis at ipsilateral ASIS, and movement arm

in line with the longitudinal axis of the femur. Hip

internal- and external rotation was measured with the

subject seated with knees flexed at 900.17,21 The

goniometer’s stationary arm was positioned perpendicular to

the floor, axis at the patella, and movement arm in line

with the longitudinal axis of the tibia.17,21

The subjects’ standing posture was then evaluated for

static anomalies of tibial valgus and subtalar pronation

21

and documented on the evaluation forms. To efficiently

produce the subjects’ normal stance, they were asked to

walk forward four steps and stand comfortably while the

observed postures were recorded as tibial valgus and/or

subtalar pronation.

Next, the subjects were asked to perform the Overhead

Squat19 and simulated jump recovery to observe for dynamic

and/or functional compensations, respectively. For the

Overhead Squat, the researcher minimally instructed the

athlete by saying, “Perform your normal squat with arms

overhead,” and then recorded the postural deviations, if

any. A properly-executed squat is performed when all of

the following criteria are met: feet maintained in a

neutral position (no pronation or “toeing out”), knees

maintained in a neutral position (no valgus or varus

motion), weight distributed evenly throughout the motion,

core stabilization performed to prevent abdominal

protrusion and/or low back rounding/protrusion, scapulo-

thoracic stabilization to prevent scapular protraction, and

head maintained in a neutral position (not forward).19 The

athlete was permitted one trial squat and the second squat

was analyzed, recorded, and video-taped from the sagittal

view.

22

For the jump recovery, the athlete was instructed to

reach as high as possible while merely standing at the base

of the Vertec. The lowest vane was then positioned at this

maximum standing reach height. The athlete was instructed

to jump as high as possible, squatting as much as necessary

and without taking any step, to displace the vanes at their

maximum height reached with an extended arm, and land on

both legs simultaneously. The athlete was then permitted

one practice jump. Three actual jumps were then performed

at maximal effort, and the athlete was asked to displace

the vanes at the maximal height reached. Jump heights were

recorded in inches and later converted to centimeters.

Thirty seconds recovery time was permitted to the

participants between each jump. Resultant bilateral tibial

valgus and/or subtalar pronation, in addition to fully

extended knees during the landing phase of the assessment

were documented on the evaluation forms. Both the Overhead

Squat and the jump recovery were video-taped from a sitting

position, in the sagittal plane, approximately 10ft away

for later analysis.

23

Hypotheses

The following hypotheses were considered:

1) An increased Q-angle past the normal average value

will coincide and negatively correlate with tibial valgus

and subtalar pronation in static standing posture, and will

lead to the same observed dynamic and functional postural

discrepancies (tibial valgus and subtalar pronation, as

measured by the Overhead Squat and jump recovery).

2) Discrepancies in hip active range of motion,

specifically decreased hip abduction, extension, and/or

external rotation, and increased hip adduction, flexion,

and/or internal rotation past the normal values, will

result in tibial valgus and subtalar pronation, and will

lead to the same observed dynamic and functional postural

discrepancies (tibial valgus and subtalar pronation, as

measured by the Overhead Squat and jump recovery).

Data Analysis

Data from the evaluation form was descriptively

analyzed to determine the relationship between hip AROM,

and static, dynamic, and functional postural discrepancies

24

whereby trends in static standing posture should produce

similar results in dynamic and functional assessments, and

result in a potential profile for the jumping female

athlete. A Pearson Product Moment Correlation was also

used to determine the relationship between Q-angle (in

degrees), tibial valgus, and subtalar pronation (“present”

= 1, “not present” = 2). Statistical analysis using SPSS

version 12.0 (SPSS Inc., Chicago, IL) with an alpha level

set a priori at < 0.05 was used for the correlation.

25

RESULTS

The following section encompasses the information

obtained through the collection and analysis of the

demographic data, Q-angle and active hip range of motion

measurements, standing posture, and performance of the

Overhead Squat and jump recovery. The results have been

divided into the subsequent sections: (1) Demographic Data,

(2) Hypothesis Testing, and (3) Additional Findings.

Demographic Data

Ten female Collegiate Division II Volleyball players

completed the study. The average age of the sample was 20

years (SD = 0.88yrs), the average height was recorded at

174.24cm (SD = 5.61cm), and the average weight was recorded

at 74.57kg (SD = 11.07kg).

Hypothesis Testing

The following hypotheses were investigated for this

study:

Hypothesis 1: An increased Q-angle past the normal average

value will coincide and negatively correlate with tibial

26

valgus and subtalar pronation in static standing posture,

and will lead to the same observed dynamic and functional

postural discrepancies (tibial valgus and subtalar

pronation, as measured by the Overhead Squat and jump

recovery).

Conclusion: As illustrated in Table 1, one of the ten

athletes (10%), Subject 07, exhibited a Q-angle greater

than the normal value of 180. This athlete, furthermore,

was the only subject to exhibit the traits of tibial valgus

and subtalar pronation during all of the assessments of

standing posture, Overhead Squat, and jump recovery in

support of the hypothesis.

Subject 05 had a Q-angle of only 90 (half of the

average measurement), and still presented with tibial

valgus and subtalar pronation in all assessments with the

exception of standing posture. Subject 10, on the other

hand, with the smallest Q-angle of 50, presented tibial

valgus in her standing posture, as well as jump recovery,

but did not exhibit the characteristic in the Overhead

Squat. No other discrepancies were reported.

A Pearson correlation coefficient was calculated to

determine the relationship between standing posture and

performance of the Overhead Squat and jump recovery. A

27

perfect positive correlation was found when comparing the

presence of subtalar pronation during standing posture and

the Overhead Squat (r(9) = 1.00, P = 0.01), indicating a

perfect linear relationship between the two variables.

Subjects with subtalar pronation in standard standing

posture will exhibit subtalar pronation during the

performance of the Overhead Squat. No other correlations

were significant.

28

Table 1. Q-angle Compared to Standing Posture, Overhead Squat, and Jump Recovery

Posture OH Squat Jump Recov

Subj# Q-angle

Valgus Prona tion

Valgus Prona tion

Valgus Prona tion

1. X2. X01 -7

X X

3. X1. X X2. X X02 -6 X 3. X X1. X X2. 03 -11 3. X X1. X 2. X 04 -6 X 3. X 1. 2. X X05 -9 X X X 3. 1. X X2. X X06 -4 X 3. X X1. X X2. X X*07 +2 X X X X 3. X X1. X X2. X X08 -6 3. X X1. X X2. X X09 -5 X X 3. X X1. X X2. X X10 -13 X

3. ____________________________________________ An X indicates presence of the trait during the assessment. Q-angle measurements are noted as deviations from the average value of 180. *Subject 07 exhibited a Q-angle greater than this value, and tibial valgus and pronation was noted throughout all of her assessments.

29

Hypothesis 2: Discrepancies in hip active range of motion,

specifically decreased hip abduction, extension, and/or

external rotation, and increased hip adduction, flexion,

and/or internal rotation past the normal values, will

result in tibial valgus and subtalar pronation, and will

lead to the same observed dynamic and functional postural

discrepancies (tibial valgus and subtalar pronation, as

measured by the Overhead Squat and jump recovery).

Conclusion: As illustrated in Table 2, none of the subjects

exhibited all of the anticipated deviations in active hip

ROM simultaneously, namely decreased abduction, extension,

and external rotation, and increased adduction, flexion,

and internal rotation. Therefore, Hypothesis 2 was not

supported as the hip ROM measurements could not be

correlated with the subjects’ standing posture nor

performance of the Overhead Squat or jump recovery.

30

Table 2. Active Hip ROM Compared to Standing Posture, Overhead Squat, and JumpRecovery

Posture OH Squat Jump Recov

Sub# Flex Ext Abd Add IR ER Valg Pron Valg Pron Valg Pron1. X2. X*01 -3 -1 +4 +24 +3 -1 X X3. X1. X X2. X X02 -32 -8 0 +11 -4 -7 X3. X X1. X X2.*†03 -20 -1 -8 +9 +6 -13. X X1. X2. X04 -11 -5 -13 +4 -1 +21 X3. X1.2. X X*05 -10 -3 +1 +5 +2 +1 X X X3.1. X X2. X X†06 -7 -10 -12 +16 -1 -2 X3. X X1. X X2. X X07 -8 -10 -5 +5 -3 0 X X X X3. X X

31

Sub# Flex Ext Abd Add IR ER Valg Pron Valg Pron Valg Pron1. X X2. X X†08 -16 -13 -2 +6 -1 -53. X X1. X X2. X X*†09 -18 -12 -10 +13 +5 -6 X X3. X X1. X X2. X X10 -41 -17 +1 +8 -11 -16 X3.

_______________________________________________________________Flex indicates hip flexion supine with knee bent and neutral pelvis (Avg. 1220)Ext indicates hip extension prone with knee extended (Avg. 220)Abd indicates hip abduction supine (Avg. 440)Add indicates hip adduction supine (Avg. 100)IR indicates hip internal rotation seated with knee bent to 900 (Avg. 330)ER indicates hip external rotation seated with knee bent to 900 (Avg. 340)Valg indicates tibial valgusPron indicates subtalar pronation

None of the subjects exhibited the proposed patterns of hip range of motion: ↓ abd,ext, and ER, ↑ add, flex, and IR. Therefore, the hip ROM measurements cannot becorrelated with the subjects’ standing posture, performance of the Overhead Squat,or jump recovery. Hypothesis 2 was not supported.*Subjects 01, 03, 05, & 09, showed increased hip IR and add, while †Subjects 03, 06,08, & 09 showed decreased hip ER and abd.Subjects 03 and 09 exhibited all assumptions but increased hip flexion.

32

Additional Findings

Following the testing of the hypotheses, the data was

analyzed for any further findings. Upon analysis of Table

3, all ten of the subjects (100%) exhibited tibial valgus

and/or subtalar pronation during jump recovery. Only one

of the ten (10%), Subject 01, did not demonstrate tibial

valgus while pronating, and only one of the ten (10%),

Subject 04, did not demonstrate subtalar pronation while

allowing tibial valgus. The only occurrences when neither

of these characteristics was noted was when the subject

recovered with knees fully extended rather than allowing

the knees to flex to absorb the impact. However, only two

of the seven subjects (28.6%) who had anecdotally reported

previous injury recovered from jumping with this supposed

problematic position of knees fully extended. Subjects 03,

05, and 10 support this conclusion, since they present with

tibial valgus and subtalar pronation during one or two of

the trials, and with knees fully extended during the other

trial(s). Conversely, Subject 07’s third trial presents

tibial valgus, subtalar pronation, and knee extension

simultaneously.

Of the 10 subjects, seven women (70%) had anecdotally

reported previous history of knee injury. Two of these

33

seven (28.6%, Subjects 04 and 09), injured athletes had

sustained an ACL tear, four (57.1%, Subjects 02, 06, 08,

and 10), had patellar tendonitis, and one (14.3%, Subject

07), had a history of subluxing patella. One of the ACL-

injured women sustained trauma in 1999, and the other in

July of 2004. Three of the four (75%) athletes with

patellar tendonitis had reported a micro-trauma within the

past five months. The athlete with a history of subluxing

patella has not had an occurrence since 1996. None of the

subjects with tendonitis or subluxing patella required

surgery, however, both of the ACL victims necessitated

surgical repair.

All seven subjects (100%) who reported a history of

knee injuries produced tibial valgus, if not both traits,

during jump recovery. Subject 04, with a previous medical

history of the female athlete triad (ACL, MCL, and medial

meniscus), was the only subject to possess only tibial

valgus, not both characteristics. On the other hand,

Subjects 01, 03, and 05, have never sustained knee

pathology, but presented at least one of the traits during

jump recovery. Subject 05 demonstrated both

characteristics during the Overhead Squat.

34

Table 3. Knee Pathology Compared to Standing Posture, Overhead Squat, and Jump Recovery

Posture OH Squat Jump Recovery

Subj#

Knee Injury

Valg Pron ation

Valg Pron ation

Valg Pron ation

Knee Ext

1. X2. X01

X X

3. X1. X X2. X X†02 X X 3. X X1. X X2. *X 03 3. X X1. X 2. X †04 X X 3. X 1. *X 2. X X05 X X X 3. *X 1. X X2. X X†06 X X 3. X X1. X X2. X X†07 X X X X X 3. X X *X1. X X2. X X†08 X 3. X X1. X X2. X X†09 X X X 3. X X1. X X2. X X†10 X X

3. *X____________________________________________ Knee ext indicates that subject landed with knees fully extended. An X indicates presence of the trait. All subjects presented with one of the traits, if not both, during jump recovery. *The only occurrences when neither of these characteristics was noted was when the athlete recovered with knees fully extended. †All seven subjects who reported a history of knee injuries produced tibial valgus, if not both traits, during jump recovery.

35

With regards to menstruation, of the three women who

lacked a normal menstrual cycle, two (66.67%) had never

sustained a knee injury, and of the seven remaining women

who menstruate regularly, six (85.71%) have sustained a

knee injury. This leads to the conclusion that hormonal

changes may effect the physiological factors that affect

knee stability; however, more research would need to be

collected to correlate the menstrual cycle with the time of

injury.

As additional information, the following vertical jump

heights were also recorded in Table 4. No other measures

strongly nor significantly correlate with jump height.

36

Table 4. Vertical Jump Heights for 10 Division II Female Volleyball Athletes

Subj# Jump Height (cm)1. 45.72 2. 52.07 01 3. 52.07 1. 41.91 2. 43.18 02 3. 43.18 1. 36.83 2. 43.18 03 3. 39.37 1. 40.64 2. 43.18 04 3. 43.18 1. 33.02 2. 39.37 05 3. 39.37 1. 35.56 2. 35.56 06 3. 36.83 1. 48.26 2. 49.53 07 3. 49.53 1. 49.53 2. 49.53 08 3. 53.34 1. 31.75 2. 34.29 09 3. 39.37 1. 43.18 2. 44.45 10 3. 46.99

____________________________________________ Additional information showing jump heights of all the participating athletes X = 42.80cm, SD = 5.82cm

37

DISCUSSION

To discuss the findings of this study, the following

sections are presented: (1) Discussion of Results, (2)

Conclusions, and (3) Recommendations.

Discussion of Results

The primary purpose of this study was to investigate

the relationship between standing posture, active hip range

of motion, and postural control in female collegiate

Volleyball athletes. With the increased prevalence of knee

injuries in female athletics, the athletic trainer is faced

with many concerns regarding his/her athletes’ safety and

well-being, especially those working with repetitive

jumping athletes.

Lack of postural control, stemming from core and

lumbo-pelvic hip complex weaknesses, is a suggested cause

of knee injury.3,6 With improper muscle recruitment patterns

in the hip, and possibly even the entire lower extremity,

come muscular imbalances and compensatory movements.

Faulty posture has been noted as a factor in causing these

imbalances.3-5,19 Discrepancies in the hip lead to

discrepancies further down the kinetic chain, such as

38

increased Q-angle, tibial valgus, and subtalar pronation,

posing a lot of stress on the soft tissues of the

vulnerable knee.4,5,12,19

The Overhead Squat and the jump recovery assessments

can be useful tools when evaluating athletes’ functional

movement and neuromuscular control.19,23 The specialist who

is conducting the assessment can appropriately analyze the

athletes’ capabilities of creating force, stabilizing

against force, and reducing the impact of force, which can

be compared to their performance in actual sport. Again,

without a stable core, these impacts may be transferred to

weaker components of the body, like muscles and joints.

According to Lathinghouse and Trimble, Q-angle decreases

with an isometric quadriceps contraction, and the magnitude

of this decrease is dependent upon the magnitude of the Q-

angle at rest.28 An excessive Q-angle may predispose women

to greater lateral displacement of the patella during

rigorous activities and sports in which the quadriceps

muscle is stressed.28 In support of Guerra, an increased Q-

angle, according to this study, does tend to create more

valgus at the tibiofemoral joint; however, it is not the

only reason tibial valgus occurs.26 The only athlete to have

a Q-angle past the normal average was the only athlete to

also possess tibial valgus and subtalar pronation

39

throughout all of the assessments. However, many of the

athletes presented with tibial valgus in the assessments

even without a Q-angle greater than the average of 180.

This information suggests that the incorrect mechanics

likely happen due to improper education on jumping

correctly, compensatory motions possibly resultant from

injury, and lack of postural control of the hip and knee

musculature.7,10,12

Typically, when characteristics such as tibial valgus

and subtalar pronation are observed in standard posture,

one could assume they would be distinguished during

movement. If an athlete does not have the correct muscular

recruitment to stand in an ideal posture, then why would

they not display these patterns in a functional activity?

Chances are, if the characteristics noted during standing

posture are not also noted during functional activity,

these anomalies are structural more so than functional (ie,

an increased Q-angle).3,4,13 Conversely, only subtalar

pronation in standard posture correlated with subtalar

pronation during the Overhead Squat. This does not

specifically support nor refute Lephart’s reasoning that

postural discrepancies of standing posture will be

replicated while in motion.4,13 This could mean that athletes

are finding other ways to control for the unwanted tibial

40

valgus, for example, by limiting hip and knee flexion as

exhibited in the study. According to the data, when an

athlete landed with knees fully extended, and therefore

hips minimally flexed, they did not exhibit the tibial

valgus that may have been presented in the postural

assessment and Overhead Squat. No other correlations were

made between the static measures and the dynamic and

functional measures.

As with Q-angle, active hip range of motion is an

important variable when considering an athletes’ mechanics.

Suitable length-tension relationships are vital when

performing dynamic and functional movements.18,22 If one

muscle or muscle group is too tight, the body will

compensate and potentially cause injury. The same happens

when a muscle or muscle group does not produce the correct

amount of tension. Typically, certain patterns may be

witnessed; if one muscle group is shortened, other muscle

groups may shorten also, and opposing muscle groups may be

lengthened and become less-productive to adjust to this

tightness or over-productivity.18,19,22

In this case, probable characteristics for Volleyball

athletes’ active hip range of motion that may cause them to

present with tibial valgus and subtalar pronation were

considered. Specifically, the following deviations were

41

expected: weak gluteals and external rotators resulting in

decreased hip abduction, extension, and external rotation,

and tight adductors and hip flexors resulting in increased

adduction, flexion, and internal rotation. However, no

subjects followed this pattern precisely. On the other

hand, two of the subjects exhibited all of the desired AROM

relationships except for increased hip flexion. Perhaps

hip flexion is not a significant constituent of this

pattern. While jumping, some athletes may reduce the

amount of hip flexion, and thus knee flexion, to control

the amount of tibial valgus being permitted. This could

also possibly be due to the fact that neutral pelvis was

maintained for the flexion measurements, as well as the

rest of the measurements, but could not be accounted for

during the functional movements. Consequently, some

athletes may subconsciously attempt to correct the faulty

mechanics of the lower extremity by wrongly adjusting the

pelvis from a neutral position. However, the researcher

did not observe for nor document pelvic position during the

Overhead Squat or jump recovery. Roach and Miles did not

report that pelvic position was standardized when

performing their study on the effect of age on hip and knee

AROM.18 Neutral pelvis could be assumed in this case; but in

the event that it was not maintained, it may have skewed

42

the interpretation of the AROM data because additional

motion was permitted in the pelvis when Roach and Miles

performed their AROM assessments.

In support of Hass’s and Ashley’s findings, all ten of

the subjects exhibited one, if not both, of the traits

(tibial valgus and subtalar pronation) during the jump

recovery.10,23 One interesting finding was that the only time

that they did not have signs of the anomalies was when they

landed with knees fully extended. In addition, all seven

of the subjects who had reported a history of knee injury

coincidently demonstrated tibial valgus, if not both traits

during the jump recovery, indicating that this uncontrolled

motion may be a culprit for pathology.

In addition to improper mechanics posing additional

stress on stabilizing structures during functional

activity, hormonal changes have been found to have an

effect on the physiological factors that affect knee

stability, according to Wojtys.9 In support of her

conclusions, two of the three (66.7%) athletes with

amenorrhea had never sustained a knee injury, while six of

the seven (85.7%) regularly menstruating participants had.

These findings seem to support the belief that hormonal

productions present in menstruating women could potentially

weaken the static supports of certain articulations.

43

Conclusions

Q-angle was directly correlated with the presence of

tibial valgus and subtalar pronation during standing

posture, dynamic activity, and functional activity. As

well, subtalar pronation in standing posture was directly

correlated with pronation while squatting. However,

patterns among hip AROM were not as conclusive. Perhaps

this could indicate that a functionally sound performance

of the Overhead Squat and jump recovery is not dependant

upon the subjects’ hip AROM measurements. Otherwise,

subjects’ may subconsciously adjust pelvic position to

compensate for abnormal length-tension relationships

occurring at the hip. Furthermore, all ten of the subjects

exhibited tibial valgus and/or subtalar pronation during

jump recovery, suggesting that females have either not

received proper instruction on correct landing biomechanics

or that they are not neuromuscularly efficient enough to

prevent these faulty biomechanics from occurring.

Additionally, females who menstruate regularly may be more

susceptible to injury due to the physiological effect of

hormones on soft tissues’ stability.

44

Recommendations

The researcher makes the subsequent recommendations

for further study related to this topic. Collection of

data from volleyball athletes of other divisions/schools

should be done to limit bias. The results discussed here

are only applicable to athletes of the California

University of Pennsylvania’s Division II Female Volleyball

team, and are intended to represent comparable athletes.

Q-angle should be also measured in standing, in addition

to supine to see if there is any difference noted. Q-angle

in this position takes into account contraction of the

quadriceps to maintain the standing posture.27,28 According

to Lathinghouse and Trimble, Q-angle decreases with an

isometric quadriceps contraction, and the magnitude of this

decrease is dependent upon the magnitude of the Q-angle at

rest.28 An excessive Q-angle may predispose women to greater

lateral displacement of the patella during rigorous

activities and sports in which the quadriceps muscle is

stressed.28

Pelvic position during squatting and landing should be

analyzed to observe for anterior- or posterior-tiling of

the pelvis to compensate for abnormal length-tension

relationships occurring at the hip. This may further

45

explain why the hip AROM measurements did not have any

significant correlations with the Overhead Squat or jump

recovery assessments.

The menstrual cycle should be compared with time of

injury and time of testing. Hormonal changes have been

linked to ligamentous laxity, and furthermore, to the

incidence of knee injury.14,15 It would be interesting to

personally discover precisely when in the menstrual cycle

women are most vulnerable.

46

REFERENCES

1. Prentice WE. Rehabilitation Techniques for Sports Medicine and Athletic Training. 4th ed. New York, NY: McGraw-Hill Companies Inc., 2004, Ch 10:201-223.

2. Akuthota V, Nadler SF. Core strengthening. Arch Phys Med Rehabil. 2004;85(3 Suppl 1):S86-92.

3. Massie DL, Haddox A. Influence of lower extremity biomechanics and muscle imbalances on the lumbar spine. JOrthop Sports Phys Ther. 1999;4:46.

4. Tiberio D. Pathomechanics of structural foot deformities.

Phys Ther. 1998;68:1840. 5. Krivickas LS. Anatomical factors associated with overuse

sports injuries. Sports Med. 1997;24:132. 6. Mitchell B, Colson E. Lumbopelvic mechanics. British

J Sports Med. 2003;37(3):279-280.

7. Pollard CD, Davis IM, Hamill J. Influence of gender on hip and knee mechanics during a randomly cued cutting

maneuver. Clin Biomech. 2004;19(10):1022-31. 8. Starkey C, Ryan J. Evaluation of Orthopedic and Athletic Injuries. 2nd ed. Philadelphia, PA: F.A. Davis Company, 2002, 71-79, 120-121, 205-207, 244- 268, 285-293, 303-318. 9. Wojtys EM, Huston LJ, Lindenfeld TN, Hewett TE, Greenfield ML. Association between the menstrual cycle and anterior cruciate ligament injuries in female athletes. Am J of Sports Med. 1998;26:614. 10. Hass CJ, Schick EA, Tillman MD, Chow JW, Brunt D, Cauraugh JH. Knee biomechanics during landings: comparison of pre- and post-pubescent females. Med. Sci. Sports Exerc. 2005;37(1):100-107. 11. Harmon KG, Ireland ML. Gender differences in non- contact anterior cruciate ligament injuries. Clin. Sports Med. 2000;19:287-302.

47

12. Huston LJ, Greenfield ML, Wojtys EM. Anterior cruciate ligament injuries in the female athlete: potential risk factors. Clin. Orthop. 2000;50-63. 13. Lephart SM, Ferris CM, Riemann BL, Myers JB, Fu FH. Gender differences in strength and lower extremity kinematics during landing. Clin. Orthop. 2002;162-169.

14. Heitz NA, Eisenman PA. Hormonal changes throughout the menstrual cycle and increased anterior cruciate ligament laxity in females. J Athletic Training.

1999;34:144.

15. Cheah SH, Ng KH, Johgalingam VT, Ragavan M. The effects of oestradiol and relaxin on extensibility and collagen organization of the pregnant rat cervix. J Endocrinol.

1995;146:331–337. 16. McLean SG, Lipfert SW, Van Den Bogert AJ. Effect of

gender and defensive opponent on the biomechanics of sidestep cutting. Med Sci Sports Exerc. 2004;36(6): 1008-1016. 17. Norkin CC, White DJ. Measurement of Joint Motion: A

Guide to Goniometry. 3rd ed. Philadelphia,PA: F.A. Davis Co,2003, 176-186.

18. Roach KE, Miles TP. Normal hip and knee active range of motion: the relationship to age. Phys Ther. 1991;71:656 19. Clark MA, Russell AM. NASM OPT: Optimum Performance

Training for the Performance Enhancement Specialist. 1st ed. Calabasas, CA: National Academy of Sports Medicine,

2001, 93-114, 187-241. 20. Kendall FP, McCreary EK, Provance PG. Muscles: Testing and Function. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 1993, 32. 21. Berryman-Reese N, Bandy WD. Joint Range of Motion and Muscle Length Testing. Philadelphia, PA: W.B. Saunders Co., 2002, 49-50. 22. Simoneau GG, Hoenig KJ, Lepley JE, Papanek PE. Influence of hip position and gender on active hip internal and external rotation. J Orthop Sports Phys Ther. 2001;28:158-164.

48

23. Ashley CD, Weiss LW. Vertical jump performance and

selected physiological characteristics of women. Journal of Strength and Conditioning Research. 1994;8:5-11. 24. MF Athletic Company. 2004. Available at

http://www.performbetter.com/detail.aspx_Q_ID_E_4133_A_CategoryID_E_194.

25. Power K, Behm D, Cahill F, Carroll M, Young W. An acute bout of static stretching: effects on force and jumping performance. Med Sci Sports Exerc. 2004;36: 1389-1396. 26. Guerra JP, Arnold MJ, Gajdosik RL. Q-angle: effects of isometric quadriceps contraction and body position. J

Orthop Sports Phys Ther. 2002;19:200. 27. Di Brezzo R, Fort LI, Hall K. Q angle: the relationship with selected dynamic performance variables in women. Clinical Kinesiology. 1996;50(3):66-70. 28. Lathinghouse LH, Trimble MH. Effects of isometric quadriceps activation on the Q-angle in women before and after quadriceps exercise. J Orthop Sports Phys Ther. 2000;30(4):211-216.

49

APPENDIX A

Review of the Literature

50

Introduction

The prevalence of knee injuries is a serious problem

for athletic trainers, particularly those working with

female athletes. Knee injuries have been traced back to

defects such as: lack of core strength, lower-crossed

syndrome, increased Q-angle, genu valgum, pes

planus/pronation, as well as imbalances in flexibility and

functional range of motion.1,2 While core stability and

postural control is a necessary component to every

athlete’s training regimen, its beneficial effects on power

and function have often been ignored.2

The kinetic chain works synergistically to produce

force concentrically, reduce force eccentrically, and

dynamically stabilize isometrically against abnormal

forces. When functionally efficient, each component of

the core disperses weight, absorbs force, and transfers

ground reaction forces.2 Core strength is also mandatory,

specifically in lower extremity dominant sports, to

provide proximal stability while in competition.2,3 If the

distal musculature is strong but the core is weak, there

will not be enough force created to produce or control

efficient movements. A weak core is a typical cause of

inefficient movements that could lead to injury.2,3

51

Neuromuscular efficiency is promoted by the

appropriate combination of postural alignment (static and

dynamic) and stability, which allows the body to absorb

momentum at the correct joint, in the correct plane, and at

the correct time.2 As this efficiency decreases, so does the

body’s ability to react accordingly to abnormal forces.

This could potentially lead to compensation and

substitution patterns, as well as poor posture during

functional activities.4 Pathology of structures within the

neuromusculoskeletal system can result from skeletal

malalignment, which has been defined as either abnormal

joint alignment or deformity within a bone. Pathology can

also result from correlated or compensatory motions or

postures, which may accompany skeletal malalignment.5,6

Consequently, mechanical stress is placed on the static

(ligaments and bones) and dynamic (muscles and tendons)

tissues causing repetitive microtrauma, incorrect

mechanics, and injury.4 Sometimes this overloading of joints

and small muscles is due to the core not sufficiently

contributing to the effort.2 Therefore, stability and

movement are critically dependent on the coordination of

all the muscles surrounding the lumbo-pelvic hip complex.5

It is imperative to link common lower limb skeletal

52

malalignments to their correlated and compensatory motions

and postures.5,6

If more athletic trainers and coaches were aware of

their role in optimal performance, core stability, postural

control, and functional flexibility might be incorporated

more readily into every athlete’s conditioning program.

However, do we as athletic trainers know enough about these

matters to correct improper mechanics and potentially

prevent episodes like these from occurring?

This paper will review: (1) The Importance of Core

Stability, (2) Postural Deviations, (3) Functional Range of

Motion of the Lower Extremity, and (4) Knee Injuries Often

Sustained by Female Jumping Athletes.

Core Stability

Composition of the Core

The core is sometimes referred to as the lumbo-pelvic-

hip complex and is where the human body’s center of gravity

resides. All motion stems from this “core”, comprised of

29 muscles.2,7 To better comprehend what goes into core

training, it is imperative to have a good understanding of

these muscles that supply the entire kinetic chain with

neuromuscular control and efficiency. The core can be

53

thought of as a box with the abdominals in the front, the

paraspinals and gluteals in the back, the diaphragm as the

roof, and the hip musculature as the bottom. Combined,

these muscle groups create stabilization and force-couple

relationships that normal function is dependent upon.2,7

The lumbar muscles that contribute to core

stabilization are the transversospinalis group, erector

spinae, quadratus lumborum, and latissimus dorsi. The

abdominals consist of the rectus abdominis, external

oblique, internal oblique, and transversus abdominis.8 The

transversus abdominis is the most important abdominal

muscle because it is active during all trunk movements and

contracts before any other abdominal prior to the

initiation of any limb motion. The back and abdominal

muscles combined provide sagittal, frontal, and transverse

plane stabilization by controlling forces that are applied

to the body. The core-stabilizing hip muscles are

comprised of the iliacus, psoas, gluteus medius, gluteus

maximus, and hamstrings. Any disruption of these force-

couples can place the body in incorrect alignment and

predispose an athlete to postural imbalances, unnecessary

body aches, and potential injury.8

54

Importance of Core Strengthening

When normal length-tension relationships are

established, the body is provided with an environment to

allow optimal arthrokinematics during functional kinetic

chain movements. The kinetic chain works synergistically

to produce force concentrically, reduce force

eccentrically, and dynamically stabilize isometrically

against abnormal forces.2 When functionally efficient, each

component of the core disperses weight, absorbs force, and

transfers ground reaction forces. Core strength is also

mandatory, specifically in lower extremity sports, to

provide proximal stability while in competition. If the

extremity muscles are strong but the core is weak, there

will not be enough force created to produce efficient

movements. Again, a weak core is a typical cause of

inefficient movements that lead to injury.3

All athletes should incorporate core stability into

their conditioning to gain neuromuscular control, strength,

power, and muscular endurance of the lumbo-pelvic hip

complex. Neuromuscular efficiency is promoted by the

appropriate combination of postural alignment (static and

dynamic) and stability strength, which allows the body to

absorb momentum at the correct joint, in the correct plane,

and at the correct time. As this efficiency decreases, so

55

does the body’s ability to react accordingly to abnormal

forces. This could potentially lead to compensation and

substitution patterns, as well as poor posture during

functional activities.8 Consequently, mechanical stress is

placed on the static (ligaments and bones) and dynamic

(muscles and tendons) tissues causing repetitive

microtrauma, incorrect mechanics, and injury. Therefore,

stability and movement are critically dependent on the

coordination of all the muscles surrounding the lumbo-

pelvic hip complex.

Athletes with poor posture, asymmetries in stance and

gait, chronic or repetitive injuries, overuse or non-

traumatic injuries such as tendonitis, patellofemoral

dysfunction, or non-contact ACL injuries are good

candidates for application of core stabilization.

Sometimes this overloading of joints and small muscles is

due to the core not doing its share of the work.2 However,

before any implementation of strengthening can occur, an

assessment should be performed to provide a basis of the

athlete’s capabilities of core stability.

Assessment of Core Strength and Stability

Prior to the commencement of a core stabilization

program, a baseline assessment should be administered to

56

determine the athlete’s muscle imbalances, arthrokinematic

deficits, core strength, core neuromuscular control, core

muscle endurance, core power, and overall function of the

lower extremity kinetic chain. Since sports activity

involves movement in the sagittal, frontal, and transverse

planes, the core musculature should also be assessed and

trained in these planes. However, the athletic trainer

should try to rid the athlete of asymmetries and incorrect

mechanics before progressing to a more intense, functional

capacity.7,8

Testing for Core Stability. Core strength can be

tested by utilizing the straight leg lowering test. The

athlete is positioned supine with a blood pressure cuff

(inflated to 40 mmHg) placed under the lumbar spine at

approximately L4-L5. The athlete flexes the hips to 900

with the knees in full extension. The athlete is then

instructed to perform a “drawing-in” maneuver (pull

bellybutton to spine) to activate the transversus abdominis

and put the pelvis in a posterior pelvic tilt. The athlete

then lowers the legs toward the table while maintaining a

flat back. The examiner then records the hip angle with a

goniometer when any pressure in the cuff is released.8

Lower abdominal neuromuscular control can be assessed

similarly. The athlete is again placed supine, but with

57

hips and knees flexed to 900, and the blood pressure cuff is

positioned the same. The athlete performs the drawing-in

maneuver and lowers the legs until the cuff pressure

decreases. This test depicts the ability of the lower

abdominals to stabilize the lumbo-pelvic hip complex. At

the point where the pelvis anteriorly tilts, the hip

flexors work as the stabilizers. This causes anterior

shearing and compressive forces at L4-L5 and inhibits the

transversus abdominis, internal oblique, and multifidus, a

common cause of low-back pain. Performing activity with

inhibition of these key stabilizers causes muscle

imbalances and inefficient neuromuscular control in the

kinetic chain.8

Erector spinae performance can be assessed by having

the athlete lie prone with hands crossed behind the head.

The goniometer is adjusted with axis at the axilla,

adjustable arm parallel with the lateral side of the body,

and the stationary arm parallel to the table. The athlete

is instructed to extend at the lumbar spine to 300 and hold

for as long as possible while the athletic trainer times

the test.8

Testing for Core Power. Power of the core can be

tested by performing an overhead medicine ball throw. The

athlete is instructed to hold a 4kg medicine ball between

58

the legs as they squat down. They then jump as high as

possible while simultaneously throwing the ball backward

over their head. The distance is then measured from the

starting line to the point where the medicine ball stops.

This is actually an assessment of total body power

production with an emphasis on the core.7

Although adequate strength, power, muscular endurance,

and neuromuscular control are vital for core stabilization,

performing exercises incorrectly or that are too advanced

for the athlete’s capabilities could be detrimental.

Exercise of the core musculature is more than trunk

strengthening. Motor relearning of inhibited muscles may

be more important than strengthening in some patients, such

as patients with low-back pain. For core stability to be

accomplished, the athletic trainer must first correct this

asymmetrical and compensatory movements.2,7

Strengthening Strategies

A comprehensive core stabilization program should be

systematic, progressive, and functional. It should begin

in the most challenging environment an athlete can control.

The program should be manipulated regularly by altering any

of the following variables: plane of motion, range of

motion, loading parameters (Physioball, medicine ball,

59

bodyblade, weight vest, dumbbell, rubber tubing, etc.),

body position, amount of control, speed of execution,

amount of feedback, duration (sets, reps, tempo, time under

tension), and frequency.9 The following are key concepts for

proper exercise progression: slow to fast, simple to

complex, known to unknown, low force to high force, eyes

open to eyes closed, static to dynamic, correct execution

to increased reps/sets/intensity. The importance of

quality before quantity should be stressed. An athlete who

trains with poor technique and poor neuromuscular control

will develop poor motor patterns and poor stabilization.

The focus of the program must be on function.7,9

Static postural alignment is the first step in the

core stabilization program. The goal is to perform a

posterior pelvic tilt (PPT) to stabilize the pelvis before

adding any additional movements. Abdominal training

without proper pelvic stabilization increases intradiscal

pressure to dangerous levels, causing buckling of the

ligamentum flavum and narrowing of the intervertebral

foramen.9 Motor relearning can be obtained by performing

PPTs 5-10 repetitions every hour, which also reduces the

risk of neuromuscular overloading. Progress the athlete to

decreased foot pressure and reduced hand support to

maintain the position.9 Electromyographic (EMG) recordings

60

display higher abdominal activity, rectus abdominus and

obliques particularly, when a posterior pelvic-tilt was

performed, rather than a drawing-in maneuver (pulling belly

button towards back).10

A fundamental progression uses a single-knee-to-chest

exercise to facilitate the posterior pelvic tilt. The

athlete then lowers the leg to the floor with the knee

flexed at 450, maintaining alignment and contact with the

floor. This can be modified by extending the knee 5-100,

further by sliding the leg across the ground, and even

further by incorporating both knees-to-chest. These

exercises can also be performed on a foam roller to enhance

proprioceptive application.8

Bridging is an exercise that recruits the gluteus

maximus in addition to the lower abdominals. The athlete

must focus on lifting the belly button to the ceiling while

lifting the hips, pelvis, and lower lumbar spine as a unit.

The goal is hip extension to neutral through the hip and

neutral pelvis, with minimal assistance from the feet.

When this is accomplished, the athlete can progress to

single-leg bridging and/or bridging with feet resting on a

Physioball.7

Planks can also be administered. The athlete should

be instructed to support body prone on elbows with a

61

neutral pelvis. To incorporate the obliques, this exercise

can also be done laterally on a single elbow. Quadraped

position, with the athlete on all fours maintaining a

neutral pelvis, is a good exercise for the lumbar

extensors. Progress to extending alternate arms and legs

simultaneously (ie, right arm with left leg, left arm with

right leg), then advance to doing them on a Physioball.

Abdominal exercises that are typically performed on the

floor in the sagittal, frontal, and transverse planes can

also be carried out on the Physioball for a more difficult

routine.7 Execution of any functional activity on an

unstable surface could potentially be though of as “core

stabilizing” since the body must achieve neuromuscular

efficiency to perform the exercise.11

There is a vast assortment of equipment on the market

to directly strengthen the abdominals, such as the Abflex

machine, the AbRoller, the ABslide, the AB-Doer, the Nordic

Track Ab Works, and the Nautilus crunch machine, to name a

few. When surveying the results of EMG recordings,

professionals have suggested that these devices are most

effective if they not only mimic the mechanics of a

traditional crunch, but also provide external resistance to

increase the involvement of the musculature.12-14

62

Postural Deviations

Postural deviations, including muscular imbalances and

neuromuscular discrepancies, can disrupt a person’s

mechanics and possibly induce chronic pains and injury

while participating in sport.2 These imbalances and

functional adaptations need to be corrected to avoid

problematic situations for the athlete, as well as the

athletic trainer.

It is extremely common for an athlete to develop

tightness in their psoas muscle, the main hip flexor. A

tight psoas increases shear force and compressive force at

the L4-L5 junction. A tight psoas also causes reciprocal

inhibition of the gluteus maximus, multifidus, deep erector

spinae, internal oblique, and transversus abdominis. Lack

of lumbo-pelvic-hip complex stabilization prevents

appropriate movement sequencing and causes synergistic

dominance by the hamstrings and superficial erector spinae

during hip extension. This postural defect is commonly

referred to as lower-crossed syndrome and can potentially

lead to hip extensor mechanism dysfunction during

functional movement patterns.3,7 It also decreases the

ability of the gluteus maximus to decelerate femoral

internal rotation during heel-strike, which predisposes an

63

athlete with a knee ligament injury to abnormal forces and

repetitive microtrauma.2

During closed-kinetic chain movements, the gluteus

medius decelerates femoral adduction and internal rotation.

A weak gluteus medius increases frontal- and tansverse-

plane stresses at the patellofemoral and tibiofemoral

joints. It also leads to synergistic dominance of the

tensor fascia latae and the quadratus lumborum, a common

mechanism of iliotibial band and lumbar erector spinae

tightness. The athletic trainer must address the altered

hip muscle recruitment patterns or accept it as an injury-

adaptive strategy and thus accept the unknown long-term

consequences of this dysfunction.2,7 This entails a full

lower extremity range of motion assessment.

Overuse injuries, such as shin splints and

tendonitis, are often caused by abnormal biomechanics of

the lower extremity.5 While we as clinicians may feel more

informed about the effect that lower extremity biomechanics

can have on pathologies ranging from the foot to the hip,

it is also important to consider the effect of lower

extremity biomechanics on the pelvis and lumbar spine.

Abnormal biomechanics may cause compensatory movements that

lead to pathology of the pelvis and lumbar spine. Muscle

imbalances of the hip and/or lower extremity may contribute

64

to the onset of low back pain. Therefore, a comprehensive

evaluation for low back pain should include assessment of

the lower extremity for such abnormalities.8,9

Quadriceps angle, or Q-angle, is defined as the

relationship between the line of pull of the quadriceps and

the patella tendon.15 Women, typically possessing larger

pelvic widths, tend to have a greater Q-angle, thus,

possessing greater tibial valgus which could potentially

increase lateral tracking of the patella.15,16

Motion at the subtalar joint (STJ) consists of

pronation and supination. Pronation is an important

component to STJ range of motion because it provides shock

absorption and allows the foot to adapt to changes in

terrain. Supination is important because it allows the

foot to become a rigid lever for propulsion. During gait,

the STJ influences motion that occurs throughout the lower

kinetic chain by transmitting forces between the foot and

lower extremity.6

Abnormal biomechanics, whether due to acute injury,

structural deformity, or muscle imbalance, will cause the

body to compensate and alter its normal function. For

instance, an athlete with a tight gastrocnemius may lack

sufficient dorsiflexion for gait and will compensate by

toeing-out, or externally rotating the feet, while walking.

65

Often it is compensatory motions such as this that lead to

microtrauma and injury.5

While a certain amount of STJ pronation is needed for

normal gait, excessive or limited amounts of either motion

may contribute to abnormal mechanics which are generated

throughout the lower kinetic chain, pelvis, and lumbar

spine.6

Hyperpronation, or pronation that occurs beyond the

midstance period of the gait cycle, leads to a hypermobile

foot and is commonly identified as a contributor to

pathologies of the entire lower extremity, hip, and

sacroiliac joint.6 This is typically the result of tight

peroneals, gastrocnemius, soleus, and iliotibial band, and

lengthened/weak posterior tibialis, flexor digitorum

longus, flexor hallucis longus, and anterior tibialis.6,7

This common postural defect can be referred to as pronation

distortion syndrome, and may be the culprit for injuries

such as plantar fasciitis, posterior tibialis tendonitis,

medial tibial stress syndrome, anterior knee pain, and low

back pain.7

Conversely, the absence of normal STJ pronation during

gait and functional activity lowers the shock absorption

ability in the lower extremity, pelvis, and lumbar spine.

An athlete who presents with a supinated gait pattern will

66

have a rigid foot, which does not allow for optimal force

attenuation, possibly resulting in overuse injuries and/or

low back pain.5,6

Functional Range of Motion in the Lower Extremity

Muscle inflexibility also predisposes athletes to

the development of a variety of overuse injuries.5

Flexibility deficits may be improved by an appropriate

stretching program. Unfortunately, lower extremity

malalignment is less amenable to intervention. Orthotics

are often prescribed to improve lower extremity

alignment. However, studies have not shown that orthotics

have any effect on knee alignment and, while they can

alter subtalar joint alignment, the clinical benefit of

this remains unclear.4 Awareness of anatomical factors

that may predispose athletes to overuse injuries allows

the athletic trainer to develop individual rehabilitation

programs designed to decrease the risk of overuse injury.

In addition, the clinician can advise the athlete on the

importance of avoiding extrinsic factors that may result

in overuse injury.4

Range of motion of each segment of the lower extremity

must be within normal limits to ensure standard length-

67

tension relationships and ultimately produce regular

arthrokinematics. If one muscle, or group of muscles, is

incapable of proper lengthening, it can create imbalances

throughout the entire kinetic chain.

Typical ranges for ankle range of motion are: 200 of

dorsiflexion, 500 of plantarflexion, 200 of inversion, and

50 of eversion.17 It is common to see athletes with

excessive foot pronation, or adduction and plantarflexion

of the talus and eversion of the calcaneus, while the foot

is weight-bearing. It is sometimes visibly apparent upon

inspection when the medial concavity of the foot drops.

This can be caused either statically or dynamically. The

static deformity is caused by the inefficiency of the

spring ligament, connecting the navicula to the

sustentaculum tali of the calcaneus, to support the medial

longitudinal arch. Dynamically, it can be triggered by

over-activity of the peroneals and inhibition of the

posterior tibialis.18,19 Athletes with this type of posture

are predisposed to medial tibial stress syndrome and other

chronic lower leg pains.

Ranges of motion for the knee include: 135-1450 of

flexion, 0-100 of extension, and minimal rotation of the

tibia at extremes of flexion and extension.17 Genu valgum,

or tibial valgus, is a disorder characterized by “knocked-

68

knees.” With excessive genu valgum, the knees are visibly

closer together than the ankles during stance. Objectively

measuring a person’s Q-angle determines if this condition

is present. It usually occurs because of structural

anomalies secondary to muscular weaknesses at the hip, or

hyperpronation of the feet. Genu valgum can lead to a

variety of different postural deviations in the lower

extremity, such as increased foot pronation, internal

tibial rotation, medial patellar positioning, and internal

femoral rotation.19

Normal hip ranges of motion are as follows: 120-1300 of

flexion, 10-200 of extension, 450 of abduction, 300 of

adduction, 450 of internal rotation, and 500 of external

rotation.17,20,21 When the pelvis is in neutral position,

there is typically an 8-100 angle between the anterior

superior iliac spine (ASIS) and the posterior superior

iliac spine (PSIS). An overly anteriorly tilted pelvis

produces more than 100 difference while an overly

posteriorly tilted pelvis produces less than 80

difference.2,18

The amount of range of motion present in all joints of

males and females appears to differ, but not with respect

of all joints. However, in almost all cases, the greater

amount of range of motion is found in the female

69

population. In a study of 60 college-age subjects

investigating the influences of hip position and gender on

hip rotation, females demonstrated a statistically greater

range of active hip internal and external rotation compared

with males.21 Increased internal, but not external, hip

rotation in females has also been reported by Svenningsen

et al.,20 who studied 761 Norwegian subjects ranging in age

from 4 years to adulthood (the 20s). Other motions of the

hip that have been reported as being increased in females

compared with males are hip flexion and hip abduction in

adolescents and young adults.20

Without normal length-tension relationships, an

athlete is more prone to injury due to improper passive

lengthening and faulty eccentric contraction of the

musculature to absorb the force. It is partially the

athletic trainer’s duty to ensure that his/her athletes are

stretching properly prior to intense activity, especially

those with possible imbalances and discrepancies.

Knee Injuries Sustained by Female Jumping Athletes

Female participation in athletics has increased

dramatically over the last decade. Accompanying the

increase in sports participation is the increase incidence

70

of injury.22 Anterior cruciate ligament (ACL) sprains and

tears, patellar tendonitis, and subluxing patella are just

a few of the typical knee injuries seen regularly in the

jumping, female athletic population. Many of these

occurrences are due to valgus motion of the knee during

jump recovery as a result of muscular imbalances.22

ACL Injury

Rupture of the ACL is one of the most common and

potentially traumatic sports-related knee joint injuries.23

Injury to the ACL results from a force causing an anterior

displacement of the tibia relative to the femur, a

posterior displacement of the femur on the tibia, or from

hyperextension of the knee. The majority of ACL sprains

occur as a result of non-contact rotational stress, such as

when an athlete cuts or pivots, ultimately producing loads

that cannot be supported by bony structures and muscles,

thus leading to large ligament loads.23

Upon evaluation of simulated “game-instances” in a

laboratory setting, it was found that females exhibited

increased knee valgus and foot pronation, and decreased hip

flexion, hip abduction, hip internal rotation, knee

flexion, and knee internal rotation when compared to their

male counterparts.23 Males had more variability in hip

71

rotation, while females had more variability in knee

rotations. With decreased knee flexion in cutting and jump

recovery, comes increased anterior drawer action of the

quadriceps, and furthermore, the hamstring becomes less

capable of protecting the ACL against these detrimental

forces. All of these joint angle differences during

performance can contribute to the gender-based

dissimilarities. If neuromuscular control, rather than

anatomy, is responsible for knee valgus, prevention of ACL

injuries in women may be possible. McLean, Lipfert, and Van

Den Bogert summarize by claiming,

“Increased hip external rotation in females will

cause increased valgus and pronation. With

increased external rotation of the limb, valgus

load becomes more sensitive to the amount of hip

rotation and women compensate for this by

controlling their hip rotation more tightly.

When this control diminishes, due to fatigue or

an unexpected perturbation, valgus may rise to a

level where ACL injury occurs.”23(p 1010)

Women appear to suffer four to eight times the number

of ACL injuries for the same sports as men. Numerous

explanations and hypotheses have been put forth with little

convincing objective evidence.24 A greater Q-angle (normal

72

for females is ~ 180), anterior pelvic tilt, anteverted

hips, genu valgum, genu recurvatum, and subtalar pronation

are some of the anatomical differences that may predispose

a female to knee injury.18,22 Education about proper dynamic

stabilization of the muscles acting on the knee, as well as

hip joint, is vital.

Both intrinsic and extrinsic factors have been

proposed to contribute to the greater knee injury rate in

female athletes compared with their male counterparts.25,26

Specifically, intrinsic factors refer to lower extremity

skeletal malalignments, including excessive Q-angle, genu

valgum, femoral anteversion, and general joint laxity.

However, most of the skeletal variations between males and

females develop only after the rapid growth associated with

puberty. Not surprisingly then, post-pubescent females

suffer the highest rate of lower-limb injury when compared

with both the prepubescent female and male athletes.25-27

Some of the extrinsic factors associated with ACL

injury include motor control strategies, coordination of

movement patterns, and the level of conditioning and

muscular strength. Coincidentally, only recently have

extrinsic factors, such as jumping and landing strategies,

related to ACL injuries, been studied.25,27 Most landing

studies have focused on kinetics, neuromuscular activity,

73

and kinematics in the sagittal plane without regard to

maturation and frontal plane motion. The kinematics of

high-risk landing patterns have been identified and many

components of these parallel the variations in female

structural alignment with altered motion occurring in the

frontal plane.25,27 Recent research in college-aged

participants has identified gender differences in lower

extremity kinematics and kinetics during landing

activities, indicating that female athletes may possess

altered motor control strategies that result in knee

positions in which an ACL injury may occur.25,28 However,

there is a scarcity of information on the landing control

strategies in young pre-adolescent female sport

participants. Perhaps the reduced injury rate in this

population is a result of using landing strategies that are

“safer” than older female participants. Conversely, these

older female athletes may be utilizing landing strategies

that become injurious when changes in the skeletal

architecture are influenced by the onset of

menstruation.25,28

In a study performed to examine the correlation

between static postural faults in female athletes and the

prevalence of noncontact ACL injury, seven variables were

measured: standing pelvic position, hip position, standing

74

sagittal knee position, standing frontal knee position,

hamstring length, prone subtalar joint position, and

navicular drop test (a test comparing distance between the

navicular and the floor in seated and weight-bearing

positions).22 A conditional step-wise logistic regression

analysis revealed that postural defects such as knee

recurvatum, excessive navicular drop, and excessive

subtalar joint pronation proved to be significant

discriminators between the ACL-injured and non-injured

groups. These findings may have implications regarding

rehabilitation techniques in athletic training, encouraging

correction of these postural discrepancies.22

One striking difference between men and women is the

female hormonal cycle.24,29,30 The basis for this cycle is the

endocrine coordination between the hypothalamus,

the pituitary gland, and the ovaries. The coordination

among these centers occurs through the circulatory system

via hormones. During the course of this cycle, the

absolute levels of estrogen and progesterone, and the ratio

of these hormone concentrations, change over the mean

cycle duration of 28 days.24,29

Estrogen, progesterone, and relaxin affect many

tissues and systems distant from the ovarian follicles.29

Estrogen affects soft tissue strength, muscle function, and

75

the central nervous system, but the effects of progesterone

are less well understood. Progesterone can act as a

central nervous system anesthetic, and relaxin can

drastically diminish collagen tension. Interestingly, the

female monthly cycle represents a series of complex

interactions between these hormones, and such interactions

may play a role in the susceptibility of women to serious

knee injuries, especially ACL tears.24,30

In another study designed to investigate the variation

in ACL injury rates during the female monthly cycle, a

significant association was found between the stage of

the menstrual cycle and the likelihood for an ACL injury.24

In particular, there were more injuries during the

ovulatary phase of women with regular cycles (days 10 to

14) than expected. In contrast, significantly fewer

injuries occurred during the follicular phase (days 1 to

9). The increased incidence of ACL injury in women during

the ovulatory phase of the menstrual cycle, when a surge

in estrogen production occurs, suggests that the epidemic

of noncontact ACL tears in female athletes may be related

to hormonal fluctuations.24 The association observed

between the ovulatory phase and the rate of ACL injury is

statistically significant but requires further

investigation to establish its clinical and practical

76

significance.24 As well, females lack the testosterone-

driven boost that males possess to achieve sufficient

hypertrophy.29 Rather than allowing minimal tibial rotation,

a girl’s knee may move in various planes during provocative

motions, posing a lot of stress on the soft tissue

structures.29

Patellar Maltracking, Subluxation, and Dislocation

The onset of patellofemoral dysfunction has been

attributed solely to an increased Q-angle.31 Normal tracking

of the patella within the femoral trochlea depends on the

relationships between the alignment of the femur on the

tibia, the Q-angle, the integrity of the patella’s soft

tissue restraints, foot mechanics, and the flexibility of

the quadriceps, hamstrings, iliotibial band.31

Patellar tracking disorders may be congenital;

however, injury to the patella or knee may cause a

discrepancy in the anatomical structuring. For example, a

lateral dislocation of the patella results in tearing of

the medial restraints, increasing laxity. An injury to the

knee can also cause atrophy of the vastus medialis oblique

(VMO), increasing the amount of lateral patellar glide with

subsequent shortening of the lateral restraints. Other

variables affecting the equation are increased body weight

77

and gait mechanics. The lack of appropriate muscle length

and excessive pronation can also contribute to patellar

maltracking.31

Acute, chronic, or congenital laxity of the medial

patellar restraints or abnormal tightness of the lateral

retinaculum results in increased lateral glide of the

patella, predisposing patients to subluxations and

dislocations. The patella is most apt to dislocate or

subluxate when the maximum strain is placed on the lateral

patellar restraints, normally within the ranges of 20 to 300

of knee flexion or after a valgus blow to the knee.31

Resultant patellar fractures or osteochondral damage may

ensue. Prophylactic bracing and rehabilitation to

strengthen the VMO and hip musculature are noninvasive ways

to correct patellar tracking problems.31 However, some

chronic dislocators would better benefit from a surgical

repair, which involves shifting the patellar tendon

attachment to correct the tracking discrepancies.31

Patellar Tendonitis

Patellar tendonitis most often has an insidious onset

in individuals participating in jumping activities, running

sports, and weight lifting.18 Acute tendonitis can also

occur as a result of a blow to the tendon. Repetitive

78

motions on a biomechanically malaligned extensor mechanism

can result in unequal loads on the extensor tendon.

The most common site of pain associated with patellar

tendonitis is the inferior pole of the patella; however,

pain may also be present at the superior pole in the case

of quadriceps tendonitis (jumper’s knee), in the middle of

the tendon, or at the tendon’s attachment to the tibial

tuberosity.15 Resisted knee extension may increase pain to

the point that strength is inhibited. The end range of

passive knee flexion elicits pain and may result in

decreased quadriceps flexibility. Crepitus can be palpated

in tendons during active or resisted movements. A cho-pat

strap can be worn during activity to disperse the forces

exerted on the tendon itself; however, surgical debridement

of the tendon may be suggested to cases unresolved by the

noninvasive method.15 On the other hand, the incidence of

these overuse injuries could possibly be limited with

proper core strengthening, and treatment by the athletic

trainer would be minimal.

Summary

Biomechanical interaction of the entire lower

extremity, as well as the core, may be important

79

contributors to the risk of knee injury. Understanding the

interaction between trunk motion and those of the lower

limb joints during functional activity may provide further

insight into the resultant injury mechanism.8,23 For

instance, trunk accelerations at contact will have a

significant impact on the coupled hip and knee flexion, and

more than likely, on alternative plane loading at the knee

joint.23 The athletic trainer is responsible for recognizing

muscular imbalances to ensure optimal performance and

possible prevention of injuries altogether.

Posture and flexibility provide a basis for which all

movement occurs.16 For the movement to be optimal, these

primary factors should be assessed and trained in order to

supply an optimal environment for the desired level of

function.16

Females tend to possess a greater Q-angle,15 increased

hip range of motion, and tibial valgus and pronation in

static standing posture, thereby resulting in these same

traits in dynamic and functional postures while

participating in activity.21 These characteristics, in

addition to having weaker musculature, automatically

predispose them to greater risk of knee injury.21 It is our

job, as athletic trainers, to recognize these warning signs

and appropriately rehabilitate our athletes accordingly.

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APPENDIX B

The Problem

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Statement of the Problem

The purpose of this study is to portray the

correlation between standing posture, hip range of motion,

and postural control in female collegiate volleyball

players. The results of this study will hopefully outline

a potential profile for injury prevention in this

susceptible population.

Definition of Terms

The following terms are included to ensure the reader

accurate understanding of key concepts: 18,32

1) Anteverted hips- an inward rotation of the thigh bone,

also known as the femur, causing the knees and feet to

inwardly rotate; “pigeon-toed” gait.

2) Arthrokinematics- the movement of the articular surfaces

in relation to the direction of movement of the distal

extremity of the bone.

3) Closed-kinetic chain- any movement of the kinetic chain

with the distal segment fixed, or meeting sufficient

resistance; weight-bearing.

4) Compensatory movements- accessory motions that occur

due to postural deviations, muscle weakness, or muscle

tightness.

5) Core/Lumbo-pelvic-hip complex- where the human body’s

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center of gravity resides and all motion begins.

6) “Drawing-in” maneuver- pull navel to ground while lying

supine.

7) Force-couple relationships- two forces whose points of

application occur on opposite sides of an axis and in

opposite directions to produce movement.

8) Functional range of motion- the angle through which a

joint moves from anatomical position to the extreme

limit of segment motion in a particular direction.

9) Genu recurvatum- also referred to as “back knee”;

condition wherein the knee is hyperextended such that

the lower extremity curves.

10) Genu valgum/tibial valgus- commonly known as “knock-

knees”; knees are closer to the midline of the body

than normal and closer together than the feet in

standing position; Q-angle smaller than 1700.

11) Kinetic chain- a combination of several joints uniting

successive segments.

12) Length-tension relationships- tension produced by a

muscle compared to the length of the muscle.

13) Lower-crossed syndrome- postural deviation wherein the

pelvis becomes anteriorly tilted due to tightness of

the lumbar extensors and hip flexors, and weakness of

the abdominals and gluteus maximus.

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14) Medial tibial stress syndrome- commonly referred to as

“shin splints” wherein the connective tissues that

connect the soleus and posterior tibialis muscles

to the periosteum of the posteromedial tibia become

irritated and inflamed.

15) Neuromuscular control- the motor response to sensory

input; adjustment of muscles to destabilizing

forces.

16) Pes planus/pronation- combined conditions of

dorsiflexion, eversion, and abduction of the foot;

flattening of the medial longitudinal arch.

17) Proprioception- conscious and unconscious appreciation

of joint position.

18) Quadriceps-angle/Q-angle- the line of pull of the

quadriceps tendon and the patellar tendon with patella

as the center.

19) Reciprocal inhibition- when motor neurons transmit

impulses to muscles, causing them to contract, the

motor neurons that supply their antagonists are

simultaneously and reciprocally inhibited, or prevented

from firing.

20) Synergist- a muscle that contracts at the same time as

the agonist (primary movement muscle).

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21) Synergistic dominance- the synergist replaces the

agonist as the primary mover.

Basic Assumptions

For the purpose of this study, the following

considerations will be assumed:

1) Subjects will put forth their best effort, provided

that they are instructed properly.

2) The Overhead Squat is a valid assessment of overall

dynamic neuromuscular control.

3) The jump recovery is a valid assessment of the

functional mechanics of the vertical jump.

4) Goniometric recordings are a valid and reliable measure

of flexibility and range of motion.

5) Females are more susceptible to knee injuries due to

hormonal differences, increased Q-angle, genu valgum,

and their tendency to recover from a jump with fully-

extended knees.

Limitation of the Study

Results could be limited to those female athletes

participating in Division II collegiate volleyball.

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Significance of the Study

The prevalence of knee injuries in female athletes is

a serious problem for athletic trainers, particularly those

working with female volleyball athletes. Knee injuries

have been traced back to defects such as: lack of core

strength, lower-crossed syndrome, increased Q-angle,

genuvalgum, pes planus/pronation, as well as imbalances in

flexibility and functional range of motion.1,2 While core

stability and postural control is a necessary component to

every athlete’s training regimen, its beneficial effects on

power and function have often been ignored.2 If more

athletic trainers and coaches were aware of their role in

optimal performance, core stability and postural control

might be incorporated more readily into every athlete’s

conditioning program. However, do we as athletic trainers

know enough about core stability and postural control to

correct these improper mechanics and potentially prevent

episodes like these from occurring? This thesis will

attempt to correlate standing posture, hip range of motion,

and postural control in female athletes to possibly promote

incorporation of these vital concepts into rehabilitation

for the purposes of prevention of initial injury, as well

as recurrence of injury.

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APPENDIX C

Additional Methods

87

APPENDIX C1

Informed Consent

88

Informed Consent Form

1. “Catie Dougherty, ATC, who is a Graduate Athletic Training Student, has requested my participation in a research study at this institution. The title of the research is The Relationship between Standing Posture, Functional Hip Range of Motion, and Postural Control in Female Collegiate Volleyball Players.”

2. "I have been informed that the purpose of the research is to correlate postural defects and functional hip range of motion with measures of postural control in the female Division II volleyball athletes." 3. "My participation will involve evaluation of my posture, hip range of motion, and performance of two (2) functional tests (Overhead Squat and vertical jump). It will require one session of approximately 30-40 minutes of my time and will be video-taped for optimal analysis." 4. "Delayed onset muscle soreness (DOMS) is the only foreseeable risk with the performance of this study, however, I will perform the warm-up as advised. This risk is no different than what is possible in a normal volleyball practice session.” 5. "There are no feasible alternative procedures available for this study." 6. “I am aware that performance of the tests will be video- taped for later analysis by only the researcher and the research advisor.” 7. "I understand that the possible benefits of my participation in the research are to contribute to existing research, enhance injury prevention and understand mechanisms of injury, and/or to enhance the rehabilitative process of my withstanding injury.” 8. "I understand that the results of the research study may

be published but that my name or identity will not be revealed. In order to maintain confidentiality of my records, Catie will maintain all documents in a secure location in which only the student researcher and research advisor can access."

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9. "I have been informed that I will not be compensated for my participation."

10. “I have been informed that any questions I have concerning the study or my participation in it, before or after my consent, will be answered by Catie Dougherty, ATC, dou9999@cup.edu, (412)480-6486, and/or Rebecca A. Hess, Ph.D., hess_ra@cup.edu, (724)938-4359.

11. “I understand that written responses may be used in quotations for publication but my identity will remain anonymous.” 12. "I have read the above information. The nature, demands, risks, and benefits of the project have been explained to me. I knowingly assume the risks involved, and understand that I may withdraw my consent and discontinue participation at any time without penalty or loss of benefit to myself. In signing this consent form, I am not waiving any legal claims, rights, or remedies. A copy of this consent form will be given to me upon request."

Subject's signature________________________________________ Date _______________

13. "I certify that I have explained to the above individual the nature and purpose, the potential benefits, and possible risks associated with participation in this research study, have answered any questions that have been raised, and have witnessed the above signature." 14. "I have provided the subject/participant a copy of this signed consent document if requested."

Investigator’s signature___________________________________ Date________________

Approved by the California University of Pennsylvania IRB

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APPENDIX C2

Institutional Review Board (IRB)

91

92

93

94

95

APPENDIX C3

General Demographic Information

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Subject #: ________________ Age:__________

Height: __________ Weight: __________

1) Do you have any history of knee injuries? Yes / No

2) If yes, what was the diagnosis?

__ ACL tear

__ Patellar tendonitis

__ Subluxing patella

__ Other

If indicated, what was the date of your last injury?

_________________

3) Have you had knee or ankle surgery? Yes / No

If indicated, which leg? R / L

4) Do you have a regular menstrual cycle? Yes / No

5) First day of last menstruation: ______________

6) Vertical Jump Heights: Trial 1: _____________

Trial 2: _____________

Trial 3: _____________

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APPENDIX C4

Evaluation Form

98

Q-Angle and Active Hip ROM

Subject Q-Angle Flex Ext Abd Add IR ER

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Standing Posture/ Overhead Squat/ Jump Recovery/ Static Dynamic Functional

Subj# Valgus Pronation Valgus Pronation Valgus Pron / 1. 2. 3. 1. 2. 3. 1. 2. 3. 1. 2. 3. 1. 2. 3. 1. 2. 3. 1. 2. 3. 1. 2. 3. 1. 2. 3. 1. 2. 3.

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APPENDIX C5

Active Hip Range of Motion

Measurements

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Active Hip Range of Motion (in Degrees)

Motion Mean (SD)

Flexion: 122 (12)

Extension: 22 (8)

Abduction: 44 (11)

*Adduction: *10 (not reported)

Internal Rotation: 33 (7)

External Rotation: 34 (8)

Ref. Roach and Miles33(p32) *Adduction value obtained from Kendall, McCreary, and

Provance34(p32)

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APPENDIX C6

Overhead Squat Assessment

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TOTAL BODY PROFILE Overhead Squat Objective: To observe for total body neuromuscular efficiency, integrated functional strength and functional flexibility Foot and Ankle

Feet flatten (pronate): Y / N � Externally rotate (turn out): Y / N Knees

Knees buckle inward: Y / N � Knees bow outward: Lumbo-Pelvic-Hip Complex

Asymmetrical weight shifting: Y / N � Low back arches: Y / N � Low back rounds: Y / N � Abdomen protrudes: Y / N Shoulder Complex

Shoulder protraction/abduction: Y / N � Shoulder elevation: Y / N � Scapular winging: Y / N Head

Forward Head: Y / N

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ABSTRACT

Title: The Relationship between Standing Posture, Functional Hip Range of Motion, and Postural Control in Female Collegiate Volleyball Players

Researcher: Catherine L. Dougherty Adviser: Dr. Rebecca Hess Purpose: The purpose of this study was to portray any

correlation between standing posture, active hip range of motion, and postural control in female collegiate volleyball players. The results were used to outline a potential profile for injury prevention in this susceptible population.

Methods: Ten members of the California University of

Pennsylvania’s Female Volleyball team participated in the study. The subjects’ Q-angle, active hip range of motion, standing posture, and performance of the Overhead Squat and jump recovery were analyzed for characteristics that would generate a female volleyball players’ profile and could potentially lead to injury. Frequency tables and Pearson Correlations were used to analyze the data.

Findings: The amount of Q-angle can be correlated with

the performance of the assessments. The sole athlete who possessed a Q-angle greater than the average exhibited tibial valgus and subtalar pronation throughout all of the assessments. Subtalar pronation in standing posture can be correlated with pronation while squatting. However, no direct correlation between active hip range of motion, standing posture, and performance of the assessments were reported. Additionally, all ten subjects displayed at least one of the supposed traits during jump recovery. The only incidence when neither trait was exhibited was when the athlete recovered with knees fully extended. All

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seven subjects who reported a history of knee injuries produced tibial valgus, if not both traits, during jump recovery. With regards to menstruation, of the three women who lacked a normal menstrual cycle, two had never sustained a knee injury, and of the seven remaining women who menstruate regularly, six have sustained a knee injury.

Conclusions: Q-angle is directly correlated with the presence of tibial valgus and subtalar pronation during standing posture, dynamic activity, and functional activity.

Subtalar pronation in standing posture can be correlated with pronation while

squatting. However, patterns among active hip range of motion were not as conclusive.

Perhaps this could indicate that a functionally sound performance of the Overhead Squat and jump recovery is not dependant upon the subjects’ active hip range of motion measurements. Otherwise, subjects’ may subconsciously adjust pelvic position to compensate for abnormal length- tension relationships occurring at the hip. Furthermore, all ten of the subjects exhibited tibial valgus and/or subtalar pronation during jump recovery, suggesting that females have either not received proper instruction on correct landing biomechanics or that they are not neuromuscularly efficient enough to prevent these faulty biomechanics from occurring. Additionally, females who menstruate regularly may be more susceptible to injury due to the physiological effect of hormones on soft tissues’ stability.