Scientific Method of Problem Solving• Develop (define and delimit) the problem• Formulate the general hypothesis:

– Overload training improves strength– (e.g., 3 sets of bp 3 d/w will improve bp strength)

• Formulate the specific hypothesis:– If A (general) is true, then B (specific) will be true – (e.g., if the general hyp is true, then posttest > pretest)

• Gather , analyze, and interpret the data – If B is true (significant difference), what about A?– If B is not true (no sig diff), what about A?

• Discuss the results– Is B without A very unlikely, or are there alternative explanations?

Sport biomechanics – outline

• Reading assignments:– Kreighbaum & Barthels – Module J (pp 335-353, Ch 11

(pp 370-384), esp pp 372-375 on baseball pitch– Adrian – Ch 17, esp pp 333-339, Ch 18, esp 365-369– Review Welch paper in JOSPT on baseball hitting (see

questions related to this article on last slide)– Review Harms and Noble paper on warmup and bat

velocity (specific summary assignments)– Review Nicholls and Elliott paper in JAB on bat

kinematics (specific summary assignments)

Biomechanical correlates of participation in

sports: areas of interest and effort

• Evaluate process – technique – optimize efficiency, or outcome• Injury potential/prevention• How to enhance acquisition of sport skills– motor learning• Design appropriate conditioning programs to enhance

performance• Equipment Design and Selection

– ground-foot interfaces – protective equipment (pads, gloves, head gear)– striking implements– balls– Sports playing surfaces

Exercise and Sport Biom Prof Org • American College of Sports Medicine• International Society of Biomechanics in Sports• Biomechanics academy of AAHPERD • North American Society of Biomechanics• International Association for Sports Surface Sciences• International Society of Biomechanics • American society of Biomechanics • Canadian Society of Biomechanics• European Society of Biomechanics • Formosan Society of Biomechanics • International Sports Engineering Association • International Shoulder Group • ISB Technical Group on the 3-D Analysis of Human Movement. • European Society for Movement Analysis in Adults and Children

• ca/biomechanics/

Sport biomechanics journals• Research quarterly for exercise and sport• Medicine and science in sport and exercise• Journal of applied biomechanics• Sports biomechanics• International journal of sport and health science• Journal of sports sciences• Sports engineering• Pediatric exercise science• Journal of orthpaedic and sport physical therapy• Journal of biomechanics• Journal of athletic training• Journal of strength and conditioning research• Journal of electromyographic kinesiology• Sports medicine

Throwlike and Pushlike Movement Patterns

• Usual objectives of throw and push patterns• projection of objects for greatest horiz or vert dist

– ex : javelin, discus, shotput

• projection of objects for accuracy with speed a factor

– ex: volleyball, tennis, racquetball, baseball pitch

• Movement pattern terminology review• Throwing patterns are further defined as underarm, sidearm, or overarm

Skills listed under each pattern differ because of constraints– ex: rules governing implement or ball, rules governing target.

• Open and Closed chain movements• Open kinetic chain - sequential segmental action, end segment is free to

move (e.g., baseball pitch)

• Closed kinetic chain - simultaneous end segment movement, end segment meets with “considerable resistance “ (e.g., shot put)

Common movement patterns

Throwlike and Pushlike Movement Patterns• Characteristics of throw-like patterns

– can be a strike or a kick

– high end-point velocity is critical

– sequential segmental action, object lags behind elbow and/or shoulder

• Open kinetic link model - Figure J.1, p 338; J.2, p 339

• Linear motion of a point on a rotating segment: V = r• Sequencing segmental rotations - kinetic link principle

– system has a base and a free open end

– segmental masses progressively decrease

– an external torque is applied at the base to initiate the movement

– segmental rotational acceleration is timed sequentially

• A model of an open kinetic link system - Fig J.4, p 343

• Throwlike movements performed while in the air - Fig J.5, p 345

Three-segment kinetic link model

Three-segment model: (Fig j.2, p 339)

Whip-like action of segmental system

Three-segment model when airborne:

Throwing motion (sequential)

Segmental sequence when throwing

Phases of pitching:1. Windup (a-k)2. Early Preparation (l-m)3. Late preparation (n-p)4. Release (r-u)

From: Feltner, M. & Dapena,J. (1986) Dynamics of shoulder and elbow joints ofthe throwing arm during a baseball pitch. Int J Biomech235-259.

Javelin – similarTo baseball pitch

Shotput – some throw & some push

AmericanSports

MedicineInstituteanalyzes pitching

(www.asmi.org)

The kinetic chain illustrated in baseball pitch

Poor technique can cause both injury and poor performance

Throwlike and Pushlike Movements

• Pushlike patterns - Simultaneous segmental actions– Objective is accuracy, or large motive force

– Distal segments move simultaneously, resulting in rectilinear movement of distal segment

– Four differences in throw and push. In throws:• distal segment “lags back”, segments move sequentially, object moves

curvilinearly, wheel-axle movements (shoulder and hip rotation) involved

• Movements lie on a throw-push continuum, the location depending on constraints of performer and object:– performer strength and skill

– object mass, size, and shape

Pushing Motions

Development of throwing motion

Developmental stages of throwing

• Stage 1- ball thrown primarily with elbow extension – no rotation of thorax or arm

• Stage 2 - Thoracic rotation accompanies backward motion of the arm. The throw is initiated by the arm swing forward. Some arm rotation as well as forearm extension at various times

• Stage 3 - step is taken with same side foot to initiate throw

• Stage 4 – step is taken with contralateral foot, thoracic rotation, arm rotation, elbow extension

Side arm striking pattern: The baseball swing

Stance StrideSwing

Lift front foot Bat begins moving forward

Ball-bat impact

Follow-through

Description of the baseball swing

Questions related to Welch JOSPT paper on baseball hitting

• What type of study was this? Experimental, correlational, or descriptive?• What is the purpose of the study?• What is the primary contribution of this study to the scientific or professional

community?• To what conditions and subject populations can the results be applied?• What type of motion analysis system was used in the study?• Were the data collection and reduction methods (time and position resolution,

synchronization methods, data smoothing procedures, etc.) adequate?• Which segments were included in the analysis related to the kinetic link

principle? Were any relevant segments missing?• What three events separated the stance, stride, swing, and follow-through?• Were the findings consistent with the kinetic link principle?• Do you have any suggestions as to how the study could be improved?