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REHABILITATION
Shoulder and Scapular Kinematics during the Windmill Softball Pitch:
The Effect of Fatigue
Poster # 46 Sherry I Backus, PT, DPT, MA*
Andrew P Kraszewski, MS* Andreas Kontaxis, PhD* Mandi S Gibbons, MS*
Jennifer Bido, BA*
Jessica Graziano, PT, DPT, CSCSǂ Jocelyn F Hafer, MA* Kristofer J Jones, MD°
Howard J Hillstrom, PhD* Stephen Fealy, MD°
Hospital for Special Surgery *Motion Analysis Laboratory, Rehabilitation Department
ǂSports Rehabilitation and Performance Center, Rehabilitation Department °Sports Medicine and Shoulder Service, Orthopaedic Surgery Department
HSS educational activities are carried out in a manner that serves the educational component of our Mission.
As faculty we are committed to providing transparency in any/all external relationships prior to giving an academic presentation.
Disclosure: We DO NOT have a financial relationship with any
commercial interest.
Background
Clinical problem – The repetitive stress of pitching alters structural and functional
mechanics of the shoulder complex.1
from Maffet et al, 19972
Background
Pitch count – Guidelines have been adopted by Little League for the young
baseball pitcher.3 – No guidelines available for the female windmill (underhand) throwing
athlete.4
Kinematics – Humeral-thoracic kinematics of the windmill softball pitch have been
reported.5 – Glenohumeral (GH) and scapulo-thoracic (ST) motions have not
been documented during the windmill pitch.
Fatigue during a game length simulation – Impact of fatigue on performance (ball speed) as well as on GH and
ST kinematics is unknown.
Background
Purpose – To measure pitching performance, GH and ST kinematics in high
school female windmill softball pitcher – To identify the changes in performance and kinematic adaptions
due to fatigue in a simulated game situation
Methods
Subjects – N = 8 female high school athletes (age range = 14-18 yrs) – No history of previous shoulder injury
Motion Data Collection – Kinematics
• All testing in a motion analysis laboratory • 12 camera 3D motion capture system • 250 frames/sec • Coordinate systems
– Both passive reflective marker clusters and manual palpating digitizer4
– Hand, forearm, humerus, scapula and trunk segments – Marker placement and calibration of bony landmarks – Followed ISB recommendations6 and Kontaxis7 – Custom built scapular tracker, based on Karduna8
Methods
Testing Set-up – Artificial pitching mound, regulation distance (43’) from home plate – Pitching target with a designated strike zone – Radar gun for ball speed
Pitching Protocol – Fastball pitches – 105 pitches total: 15 pitches x 7 sets – 5 minutes rest between sets
Outcome Measures – Ball speed
• Last 5 pitches from all 7 sets – GH & ST kinematics
• Last 5 pitches from first & last sets
Methods II
Kinematics – Normalized across the throw from Initial-drive (wind-up) to ball
release
Results: Pitching Performance
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6 7
Bal
l Spe
ed (m
ph)
Pitch Set
Ball Speed Across All Sets
Subject 01 Subject 02 Subject 03 Subject 04 Subject 05 Subject 06 Subject 07 Subject 08
No change within subjects across 105 pitches
Results: GH Kinematics - All Subjects
Kinematics – Average across subjects:
• GH kinematics were consistent between Set 1 and Set 7
-‐125
-‐75
-‐25
25
75
125
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al-‐Drive to Release (%)
GH FLEX/EXT Set 1 ± 1 sd Set 7
-‐125
-‐75
-‐25
25
75
125
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al-‐Drive to Release (%)
GH IR/ER Set 1 ± 1 sd Set 7
-‐125
-‐75
-‐25
25
75
125
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al-‐Drive to Release (%)
GH ABD/ADD Set 1 ± 1 sd Set 7
Results: GH Kinematics – Representative Subject
-‐125
-‐75
-‐25
25
75
125
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al Drive to Release (%)
GH FLEX/EXT Set 1 Set 2 Set 3 Set 4 Set 5 Set 6 Set 7
Results: GH Kinematics – Representative Subject
-‐125
-‐75
-‐25
25
75
125
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al Drive to Release (%)
GH ER/IR Set 1 Set 2 Set 3 Set 4 Set 5 Set 6 Set 7
No change across 105 pitches for GH kinematics
Results GH Kinematics- All Subjects, Sets 1 & 7
-‐150
-‐125
-‐100
-‐75
-‐50
-‐25
0
25
50
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al Drive to Release (%)
GH IR/ER
Subj 1 Set 1
Subj 1 Set 7
Results GH Kinematics- All Subjects, Sets 1 & 7
-‐150
-‐125
-‐100
-‐75
-‐50
-‐25
0
25
50
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al Drive to Release (%)
GH IR/ER
Subj 1 Set 1
Subj 1 Set 7
Subj 2 Set 1
Subj 2 Set 7
Results GH Kinematics- All Subjects, Sets 1 & 7
-‐150
-‐125
-‐100
-‐75
-‐50
-‐25
0
25
50
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al Drive to Release (%)
GH IR/ER
Subj 1 Set 1
Subj 1 Set 7
Subj 2 Set 1
Subj 2 Set 7
Subj 3 Set 1
Subj 3 Set 7
Results GH Kinematics- All Subjects, Sets 1 & 7
-‐150
-‐125
-‐100
-‐75
-‐50
-‐25
0
25
50
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al Drive to Release (%)
GH IR/ER
Subj 1 Set 1
Subj 1 Set 7
Subj 2 Set 1
Subj 2 Set 7
Subj 3 Set 1
Subj 3 Set 7
Subj 4 Set 1
Subj 4 Set 7
Results GH Kinematics- All Subjects, Sets 1 & 7
-‐150
-‐125
-‐100
-‐75
-‐50
-‐25
0
25
50
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al Drive to Release (%)
GH IR/ER
Subj 1 Set 1
Subj 1 Set 7
Subj 2 Set 1
Subj 2 Set 7
Subj 3 Set 1
Subj 3 Set 7
Subj 4 Set 1
Subj 4 Set 7
Subj 5 Set 1
Subj 5 Set 7
Results GH Kinematics- All Subjects, Sets 1 & 7
-‐150
-‐125
-‐100
-‐75
-‐50
-‐25
0
25
50
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al Drive to Release (%)
GH IR/ER
Subj 1 Set 1
Subj 1 Set 7
Subj 2 Set 1
Subj 2 Set 7
Subj 3 Set 1
Subj 3 Set 7
Subj 4 Set 1
Subj 4 Set 7
Subj 5 Set 1
Subj 5 Set 7
Subj 6 Set 1
Subj 6 Set 7
Results GH Kinematics- All Subjects, Sets 1 & 7
-‐150
-‐125
-‐100
-‐75
-‐50
-‐25
0
25
50
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al Drive to Release (%)
GH IR/ER
Subj 1 Set 1
Subj 1 Set 7
Subj 2 Set 1
Subj 2 Set 7
Subj 3 Set 1
Subj 3 Set 7
Subj 4 Set 1
Subj 4 Set 7
Subj 5 Set 1
Subj 5 Set 7
Subj 6 Set 1
Subj 6 Set 7
Subj 7 Set 1
Large between- & small within-subject variation
Results: ST Kinematics - All Subjects
Kinematics – Average across subjects:
• ST kinematics were consistent between Set 1 and Set 7
-‐50
-‐25
0
25
50
75
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al-‐Drive to Release (%)
ST Post Tilt/Ant Tilt Set 1 ± 1 sd Set 7
-‐50
-‐25
0
25
50
75
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al-‐Drive to Release (%)
ST IR/ER Set 1 ± 1 sd Set 7
-‐50
-‐25
0
25
50
75
0 20 40 60 80 100
Angle (°)
Pitch from Ini4al-‐Drive to Release (%)
ST Up/Down Rot Set 1 ± 1 sd Set 7
Discussion
The study has demonstrated a protocol for the investigation of underhand softball pitching. – To our knowledge, this is one of the first studies to analyze GH as
well as ST kinematics during softball pitching.
For the windmill underhand pitcher, 105 pitches was not sufficient to induce changes in performance or GH and ST kinematics – May require more pitches to demonstrate changes with increasing
fatigue – More variation between subjects than within subjects
• Normalization to specific phases rather than the entire throw may reduce the between pitcher variation for selected phases
Discussion
Ball Speed – Ball speed was very consistent across subjects throughout the
pitching protocol
Shoulder kinematics during the pitching motion demonstrate large and complex GH joint excursions – Very consistent patterns were observed for all 3 GH rotations
This is an ongoing pilot study and more athlete recruitment is planned to build a database of normative shoulder and full-body kinematics.
References Cited 1. Bigliani LU, et al. Shoulder motion and laxity in the professional baseball player.
(1997) Am J Sports Med. 25(5):609-13. 2. Maffet MW, et al. Shoulder muscle firing patterns during the windmill softball
pitch. (1997) Am J Sports Med. 25(3):369-74. 3. Lyman S, et al. Effect of pitch type, pitch count, and pitching mechanics on risk of
elbow and shoulder pain in youth baseball pitchers. (2002) Am J Sports Med. 30(4):463-8.
4. Shanley E, et al. Shoulder range of motion, pitch count, and injuries among interscholastic female softball pitchers: A descriptive study. (2012) Int J Sports Phys Ther. 7(5):548-57.
5. Werner SL, et al. Biomechanics of youth windmill softball pitching. (2005) Am J Sports Med. 33(4):552-60.
6. Wu G, et al. ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion--part II: Shoulder, elbow, wrist and hand. 2005 J Biomech. 38(5):981-92.
7. Kontaxis A, et al. A framework for the definition of standardized protocols for measuring upper-extremity kinematics. (2009) Clin Biomech (Bristol, Avon). 24(3):246-53.
8. Karduna AR, et al. Dynamic measurements of three-dimensional scapular kinematics: A validation study. (2001) J Biomech Eng. 123(2):184-90.
ACKNOWLEDGEMENTS The investigating team would like to acknowledge the support of the Institute for Sport Medicine Research (Hospital for Special Surgery, NY) who funded this study.
