1. Muscles and Movement Dan Foster, PhD, ATC January 7, 2010 Rothbart B, May 2009

2. Athletic Training Assessment Skilled Movement Deficiency Rule-out life & limb threatening injuries »or Rule-out referral issues »or Functional status Philosophy of approach for deficiencies and functional status: minor alterations in precision of movement lead to injury and pain, caused by changes in muscle length, strength, stiffness, and movement patterns

3. Key Elements Assessment of alignment –Indicates possible muscle length changes and joint alignment –Interfere with optimal movement Movement patterns Specific muscle length and strength testing Borstad J, Phys Ther, 2006 Whyte E, Gait & Post, 2010 Garner B, BioMed Engineer, 2004

4. Scapular & Humeral Alignment Vertebral border parallel to spine ~ 3 in. away Between T2 – T7 Flat on chest wall Rotated 30 o anteriorly Less than 1/3 protruding Cubital fossa forward Humerus vertical Garner B, BioMed Engineer, 2004 Kibler W, AJSM, 1998

5. Alignment Issues Downwardly rotated

6. Scapular Motions Scapula variable during first 30 o abd or 60 o flex Remaining 120 o Humeral and 60 o Scapular Timing often 140 o Humeral flex when scapula stops Inman V, JBJS, 1944

7. Muscle Physiology and Control Strength Length Stiffness Timing Repeated movement Sustained postures MuscleNerveMotor Control Movement impairment

8. Muscle Strength Capacity –Fiber number –Contractile elements Hypertrophy/Atrophy –Arrangement Series/Parallel –Length of fibers –Configuration Overlapped, lengthened, disrupted Wilkie D, Br. Med Bull, 1956 Tipton C, Am J Physiol, 1970

9. Muscle Length Prolonged elongation Strain injury and continuous tension Sustained stretching Kendall F, 1993

10. Muscle Stiffness Change in tension per unit change in length Contributes to movement patterns –Active and passive stiffness –A factor in compensatory motion in contiguous joints Sahrmann S, 2002

11. Movement Timing Altered recruitment patterns –Upper trapezius dominance Learned Preferred pattern due to pain Delayed or insufficient action Stabilizing muscle causes movement

12. Case 16 YO ♀ swimmer with B shoulder pain R>L Cumul pain occurs in flex & abd at ~100 o Swimmer since 6, ranked high at one time Works hard, weight training & swim despite 5’7” 127# Slight thoracic kyphosis, weak abs B shoulder girdle elevation, arms abd

13. B scapular abd Humerus glides sup, at 120 o flex humerus med rotates/pop, glide sup on return to neutral Trunk ext on shoulder flex to counterbalance –If trunk is stabilized, flex is limited Trapezius & Rhomboids are short (hard to determine) Deltoid & Supraspinatus are short Lat rotators are stiff Lower & mid Trapezius are weak Deltoid becomes dominant on ER – Humeral ext, winging, and humeral head glide sup On IR & ER immediately initiates scapular motion Serratus is weak and wings in quadruped position

14. Diagnosis? Impingement –Supraspinatus tendinopathy –Subacromial or subdeltoid bursitis –Bicepital tendinopathy Humeral superior glide – primary –During shoulder flexion with elbow flexion sx ↓ Scapular abduction - secondary

15. Treatment Primary emphasis –Stretch deltoid and decrease dominance –Improve control of trapezius and serratus ant Learn how to control IR/ER without other motions (supine) Target infraspinatus and teres minor (prone & standing) Control scapula and sup glide on IR (prone)

16. Exercises

17. Outcome Within 4 weeks (no swimming) –Arms at side during rest –Arms flex without pain to 180 and w/o moving trunk –No medial rotation with popping –Tolerates 4 pounds of load –Ready to step up her activity and resume swimming when she can go through her stroke without popping

18. Summary Minor alterations in precision of movement lead to injury and pain, caused by changes in muscle length, strength, stiffness, and movement patterns The influence of multiple muscle interactions acting on multiple joints in functionally oriented tasks is where we might go with deficiency screening and rehab recovery