Question

Name one sport/athletic activity that requires athletes to have highly developed/strong muscles that perform arm (glenohumeral) medial rotation.

Important: Briefly explain (1-2 sentences) why athletes performing this activity would require strong muscles for medial rotation.

Briefly describe (2 sentences) what occurs in the sarcomere when calcium is absent and not freely available in the cytoplasm of the muscle cell. In your answer you should include a statement showing your understanding of the role of calcium in muscle contraction

Answer 1

Baseball.

Baseball players require strong muscles for medial rotation because shoulder instability is a common scenario in players with weak muscles leading to muscles deficits that occur in shoulder instability. General strengthening exercises are prescribed for rehbilitation.

Calcium released from sarcoplasmic reticulum bind to Troponin C that unmasks the myosin binding sites on actin. This leads to actin-myosin binding triggering muscle contraction. When calcium is absent and not freely available in the cytoplasm of muscle cell, the exposure of the myosin-binding site on actin filament to allow cross-bridge formation between the actin and myosin microfilaments will not occur as the binding of calcium to troponin and resultant pulling off of tropomyosin from the myosin binding site on actin does not occur. As a result, the thin filaments are not pulled by the myosin heads to slide past the thick filaments toward the center of the sarcomere.