This is a narrative review of shoulder EMG muscle recruitment across seven upper extremity sports. It maps which muscles fire, how hard, and in which phase during baseball pitching, football throwing, windmill softball, volleyball, tennis, batting, and golf. EMG data are integrated with kinematics and kinetics to explain the shoulder injury mechanism.
When you evaluate a throwing athlete with shoulder pain, anchor your thinking to the phase of throwing. Arm cocking and deceleration generate the highest muscle activity and distractive loads near bodyweight, so this is where the cuff, labrum, and capsule fail.
The posterior cuff is the workhorse. Infraspinatus and teres minor generate a posterior humeral force that unloads the anterior capsule during cocking, then eccentrically decelerate the arm. Weak or fatigued posterior musculature underlies undersurface cuff tears, internal impingement, and labral pathology.
Use the instability-to-SLAP mental model: chronic anterior instability drives compensatory biceps overactivity, which loads the labral anchor and over time produces a SLAP lesion. This links physical exam instability findings to the labrum on your differential.
For rehab, prioritize posterior cuff and scapular stabilizer strengthening (serratus anterior fires up to 106% MVIC) plus lower extremity and trunk conditioning, since proximal weakness increases distal shoulder load.
This is a narrative review of shoulder EMG muscle recruitment across seven upper extremity sports. It maps which muscles fire, how hard, and in which phase during baseball pitching, football throwing, windmill softball, volleyball, tennis, batting, and golf. EMG data are integrated with kinematics and kinetics to explain the shoulder injury mechanism.
When you evaluate a throwing athlete with shoulder pain, anchor your thinking to the phase of throwing. Arm cocking and deceleration generate the highest muscle activity and distractive loads near bodyweight, so this is where the cuff, labrum, and capsule fail.
The posterior cuff is the workhorse. Infraspinatus and teres minor generate a posterior humeral force that unloads the anterior capsule during cocking, then eccentrically decelerate the arm. Weak or fatigued posterior musculature underlies undersurface cuff tears, internal impingement, and labral pathology.
Use the instability-to-SLAP mental model: chronic anterior instability drives compensatory biceps overactivity, which loads the labral anchor and over time produces a SLAP lesion. This links physical exam instability findings to the labrum on your differential.
For rehab, prioritize posterior cuff and scapular stabilizer strengthening (serratus anterior fires up to 106% MVIC) plus lower extremity and trunk conditioning, since proximal weakness increases distal shoulder load.