Muscle activity relationships during isometric shoulder internal and external rotation using the ForceFrame dynamometer and athletic shoulder tests in baseball athletes

The ASH and shoulder rotational tests' results showed different shoulder and trunk neuromuscular activation levels, demonstrating a low relationship between the prime movers for ASH positions and muscles activated during shoulder rotation. This implies that muscle synergies vary significantly depending on joint positioning and test mechanics. It also emphasizes the importance of using multiple test batteries to capture force production deficits and abnormalities that are relevant to overhead athletes. The results support rehabilitation progression starting with infraspinatus strengthening in neutral shoulder abduction, followed by scapular stabilizer training at wider abduction angles to restore functional overhead capacity. Acute or chronic performance may be monitored weekly for further training optimization, return-to-sport decisions, and injury prevention in elite overhead throwing athletes.