Werner and colleagues measured elbow motion, loads and muscle activity through the baseball pitch.
Laboratory study of 7 healthy college and minor league pitchers recorded with synchronized high‑speed video and surface EMG.
Key Findings
Peak varus torque at the elbow, resisting valgus stress, reached 120 Nm near maximum shoulder external rotation.
Citing earlier cadaver work, the authors note the ulnar collateral ligament alone cannot withstand a valgus load this large.
The wrist flexor‑pronators, arising on the medial epicondyle, fired throughout the pitch and peaked before maximum external rotation. Triceps and anconeus were also active then and may stabilize the joint by compressing it.
Elbow extension before release came with falling biceps and rising triceps activity. The authors judge triceps torque too small for the speed seen and suggest biceps release, letting centrifugal force extend the elbow, may matter more.
Joint loads were estimated from video accelerations and cadaver‑based segment masses, not measured directly, in 7 pitchers.
Authors' conclusion
Triceps, wrist flexorpronator, and anconeus activity during peak valgus stress suggests that these muscles may act as dynamic stabilizers to assist the ulnar collateral ligament in preventing valgus extension overload.
Werner and colleagues measured elbow motion, loads and muscle activity through the baseball pitch.
Laboratory study of 7 healthy college and minor league pitchers recorded with synchronized high‑speed video and surface EMG.
Key Findings
Peak varus torque at the elbow, resisting valgus stress, reached 120 Nm near maximum shoulder external rotation.
Citing earlier cadaver work, the authors note the ulnar collateral ligament alone cannot withstand a valgus load this large.
The wrist flexor‑pronators, arising on the medial epicondyle, fired throughout the pitch and peaked before maximum external rotation. Triceps and anconeus were also active then and may stabilize the joint by compressing it.
Elbow extension before release came with falling biceps and rising triceps activity. The authors judge triceps torque too small for the speed seen and suggest biceps release, letting centrifugal force extend the elbow, may matter more.
Joint loads were estimated from video accelerations and cadaver‑based segment masses, not measured directly, in 7 pitchers.
Authors' conclusion
Triceps, wrist flexorpronator, and anconeus activity during peak valgus stress suggests that these muscles may act as dynamic stabilizers to assist the ulnar collateral ligament in preventing valgus extension overload.