Paper 19: Fatigue of the Dynamic Stabilizers of the Medial Elbow in Baseball Pitchers

Objectives: The flexor carpi ulnaris (FCU) and digitorum superficialis (FDS) are thought to provide dynamic stability the medial elbow, with a lesser contribution from pronator teres (PT). purposes of this study were to: (1) determine whether middle finger (MF) and/or ring (RF) flexion strength tests selectively activate FCU FDS, (2) if MF or RF fatigue more sensitive measures pitching than grip strength. It was hypothesized that would FDS during performance occur earlier be pronounced fatigue. Methods: Surface electromyographic (EMG) signals recorded FCU, PT hand-held dynamometry testing in 10 healthy men (36±12 yr). EMG amplitudes, expressed as percent maximal voluntary contraction (MVC) based on standard MVC for each muscle, compared between muscles repeated analysis variance (ANOVA). Field Testing performed 18 baseball pitchers (age 17±4 yr) throwing 4 innings simulated game (16 pitches per inning plus 5 warm up inning; fast balls, curve 2 change ups inning). flexion, prior after inning. A full test (FG) modified 3 (3F) employed. Fatigue responses (MF, RF, FG, 3F) 4x4 (innings by test) ANOVA. Additionally, classified marked (>20% loss), moderate (10-20% loss) minimal (<10% loss). estimated there 80% power detect 10% difference (P<0.05). Results: activated (MF 66%, 93%) 74%, 61%) 35%, 23%; muscle effect P=0.008) indicating both targeted stabilizers elbow. In greater dominant versus nondominant hand (7% P=0.039). There no dominance other three (RF P=0.154, FG P=0.790, 3F P=0.897). differed significantly (P<0.001). After fourth (21%) (7%, P<0.001), (5%, P=0.002) P<0.001) evident early progressive. first (22%) had (17%) By end (56%) 6 (33%) contrast, four only (28%) fatigue, Conclusions: is valid elbow performance. 50% 89% some evidence training improve resistance recommended maintain