Abstract
The diagnostic value of isokinetic indices of shoulder internal (IR) and external rotation (ER) in collegiate pitchers (P) has been well documented; however, data simultaneously showing isokinetic values throughout the velocity and joint angle spectra are non-existent. Purpose. The purpose of this study was to develop three-dimensional isokinetic concentric and eccentric angle-torque-velocity surfaces for the shoulder IR and ER muscles of collegiate baseball P and non-throwing athletes (NP) and to compare the differences in the specific variables associated with their topography. The dependent variables included torque (T), torque x angle (TA), torque x velocity (TV), and torque x velocity x angle (TVA). Methods. Fourteen collegiate athletes (P=7, NP=7) volunteered for this study. The torque generated by pitchers and non-throwing athletes throughout their shoulder joint range of motion was measured at nine different isokinetic speed settings for concentric IR and the same nine speed settings for concentric ER. The speed settings used were: 0.52, 1.05, 1.57, 2.62, 3.66, 4.71, 5.76, 6.98, and 7.85 rad·s -1. The torques generated at five different isokinetic speed settings during eccentric IR and the same five speed settings for eccentric ER were also measured. The speed settings for eccentric tests included: 0.52, 1.05, 1.57, 2.09, and 2.62 rad·s-1. Primary statistical analyses focused on determining whether the response planes differed between P and NP for eccentric and concentric contractions during both internal and external rotation; therefore, separate MANOVA models were utilized in each analysis under the constraint that a positive non-zero torque value was recorded. Results. Isokinetic indices of T, TA, TV, and TVA significantly predict group membership in either the P and NP groups for concentric IR and eccentric IR and ER when the torques are relative to body weight. Conclusion. The results of this study suggest that relative isokinetic velocity-angle-torque surfaces produced during shoulder concentric and eccentric IR and eccentric ER may be used as templates to diagnosis decrements in force production at specific angles and speeds of contraction and that these results may be used to design training and rehabilitation programs that can target the athlete's or patient's speed and/or angle-specific strength deficits.