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Thesis

A comparison of eccentric internal rotation peak torque to concentric internal rotation peak torque ratios in youth pitchers and non-pitchers

1 May 1991

Abstract

The purpose of this study was to compare eccentric internal rotation to concentric internal rotation mean peak torque ratios produced by the dominant and non-dominant shoulders of youth baseball pitchers (P) and non-pitchers (NP), The dominant arm ratio was compared with the non-dominant arm ratio within each group and between groups. Twelve pitchers and twelve non-pitchers between the ages of 11-14 years (12.3 +/- 0.92) performed 5 maximal concentric internal rotations at 90o/sec and 120o/sec and 5 maximal eccentric internal rotations at the same speeds with the dominant and non-dominant arms while seated with the glenohumeral joint at 45o abduction and 45o flexion. Means and standard deviations are given for each contraction type and speed. Comparative graphics on this data are also presented. A 2 x 2 x 3 (group x arm x speed) ANOVA was performed on the eccentric/concentric mean peak torque ratios. A group x arm interaction existed (F(1 ,44) = 4.689, Q = .0358). Post-hoc analysis revealed a significant difference at both test speeds between the dominant the dominant arm of the P and NP groups such that the NP group displayed a greater torque ratio (F (1,46) = 7.057). Also, within the P group, the non-dominant arm generated a significantly greater ratio than the dominant arm (t = 2.921, Q = ,0077), No significant difference existed between the dominant and non-dominant arm within the NP group. This data shows the existence of possible training induced strength imbalances within this population that could continue to progress and produce injury.


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