Functional Isokinetic Strength Ratios in Baseball Players With Injured Elbows

in Journal of Sport Rehabilitation
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Elbow injuries are widely reported among baseball players. The elbow is susceptible to injury when elbow-flexor and -extensor forces are imbalanced during pitching or throwing. Assessment of muscle-strength ratios may prove useful for diagnosing elbow injury.


The purpose of this study was to assess the relationship between the elbow-flexor and -extensor functional isokinetic ratios and elbow injury in baseball players.


Retrospective study.


Biomechanics laboratory.


College baseball players with (n = 9) and without (n = 12) self-reported elbow pain or loss of strength were recruited.

Intervention and Main Outcome Measures:

Trials were conducted using a dynamometer to assess dominant-arm flexor and extensor concentric and eccentric strength at angular velocities of 60° and 240°/s. Functional isokinetic ratios were calculated and compared between groups.


Regression analysis revealed that a ratio of biceps concentric to triceps concentric strength greater than 0.76 (the median value) significantly predicted elbow injury (P = .01, odds ratio of injury = 24). No other ratios or variables (including position played) were predictive of injury status.


These findings suggest that the ratio of biceps concentric to triceps concentric functional strength strongly predicts elbow-injury status in baseball players. Assessment of this ratio may prove useful in a practical setting for training purposes and both injury diagnosis and rehabilitation.

Y-C Lin, Chieh, and Chou are with the Dept of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital, Gueishan Township, Taiwan. Thompson is with the Dept of Social Sciences, University of California, Santa Cruz. Kung is with the Dept of Sports Training Science—Balls, National College of Physical Education and Sports, Kueishan, Taiwan. J-C Lin is with the Graduate Institute of Sport Coaching Science, Chinese Culture University, Taipei, Taiwan.