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EFFECTS OF SEX AND LIMB ON ISOKINETIC QUADRICEPS CONCENTRIC TO HAMSTRINGS ECCENTRIC WORK RATIOS

Abstract

BACKGROUND: Several mixed isokinetic ratios of eccentric knee flexor (KF) peak torque (PT) to concentric knee extensor (KE) PT have demonstrated to aid in predicting hamstring injury. As PT is based upon the single maximal value recorded through a range of motion, considering the sustainability of PT production through the ROM might provide additional insight by measuring the average work values. PURPOSE: To explore mixed average work per repetition ratios (AWPRR) between test velocities, limbs, and sexes. METHODS: Following a standardized warm up, 20 healthy and physically active women (23.3±3.5years) and 20 men (25.3±3.0years) performed concentric (c60 and c240 degrees·s-1) and eccentric (e30 and e120 degrees·s-1) knee flexion and extension protocols using both the dominant and non-dominant limbs. The order of limb and test mode were randomized. The average work for each repetition from each set was used to create three eccentric hamstring to concentric quadriceps ratios: e30/c240, e120/c240, and e30/c60. A limb, by sex by ratio analysis of variance was used for statistical analysis. RESULTS: While there were no significant limb or sex effects on the work ratios based on the interactions and main effects (P>.296), there were significant differences between the ratios (P<.001). Post hoc analyses revealed the e120-c240 (107.3±28.9%) to be significantly greater than e30-c60 (P<.001, d=.78) and e30-c240 (P<.001, d=.60). Additionally, the e30-c60 (85.8±18.9%) was significantly greater (P=.001, d=.26) than the e30-c240 (78.1±21.7%). CONCLUSION: AWPRR were similar between the limbs and sexes in healthy individuals. This provides clinicians with some additional preliminary criteria for potential injury screening and rehabilitation discharge (i.e., conducting bilateral comparisons, and unilateral ratios). The ratio differences revealed are consistent with the eccentric and concentric force-velocity relationships. Future research is suggested to consider the efficacy of AWPRR for hamstring injury and reinjury risks.

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