The effects of fatigue on the knee flexor\extensor ratio
Research focused on identifying risk factors of injury has included the flexor/extensor ratio. Studies have yet to examine the effects of fatigue on this ratio. The purpose of the present study was to compare the knee flexor/extensor ratio before and after a fatiguing task to determine if the ratio is altered. Twenty- seven (N=27, male=20 and female =7) healthy high school varsity and collegiate athletes (ages 15-24 yrs, mean 19.2 yrs.) participated in the study. Individuals' dominant leg knee flexor and extensor muscles were tested with the Cybex 340 dynamometer at speeds of 60, 180 and 300°/second. The flexor/extensor ratio was calculated by the Cybex 340 computer. Subjects were then fatigued by having them run against a resistance and immediately post-tested on the Cybex 340. A significance level of 0.05 was used for all hypothesis testing. A 2X3 ANOVA with repeated measures was used to compare pre-test verses post-test values. ANOVA procedures were used to compare effects of speed within subjects. The analysis of variance revealed a significant difference between pre- and post-test (p= 0.027), indicating fatigue does have an effect on the flexor/extensor ratio. The dependent t-test reveals a significant change in the flexor/extensor ratio only at 60°/second. The ANOVA showed a significant difference (p<0.05) in ratios when comparing effects of speed. The flexor/extensor ratio increased as the speed increased. The findings of the present study indicate that fatigue does have an effect on the flexor\extensor ratio. However, there was a great individual variance between subjects.