Effects of various rest intervals on isokinetic knee extension and flexion strength.

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Johnson, Timothy
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Middle Tennessee State University
This study investigated the effects of various rest intervals on isokinetic knee extension and flexion strength. Thirty male subjects, age 24.23 {dollar}\pm{dollar} 4.80 years, height 181.74 {dollar}\pm{dollar} 7.44 centimeters, weight 88.4 {dollar}\pm{dollar} 16.05 kilograms, and body fat 18.07 {dollar}\pm{dollar} 7.66 percent, were tested on a Cybex isokinetic dynamometer under three different rest interval treatments. The treatments consisted of a one-, three-, or five-minute rest interval administered between four sets of five maximal repetitions of isokinetic extension and flexion exercise at a controlled velocity of sixty degrees per second. All subjects visited the Human Performance Laboratory on four separate occasions. The initial visit was to measure physical characteristics and acquaint each subject with the Cybex by a bilateral comparison of knee extension and flexion strength. This bilateral test was used to determine the dominant limb. All successive visits were conducted on non-consecutive days with the rest interval treatment being randomly assigned and the dominate limb used for all further testing. Multivariate, univariate, and pair-wise contrasts were conducted to analyze the data. A significant difference (p {dollar} less than {dollar}.05) was obtained between the one-minute and three-minute treatments and between the one-minute and five-minute treatments. There were no differences between the three-minute and five-minute treatments. The Pearson Correlation Coefficients for fat-free body weight and the strength measurements revealed significant relationships (p {dollar} less than {dollar}.05). Fat-free body weight was significantly correlated with 47 of 48 strength measurements. It is concluded that a three-minute rest interval allowed the muscle sufficient time for recovery after five isokinetic knee extension and flexion repetitions.