The purpose of this study was to examine the effect of five days of creatine loading on the isokinetic properties of the knee extensors in male athletes. Thirty active, healthy subjects voluntarily participated in the study and were divided into three groups of 10 subjects; that is, creatine, placebo, and control. First, the isokinetic parameters of the knee extensors of the preferred leg were measured by Biodex isokinetic dynamometer at the speed of 180 d/s. These parameters include peak torque, time to peak torque, rate of peak torque development, and peak power. Creatine supplementation was conducted for five days, 20 grams daily in four consecutive meals. For the placebo group, glucose supplementation was given in the same way as the creatine. Afterwards, the parameters of knee extensors were measured again. Mixed 2 3 analysis of variance and Tukey’s post hoc tests were applied for data analysis. The results showed that after creatine loading, peak torque increased by 10.5% ( 0.05), rate of peak torque development increased by 26% ( 0.05) peak power increased by 11% ( 0.05), and time to peak torque decreased by 12% ( 0.05). In conclusion, five days of creatine loading significantly improved the mechanical properties of the knee extensors as well as most of the properties of isokinetic contractions.
