The comparative effectiveness of isokinetic and isotonic strength trainings on quadriceps maximum power

Abstract

The present study compares the effectiveness of isokinetic and Isotonic exercises on maximum power of quadriceps in 45 healthy young males. The subjects were randomly assigned into three groups (n=15): Group A- Isokinetic group, Group B- Isotonic group, Group C-Control group. Maximum power of quadriceps at velocities of 220°/sec, 160°/sec 100°/sec and 40°/sec was tested twice with a gap of 4 weeks using isokinetic dynamometer. The isokinetic protocol consisted of one set of ten repetitions at velocities of 220°/sec, 160°/sec, 100°/sec, and 40°/sec each while, the Isotonic protocol included three sets of 10 repetitions at 50% 10 RM, 75% 10 RM and 100% 10 RM. Each exercise protocol was performed thrice a week for four weeks with 1 minute rest interval. The subjects in the control group were not prescribed any kind of exercise training. Paired t-test showed significant changes at 220°/sec (t=7.15, p<0.001), 160°/sec (t=7.54, p<0.001), 100°/sec (t=9.24, p<0.001) and 40°/sec (t=7.59, p<0.001) in Group A, also at 2200/ sec (t=8.56, p<0.001), 160°/sec (t=8.80, p<0.001), 1000/ sec (t=10.11, p<0.001) and 40°/sec (t=10.50, p<0.001) in Group B and non-significant changes in Group C. Post-test One way ANOVA revealed significant changes at 220°/sec (F= 10.85, p<0.001), 160°/sec (F=16.96, p<0.001), 1000/ sec (F=14.60, p<0.001) and 40°/sec (F=14.00, p<0.001). Isotonic exercises were found to be more effective than Isokinetic exercises in increasing the maximum power at high velocity.