Effect of pre-fatigue method by leg extension exercise on recruitment state of synergists in thigh muscles during leg press exercise

Abstract

The purpose of this study was to examine the recruitment state of synergistic muscles in the thigh muscles in leg press exercise with and without pre-fatigue method using transverse relaxation time (T2) on muscle functional magnetic resonance imaging (MRI). Nine healthy male subjects performed the following two types of exercise trials on separate days: 1) 5 sets of a leg press exercise with pre-fatigue method, which consisted of 3 sets of knee extension exercise (LP-pre), 2) 5 sets of a leg press exercise without pre-fatigue method (LP). Both exercises were performed at a load of 80% one-repetition maximum. Before and immediately after exercise, T2-weighted MR images of right-thigh were taken to calculate T2 values of twelve-thigh muscles. The T2 values for quadriceps femoris muscle and hamstrings in LP increased significantly after the exercise, except in the adductor magnus, adductor longus, gracilis, and sartorius. In contrast, the T2 values for all of the twelve-thigh muscles in LP-pre increased significantly after the exercise. Upon comparison between the two trials, the percentage changes in T2 value for the adductor magnus, adductor longus, and sartorius in LP-pre were found to be significantly greater than those in LP. These results suggest leg press exercise with pre-fatigue method may be effective to increase activity of synergistic muscles in thigh muscles during exercise.