CONCENTRIC ISOKINETIC TRAINING AND HYPERTROPHY OF THE QUADRICEPS FEMORIS MUSCLES 684

Abstract

The purposes of this study were to determine the effects of unilateral leg extension concentric isokinetic resistance (CIR) training on: 1) hypertrophy at the largest anatomical cross-section (CSA) of the vastus intermedius (VI), vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) muscles in the trained and untrained limbs and 2) strength of the quadriceps femoris muscle group in the trained and untrained limbs. Sixteen untrained young adult males (X age ± SD = 25 ± 5 yrs) volunteered to serve as subjects. The subjects were divided into two groups: 1) training group (TG, n=8) and 2) control group (CG, n=8). The TG performed six sets of ten repetitions of extension of the nondominant leg at 120°·s-1 three times per week for eight weeks on a Cybex II isokinetic dynamometer. The CG did not train. Pretraining and posttraining leg extension peak torque at 120°·s-1 and the largest CSA of each muscle of the quadriceps femoris were determined utilizing a Cybex II dynamometer and magnetic resonance imaging scanner, respectively. A 4-way mixed factorial ANOVA (group × time × limb × muscle) indicated signficant(p<0.05) increases in CSA for each of the quadriceps femoris muscles(VI=4.3%, VL=4.1%, VM=0.4%, and RF=9.4%) for the trained limb of the TG. A 3-way mixed factorial ANOVA (group × time × limb) indicated significant (p<0.05) increases in peak torque for the trained (17.7%) and untrained limbs (9.3%) of the TG. The results indicated that the CIR training resulted in increased strength and hypertrophy of the trained limb, as well as a cross-training effect for strength in the untrained limb that was not accompanied by hypertrophy.