The effects of unilateral concentric isokinetic training on muscle cross-sectional area

The purposes of this study were to (1) determine the effect of concentric isokinetic training on the cross-sectional area (CSA) of selected extensor and flexor muscles of the forearm and leg, (2) examine the potential for preferential hypertrophy of individual muscles within a muscle group, (3) identify the location (proximal, middle, or distal) of hypertrophy within an individual muscle, and (4) determine the effect of unilateral concentric isokinetic training on muscular strength and hypertrophy in the contralateral limb. Thirteen male college students (X $\pm$ SD age = 25.08 $\pm$ 6.13) volunteered to perform six sets of ten repetitions of forearm and leg extension and flexion of the non-dominant extremities three days per week for eight weeks, using a Cybex II isokinetic dynamometer. Pre-training and post-training peak torque and muscle CSA measurements for both the dominant and non-dominant extremities were determined utilizing a Cybex II isokinetic dynamometer and magnetic resonance imaging (MRI) scanner, respectively. The results of repeated measures ANOVA analyses indicated significant (p $\u3c$ 0.01) hypertrophy in all trained muscle groups as well as preferential hypertrophy of individual muscles and at specific locations within the semitendinosus and biceps femoris muscles. The only muscle that demonstrated hypertrophy on the contralateral side was the semitendinosus at the proximal level. In addition, significant (p $\u3c$ 0.01) increases in peak torque occurred for all movements on the trained side and only leg flexion on the contralateral side