Effect of strength training on regional hypertrophy of the elbow flexor muscles

INTRODUCTION: Muscle hypertrophy is the main structural adaptation to strength training. We investigated the chronic effects of strength training on muscle hypertrophy in different regions of the elbow flexor muscles. METHODS: Eleven untrained men (21.8 ± 1.62 years) underwent magnetic resonance imaging to determine the proximal, medial, distal, and mean cross-sectional areas (CSA) of the elbow flexors. The volunteers completed 12 weeks of strength training. The training protocol consisted of 4 sets of 8-10 maximum repetitions of unilateral elbow flexion. The interval between sets was 120 s. The training frequency was 3 sessions per week. RESULTS: The magnetic resonance images verified the presence of significant and similar hypertrophy in the distal, medial, and proximal portions of the elbow flexor muscles. CONCLUSIONS: Muscle hypertrophy may be assessed using only the medial CSA. We should not expect different degrees of hypertrophy among the regions of the elbow flexor muscles. Muscle Nerve 54: 750-755, 2016.