Rate Of Velocity Development Positively Correlates With Quadriceps Cross Sectional Area

Abstract

Although isokinetic dynamometers purport to move a limb at a constant speed, the tested limb achieves a variety of velocities through the range of motion. To perform an isokinetic movement, the tested limb must overcome its inertia through increased torque until the limb angular velocity equals the velocity prescribed by the isokinetic device. The rate of change of velocity over time necessary to achieve the prescribed angular velocity is known as RVD. The purpose of this study was to determine the relationship between muscle cross-sectional area (CSA) and RVD of the quadriceps in recreationally trained males during isokinetic concentric knee extension. On two separate visits, 57 male (age 23.67 ± 2.17 years; height 178.39 ± 7.58 cm; mass 80.49 ± 15.33 kg) subjects performed three maximal concentric knee extension repetitions of their dominant leg on an isokinetic dynamometer at 15 randomized angular velocities (30-500°·s−1). Investigators calculated muscle cross sectional area (CSA) via the Housh equation using skinfold and circumference of the anterior thigh. A Pearson correlation calculated the relationship between muscle CSA of the quadriceps and RVD. Muscle CSA of the quadriceps significantly (p < 0.05) correlated with RVD measures from 90°·s−1 through 500°·s−1 with r values increasing from 0.33 to 0.56, respectively. However, no significant correlation existed between muscle CSA and RVD at speeds of 30°·s−1 and 60°·s−1. Muscle CSA significantly correlated with RVD at the tested angular velocities between 90°·s−1 through 500°·s−1 with an increasing trend. Consequently, increased muscle quantity may lead to increased RVD during an isokinetic knee extension exercise. Therefore, training at high velocities and with sufficient loads to induce muscle hypertrophy might improve performance during high velocity dynamic movements. Training designed to increase muscle CSA might increase RVD during isokinetic knee extension movements. Increasing RVD (and therefore reducing time to achieve a desired velocity) might represent a desirable adaptation for any dynamic movement.