Bilateral deficit in power production during multi-joint leg extensions

Abstract

The purpose of this study was to determine the presence of the bilateral deficit both as a function of overall and individual joint power. Most studies addressing the deficit have assessed force; however, in most sporting events maximal power is more important than maximal force production. To address this, in the current study we assessed the bilateral deficit for multi-joint movements as measured by overall lower extremity and individual joint power. We assessed power production using an isokinetic machine permitting both unilateral and bilateral leg extensions. Several significant effects and interactions between the contraction type (unilateral, bilateral, alternating unilateral), side of the body, lower extremity joint, and percentage of a 1-RM load were revealed. All interactions were between the lower extremity joints (hip, knee, ankle) and involved the contraction protocol (P=0.001), the percentage of 1-RM load (P=0.0002), and the side of the body (P=0.0003). Taken together, the results indicate that the bilateral deficit is manifested using a measure of power, but more importantly, the deficit has differential implications based on the overall resistance, and various joints involved in the movement. In conclusion, a reduction in power generation was evidenced for both simultaneous contractions of the leg extensors as well as reciprocal contractions. With reduced contributions from the knee joint during bilateral and reciprocal contractions, combined with past research demonstrating differential activation of mono-articular knee joint muscles, evidence for reduced contributions from the peripheral nervous system are suggested based on the results of this study.