MEASUREMENT OF MULTI-JOINT LOWER EXTREMITY EXTENSION POWER USING A CLINICALLY APPLICABLE LEG PRESS TOOL: THE CONCURRENT VALIDITY

Abstract

Multi-joint leg extension power, a critical determinant of physical functioning, declines with age. Exercise can slow this decline and is usually prescribed based on maximum power. Currently available tests to assess maximum power can be unsafe for the elderly. This study assessed the concurrent validity of leg extension power measured with a new leg press + IMU system compared to that obtained using a squat jump on force plates. The load in each test equaled body weight. Bland-Altman analysis demonstrated a significant systematic difference, with the squat jump generating higher power in 21 young adults. The magnitude of difference was greater for 10 participants who used a countermovement in the squat test, which is known to increase power output. The difference in power between the 2 systems was negligible after accounting for the higher load created by additional weight of the legs in the leg press + IMU system.