Impact of performing heavy-loaded barbell back squats to volitional failure on lower limb and lumbo-pelvis mechanics in skilled lifters

ABSTRACT

A common practice in resistance training is to perform sets of exercises at, or close to failure, which can alter movement dynamics. This study examined ankle, knee, hip, and lumbo-pelvis dynamics during the barbell back squat under a moderate-heavy load (80% of 1 repetition maximum (1RM)) when performed to failure. Eleven resistance trained males performed three sets to volitional failure. Sagittal plane movement dynamics at the ankle, knee, hip, and lumbo-pelvis were examined; specifically, joint moments, joint angles, joint angular velocity, and joint power. The second repetition of the first set and the final repetition of the third set were compared. Results showed that while the joint movements slowed (p < 0.05), the joint ranges of motion were not altered There were significant changes in most mean joint moments (p < 0.05), indicating altered joint loading. The knee moment decreased while the hip and lumbo-pelvis moments underwent compensatory increases. At the knee and hip, there were significant decreases (p < 0.05) in concentric power output (p < 0.05). Whilst performing multiple sets to failure altered some joint kinetics, the comparable findings in joint range ofmotion suggest that technique was not altered. Therefore, skilled individuals appear to maintain technique when performing to failure.