An induced acceleration analysis of the barbell back squat

Abstract

The barbell squat exercise is performed in settings ranging from rehabilitation through to developing muscle size, strength and power. Unfortunately, the lower extremity coordination producing the squat is not clearly understood. This thesis involves three studies evaluating how lower limb joints and muscles coordinate varied squat performance. Study one-three included 13 females who performed squats at three randomized depths (above parallel, parallel, below parallel) using 85% of their 1 repetition maximum at each respective depth. In study one, performance was evaluated by estimating the individual muscle force production and the individual muscle contribution to whole body acceleration using a musculoskeletal model. In study two, performance was evaluated by estimating the individual muscle force production and the individual muscle contribution to the lower body joint accelerations using a musculoskeletal model. In study three, knee joint contact loads were estimated using an advanced musculoskeletal model. Because muscles can accelerate all joints in the body, including a joint that it does not span, musculoskeletal models are necessary to determine muscle function. Varied coordination indicates that depth and load specificity is important and should be taken into consideration when programming based on the status and goals of the individual.