Is the rear foot elevated split squat unilateral? An investigation into the kinetic and kinematic demands

The purpose of the study was to determine the unilateral nature of the rear foot elevated split squat (RFESS). Specifically, the production of force by the rear leg was examined to better understand its role, if any, toward successful completion of the exercise. Male volunteers were recruited, (n = 26, age = 23.8 ±4.6 years, mass = 88.1 ±10.7kg, height = 1.79±0.1m), who were recreationally trained and engaged in a structured strength and conditioning program including both bilateral and unilateral exercise and had at least two years supervised training experience. Subjects participated in an incremental five repetition maximum protocol, following familiarisation. Kinetic data was recorded via two independent force plates, one integral to the floor and the second mounted on top of solid weightlifting blocks. Kinematic data was captured through three-dimensional motion analysis. A total of 715 repetitions were analysed, the mean contribution of the lead foot to total vertical force production was 84.36 ±3.6%. An almost certainly small positive correlation (rho = 0.25, CI 0.18, 0.33), was found between percentage of force produced by the lead foot, with increasing exercise intensity. A most likely trivial, non-significant correlation (rho = -0.01, CI -0.09,0.06) with rear foot force production, representing the mass of the rear leg. Data from this study does not indicate that the rear foot contributes to the kinetic demands of the exercise and therefore suggests that the RFESS is a valid unilateral exercise.