Analysis of Single and Double Leg Squats in Professional Sports People Using Inertial Measurement Units
The purpose of this study is to examine ankle, knee and hip movement in the sagittal plane and the knee movement in the coronal plane of professional sports people when performing both single and double-legged squats. The use of IMUs enabled accurate measurements in a routine training environment, with the potential for immediate feedback of the data to the trainer/coach/ player. One hundred and two football and fifty nine rugby players performed double leg squats and single leg squats on both legs. IMUs were mounted on the pelvis, thigh and calf of each leg and data captured when the players performed the squats at their training ground. The mean and standard deviation values were calculated and differences of flexion angles between footballers and rugby players were analysed using multi-variate analysis of variance (MANOVA) using SPSS. The results for the double leg squat gave the average hip, knee and ankle angles of 107°, 98° and 25° respectively for both rugby and football players. For the single leg squats there was no difference between the average hip, knee and ankle flexion on the dominant or non-dominant side. In the coronal plane the majority of the knees moved to a varus position of 15˚ and 13˚ for the non-dominant and dominant legs respectively. The conclusions are that there is minimal difference between football and rugby players when performing squats. However, few players are symmetrical and the variation between players is high, both in the sagittal and coronal plane. The practical application would be to measure players during training to identify weaknesses, set an exercise programme and monitor rehabilitation.