Comparative dynamic analysis of the effect of a well-performed technique of the snatch on the knee joint

Abstract

The Snatch is part of the sport of weightlifting currently used in recreational strength training workouts, and it has shown a high potential of musculoskeletal injury risk of lower limbs due to poor executions of the exercise. The main purpose of this study is to present a comparative dynamic analysis of motion on cross fitters of the same gender but of different sport level (beginner and professional), based on position and force data obtained from a capture motion analysis using the “Helen Hayes” protocol. The dynamic reactions on the knee joint of two women performing the Snatch with and without a weighted bar are presented for the three phases of a well-performed technique. Subjects were instrumented with “Moticon” force sensors (Sensing Foot Dynamics) operating at 50 Hz; four cameras “OptiTrack Prime 13” at 100 Hz with passive markers were used to provide the input parameters of the dynamic analysis. Information found indicates that there is a 6.11% increase in the reaction forces supported by the knee joint of the beginner compared to the one of the professional crossfitter. However, power generation along the complete motion of the Snatch is 171.81% higher for the beginner during the catching phase when using a not weighted bar and 5.08% higher for the professional women during the second pull when using the bar.