Kinematic characteristics of national and college level weightlifters during snatch technique using wearable inertial sensors

Weightlifting performance is strongly dependent on technique, explosive strength, and flexibility. There are two major lifts involved in competition: the snatch and the clean and jerk, where the snatch is the most technical component of the weightlifting competition. Most of the technical analyses have been done using either video analysis or conventional optical camera systems. However, few studies have investigated the kinematic characteristics of the weightlifters using the inertial measurement unit (IMU) sensors. In this study, we investigated the joints kinematics of the trunk, shoulder, elbow, hip, and knee as well as the main phases during the snatch technique for national and college level weightlifters using multiple IMU sensors. Seven female Mongolian weightlifters (3-national level and 4-college level) participated. Each participant performed three snatch attempts at 70 % of one-repetition maximum. The joints angles were calculated using 3-axis acceleration and 3-axis gyroscope data from the IMU sensors based on the Madwick filtering. The six main phases of the snatch technique were defined based on knee flexion. All parameters were compared between the national and college level weightlifters. The national team showed a higher elbow range of motion and a greater extension of the hip and knee joints at the second pull than college-level athletes. In addition, the college team does not exhibit the transition phase and the proportion of the turnover phase was larger. This study provides a kinematic difference between the two different level weightlifters, which may help coaches and athletes to improve training strategy and weightlifting performance.