BIOMECHANICAL ALTERATIONS DURING THE SNATCH MOVEMENT AFTER REPEATED REPETITIONS

Abstract

High Intensity Weightlifting (HIW) is a style of exercise that utilizes one of the two Olympic weightlifting movements, the snatch. The majority of HIW workouts are scored by time and have a goal to do the required repetitions as fast as possible leaving very little time for rest. The sense of urgency to go as fast as possible often results in technique change throughout the workout. Little research exists on biomechanical technique alterations that may lead to injury during HIW movements. If researchers can quantify mechanical alterations after multiple lifting attempts, then they may be able to aid athletes during HIW workouts and help minimize technique alterations. Minimizing technique alterations may improve performance and reduce the risk of injury in HIW activities. The purpose of this study is to quantify the 3D biomechanical alterations in snatch movement after repeated repetitions. 17 (7 males, 10 females) recreational weightlifters completed 30 repetitions of the snatch for time. The weight used for collection was based off 60% of the participant's estimated one rep max snatch and was held constant for all 30 repetitions. Participants were allowed to take as much rest between repetitions as they desired but had the goal of completing the 30 repetitions as fast as possible. The 3 phases of interest for each lift were the start, bar at the knee level, and the catch. All 30 lifts were analyzed for each condition in each participant, however the averages of the first 3 lifts and the last three lifts were used for analysis. The kinematic variables of interest were 3D body segment angle positions and joint angular velocity at the key phases. The barbell variables of interest were peak height, peak velocity, and maximum barbell displacement. Analysis of the velocity variables revealed a significant decrease in shoulder velocity when the bar is at the knee in the frontal plane (P = 0.024*) and shoulder velocity in the catch position (P = 0.028*). Angular position variable analysis revealed a significant decrease in average shoulder angular position in the start (P = 0.039*). When the bar was at the knee there was a significant decrease in average hip angular position (P = 0.014) and a significant increase in trunk angular position (P = 0.002*). There was also a significant increase in average knee angular position in the catch phase of the snatch (P = 0.007*). Barbell variable analysis revealed that barbell maximum velocity showed a significant decrease from the first three repetitions to the last three repetitions (P = 0.000*). There was also a significant decrease in barbell maximum height from the first three repetitions to the last three repetitions (P = 0.001*). Throughout this study, results indicate that significant alterations of technique were present in this repeated lifting task, however participants displayed individualized approaches to their technique modifications. Moving forward, coaches should instruct athletes to limit technique alterations that are highly correlated with injury risk.