Lower Extremity Joint Power Production during Olympic Weightlifting Exercise

Abstract

Athletic performance can be maximized with power training. Olympic weightlifting exercises are particularly beneficial due to biomechanical similarities to a number of sporting events and the fact that these exercises result in power outputs greater than other modes of exercise. PURPOSE: To determine the optimal loads for mechanical power production of individual lower extremity joints during the pull-phase of the clean exercise. METHODS: Ten weightlifters (BW = 92.5 kg, 1-RM= 113.1 kg) performed five sets of 1–3 repetitions of the clean exercise. However, only the first lift of each set was analyzed. Loads lifted represented 35, 50, 65, 75, and 85% of the subject's 1-RM. Three-dimensional lower extremity joint kinematics were collected with a VICON Motion Capture System at 250 Hz while bilateral ground reaction forces were collected using Kistler force plates at 1250 Hz. Joint moments were determined using an inverse dynamics approach. Sagittal plane joint powers were calculated for three joints of the right lower extremity (hip, knee, and ankle). Comparisons between loads and across joints were made using Student's t-test. Statistical significance was set at □ = .05. RESULTS: Mechanical power output at the hip was significantly greater than at the knee or ankle, while no major differences were found between the latter two. Hip and ankle joint power did not change significantly after reaching 50% and 65% of 1-RM, respectively. Knee joint power output achieved a maximum at 75% of 1 -RM, which was significantly different from all other loads (Table 1).Table 1: Peak power output at the lower extremity joints for 5 magnitudes of clean lift. All values are given in Watts/kg ± SD.CONCLUSIONS The optimal load for lower extremity power production varies depending on the respective joint. Power outputs at the hip and ankle become relatively constant as higher lifting intensities are approached whereas the knee joint displays a distinct maximum at 75% of 1 -RM. This information should be considered when designing resistance training programs aimed to improve power production of the lower extremity.