| Summary: | 碩士 === 國立臺灣體育運動大學 === 體育研究所 === 99 === Barbell squat is an important strength training to enhance muscle strength in weightlifters. Previous studies investigated different techniques and loadings in barbell squat; moreover, biomechanical evidences were proved in the sagittal plane. Besides, the previous researches also documented that it induced greater joint power throughout rebounding technique in bench press. However, the effect of rebounding technique which influences biomechanics of lower extremities is still unknown in barbell squat. Objectives-The purpose of this study was to estimate the full three-dimensional biomechanical parameters of lower limbs during a barbell squat with different techniques and loadings (60%, 70%, 80% of 1 RM). Methods-Thirteen male weightlifters (age: 20.0±2 years old; body height: 170.7±6.8; body weight: 88.8±20 kgw) from college weightlifting team members were recruited in this study. VICON motion analysis system (VICON Motion System Ltd., UK) was used to collect the trajectories of the reflective markers at 250 Hz. Two force plateforms (Kistler Instrumente AG, Switzerland) were synchronized with the motion analysis system to collect ground reaction forces and moments at 1000 Hz. Each subject was asked to perform the barbell squat using different weights (60%, 70%, 80% of 1 RM) combined with different rebounding skills (with/without rebounding). The paired-t test and repeated measure ANOVA were be used to analyze the effects of different weights combined with different techniques in biomechanical data during barbell squat. Results-The peak anterior/compression/medial forces of ankle joint, the peak knee joint force toward anterior direction, and peak hip joint force toward posterior direction were significantly greater in barbell squat with rebounding comparing to the skill without rebounding. The peak medial force of knee joint and peak anterior/lateral forces of hip joint were increased with lifting weights in non-rebounding skill. There were peak anterior/medial/compression forces of ankle joint, peak anterior and compression forces of knee joint, and peak anterior/posterior/lateral/compression forces of hip joint increasing by rebounding skill with lifting weights. The knee flexor moment was significantly increased with lifting weights both in rebounding and non-rebounding skills. Conclusion- These results suggest that knee flexor play an important role for generating power in barbell squat exercise. The adequate strength training is needed to enhance muscle strength in lower limbs in weightlifters.
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