Purpose The purpose of this study was to identify the lower extremity muscles length change according to the increase of the weight during snatch. Also, through the muscle contraction velocity analysis, it is necessary to identify muscles that require rapid muscle contraction. Methods The subjects were 10 national weight-lifters. Their mean age was 29 ± 3.84 yrs, body weight 71.3 ± 16.04 kg, height 1.63 ± 0.07 m, and the highest recorded height 128 ± 36.30 kg. Experiments were performed during the snatch to 70%, 80%, and 90% of the individual highest records. The analysis variables were the lower extremity angle, angular velocity, muscle length and muscle contraction velocity and were calculated by biomechanical modeling. Statistical analysis was performed with a repeated measure with one-way ANOVA to analyze the difference between the increase weight (70%, 80%, 90% of peak) and the dependent variable (angel, angular velocity, muscle length and muscle contraction velocity). Results According to the results of the study, there was no statistical difference in angle, angular velocity and muscle length with increasing weight. However, in the comparison of the muscle length, muscle length of the vastus medialis, vastus lateralis, biceps femoris, rectus femoris were statistically higher than other muscles. Also muscle contraction velocity of the rectus femoris, biceps femoris, vastus medialis, vastus lateralis, rectus femoris were statistically higher than other muscles. Conclusion In the snatch, the dominant muscles were the muscles around the femur, and the co-contraction of biceps femoris and great adductor muscles would contribute to improve the performance.
Purpose The purpose of the study was to perform a comparative analysis of the YANG Hak Seon technique carried out by "K" athlete with the kinematical data of "Y" athlete and propose a method to improve the YANG Hak Seon technique of "K" athlete. Method The subject recruited for the study was a male athlete from Korean national team (Age: 21, height: 1.65 m, body weight: 59.6 kg, and career: 11 years). Four high - speed cameras were used to analyze the 3D motion of the YANG Hak Seon technique performed by "K" athlete. The variables selected for analysis were the velocity of COM, displacement of COM, the rotational & torsional angle of the trunk and rotational & torsional angular velocity of the trunk. The results obtained were compared to the preexisting data of the "Y" athlete (data set from the published research). Results Firstly, the horizontal displacement of the YANG Hak Seon technique of the "K" athlete was observed to be shorter along with lower vertical displacement during landing compared to “Y” athlete. In addition, the overall horizontal velocity was low and vertical velocity was not generated which rises during the BC (board contact) phase. Although the rotational angular velocity of the trunk was lower during the BC, HC (horse contact) phase and LD (landing) phase, torsional angular velocity was higher during the LD. Conclusion In order to improve the completeness of the YANG Hak Seon technique of the K player, it is necessary to enter with a fast and low posture on the footplate during the initial phase. In the BC phase, it is essential to raise the COM simultaneously while landing on the footplate and increase the rotational angular velocity of the trunk.
