不同頻率連續垂直跳對下肢勁度的影響

Effects of hopping with different frequencies on leg stiffness

研究的目的探討5種不同頻率（1.5 Hz、2.1 Hz、3.0 Hz和最大高度頻率和自選頻率）連續垂直跳對下肢勁度和關節角勁度的影響。以6名大學籃球隊男性（年齡：21.5±1.9歲|身高：188.5±4.6公分|體重：81.8±4.5公斤）為受詴者。實驗使用10台Vicon Motion System紅外線攝影機（250Hz）、2塊KISTLER測力板（1000Hz）和Vicon Nexus軟體同步擷連續垂直跳動作的運動學及動力學參數，並使用Visual 3D軟體結合人體肢段參數進行計算，所得資料使用SPSS統計軟體進行重複量數單因子變異數分析，顯著水準為α＝.05，以LSD法進行事後比較。研究結果顯示在著地期間連續垂直跳動作隨著頻率的增加，著地時間、空中時間、重心位移和下肢各關節角位移也隨著減少。在最大高度頻率垂直跳動作期間，有較大的最大反作用力。在3.0 Hz連續垂直跳動作期間，且有較大的下肢勁度和踝關節角勁度。隨著頻率增加，著地時受詴者的髖、膝關節比較伸直。故在評估不同頻率連續垂直跳動作的下肢勁度時，人體可以透過踝關節角勁度來調節，獲得較佳的運動表現。

The purpose of this study was to investigate how humans adjust leg stiffness over a range of hopping frequencies. Six male basketball subjects performed in place hopping on two legs (age: 21.5 ± 1.9 years| height: 188.5 ± 4.6 cm| weight: 81.8 ± 4.5 kg). They were instructed to hop in place at five frequencies (1.5, 2.1, and 3.0 Hz, perform hopping with maximal effort and Self-selected frequencies). Ten Vicon Motion System cameras (250Hz), two Kistler force plates (1000Hz) and Vicon Nexus software were used simultaneously to capture kinematic and kinetic variables of hopping. Visual 3D software was used for calculations. A one-way repeated-measure ANOVA was performed for statistical analysis and LSD post-hoc were adopted to analyze the statistical difference with an alpha level of .05. The results showed that contact time, air time, COM displacement, hip and knee angular displacement decreased with an increase in hopping frequency. At the 3.0 Hz hopping frequency, there were greater leg stiffness and ankle stiffness. The subject's hip and knee joints are straighter with increased hopping frequency during landing. These results suggest that over the range of hopping frequencies we evaluated, humans adjust leg stiffness by altering ankle stiffness. Therefore, when evaluating the leg stiffness of hopping at different frequencies, the human body can be adjusted through the ankle joint stiffness to obtain better exercise performance.