以慣性感測器測量疲勞前後跳躍動作著地時足部變化

Abstract

目的：利用陀螺儀了解疲勞前後跳躍著地時足部動作參數的變化。方法：本實驗招募12名健康女性，在熱身後收取3次疲勞前下蹲跳數據後進行疲勞誘發運動處理程序，達到疲勞後收取3次疲勞後下蹲跳數據。利用動作分析系統了解著地瞬間踝關節角度並用慣性感測器了解著地瞬間加速度值與蹠骨動作角速度值及著地緩衝期加速度與角速度第一極值與傾角變化量，並以皮爾森相關係數了解陀螺儀及動作分析系統測得之蹠骨角速度值的相關性及魏克生符號檢定比較疲勞前後的結果。結果：著地緩衝期中，慣性感測器與動作分析系統測得之蹠骨角速度值之相關性在三個平面動作上皆有高度相關 (背屈/蹠屈：r=0.977；內翻/外翻：r=0.993；內收/外展：r=0.956)。疲勞後著地瞬間踝關節外展角度顯著增加 (疲勞前：-9.39±5.48度，疲勞後：-11.80±4.32度；p=.033)、前後方向加速度值由向前顯著改變為向後(疲勞前：-0.25±0.46 G，疲勞後：0.25±0.69 G；p=.033)且外翻角速度顯著增加 (疲勞前：-57.20±45.20度/秒，疲勞後：-118.68±52.66度/秒；p=.016)。著地後的向外側的加速度極值 (疲勞前：-0.80±0.27 G，疲勞後：-1.07±0.23 G；p=.016)及外翻角速度極值 (疲勞前：-78.92±33.73度/秒，疲勞後：-127.33±50.60度/秒；p=.050)顯著增加，緩衝期的外翻角度變化量顯著增加 (疲勞前：-0.76±5.91度，疲勞後：-4.44±4.72度；p=.021)。結論：放置在足部的慣性感測器可偵測到疲勞前後足部動作變化，而足部外翻角速度的變化可發展為疲勞指數的參數。Purpose: To investigate if IMU is suitable to measure the biomechanical changes of foot after fatigue and find the parameter of foot fatigue index when landing. Methods: There were 12 female subjects recruited in this study. Foot kinematic parameters were collected by accelerometer, gyro sensor, and 3D motion analysis system. Pearson’s correlation coefficient was used to assess the correlation between the data of angular velocity collected from gyro sensor and motion analysis system, and the Wilcoxon Signed Ranked Test was used to compare the data before and after a fatigue protocol. Results: There were significant correlations between the data of angular velocity collected from gyro sensor and motion analysis system. When landing, ankle abduction angle and angular velocity in the eversion increased significantly after a fatigue protocol, and the acceleration changed from anterior to posterior after a fatigue protocol. The first peak value of acceleration after landing was significantly increased in lateral axis after a fatigue protocol. The first peak value of angular velocity in the eversion after landing was significantly increased, and it was also changed in dorsiflexion/ plantarflexion and adduction/abduction, but not significantly after a fatigue protocol. Inclination angle in the eversion was significantly increased, and the others were changed but not significantly after a fatigue protocol. Conclusion: The IMU on the foot could detect the biomechanical changes after fatigue, and the changes of angular velocity in eversion which is detected from IMU could be used as one of the parameter of foot fatigue index.