下肢肌群疲勞對動態姿勢穩定的影響

Abstract

目的：藉由不同的生物力學參數來比較下肢肌群疲勞與不同方向躍起著地對動態姿勢穩定的影響。方法：12名受試者(24±0.9歲, 172.7±3.6 公分, 70.6±8.3 公斤)皆需進行不同方向（前、斜、橫）的雙腳起跳以及支撐腳單腳著地，騰空時需以雙手觸摸目標物（50%最大垂直跳高度），著地時雙手則置於腰部兩側，並維持三秒鐘的姿勢穩定，若上述動作無法完成即算失敗。誘發性疲勞測驗為進行連續重複的深蹲和墊腳尖的動作並搭配柏格運動自覺量表來界定疲勞。結果：在不同方向的躍起著地時，前跳在著地後會產生較大的髖關節和膝關節屈曲角度以及較小的踝關節背屈角度，橫跳在著地後會產生較小的髖關節和膝關節屈曲角度以及較大的踝關節背屈角度。在疲勞前後的躍起著地時，疲勞後髖關節和膝關節的最大屈曲角度會比疲勞前還小。結論：在不同方向的躍起著地的比較，進行橫跳方向的著地會使用較多的踝關節策略，前跳則使用較多的髖關節策略，而斜跳則是髖關節和踝關節策略都有使用到。在疲勞前後躍起著地的比較，較小的髖關節與膝關節的屈曲角度是為了要快速的維持姿勢的穩定。

Purpose：The aim of this study was to analyze biomechanical parameters on dynamic postural stability which associated with different jump-landing directions when lower extremity muscles were fatigued. Methods：12 healthy subjects (24±0.95years old, 172.7±3.6 cm, 70.6±8.3 kg) were recruited for this study. All subjects required to jump with double-leg at three different directions (forward, diagonal and lateral) and landed with single-leg (supporting leg only). During jump-landing task, subjects were asked to touch an object which was placed at 50% of their maximum jumping height with both hands. When landed with single-leg, subjects were asked to maintain their balance for 3 seconds. If the trial which the subject was unable to perform requirements above, it would be considered as a ‘failed trial’. Fatigue protocol included repeated squat and toe-raised with one third load of each subject’s body weight. The Borg rating of perceived exertion (RPE) was used to assess the level of muscle fatigue (level 17). Results：Greater hip flexion angle, knee flexion angle and smaller ankle plantarflexion angle were found during forward jump-landing protocol. Smaller hip flexion angle, knee flexion angle and greater ankle plantarflexion angle were found when performing lateral jump-landing protocol. However, when muscle fatigued, the peak hip flexion angle and knee flexion angle were decreased when compared to control trials. Conclusions：When performing later jump-landing protocol, our body might rely on more ‘ankle strategy’ during landing period. ‘Hip strategy’ may be used when performing forward jump-landing protocol. However, both strategies could be used when proceeding diagonal jump-landing protocol. On the other hand, smaller flexion angle occurred when lower extremity muscle fatigue, we suggest that our body tried to maintain postural stability with a stiffer body posture after jump-landing protocol.