不同踩踏頻率及負荷對自行車踩踏下肢對稱性之影響

目的：實驗一：探討不同踩踏頻率 (75、90、105 rpm) 及負荷 (150、200、250 watt)，對下肢運動學、肌肉活化之對稱性影響；實驗二：探討不同踩踏頻率 (75 rpm及90 rpm)及疲勞程度 (10%，30%，50%，70%，90%)對運動學、肌肉活化之對稱性影響。方法：本實驗募集10位具有自行車騎乘習慣（身高171.8±9.3公分、體重67.1±12.0公斤、年齡21.7±2.5歲）及從事自行車運動1年以上之受試者，透過動態動作分析系統、肌電圖及慣性測量感應器比較實驗一：不同踩踏頻率及不同負荷之下肢對稱性影響；實驗二：不同踩踏頻率及疲勞程度之下肢對稱性影響。本研究使用重複量數二因子變異數分析，顯著水準訂為α = .05。結果：實驗一:騎乘最佳踩踏頻率及負荷，為105 rpm，250 watt，使股二頭肌、踝關節內翻及加速規ACC Y-max對稱性較高。實驗二:疲勞時間30%及50%下，騎乘最佳踩踏頻率為75 rpm，腓腸肌活化、膝關節內翻角度、ACC X-min、Z-min及陀螺儀GYR X-min對稱性較高，然而疲勞前後，90 rpm為最佳踩踏頻率，使下肢額狀面及水平面穩定性及對稱性較高。結論：較高的踩踏頻率及負荷會有較佳對稱性。另外，在長時間騎乘下，不同疲勞時間下，可以採用不同踩踏頻率之騎乘策略，已達到最佳踩踏對稱性。

關鍵字

不對稱性；疲勞；增量測試

並列摘要

Purpose: This study considers aspects of：1. Different pedaling cadence and loads to symmetry in lower limb kinematic and muscle activation. 2. Different pedaling cadence and fatigue level to symmetry in lower limb kinematic and muscle activation. Methods: Ten participants with more than one year of cycling habits enrolled in this study (height：171±9.3 cm；weight：67.1±12.0 kg；age：21.7±2.5 years old). 3D motion analyzing system, electromyography and inertial measurement unit (IMU) were instrumented in the study to capture fatigue-induced motion characteristics under the combination of different pedaling frequencies and loads. And on the other hand to compare the lower limb symmetric difference. Repeated measures two-way ANOVA had been applied in the statistical trial- significance level was set α=.05. Results: The results observed from the study including the following：1. Optimal pedaling frequency was 105rpm, 250 watts. Biceps fer, ankle inversion and ACC Y-max were found higher in symmetry. 2. During the fatigue test, 75rpm was found to be the finest pedaling frequency on 30% and 50% timeline and Gastrocnemius activation rate, knee inversion angle, ACC X-min, Z-min and GYR X-min were found higher in symmetry under those condition. However, shortly before and after fatigue, 90rpm was found the best pedaling frequency to which lower limb motion in frontal plan and sagittal plan were more stable and higher in symmetry. Conclusions: On the one hand, higher candance and workload induce better symmetry, on the other hand, it is feasible to adopt different candance in prolonged cycling and fatigue timing in order to reach optimal symmetry.