不同阻力對自行車坐姿與站姿騎乘的影響

坐姿與站姿騎乘各會受到不同阻力的影響，並非一直採用坐姿或是站姿就一定是最有效的騎乘方式。因此本研究目的在探討坐姿與站姿在不同阻力時之踏板受力與下肢肌電圖參數的變化。12名受試者以兩種姿勢（坐姿、站姿）進行固定式腳踏車騎乘，並比較在三種不同阻力（低、中、高）情況中的差別。力量感測器與表面肌電圖用來擷取受試者右腳之數據，並分析出踏板受力峰值、衝量，股直肌、股二頭肌肌電圖峰值、積分肌電圖參數。阻力的界定使用固定式腳踏車上的煞車機制，全部測試的踩踏節奏統一為50 rpm，統計方法採用二因子重複量數變異數分析。研究結果顯示坐姿的踏板受力峰值、衝量、肌電圖參數受到阻力的影響後呈現上升趨勢，而站姿的趨勢則較不一致。低阻力、中阻力時之踏板受力峰值、衝量是站姿大於坐姿，而高阻力時則會相接近。再對照肌電圖參數，低阻力時是坐姿小於站姿，中阻力、高阻力時是坐姿大於站姿。整體而言，阻力較低時是坐姿較省力，因為站姿的肌肉負擔較大；阻力較高時是站姿較有效率，因為站姿有體重重力可以幫助踩踏。本研究結論：如果實際騎乘時遭遇到不同的阻力，可以依此策略去選擇較佳的騎乘姿勢。

關鍵字

姿勢；固定式腳踏車；踏板受力；衝量；肌電圖

並列摘要

In general, people may not always ride the bike with one posture, which seems that different resistances would be a reason to change the posture. In view of this, the purpose of this study was to investigate the pedal force and electromyography (EMG) with two riding postures (seated and standing) in three levels of resistances (low, middle and high). Twelve subjects rode on a stationary bike, which a force sensor mounted on the right pedal and surface EMG was used to acquire the data from right leg. The parameters, including peak pedal force, impulse, peak EMG and integrated EMG were analyzed. Resistance was defined by the mechanism of brake from stationary bike and pedaling cadence was restricted to 50 rpm in all trials. A two-way repeated measures ANOVA was used to detect the significant differences. Our results showed that as resistance increased, seated posture displayed an increased trend in pedal force, impulse, EMG. However, standing posture was different compared to seated posture. Standing posture showed higher pedal force and impulse than seated posture at low and middle resistances, but pedal force and impulse of both postures were close to each other at high resistance. Further contrasting with EMG data, standing posture was higher than seated posture at low resistance, but standing posture displayed a smaller activation compared to seated posture at middle and high resistance. In general, seated posture could save strength at light resistance because of less muscle loading than standing posture. However, at heavy resistance, standing posture had better efficiency than seated posture, because cyclist could ride more unhindered by body weight from standing posture. This study concludes that cyclist could adopt this information, when facing different levels of resistances.