自行車座椅位置對下肢關節力學與運動表現之影響

Abstract

正確的騎乘姿勢不但可以減少運動傷害，更可以提升運動表現，但在何種姿勢調整下，可以提供較好的運動表現或騎乘舒適性，仍缺乏實證性的科學證據。因此設計三個實驗進行探討。目的：實驗一：探討自行車不同坐墊位置對運動學、動力學及肌肉活化的影響；實驗二：探討疲勞介入後對不同坐墊位置騎乘姿勢的影響；實驗三：探討自行車不同坐墊位置騎乘姿勢調整前、後的運動表現。方法：本研究三個實驗之受試者(平均身高：176.5±5.5公分；平均體重：75.4±8.4 公斤；平均年齡：25.6±3.8 歲)均相同。實驗一與實驗二：為室內實驗，透過動作分析系統、測力計、肌電儀分別觀察自行車不同坐墊位置(前後、上下)對運動學、動力學及肌肉活化的影響及探討疲勞介入後對不同坐墊位置自行車騎乘姿勢的影響。實驗三：為戶外實驗，透過SRM 功率計計算實際騎乘之功率、時間與心跳。所有的統計結果均採用重複量數變異數分析，顯著水準訂為α=.05。結果：最有效率的騎乘位置為：髖關節角度為85度，膝關節角度為145 度 (35度)，踝關節角度為90度 (下死點膝關節角度在30度，並向前移動5公分)。當坐墊位置向前移動，會有較大的平均髖、膝、踝關節及最大的踝關節關節力矩、股四頭肌及腓腸肌的肌肉活化，不同坐墊位置會使用不同的關節策略(5號使用髖關節策略與6號使用踝關節)，增加固定騎乘下的時間及減少20公里的戶外騎乘的時間。當坐墊位置向前移動，可提高騎乘之運動表現及舒適性。結論：過去研究發現在最佳自行車踩踏位置為下死點膝關節角度在30度，然而本研究發現下死點膝關節角度在30度並向前移動5公分為最有效率得騎乘位置，當坐墊位置向前移動可透過踝關節產生較有效率的踩踏提升運動表現。Proper riding posture can reduce injuries and enhance performance. However, still lack of empirical scientific evidencehas to determine the porper riding posture for better performance and riding comfort. Therefore, the purposes of this study were to investigate the most porper riding posture by processing three experimental designs. The first experiment was to determine the effects of different saddle positions on kinematics, kinetics and muscle activation during cycling. The second experiment was to exame the fatigue factors in different saddle postitions by using EMG analysis. The third experiment was to prove the effects of new saddle position on cycling performance in road riding. Methods: Fifteen participants (average height: 176.5 ± 5.5 cm; average weight: 75.4 ± 8.4 kilograms; average age: 25.6 ± 3.8 years) were recurited in this study. The first and second experiments were laboratory tests, we observed different bike seat positions (forword to backword, bottom to top) on the kinematics, kinetics and muscle activation, as well as fatigue intervention through motion analysis system, dynamometer. Third experiment was outdoor experiments, which calculate the actual riding power, time and heart rate using SRM power meter. Repeated measures analysis of variance was used for all statistical tests, the significance level was set at α = .05. Results: The most efficient riding position was at 85 degrees in the hip joint angle, the knee angle was 145 degrees (35 degrees), the ankle joint angle was 90 degrees (bottom dead point with the knee angle at 30 degrees, and move 5 cm forward). There were greater average hip, knee, ankle joint moment and maximal ankle joint moment, quadriceps and gastrocnemius muscle activation when the seat position was moved to forward. Different seat positions caused different joint strategies, hip strategy was used for the 5th position and ankle strategy was used for the 6th position. The posture in 6th saddle position could increase 24% in riding time during exhaustion test and reduce 7% on 20 km outdoor riding time. When the seat position was moved to forward, the performance and ride comfort was improved. Conclusions: Previous studies found that the best position for the knee angle was 30 degrees in bottom dead point, however, this study found that the most efficient riding position was 30 degrees in knee angle of bottom dead point and move 5 cm forward. The posture of seat position moved forward could produce more efficient pedaling and enhance performance through the ankle joint.