自行車把手特性於不同路面材質騎乘對人體上肢肌肉活化與振動的影響

The effect of different peculiarity bicycle handles and roads on the Muscle Activation and Vibration of upper arm

緒論：自行車下彎型把手，把身向下彎曲把柄低於車身上管，上昇型把手把身向上延伸把柄位置較高，平直型把身與把柄成一軸線，持握於不同路面騎乘時，會導致身體傾角不同，間接影響上肢肌肉活化，長久騎乘下可能導致傷害的產生。本文目的在於探討，自行車把不同手型式對人體上肢肌肉活化與振動的影響。方法：以18名大專生為參與者，利用DELSYS無線肌電訊號擷取系統 (1000 Hz) 內建三軸加速規 (150 Hz) 收取上肢伸腕肌、屈腕肌、肱二頭肌與肱三頭肌之肌肉活化與振動幅度 (合加速度) 。以同款自行車分別安裝三種不同把手型式，騎乘於柏油路面與石磚路面，踩踏頻率訂定為50 rpm，前10公尺到達穩定踩踏節奏，收取後20公尺之相關參數。以相依樣本二因子變異數分析 (Two-Way ANOVA) ，考驗三種把手型式在柏油與石磚路面之肌肉活化與振動幅度差異，顯著水準為 α = .05 。 結果：肌肉活化部分，兩種路面屈腕肌皆為平直型小於下彎與上昇型，此外柏油路面肱三頭肌平直與下彎型小於上昇型。振動部分，兩種路面之屈腕肌皆為平直與下彎型小於上昇型，且肱三頭肌上昇型皆小於下彎與平直型；柏油路面肱二頭肌平直型小於上昇與下彎型；石磚路面，伸腕肌平直型小於下彎與上昇型；肱二頭肌平直型小於下彎型，且皆達顯著差異。結論：建議若未追求騎乘之速度感，可選用平直型把手透過手臂與軀幹平均分擔振動的傳遞，且不失騎乘之便利性，並選擇經規劃整理過之自行車道來從事自行車運動，藉此降低上肢肌肉活化的產生，以提升騎乘時之上肢舒適度。

 

Introduction: The position of handlebar in drop handlebar is lower than the stem, while higher than the stem in bullhorn handlebar. Flat handlebars are horizontal to the stem. People cycling with different types of handlebar on diverse roads lead to different riding position, active different muscles of upper limb and cause various sport injuries when riding for hours. The aim of this study is to investigate the effect of bicycle handlebars on muscle activation and vibration. Methods: Eighteen college students were recruited. The DELSYS surface electromyography system (1000 Hz) and built-in three axes accelerometers (150Hz) were used to record the muscle activity and vibration amplitude (resultant acceleration) of extensor, flexor, bicep and tricep. Subjects were assigned to ride on the asphalt road or stone brick road with three different kinds of handlebars. The data were recorded as subjects reached at a steady cadence of 50 rpm and kept for at least 20 m. Two-way ANOVA was applied for the comparison between groups, and the statistical significance set at α =.05. Results: The muscle activation in flexor carpal muscle was significantly lower as volunteers cycling with flat handlebar than those with drop or bullhorn handlebar on both asphalt road and stone brick road. On asphalt road, the muscle activation in triceps brachii was higher as cycling with bullhorn handlebar than those with flat or drop handlebars. In vibration studies, as riding on both the asphalt road and stone brick road, the lowest vibration of flexor carpal muscle was noticed in the group using flat or drop handlebar. Cycling with flat or drop handlebar caused a higher vibration in triceps brachii muscle than that with bullhorn handlebar. The vibration of biceps brachii muscle was lower in those people riding with flat handlebar than those with bullhorn or drop handlebar on asphalt road. The highest vibration in extensor carpi ulnaris muscle was recorded as volunteers riding on the stone brick road with flat handlebar. On stone brick road, the vibration of biceps brachii muscle was lower in flat handlebar than that of drop handlebar. Conclusions: For more comfortable ride on the bike routes, we suggest bicyclist biking with the flat handlebars to separate the vibration in arms and trunk and decrease the activation of the upper limb.