Hacettepe University , Faculty of Sport Sciences, Ankara, Turkey.
J Sports Sci Med. 2013 Sep 1;12(3):512-20. eCollection 2013.
On the bicycle, the human upper extremity has two essential functions in steering the bicycle and in supporting the body. Through the handlebar, surface- induced loads are transmitted to the hand and arm of the bicycle rider under vibration exposure conditions. Thus, the purpose of the study was to investigate the effect of vibration exposure on forearm muscle activity for different road surfaces (i.e. smooth road, concrete stone pavement, rough road) and for different bicycles. Ten subjects participated in experiments and two types of bicycles, i.e. Road Bike (RB) and Mountain Bike (MTB) are compared. The acceleration magnitudes were dominant along x and z-axes. The r.m.s acceleration values in the z direction at the stem of MTB were at most 2.56, 7.04 and 10.76 m·s(-2) when pedaling respectively on asphalt road, concrete pavement and rough road. In the case of RB the corresponding values were respectively 4.43, 11.75 and 27.31 m·s(-2). The cumulative normalized muscular activity levels during MTB trials on different surfaces had the same tendency as with acceleration amplitudes and have ranked in the same order from lowest to highest value. Although road bike measurements have resulted in a similar trend of increment, the values computed for rough road trials were higher than those in MTB trials. During rough road measurements on MTB, rmsEMG of extensor muscles reached a value corresponding to approximately 50% of MVC (Maximum Voluntary Contraction). During RB trials performed on rough road conditions, rmsEMG (%MVC) values for the forearm flexor muscles reached 45.8% of their maximal. The level of muscular activity of forearm muscles in controlling handlebar movements has been observed to be enhanced by the increase in the level of vibration exposed on the bicycle. Since repeated forceful gripping and pushing forces to a handle of a vibratory tool can create a risk of developing circulatory, neurological, or musculoskeletal disorder, a bicycle rider can be considered vulnerable to developing vibration related overuse injuries and/or performance diminishing consequences. Key PointsThe muscular activity level in the forearms increases in response to random vibration transmitted to the bicycle to control handlebar movements.The level of vibration transmission depends on irregularities on road surface and bicycle type.A bicycle rider can be considered vulnerable to developing vibration related overuse injuries and/or performance diminishing consequences.
在自行车上,上肢在操纵自行车和支撑身体方面有两个基本功能。在振动暴露条件下,通过车把,表面感应的负载会传递到手和手臂。因此,本研究的目的是研究不同路面(即平整路面、混凝土路面、粗糙路面)和不同自行车对前臂肌肉活动的振动暴露影响。十位受试者参与了实验,比较了两种自行车,即公路自行车(RB)和山地自行车(MTB)。加速度大小沿 x 和 z 轴占主导地位。在 MTB 的车把处,在沥青路面、混凝土路面和粗糙路面上踩踏时,z 方向的 r.m.s 加速度值分别为 2.56、7.04 和 10.76 m·s(-2)。在 RB 的情况下,相应的值分别为 4.43、11.75 和 27.31 m·s(-2)。在不同表面上进行 MTB 试验时,累积归一化肌肉活动水平与加速度幅度具有相同的趋势,并按从低到高的顺序排列。尽管 RB 测量结果呈现出类似的递增趋势,但在粗糙路面试验中计算出的值高于 MTB 试验。在 MTB 进行粗糙路面测量时,伸肌的 rmsEMG 达到与 MVC(最大自愿收缩)大致相同的值。在 RB 进行粗糙路面条件下的试验时,前臂屈肌的 rmsEMG(%MVC)值达到其最大的 45.8%。通过增加自行车上暴露的振动水平,观察到手部肌肉活动控制车把运动的前臂肌肉的活动水平得到增强。由于反复用力握持和推动手柄等振动工具会增加循环、神经或肌肉骨骼疾病的风险,因此自行车骑手可能容易发生与振动相关的过度使用损伤和/或表现下降的后果。要点:为了控制车把的运动,传递到自行车上的随机振动会增加前臂的肌肉活动水平。振动传递的水平取决于路面和自行车类型的不规则性。自行车骑手可能容易发生与振动相关的过度使用损伤和/或表现下降的后果。