Thorpe S K S, Crompton R H, Wang W J
Department of Human Biology, University of Cape Town, Cape Town, South Africa.
Folia Primatol (Basel). 2004 Jul-Aug;75(4):253-65. doi: 10.1159/000078937.
Recent studies have indicated that chimpanzee bipedality is mechanically inefficient and dynamically unlike that of humans, thus undermining the chimpanzee analogy for mechanical aspects of the early evolution of hominid bipedalism. This paper continues this theme by measuring the forces and stresses engendered by the muscles during bipedal locomotion, for an untrained chimpanzee and for data from chimpanzees which have been encouraged to walk bipedally, presented in the literature. Peak stresses in the triceps surae were lower for the untrained chimpanzee than for the trained subjects because during the late stance phase, when peak ankle moments occur, the centre of pressure of the ground reaction force on the foot of the untrained chimpanzee stayed close to the ankle joint. In contrast, for the trained subjects it moved closer to the toes, as in human bipedalism. Quadriceps and hip extensor stresses are approximately 30% larger for the untrained chimpanzee than for the trained subjects, because the trained chimpanzees walked with a more erect posture. These results may reflect the way in which muscles can develop in response to training, since research on humans has shown that muscle physiological cross-sectional area increases as a result of exercise, resulting in smaller stresses for a given muscle force. During a slow walk, untrained chimpanzees were found to exert far greater muscle stresses than humans do when running at moderate speed, particularly in the muscles that extend the hip, because of the bent-hip, bent-knee posture.
最近的研究表明，黑猩猩的两足行走在机械效率上较低，且动态特征与人类不同，因此削弱了将黑猩猩作为人类两足行走早期进化机械方面类比的依据。本文延续这一主题，测量了一只未受过训练的黑猩猩在两足行走过程中肌肉产生的力和应力，并与文献中呈现的经过鼓励而进行两足行走的黑猩猩的数据进行对比。未受过训练的黑猩猩小腿三头肌的峰值应力低于受过训练的个体，因为在出现峰值踝关节力矩的站立后期，未受过训练的黑猩猩足部地面反作用力的压力中心靠近踝关节。相比之下，对于受过训练的个体，该压力中心则如人类两足行走时那样，更靠近脚趾。未受过训练的黑猩猩股四头肌和髋部伸肌的应力比受过训练的个体大约大30%，因为受过训练的黑猩猩行走姿势更直立。这些结果可能反映了肌肉响应训练而发育的方式，因为对人类的研究表明，运动可使肌肉生理横截面积增加，从而在给定肌肉力量下产生较小的应力。在慢走过程中，发现未受过训练的黑猩猩所施加的肌肉应力远大于人类中等速度跑步时的应力，尤其是在髋部伸展的肌肉中，这是由于其髋部弯曲、膝盖弯曲的姿势所致。
