Cavagna G A, Franzetti P, Fuchimoto T
J Physiol. 1983 Oct;343:323-39. doi: 10.1113/jphysiol.1983.sp014895.
The work done at each step, during level walking at a constant average speed, to lift the centre of mass of the body, to accelerate it forward, and to increase the sum of both gravitational potential and kinetic energies, has been measured at various speeds on children of 2-12 years of age, with the same technique used previously for adults (Cavagna, 1975; Cavagna, Thys & Zamboni, 1976). The pendulum-like transfer between potential and kinetic energies (Cavagna et al. 1976) reaches a maximum at the speed at which the weight-specific work to move the centre of mass a given distance is at a minimum ('optimal' speed). This speed is about 2 X 8 km/hr at 2 years of age and increases progressively with age up to 5 km/hr at 12 years of age and in adults. The speed freely chosen during steady walking at the different ages is similar to this 'optimal' speed. At the 'optimal' speed, the time of single contact (time of swing) is in good agreement with that predicted, for the same stature, by a ballistic walking model assuming a minimum of muscular work (Mochon & McMahon, 1980). Above the 'optimal' speed, the recovery of mechanical energy through the potential-kinetic energy transfer decreases. This decrease is greater the younger the subject. A reduction of this recovery implies a greater amount of work to be supplied by muscles: at 4 X 5 km/hr the weight-specific muscular power necessary to move the centre of mass is 2 X 3 times greater in a 2-year-old child than in an adult.
在以恒定平均速度进行水平行走时，为提升身体重心、使其向前加速以及增加重力势能和动能之和，在每个步骤所做的功，已采用先前用于成年人的相同技术，在2至12岁儿童的不同速度下进行了测量（卡瓦尼亚，1975年；卡瓦尼亚、蒂斯和赞博尼，1976年）。势能和动能之间类似钟摆的转换（卡瓦尼亚等人，1976年）在将重心移动给定距离所需的体重特定功最小的速度（“最佳”速度）时达到最大值。这个速度在2岁时约为2×8千米/小时，并随着年龄增长逐渐增加，在12岁儿童和成年人中达到5千米/小时。在不同年龄稳定行走时自由选择的速度与这个“最佳”速度相似。在“最佳”速度下，单步接触时间（摆动时间）与假设肌肉功最小的弹道行走模型针对相同身高所预测的时间高度一致（莫乔恩和麦克马洪，1980年）。高于“最佳”速度时，通过势能 - 动能转换的机械能恢复会减少。受试者年龄越小，这种减少就越大。这种恢复的减少意味着肌肉需要提供更多的功：在4×5千米/小时时，移动重心所需的体重特定肌肉功率在2岁儿童中比在成年人中高2×3倍。
