Heglund N C, Willems P A, Penta M, Cavagna G A
Pharos Systems Inc., South Chelmsford, Massachusetts 01824, USA.
Nature. 1995 May 4;375(6526):52-4. doi: 10.1038/375052a0.
In many areas of the world that lack a transportation infrastructure, people routinely carry extraordinary loads supported by their heads, for example the Sherpa of the Himalayas and the women of East Africa. It has previously been shown that African women from the Kikuyu and Luo tribes can carry loads substantially more cheaply than army recruits; however, the mechanism for their economy has remained unknown. Here we investigate, using a force platform, the mechanics of carrying head-supported loads by Kikuyu and Luo women. The weight-specific mechanical work, required to maintain the motion of the common centre of mass of the body and load, decreases with load in the African women, whereas it increases in control subjects. The decrease in work by the African women is a result of a greater conservation of mechanical energy resulting from an improved pendulum-like transfer of energy during each step, back and forth between gravitational potential energy and kinetic energy of the centre of mass.
在世界上许多缺乏交通基础设施的地区，人们经常用头顶着超乎寻常的重物，比如喜马拉雅山脉的夏尔巴人以及东非的女性。此前有研究表明，来自基库尤族和卢奥族的非洲女性搬运重物的成本比新兵要低得多；然而，她们这种经济性的机制一直不为人知。在此，我们使用测力平台研究了基库尤族和卢奥族女性头顶重物时的力学原理。维持身体和重物共同质心运动所需的单位重量机械功，在非洲女性中随负载增加而减少，而在对照组受试者中则增加。非洲女性机械功的减少是由于在每一步中，质心的重力势能和动能之间实现了更类似钟摆式的能量传递，从而更好地保存了机械能。
