Dewolf A H, Peñailillo L E, Willems P A
Laboratory of Biomechanics and Physiology of Locomotion, Institute of NeuroScience, Université catholique de Louvain, 1348 Louvain-la-Neuve, Belgium.
Exercise Science Laboratory, School of Kinesiology, Faculty of Medicine, Universidad Finis Terrae, Providencia, Santiago 7500000, Chile.
J Exp Biol. 2016 Aug 1;219(Pt 15):2276-88. doi: 10.1242/jeb.142976. Epub 2016 May 20.
When running on the level, muscles perform as much positive as negative external work. On a slope, the external positive and negative work performed are not equal. The present study analysed how the ratio between positive and negative work modifies the bouncing mechanism of running. Our goals are to: (1) identify the changes in motion of the centre of mass of the body associated with the slope of the terrain and the speed of progression, (2) study the effect of these changes on the storage and release of elastic energy during contact and (3) propose a model that predicts the change in the bouncing mechanism with slope and speed. Therefore, the ground reaction forces were measured on 10 subjects running on an instrumented treadmill at different slopes (from -9 to +9 deg) and different speeds (between 2.2 and 5.6 m s(-1)). The movements of the centre of mass of the body and its external mechanical energy were then evaluated. Our results suggest that the increase in the muscular power is contained (1) on a positive slope, by decreasing the step period and the downward movements of the body, and by increasing the duration of the push, and (2) on a negative slope, by increasing the step period and the duration of the brake, and by decreasing the upward movement of the body. Finally, the spring-mass model of running was adapted to take into account the energy added or dissipated each step on a slope.
在平地上跑步时，肌肉所做的正向外部功与负向外部功一样多。在斜坡上，所做的正向和负向外部功并不相等。本研究分析了正向功与负向功的比例如何改变跑步的弹跳机制。我们的目标是：（1）确定与地形坡度和前进速度相关的身体质心运动变化，（2）研究这些变化对接触过程中弹性能量储存和释放的影响，以及（3）提出一个预测弹跳机制随坡度和速度变化的模型。因此，在仪器化跑步机上对10名受试者在不同坡度（从 -9到 +9度）和不同速度（2.2至5.6米/秒）下跑步时的地面反作用力进行了测量。然后评估了身体质心的运动及其外部机械能。我们的结果表明，肌肉力量的增加受到限制：（1）在正坡度上，通过缩短步幅周期和身体的向下运动，并增加蹬地持续时间来实现；（2）在负坡度上，通过延长步幅周期和制动持续时间，并减少身体的向上运动来实现。最后，对跑步的弹簧 - 质量模型进行了调整，以考虑在斜坡上每一步增加或耗散的能量。
