Locomotion Laboratory, Integrative Physiology Department, University of Colorado, Boulder, Colorado 80309-0354, USA.
J Appl Physiol (1985). 2012 Feb;112(3):427-34. doi: 10.1152/japplphysiol.00554.2011. Epub 2011 Nov 3.
To quantify the energetic cost of maintaining lateral balance during human running, we provided external lateral stabilization (LS) while running with and without arm swing and measured changes in energetic cost and step width variability (indicator of lateral balance). We hypothesized that external LS would reduce energetic cost and step width variability of running (3.0 m/s), both with and without arm swing. We further hypothesized that the reduction in energetic cost and step width variability would be greater when running without arm swing compared with running with arm swing. We controlled for step width by having subjects run along a single line (zero target step width), which eliminated any interaction effects of step width and arm swing. We implemented a repeated-measures ANOVA with two within-subjects fixed factors (external LS and arm swing) to evaluate main and interaction effects. When provided with external LS (main effect), subjects reduced net metabolic power by 2.0% (P = 0.032) and step width variability by 12.3% (P = 0.005). Eliminating arm swing (main effect) increased net metabolic power by 7.6% (P < 0.001) but did not change step width variability (P = 0.975). We did not detect a significant interaction effect between external LS and arm swing. Thus, when comparing conditions of running with or without arm swing, external LS resulted in a similar reduction in net metabolic power and step width variability. We infer that the 2% reduction in the net energetic cost of running with external LS reflects the energetic cost of maintaining lateral balance. Furthermore, while eliminating arm swing increased the energetic cost of running overall, arm swing does not appear to assist with lateral balance. Our data suggest that humans use step width adjustments as the primary mechanism to maintain lateral balance during running.
为了量化人类跑步时维持横向平衡的能量成本，我们在跑步时提供外部横向稳定（LS），并测量能量成本和步幅变异性（横向平衡的指标）的变化。我们假设外部 LS 将降低跑步时的能量成本和步幅变异性（3.0 m/s），无论是有手臂摆动还是没有手臂摆动。我们进一步假设，与有手臂摆动相比，没有手臂摆动时，能量成本和步幅变异性的降低幅度更大。我们通过让受试者沿着一条线（零目标步幅）跑步来控制步幅，从而消除了步幅和手臂摆动的任何相互作用效应。我们采用了一个重复测量的方差分析，有两个内源性固定因素（外部 LS 和手臂摆动），以评估主要和相互作用效应。当提供外部 LS（主要效应）时，受试者的净代谢功率降低了 2.0%（P = 0.032），步幅变异性降低了 12.3%（P = 0.005）。消除手臂摆动（主要效应）使净代谢功率增加了 7.6%（P < 0.001），但没有改变步幅变异性（P = 0.975）。我们没有检测到外部 LS 和手臂摆动之间的显著相互作用效应。因此，当比较有手臂摆动和没有手臂摆动的跑步条件时，外部 LS 导致净代谢功率和步幅变异性的相似降低。我们推断，外部 LS 使跑步的净能量成本降低 2%，反映了维持横向平衡的能量成本。此外，虽然消除手臂摆动增加了跑步的整体能量成本，但手臂摆动似乎并没有帮助维持横向平衡。我们的数据表明，人类在跑步时使用步幅调整作为维持横向平衡的主要机制。
