Ortega Justus D, Fehlman Leslie A, Farley Claire T
Locomotion Laboratory, Department of Integrative Physiology, University of Colorado, Boulder, CO 80309-0354, USA.
J Biomech. 2008 Dec 5;41(16):3303-8. doi: 10.1016/j.jbiomech.2008.06.039. Epub 2008 Sep 23.
To gain insight into the mechanical determinants of walking energetics, we investigated the effects of aging and arm swing on the metabolic cost of stabilization. We tested two hypotheses: (1) elderly adults consume more metabolic energy during walking than young adults because they consume more metabolic energy for lateral stabilization, and (2) arm swing reduces the metabolic cost of stabilization during walking in young and elderly adults. To test these hypotheses, we provided external lateral stabilization by applying bilateral forces (10% body weight) to a waist belt via elastic cords while young and elderly subjects walked at 1.3m/s on a motorized treadmill with arm swing and with no arm swing. We found that the external stabilizer reduced the net rate of metabolic energy consumption to a similar extent in elderly and young subjects. This reduction was greater (6-7%) when subjects walked with no arm swing than when they walked normally (3-4%). When young or elderly subjects eliminated arm swing while walking with no external stabilization, net metabolic power increased by 5-6%. We conclude that the greater metabolic cost of walking in elderly adults is not caused by a greater cost of lateral stabilization. Moreover, arm swing reduces the metabolic cost of walking in both young and elderly adults likely by contributing to stability.
为深入了解步行能量消耗的力学决定因素，我们研究了衰老和摆臂对稳定代谢成本的影响。我们测试了两个假设：（1）老年人在步行过程中比年轻人消耗更多的代谢能量，因为他们在横向稳定方面消耗更多的代谢能量；（2）摆臂可降低年轻人和老年人步行过程中稳定的代谢成本。为验证这些假设，当年轻和老年受试者在电动跑步机上以1.3米/秒的速度行走时，我们通过弹性绳索向腰带施加双侧力（体重的10%）来提供外部横向稳定，分别测试有摆臂和无摆臂的情况。我们发现，外部稳定器在老年和年轻受试者中以相似的程度降低了代谢能量消耗的净速率。当受试者无摆臂行走时，这种降低幅度更大（6 - 7%），而正常行走时为（3 - 4%）。当年轻或老年受试者在无外部稳定的情况下行走且消除摆臂时，净代谢功率增加了5 - 6%。我们得出结论，老年人步行时较高的代谢成本并非由更大的横向稳定成本所致。此外，摆臂可能通过有助于稳定来降低年轻人和老年人步行的代谢成本。
