The influence of a unilateral fixed ankle on metabolic and mechanical demands during walking in unimpaired young adults
The influence of a unilateral fixed ankle on metabolic and mechanical demands during walking in unimpaired young adults
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DOI：
10.1016/j.jbiomech.2012.06.035
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发表时间：
2012-09-21
影响因子：
2.4
通讯作者：
Lewek, Michael D.
中科院分区：
文献类型：
--
作者：
Wutzke, Clinton J.;Sawicki, Gregory S.;Lewek, Michael D.
跖屈肌在行走过程中提供主要的推进力来源。当来自跖屈肌肌肉的机械功率产生有限时，其他关节可以进行补偿以保持一致的行走速度，但可能会增加代谢成本。本研究的目的是确定踝跖屈肌功率单侧减少如何影响肢体内和肢体间机械发电的重新分配以及步行代谢成本的相关变化。12名未受损的年轻人在双带仪表跑步机上以1.2 m/s的速度在优势肢体上使用踝关节支架行走。在两种条件下收集下肢运动学和动力学以及气体交换数据：（1）支架解锁（自由）和（2）支架锁定（固定）。在固定与自由条件下，支具显著降低了踝关节跖屈偏移12.96 +/- 3.60度（p < 0.001）和踝关节峰值机械功率1.03 +/- 0.51 W/kg（p < 0.001）。因此，与自由状态相比，固定状态下行走的代谢功率（W/kg）增加了7.4%（p=0.03）。在固定条件下观察到双侧髋关节机械发电增加（p < 0.001）。这些结果表明，由于机械发电从高效的踝关节肌肉肌腱重新分配到效率较低的髋关节肌肉肌腱，踝关节动力减少的步行增加了代谢需求。肢体内和肢体间机械负荷的重新分配代表了跖屈缺陷或踝足矫形器限制运动范围的病理人群中代谢需求增加的潜在机制。爱思唯尔有限公司出版
The plantarflexors provide a major source of propulsion during walking. When mechanical power generation from the plantarflexor muscles is limited, other joints may compensate to maintain a consistent walking velocity, but likely at increased metabolic cost. The purpose of this study was to determine how a unilateral reduction in ankle plantarflexor power influences the redistribution of mechanical power generation within and across limbs and the associated change in the metabolic cost of walking. Twelve unimpaired young adults walked with an ankle brace on the dominant limb at 1.2 m/s on a dual-belt instrumented treadmill. Lower extremity kinematics and kinetics as well as gas exchange data were collected in two conditions: (1) with the brace unlocked (FREE) and (2) with the brace locked (FIXED). The brace significantly reduced ankle plantarflexion excursion by 12.96 +/- 3.60 degrees (p < 0.001) and peak ankle mechanical power by 1.03 +/- 0.51 W/kg (p < 0.001) in the FIXED versus FREE condition. Consequently, metabolic power (W/kg) of walking in the FIXED condition increased by 7.4% compared to the FREE condition (p=0.03). Increased bilateral hip mechanical power generation was observed in the FIXED condition (p < 0.001). These results suggest that walking with reduced ankle power increases metabolic demand due to the redistribution of mechanical power generation from highly efficient ankle muscle-tendons to less efficient hip muscle-tendons. A within and across limb redistribution of mechanical workload represents a potential mechanism for increased metabolic demand in pathological populations with plantarflexion deficits or those that walk with an ankle-foot orthosis that restricts range of motion. Published by Elsevier Ltd.