Minimum effort simulations of split-belt treadmill walking exploit asymmetry to reduce metabolic energy expenditure.
Minimum effort simulations of split-belt treadmill walking exploit asymmetry to reduce metabolic energy expenditure.
复制标题
分体带跑步机行走的最小努力模拟利用不对称性来减少代谢能量消耗。
DOI：
10.1152/jn.00343.2022
复制
发表时间：
2023
影响因子：
2.5
通讯作者：
Hoogkamer,Wouter
中科院分区：
文献类型：
--
作者：
Price,Mark;Huber,MeghanE;Hoogkamer,Wouter
走在一个分裂带跑步机eliminated适应反应，改变基线步长不对称。然而，这种适应的根本原因很难确定。有人提出，努力最小化可能会驱动这种适应，基于这样的想法，即在快速带上采用更长的步骤，或正步长不对称（SLA），可以导致跑步机对双足步行者施加净正机械功。然而，当允许自由适应时，没有观察到人类在分裂带式跑步机上行走时会重现这种行为。为了确定最小化运动控制策略是否会导致实验观察到的适应模式，我们使用人体肌肉骨骼模型进行了不同带速组合的步行模拟，该模型最大限度地减少了肌肉兴奋和代谢率。该模型采用了增加正SLA的量，并随着带速差的增加而降低其净代谢率，在我们的最大带速比为3：1时，相对于系带行走，该模型达到了+42.4%SLA和-5.7%的代谢率。这些收益主要是通过增加制动工作和减少快速带上的推进工作实现的。结果表明，一个纯粹的努力最小化驱动分裂带步行策略将涉及大量的积极SLA，并在人类行为中缺乏这一特点点的其他因素影响电机控制策略，如厌恶过度的联合负荷，不对称，或不稳定。新&值得注意的行为观察分裂带跑步机的适应一直是不确定的，其根本原因。为了估计步态模式时，完全驱动这些可能的根本原因之一，我们模拟分裂带跑步机行走的肌肉骨骼模型，最大限度地减少其总肌肉兴奋。与实验观察不同，我们的模型在快速带上走了更长的步数，并将其代谢率降低到系带行走以下。这表明不对称性在能量上是最佳的，但人类的适应还涉及其他因素。
Walking on a split-belt treadmill elicits an adaptation response that changes baseline step length asymmetry. The underlying causes of this adaptation, however, are difficult to determine. It has been proposed that effort minimization may drive this adaptation, based on the idea that adopting longer steps on the fast belt, or positive step length asymmetry (SLA), can cause the treadmill to exert net-positive mechanical work on a bipedal walker. However, humans walking on split-belt treadmills have not been observed to reproduce this behavior when allowed to freely adapt. To determine if an effort-minimization motor control strategy would result in experimentally observed adaptation patterns, we conducted simulations of walking on different combinations of belt speeds with a human musculoskeletal model that minimized muscle excitations and metabolic rate. The model adopted increasing amounts of positive SLA and decreased its net metabolic rate with increasing belt speed difference, reaching +42.4% SLA and −5.7% metabolic rate relative to tied-belt walking at our maximum belt speed ratio of 3:1. These gains were primarily enabled by an increase in braking work and a reduction in propulsion work on the fast belt. The results suggest that a purely effort minimization driven split-belt walking strategy would involve substantial positive SLA, and that the lack of this characteristic in human behavior points to additional factors influencing the motor control strategy, such as aversion to excessive joint loads, asymmetry, or instability.NEW & NOTEWORTHYBehavioral observations of split-belt treadmill adaptation have been inconclusive toward its underlying causes. To estimate gait patterns when driven exclusively by one of these possible underlying causes, we simulated split-belt treadmill walking with a musculoskeletal model that minimized its summed muscle excitations. Our model took significantly longer steps on the fast belt and reduced its metabolic rate below tied-belt walking, unlike experimental observations. This suggests that asymmetry is energetically optimal, but human adaptation involves additional factors.