Alwan Aya, Srinivasan Manoj
Mechanical and Aerospace Engineering, The Ohio State University, 201, W. 19th Ave, Columbus, 43210, Ohio, United States.
bioRxiv. 2025 Mar 15:2025.03.13.643096. doi: 10.1101/2025.03.13.643096.
Human walking contains variability due to small intrinsic perturbations arising from sensory or motor noise, or to promote motor learning. We hypothesize that such stride-to-stride variability may increase the metabolic cost of walking over and above a perfectly periodic motion, and that neglecting such variability in simulations may mis-estimate the metabolic cost. Here, we quantify the metabolic estimation errors accrued by neglecting the stride-to-stride variability using human data and a musculoskeletal model by comparing the cost of multiple strides of walking and the cost of a perfectly periodic stride with averaged kinematics and kinetics. We find that using an averaged stride underestimates the cost by about 2.5%, whereas using a random stride may mis-estimate the cost positively or negatively by up to 15%. As a further illustration of the cost increase in a simpler dynamical context, we use a feedback-controlled inverted pendulum walking model to show that increasing the sensory or motor noise increases the overall metabolic cost, as well as the variability of stride-to-stride metabolic costs, as seen with the musculoskeletal simulations. Our work establishes the importance of accounting for stride-to-stride variability when estimating metabolic costs from motion.
由于感觉或运动噪声产生的微小内在扰动，或者为了促进运动学习，人类行走存在变异性。我们假设，这种步幅间的变异性可能会使行走的代谢成本相较于完美的周期性运动有所增加，并且在模拟中忽略这种变异性可能会错误估计代谢成本。在此，我们通过比较多次行走步幅的成本与具有平均运动学和动力学的完美周期性步幅的成本，利用人体数据和肌肉骨骼模型来量化因忽略步幅间变异性而产生的代谢估计误差。我们发现，使用平均步幅会使成本低估约2.5%，而使用随机步幅可能会使成本正向或负向错误估计高达15%。作为在更简单动力学背景下成本增加的进一步例证，我们使用反馈控制的倒立摆行走模型来表明，增加感觉或运动噪声会增加总体代谢成本，以及步幅间代谢成本的变异性，这与肌肉骨骼模拟的情况一致。我们的工作确立了在根据运动估计代谢成本时考虑步幅间变异性的重要性。
