Kraft Jennifer C, Augustine Jacqueline A, Fiddler Ryan E, Lewis Connor, Dames Kevin D
Proehl Exercise Physiology Laboratory, Kinesiology Department, SUNY Cortland, Cortland, NY, 13045, USA.
Proehl Exercise Physiology Laboratory, Kinesiology Department, SUNY Cortland, Cortland, NY, 13045, USA.
Hum Mov Sci. 2023 Apr;88:103068. doi: 10.1016/j.humov.2023.103068. Epub 2023 Feb 17.
Humans tend to select a preferred walking speed (PWS) that minimizes the metabolic energy consumed per distance traveled, i.e. the Cost of Transport (CoT). The aims of this study were to: 1. compare PWS overground vs. on a treadmill at 100 and 50% of body weight, and 2. explore whether with body weight support, PWS corresponds to the speed that minimizes CoT. Fifteen healthy adults walked overground and on a lower body positive pressure treadmill with and without bodyweight support. Walking speeds (ms) were recorded for each condition. Rate of energy expenditure (Jkgmin) and CoT (Jkgm) were then determined from 5-min walking trials with 50% bodyweight support at PWS and ± 30% of the self-selected walking speed for that condition. PWS did not differ across conditions. With 50% body weight support, for each 30% increase in walking speed, rates of metabolic energy expenditure increased ∼15% while CoT decreased by ∼14%. Thus, with 50% body weight support, PWS did not correspond with the speed that minimized CoT. Bodyweight support decreases cost of maintaining an upright body but does not decrease the metabolic demand of limb advancement, contributing to the linear yet not proportional changes in rates of energy expenditure and CoT. We conclude that bodyweight support via an AlterG® treadmill disconnects the association between PWS and minimum CoT. These findings have implications for clinical populations (e.g., obese, elderly) who may benefit from walking on a bodyweight supporting treadmill but may select speeds incompatible with their physical activity goals.
人类倾向于选择一种偏好的步行速度（PWS），该速度能使每行进单位距离所消耗的代谢能量（即运输成本，CoT）降至最低。本研究的目的是：1. 比较在地面上与在体重100%和50%的跑步机上的PWS；2. 探讨在有体重支持的情况下，PWS是否与使CoT最小化的速度相对应。15名健康成年人在有或没有体重支持的情况下，在地面上和下肢正压跑步机上行走。记录每种情况下的步行速度（米/秒）。然后，根据在PWS以及该情况下自我选择步行速度的±30%时进行的5分钟步行试验，确定能量消耗率（焦耳/千克·分钟）和CoT（焦耳/千克·米）。PWS在不同情况下没有差异。在50%体重支持下，步行速度每增加30%，代谢能量消耗率增加约15%，而CoT下降约14%。因此，在50%体重支持下，PWS与使CoT最小化的速度不对应。体重支持降低了维持直立身体的成本，但并未降低肢体前进的代谢需求，这导致了能量消耗率和CoT的线性但不成比例的变化。我们得出结论，通过AlterG®跑步机提供的体重支持打破了PWS与最小CoT之间的关联。这些发现对临床人群（如肥胖者、老年人）具有启示意义，他们可能从在体重支持跑步机上行走中受益，但可能选择与他们的身体活动目标不相符的速度。
