CURAPS-DIMPS Laboratory, EA4075, University of La Réunion, UFR SHE, Le Tampon, France.
Med Sci Sports Exerc. 2012 Apr;44(4):659-65. doi: 10.1249/MSS.0b013e318236edd8.
This study tested the hypothesis that the increase in walking economy (i.e., decrease in net metabolic rate per kilogram) after weight loss in obese adolescents is induced by a lower metabolic rate required to support the lower body weight and maintain balance during walking.
Sixteen obese adolescent boys and girls were tested before and after a weight reduction program. Body composition and oxygen uptake while standing and walking at four preset speeds (0.75, 1, 1.25, and 1.5 m·s⁻¹) and at the preferred speed were quantified. Net metabolic rate and gross metabolic cost of walking-versus-speed relationships were determined. A three-compartment model was used to distinguish the respective parts of the metabolic rate associated with standing (compartment 1), maintaining balance and supporting body weight during walking (compartment 2), and muscle contractions required to move the center of mass and limbs (compartment 3).
Standing metabolic rate per kilogram (compartment 1) significantly increased after weight loss, whereas net metabolic rate per kilogram during walking decreased by 9% on average across speeds. Consequently, the gross metabolic cost of walking per unit of distance-versus-speed relationship and hence preferred walking speeds did not change with weight loss. Compartment 2 of the model was significantly lower after weight loss, whereas compartment 3 did not change.
The model showed that the improvement in walking economy after weight loss in obese adolescents was likely related to the lower metabolic rate of the isometric muscular contractions required to support the lower body weight and maintain balance during walking. Contrastingly, the part of the total metabolic rate associated with muscle contractions required to move the center of mass and limbs did not seem to be related to the improvement in walking economy in weight-reduced individuals.
本研究旨在验证以下假设，即肥胖青少年在减肥后步行经济性（即每公斤净代谢率的降低）的增加是由支撑较低体重和在步行过程中保持平衡所需的较低代谢率引起的。
对 16 名肥胖青少年在减肥计划前后进行了测试。定量评估了站立和以四个预设速度（0.75、1、1.25 和 1.5 m·s⁻¹）以及偏好速度行走时的身体成分和耗氧量。确定了净代谢率和行走速度关系的总代谢成本。使用三 compartment 模型来区分与站立相关的代谢率的各个部分（compartment 1）、在行走过程中维持平衡和支撑体重的部分（compartment 2）以及移动质心和四肢所需的肌肉收缩部分（compartment 3）。
站立时每公斤代谢率（compartment 1）在减肥后显著增加，而平均而言，在所有速度下，行走时每公斤净代谢率降低了 9%。因此，单位距离速度关系的行走总代谢成本（即偏好的行走速度）并未随体重减轻而改变。模型的 compartment 2 在减肥后显著降低，而 compartment 3 没有变化。
该模型表明，肥胖青少年在减肥后步行经济性的改善可能与支撑较低体重和在步行过程中保持平衡所需的等长肌肉收缩的较低代谢率有关。相比之下，与移动质心和四肢所需的肌肉收缩相关的总代谢率的部分似乎与体重减轻个体步行经济性的改善无关。
