Background

Resting metabolic rate (RMR) tends to decline with aging. The age-trajectory of decline in RMR is similar to changes that occur in muscle mass, muscle strength and fitness but while the decline in these phenotypes have been related to changes of mitochondrial function and oxidative capacity, whether lower RMR is associated with poorer mitochondrial oxidative capacity is unknown.

Methods

In 619 participants of the Baltimore Longitudinal Study of Aging, we analyzed the cross-sectional association between RMR (kcal/day), assessed by indirect calorimetry, and skeletal muscle maximal oxidative phosphorylation capacity, assessed as post-exercise phosphocreatine recovery time constant (τ_PCr), by phosphorous magnetic resonance spectroscopy. Linear regression models were used to evaluate the relationship between τ_PCr and RMR, adjusting for potential confounders.

Results

Independent of age, sex, lean body mass, muscle density and fat mass, higher RMR was significantly associated with shorter τ_PCr, indicating greater mitochondrial oxidative capacity.

Conclusion

Higher RMR is associated with a higher mitochondrial oxidative capacity in skeletal muscle. This association may reflect a relationship between better muscle quality and greater mitochondrial health.

中文翻译：

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更高的骨骼肌氧化能力与更高的静息代谢率相关：巴尔的摩纵向衰老研究的结果

背景

静息代谢率（RMR）会随着年龄的增长而下降。RMR下降的年龄轨迹类似于肌肉质量，肌肉强度和适应性发生的变化，但是尽管这些表型下降与线粒体功能和氧化能力的变化有关，但较低的RMR是否与较差的线粒体氧化性有关容量未知。

方法

在619名巴尔的摩纵向衰老研究的参与者中，我们分析了通过间接量热法评估的RMR（千卡/天）与骨骼肌最大氧化磷酸化能力（以运动后磷酸肌酸恢复时间常数（τ）评估）之间的横断面联系_PCr），通过磷磁共振波谱法。线性回归模型用于评估_τPCr和RMR之间的关系，并针对潜在的混杂因素进行调整。

结果

与年龄，性别，瘦体重，肌肉密度和脂肪量无关，较高的RMR与较短的_τPCr显着相关，表明线粒体的氧化能力较高。

结论

较高的RMR与骨骼肌中较高的线粒体氧化能力有关。这种联系可能反映出更好的肌肉质量和更好的线粒体健康之间的关系。