Greater perceived physical fatigability and lower skeletal muscle energetics are both predictors of mobility decline. Characterizing associations between muscle energetics and perceived fatigability may provide insight into potential targets to prevent mobility decline. We examined associations of in vivo (maximal ATP production, ATPmax) and ex vivo (maximal carbohydrate supported oxidative phosphorylation [max OXPHOS] and maximal fatty acid supported OXPHOS [max FAO OXPHOS]) measures of mitochondrial energetics with two measures of perceived physical fatigability, Pittsburgh Fatigability Scale (PFS, 0–50, higher = greater) and Rating of Perceived Exertion (RPE Fatigability, 6–20, higher = greater) after a slow treadmill walk. Participants from the Study of Muscle, Mobility and Aging (N = 873) were 76.3 ± 5.0 years old, 59.2% women, and 85.3% White. Higher muscle energetics (both in vivo and ex vivo) were associated with lower perceived physical fatigability, all p < 0.03. When stratified by sex, higher ATPmax was associated with lower PFS Physical for men only; higher max OXPHOS and max FAO OXPHOS were associated with lower RPE Fatigability for both sexes. Higher skeletal muscle energetics were associated with 40–55% lower odds of being in the most (PFS ≥ 25, RPE Fatigability ≥ 12) vs least (PFS 0–4, RPE Fatigability 6–7) severe fatigability strata, all p < 0.03. Being a woman was associated with 2–3 times higher odds of being in the most severe fatigability strata when controlling for ATPmax but not the ex vivo measures (p < 0.05). Better mitochondrial energetics were linked to lower fatigability and less severe fatigability in older adults. Findings imply that improving skeletal muscle energetics may mitigate perceived physical fatigability and prolong healthy aging.

更高的感知身体疲劳度和较低的骨骼肌能量都是活动能力下降的预测因素。描述肌肉能量学与感知疲劳之间的关联可能有助于深入了解防止活动能力下降的潜在目标。我们检查了体内（最大 ATP 产生，ATPmax）和离体（最大碳水化合物支持的氧化磷酸化 [最大 OXPHOS] 和最大脂肪酸支持的 OXPHOS [最大 FAO OXPHOS]）线粒体能量学测量与两种感知身体疲劳度测量的关联，匹兹堡疲劳量表（PFS，0-50，更高 = 更大）和感知用力评级（RPE 疲劳度，6-20， 更高 = 更大）。肌肉、活动性和衰老研究 （N = 873） 的参与者年龄在 76.3 ± 5.0 岁之间，59.2% 为女性，85.3% 为白人。较高的肌肉能量学 （体内和体外） 与较低的感知身体疲劳性相关，均 p < 0.03。当按性别分层时，仅男性较高的 ATPmax 与较低的 PFS 体能相关;较高的最大 OXPHOS 和最大 FAO OXPHOS 与较低的 RPE 疲劳性相关。较高的骨骼肌能量学与处于最严重（PFS ≥ 25，RPE 疲劳性 ≥ 12）与最低（PFS 0-4，RPE 疲劳性 6-7）严重疲劳性层的几率降低 40-55%，均 p < 0.03。当控制 ATPmax 而不是离体测量时，女性处于最严重疲劳层的几率高 2-3 倍 （p < 0.05）。较好的线粒体能量学与老年人较低的疲劳度和较轻的疲劳度有关。 研究结果表明，改善骨骼肌能量可以减轻感知到的身体疲劳并延长健康衰老。