Skeletal muscle energetics decline with age, and physical activity (PA) has been shown to offset these declines in older adults. Yet, many studies reporting these effects were based on self-reported PA or structured exercise interventions. Therefore, we examined the associations of accelerometry-measured and self-reported PA and sedentary behavior (SB) with skeletal muscle energetics and explored the extent to which PA and sedentary behavior would attenuate the associations of age with muscle energetics. As part of the Study of Muscle, Mobility and Aging, enrolled older adults ( = 879), 810 (age = 76 ± 5 years old, mean ± SD; 58% women) had maximal muscle oxidative capacity measured via high-resolution respirometry of permeabilized myofibers (maximal oxidative phosphorylation (maxOXPHOS)) and by phosphorus magnetic resonance spectroscopy (maximal adenosine triphosphate (ATP)). Accelerometry-measured sedentary behavior, light activity, and moderate-to-vigorous PA (MVPA) were assessed using a wrist-worn ActiGraph GT9X over 7 days. Self-reported sedentary behavior, MVPA, and all PA were assessed with the Community Healthy Activities Model Program for Seniors (CHAMPS) questionnaire. Linear regression models with progressive covariate adjustments evaluated the associations of sedentary behavior and PA with muscle energetics, as well as the attenuation of the age/muscle energetics association by MVPA and sedentary behavior. As a sensitivity analysis, we also examined activPAL-measured daily step count and time spent in sedentary behavior and their associations with muscle energetics. Every 30 min/day more of ActiGraph-measured MVPA was associated with 0.65 pmol/(s × mg) higher maxOXPHOS and 0.012 mM/s higher ATP after adjusting for age, site/technician, and sex ( < 0.05). Light activity was not associated with maxOXPHOS or ATP. Meanwhile, every 30 min/day spent in ActiGraph-measured sedentary behavior was associated with 0.39 pmol/s × mg lower maxOXPHOS and 0.006 mM/s lower ATP ( < 0.05). Only associations with ATP held after further adjusting for socioeconomic status, body mass index, lifestyle factors, and multimorbidity. CHAMPS MVPA and all PA yielded similar associations with maxOXPHOS and ATP ( < 0.05), but sedentary behavior did not. Higher activPAL step count was associated with higher maxOXHPOS and ATP ( < 0.05), but time spent in sedentary behavior was not. Additionally, age was significantly associated with muscle energetics for men only ( < 0.05); adjusting for time spent in ActiGraph-measured MVPA attenuated the age association with ATP by 58% in men. More time spent in accelerometry-measured or self-reported daily PA, especially MVPA, was associated with higher skeletal muscle energetics. Interventions aimed specifically at increasing higher intensity activity might offer potential therapeutic interventions to slow age-related decline in muscle energetics. Our work also emphasizes the importance of taking PA into consideration when evaluating associations related to skeletal muscle energetics.

中文翻译：

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加速度测量和自我报告的身体活动和久坐行为与骨骼肌能量学的关联：肌肉、活动性和衰老的研究 (SOMMA)

骨骼肌能量随着年龄的增长而下降，而体力活动 (PA) 已被证明可以抵消老年人的这些下降。然而，许多报告这些影响的研究都是基于自我报告的 PA 或结构化运动干预措施。因此，我们研究了加速度测量和自我报告的 PA 和久坐行为 (SB) 与骨骼肌能量学的关联，并探讨了 PA 和久坐行为会在多大程度上减弱年龄与肌肉能量学的关联。作为肌肉、活动性和衰老研究的一部分，纳入的老年人 (= 879)、810 名（年龄 = 76 ± 5 岁，平均值 ± 标准差；58% 女性）通过高分辨率呼​​吸测量法测量了最大肌肉氧化能力透化肌纤维（最大氧化磷酸化（maxOXPHOS））和磷磁共振波谱（最大三磷酸腺苷（ATP））。使用腕戴式 ActiGraph GT9X 在 7 天内对加速度测量的久坐行为、轻度活动和中度至剧烈 PA (MVPA) 进行评估。使用老年人社区健康活动模型计划 (CHAMPS) 调查问卷对自我报告的久坐行为、MVPA 和所有 PA 进行评估。具有渐进协变量调整的线性回归模型评估了久坐行为和 PA 与肌肉能量学的关联，以及 MVPA 和久坐行为对年龄/肌肉能量学关联的衰减。作为敏感性分析，我们还检查了 activPAL 测量的每日步数和久坐行为所花费的时间及其与肌肉能量的关联。在调整年龄、地点/技术人员和性别后，ActiGraph 测量的 MVPA 每增加 30 分钟/天，maxOXPHOS 就会升高 0.65 pmol/(s × mg)，ATP 就会升高 0.012 mM/s (< 0.05)。光活动与 maxOXPHOS 或 ATP 无关。同时，ActiGraph 测量的静坐行为每花费 30 分钟/天，maxOXPHOS 就会降低 0.39 pmol/s × mg，ATP 就会降低 0.006 mM/s (< 0.05)。在进一步调整社会经济地位、体重指数、生活方式因素和多种疾病后，仅与 ATP 存在关联。 CHAMPS MVPA 和所有 PA 与 maxOXPHOS 和 ATP 产生相似的关联（< 0.05），但久坐行为却没有。较高的 activPAL 步数与较高的 maxOXHPOS 和 ATP (< 0.05) 相关，但久坐行为所花费的时间则不然。此外，年龄与男性的肌肉能量显着相关（<0.05）；对 ActiGraph 测量的 MVPA 所花费的时间进行调整后，男性中年龄与 ATP 的相关性减弱了 58%。在加速度测量或自我报告的每日 PA（尤其是 MVPA）上花费更多时间与更高的骨骼肌能量相关。专门针对增加更高强度活动的干预措施可能会提供潜在的治疗干预措施，以减缓与年龄相关的肌肉能量下降。我们的工作还强调了在评估与骨骼肌能量学相关的关联时考虑 PA 的重要性。