AbstractBackgroundThe associations between free‐living physical activity (PA) and sedentary behaviour (SB) and sarcopenia in older people and its determinants are controversial. Self‐reporting, the use of one‐size‐fits‐all cut‐points for intensity categorization when using accelerometers and the absence of a clear sarcopenia definition hampered explorations. The aim of this study is to describe the associations between objectively measured PA patterns and sarcopenia and its determinants.MethodsSubjects aged >65 with valid accelerometry and sarcopenia‐related measures from Toledo Study of Healthy Aging (TSHA) were included. Muscle mass (MM) was estimated by dual‐energy X‐ray absorptiometry. Handgrip strength (HS) was measured by dynamometry. Physical performance assessment relied on gait speed (GS). Sarcopenia presence was ascertained using Foundation for the National Institutes of Health (FNIH) criteria. PA and SB were estimated by ActiTrainer worn for 1 week and classified into time spent in SB and different PA intensity bands [light PA (LPA) and moderate‐to‐vigorous PA (MVPA)] using age‐specific cut‐points. Different multivariate linear and logistic regression models [(i) single‐parameter, (ii) partition, and (iii) isotemporal substitution models] were used for estimating associations between PA, SB, and sarcopenia determinants and sarcopenia rates, respectively. All models adjusted for age, sex, co‐morbidities (Charlson index), and functional ability (Katz and Lawton indexes).ResultsFive hundred twelve subjects from the TSHA had available data (78.08 ± 5.71 years of age; 54.3% women). FNIH sarcopenia assessment was performed in 497 subjects (23.3% were sarcopenic). In the linear regression, the single‐parameter model showed an association between MVPA and all sarcopenia determinants. In the partition model, MVPA was associated with greater MM and GS. The isotemporal substitution showed that reallocating 1 h/day of MVPA displacing SB was associated with greater values in MM [β = 0.014; 95% confidence interval (CI) = 0.004, 0.024; P < 0.01], GS (β = 0.082; 95% CI = 0.054, 0.110; P < 0.001), and HS (β = 0.888; 95% CI = 0.145, 1.631; P < 0.05). In the logistic regression, the single‐parameter model yielded a significant association between 1 h/day increase in MVPA and sarcopenia reduction [odds ratio (OR) = 0.522; 95% CI = 0.367, 0.726; P < 0.001], as did the partition model (OR = 0.555; 95% CI = 0.376, 0.799; P < 0.01). The reallocation of 1 h/day SB only yielded a significant lower sarcopenia risk by almost 50% when it was substituted with MVPA, whereas the substitution of 15 min/day yielded a significant lower sarcopenia risk by 15% (P < 0.001) but did not show any association when it was substituted with LPA.ConclusionsAn increase in MVPA replacing SB and LPA was associated with a reduction in sarcopenia prevalence and better performance across its determinants (MM, GS, and HS). LPA did not show any significant effect.

中文翻译：

---

TSHA 中老年人的久坐行为、体力活动和肌肉减少症：等时替代模型

摘要背景老年人的自由体力活动（PA）和久坐行为（SB）与肌肉减少症之间的关联及其决定因素存在争议。自我报告、使用加速度计时使用一刀切的强度分类切点以及缺乏明确的肌少症定义阻碍了探索。本研究的目的是描述客观测量的 PA 模式与肌肉减少症及其决定因素之间的关联。方法年龄 > 65 岁且具有来自托莱多健康老龄化研究 (TSHA) 的有效加速测量和肌少症相关测量的受试者均被纳入其中。通过双能 X 射线吸收测定法估算肌肉质量 (MM)。通过测力法测量握力（HS）。身体表现评估依赖于步态速度（GS）。使用美国国立卫生研究院基金会 (FNIH) 标准确定肌少症的存在。PA 和 SB 通过 ActiTrainer 佩戴 1 周进行评估，并使用特定年龄的切点将其分为 SB 花费的时间和不同 PA 强度带 [轻度 PA (LPA) 和中度至剧烈 PA (MVPA)]。不同的多元线性和逻辑回归模型[(i)单参数、(ii)分区和(iii)等时替代模型]分别用于估计PA、SB和肌少症决定因素与肌少症发生率之间的关联。所有模型均根据年龄、性别、合并症（查尔森指数）和功能能力（卡茨和劳顿指数）进行调整。结果TSHA 的 512 名受试者拥有可用数据（78.08 ± 5.71 岁；54.3% 为女性）。FNIH 对 497 名受试者进行了肌少症评估（23.3% 为肌少症）。在线性回归中，单参数模型显示 MVPA 与所有肌肉减少症决定因素之间存在关联。在分区模型中，MVPA 与更大的 MM 和 GS 相关。等时替代表明，重新分配 1 小时/天的 MVPA 取代 SB 与 MM 的更大值相关[β= 0.014；95% 置信区间 (CI) = 0.004、0.024；磷<0.01]，GS（β= 0.082；95% CI = 0.054, 0.110;磷< 0.001) 和 HS (β= 0.888；95% CI = 0.145, 1.631;磷< 0.05）。在逻辑回归中，单参数模型显示 MVPA 每天增加 1 小时与肌肉减少症减少之间存在显着关联 [比值比 (OR) = 0.522；95% CI = 0.367, 0.726;磷< 0.001]，分区模型也是如此（OR = 0.555；95% CI = 0.376、0.799；磷< 0.01）。当用 MVPA 替代时，每天 1 小时 SB 的重新分配仅使肌肉减少症风险显着降低近 50%，而每天 15 分钟的替代则使肌肉减少症风险显着降低 15%（磷< 0.001)，但当用 LPA 替代时没有显示出任何关联。结论MVPA 取代 SB 和 LPA 的增加与肌少症患病率的降低以及其决定因素（MM、GS 和 HS）的更好表现相关。LPA没有表现出任何显着的效果。