Bann David, Hire Don, Manini Todd, Cooper Rachel, Botoseneanu Anda, McDermott Mary M, Pahor Marco, Glynn Nancy W, Fielding Roger, King Abby C, Church Timothy, Ambrosius Walter T, Gill Thomas M
MRC Unit for Lifelong Health and Ageing at UCL, London, United Kingdom.
Department of Biostatistical Sciences, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America.
PLoS One. 2015 Feb 3;10(2):e0116058. doi: 10.1371/journal.pone.0116058. eCollection 2015.
Identifying modifiable determinants of fat mass and muscle strength in older adults is important given their impact on physical functioning and health. Light intensity physical activity and sedentary behavior are potential determinants, but their relations to these outcomes are poorly understood. We evaluated associations of light intensity physical activity and sedentary time-assessed both objectively and by self-report-with body mass index (BMI) and grip strength in a large sample of older adults.
We used cross-sectional baseline data from 1130 participants of the Lifestyle Interventions and Independence for Elders (LIFE) study, a community-dwelling sample of relatively sedentary older adults (70-89 years) at heightened risk of mobility disability. Time spent sedentary and in light intensity activity were assessed using an accelerometer worn for 3-7 days (Actigraph GT3X) and by self-report. Associations between these exposures and measured BMI and grip strength were evaluated using linear regression.
Greater time spent in light intensity activity and lower sedentary times were both associated with lower BMI. This was evident using objective measures of lower-light intensity, and both objective and self-reported measures of higher-light intensity activity. Time spent watching television was positively associated with BMI, while reading and computer use were not. Greater time spent in higher but not lower intensities of light activity (assessed objectively) was associated with greater grip strength in men but not women, while neither objectively assessed nor self-reported sedentary time was associated with grip strength.
In this cross-sectional study, greater time spent in light intensity activity and lower sedentary times were associated with lower BMI. These results are consistent with the hypothesis that replacing sedentary activities with light intensity activities could lead to lower BMI levels and obesity prevalence among the population of older adults. However, longitudinal and experimental studies are needed to strengthen causal inferences.
鉴于脂肪量和肌肉力量对老年人身体功能和健康的影响，确定其可改变的决定因素非常重要。轻度体力活动和久坐行为是潜在的决定因素，但它们与这些结果之间的关系尚不清楚。我们在大量老年人样本中评估了客观测量及自我报告的轻度体力活动和久坐时间与体重指数（BMI）和握力之间的关联。
我们使用了来自老年人生活方式干预与独立性（LIFE）研究的1130名参与者的横断面基线数据，该研究是一个社区居住的样本，由相对久坐的老年人（70 - 89岁）组成，他们有较高的行动能力残疾风险。使用佩戴3 - 7天的加速度计（Actigraph GT3X）和自我报告来评估久坐时间和轻度体力活动时间。使用线性回归评估这些暴露因素与测量的BMI和握力之间的关联。
更多的轻度体力活动时间和更少的久坐时间均与较低的BMI相关。这在较低强度轻度体力活动的客观测量以及较高强度轻度体力活动的客观和自我报告测量中都很明显。看电视的时间与BMI呈正相关，而阅读和使用电脑则不然。在男性中，更多时间花在较高强度而非较低强度的轻度活动上（客观评估）与更大的握力相关，而女性则不然，客观评估和自我报告的久坐时间均与握力无关。
在这项横断面研究中，更多的轻度体力活动时间和更少的久坐时间与较低的BMI相关。这些结果与以下假设一致，即用轻度体力活动取代久坐活动可能导致老年人中较低的BMI水平和肥胖患病率。然而，需要纵向和实验研究来加强因果推断。
