Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania.
Department of Genetics, Washington University School of Medicine in St. Louis, St. Louis, Missouri.
J Gerontol A Biol Sci Med Sci. 2021 Sep 13;76(10):e237-e244. doi: 10.1093/gerona/glaa281.
Lower physical activity levels and greater fatigability contribute independently to slower gait speed in older adults. To fully understand the bidirectional relations between physical activity and fatigability, and to inform potential intervention strategies, we examined whether physical activity or fatigability explains more of the other factor's association on slower gait speed.
Two generations (probands and offspring) of older adults (N = 2079, mean age 73.0 ± 10.0 years, 54.2% women, 99.7% White) enrolled in the Long Life Family Study were assessed at Visit 2 (2014-2017). Self-reported physical activity was measured with the Framingham Physical Activity Index and perceived physical fatigability using the Pittsburgh Fatigability Scale. Statistical mediation analyses were conducted separately by generation with linear mixed-effect models accounting for family relatedness and adjusted for demographics, health conditions, and field center.
Greater perceived physical fatigability explained the association of lower physical activity on slower gait speed via a 22.5% attenuation of the direct association (95% confidence interval [CI]: 15.0%-35.2%) for the probands and 39.5% (95% CI: 22.8%-62.6%) for the offspring. Whereas lower physical activity explained the association of greater perceived fatigability on slower gait speed via a 22.5% attenuation of the direct association (95% CI: 13.4%-32.8%) for the probands and 6.7% (95% CI: 3.8%-15.4%) for the offspring.
Our findings suggest that the impact of greater perceived physical fatigability on the association between lower physical activity and slower gait speed differs between younger-old and middle-to-oldest-old adults, indicating perceived physical fatigability as a potential mediator in the disablement pathway.
较低的身体活动水平和更大的疲劳感会导致老年人的步速变慢。为了全面了解身体活动和疲劳感之间的双向关系，并为潜在的干预策略提供信息，我们研究了身体活动或疲劳感哪个因素对较慢的步速的影响更大。
在第二代（被试及其后代）年长参与者（N=2079，平均年龄 73.0±10.0 岁，54.2%为女性，99.7%为白人）的 Long Life Family Study 中，于第 2 次就诊（2014-2017 年）时进行评估。使用 Framingham 身体活动指数测量自我报告的身体活动量，使用匹兹堡疲劳量表测量感知的身体疲劳度。通过线性混合效应模型，分别对每一代进行统计中介分析，考虑家族关系，并根据人口统计学、健康状况和现场中心进行调整。
更大的感知身体疲劳感通过减弱身体活动与较慢的步速之间的直接关联（95%置信区间[CI]：15.0%-35.2%）解释了身体活动较少与较慢的步速之间的关联，这种减弱作用在被试中为 22.5%（95% CI：15.0%-35.2%），在后代中为 39.5%（95% CI：22.8%-62.6%）。而较低的身体活动量通过减弱感知疲劳感与较慢的步速之间的直接关联（95% CI：13.4%-32.8%）解释了感知疲劳感与较慢的步速之间的关联，这种减弱作用在被试中为 22.5%（95% CI：13.4%-32.8%），在后代中为 6.7%（95% CI：3.8%-15.4%）。
我们的研究结果表明，感知疲劳感对身体活动与较慢的步速之间的关联的影响在年轻老年人和中老年人之间存在差异，这表明感知疲劳感可能是失能途径中的一个潜在中介因素。
