Evaluation of the Bidirectional Relations of Perceived Physical Fatigability and Physical Activity on Slower Gait Speed

Abstract

Background Lower physical activity levels and greater fatigability contribute independently to slower gait speed in older adults. However, 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. Methods Two generations (probands and offspring) of older adults (N=2,079, 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, field center. Results 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% 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. Conclusions 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.

Influence of an Upper Limb Isometric Task in Perceived and Performance Fatigability of Elderly Subjects: A Quasi-Experimental Study

“…Additionally, in our study, physical activity total time was not associated with fatigability. These results are not in accordance with other studies that show an association between physical activity and fatigability, which is not, however, related to upper limb isometric activity [ 22 , 52 , 54 ]. Higher physical activity is associated with better cardiorespiratory fitness, and more efficient energy utilization [ 22 ].…”

The Association between Poor Diet Quality, Physical Fatigability and Physical Function in the Oldest-Old from the Geisinger Rural Aging Study

“…Higher levels of perceived physical fatigue, also known as physical fatigability, was recently shown to be associated with lower levels of physical function, including slower walking speeds during the 400-m walk test [ 7 ], and have been shown to predict impending declines in physical function in older adults [ 8 ]. Recent results suggest that more perceived physical fatigability is a potential mediator in the disablement pathway [ 9 ].…”

Profiles of Accelerometry-Derived Physical Activity Are Related to Perceived Physical Fatigability in Older Adults

“…However, in these studies, physical activity was defined as the outcome, which may not wholly reflect the mechanistic relationship between physical activity and perceived fatigability. Recent work examining the bidirectional associations of physical activity and perceived fatigability using the Long Life Family Study found that there was mediation of physical activity on gait speed through fatigability, but not vice versa [ 9 ]. Thus, it is important to re-examine these relationships treating physical activity patterns as the independent variable, as doing so may more accurately reflect the aging-related disablement pathway.…”

“…Older adults > 65 years in the United States are the least physical active adults of any age group [ 19 ] and as many as 70% of older adults report chronic sleep disturbances [ 14 ], making them particularly vulnerable to the negative effects of reduced physical activity and fragmented RARs. Additionally, physical activity is an established and modifiable correlate of fatigability [ 9 , 20 ]. RAR analysis could provide specific insights as to which specific features of overall patterns of rest and activity, or combinations of features, are most strongly associated with greater perceived physical fatigability.…”