"Identifying best intervention strategies to mitigate perceived physical fatigability severity among older adults with obesity: Leveraging data from the EMPOWER Lifestyle Trial", Department of Epidemiology, School of Public Health. 

Committee:

• Nancy W. Glynn (chair), EPI
• Jason Fanning, Department of Health and Exercise Sciences, Wake Forest University
• Chaeryon Kang, Psychiatry, Biostatistics
• Bonny Rockette-Wagner, EPI
• Christopher E. Kline, Department of Health and Humna Development, School of Education
• Barbara J. Nicklas, Department of Internal Medicine, Wake Forest University School of Medicine

Abstract:

Greater perceived physical fatigability (herein fatigability), the susceptibility to physical fatigue anchored to specific tasks of quantifiable duration and intensity, is a deleterious and highly prevalent characteristic among older adults, preceding disability and death. Given robust associations with aerobic capacity and physical activity, fatigability may be modifiable through intervention; however, current literature lacks evidence in older adult populations and intervention components have not been well-described. 

This dissertation used data from the Empowered with Movement to Prevent Weight Regain (EMPOWER) randomized trial to address key knowledge gaps. Highly fatigued (80% prevalence of more severe fatigability) older adults with obesity participated in one of three physical activity interventions in combination with weight loss: 1) aerobic exercise (n=60), 2) daylong movement (n=63), and 3) aerobic exercise and daylong movement (n=60). First, we examined the time  intervention interaction on two well-validated measures of fatigability to assess effectiveness of the different interventions. Next, we examined the mediation effects of three measures of aerobic capacity and two accelerometer-measured physical activity metrics on the association between the interventions and fatigability. Finally, we investigated the associations of fatigability with weight outcomes. 

We found that fatigability measured using the Pittsburgh Fatigability Scale meaningfully improved during the intensive intervention period (6-month) and after a 12-month maintenance period. However, there were no significant time  intervention group differences in fatigability, suggesting the three interventions had similar benefits. Mediation analysis revealed improvements in fatigability may be partially attributed to lower cost-capacity ratio (a measure of effort during a slow task relative to peak effort) and higher moderate-vigorous physical activity. Finally, a clinically meaningful improvement in fatigability was associated with less weight regain during maintenance. 

Collectively, our work establishes that fatigability can be modified by diverse physical activity interventions in combination with weight loss among older adults with obesity. Specifically, interventions that concomitantly target improving cost-capacity ratio and moderate-vigorous physical activity may provide the most benefit. Lowering fatigability may also be protective in preventing weight regain, although more research is indicated. Given the numerous age-related health consequences associated with greater fatigability, public health efforts to improve fatigability may promote healthy aging.