Adiposity, Inflammation, and Physical Function in Overweight African American Adults with Osteoarthritis

Osteoarthritis (OA) affects over 30 million United States (U.S.) adults1 and 80% of those with OA have some degree of mobility limitation2. Rising adiposity levels play a serious, detrimental role to the progression of OA and physical disability, particularly in older adults3,4. Furthermore, excess visceral body fat can promote the overproduction of inflammatory proteins, including C-reactive protein (CRP), that have been linked to the onset and worsening of OA, lean muscle tissue atrophy, and overall functional decline3, 4. Thus, reducing total and regional body fat mass may have an impact on both joint burden and systemic inflammation that translates to improved physical function within the older population and particularly in those with existing OA. The positive effects of physical activity (PA) combined with dietary weight management are evident from multiple randomized controlled trials (RCT) in older, overweight and obese adults with OA leading to greater weight loss5, 6, 7, 8, 9, 10 reductions in systemic, low-grade inflammation11, 12 and improvements in subjective and objective measures of physical function. However, these studies are limited in that they were largely tightly controlled efficacy trials, were focused on primarily non-Hispanic white cohorts, and presented limited data regarding associations between changes in adiposity, body composition, inflammation, and physical function. Thus, the aim of this study was to assess the impact of an 8-week PA vs. an 8-week PA plus dietary weight management intervention on adiposity, body composition, inflammation, and objective physical function in older, overweight/obese African American adults with OA and to assess the associations between changes in adiposity, body composition, inflammation, and physical function. Results from this study confirm that a combined dietary and physical activity intervention effectiveness trial is superior to PA alone in reducing body weight, percent and total body fat, and visceral fat mass and improving physical function based on the six-minute walk test. However, the combined program was not superior for reducing systemic inflammation. Although, in a post-hoc analysis, a greater reduction in CRP was associated with fewer seconds to complete the timed-up and go physical function test suggesting that lowering systemic inflammation can have a positive impact on physical function. Given the modest effect of the interventions on the adiposity, inflammatory and physical function measures compared to existing trials, additional studies conducted on larger samples including a longer follow-up period may be needed to fully explore the effects of the interventions these outcomes and how changes in adiposity and physical function translate to improved physical function. In addition, a larger sample that includes a significant number of non-Hispanic whites would allow for exploration of possible racial/ethnic differences in response to the intervention.