The Effectiveness of an App-Based Fitness Program on Self-Perceived Physical Functioning in Older Adults: Randomized Waitlist-Controlled Trial.

Background: A decline in physical functioning can result in a loss of independence, particularly in older adults. Information and communications technologies supporting physical activity, such as fitness apps, are perceived as promising tools to increase activity levels. However, only little is known about fitness apps' impact on older people's abilities and skills to accomplish activities of daily living. Objective: In this study, we aimed to investigate whether a newly developed app-based physical activity program improves self-perceived physical functioning or at least prevents a functional decline in older adults. Methods: We targeted older adults in their early years of retirement and conducted a randomized waitlist-controlled trial in Austria. The app-based program was received by the intervention group (IG) for a period of 14 weeks first; afterwards, the IG handed over the devices to the control group (CG). Both groups had 3 appointments with a fitness coach. The app comprised 3 functions, a multicomponent fitness exercise program, recommendations for outdoor activities, and e-learning courses. Self-perceived physical functioning was measured by 4 common daily life activities rated on 6-point scales. Data were collected through online surveys at 3 time points, 8 weeks before intervention start (t-1), at intervention start (t0), and 14 weeks later at the end of the intervention (t1). We estimated generalized linear mixed models and derived average marginal effects. The effects are presented as differences in percentage points resulting from differences in estimated probabilities between groups before and after the intervention. Results: A total of 219 participants between 60 and 72 years, 96 in the IG and 123 in the CG, were analyzed. The intervention significantly increased the self-perceived abilities of "climb up stairs and carry something" (odds ratio [OR] 2.67, 95% CI 1.37-5.18; P=.004) and of "lift and carry groceries" (OR 1.99, 95% CI 1.02-3.89; P=.04). On the contrary, no significant impact on the ability to "walk 1 km" (OR 1.91, 95% CI 0.85-4.30; P=.12) and "stretch to the toes" (OR 1.31, 95% CI 0.62-2.76; P=.48) was found. The probability of rating "climb up stairs and carry something" as "very easy" increased by 8.8 percentage points (95% CI 2.6-14.9; P=.005) and "lift and carry groceries" by 7.9 percentage points (95% CI 0.5-15.3; P=.04). Predicted probabilities showed that outcomes improved in the IG and remained unchanged in the CG. Conclusions: Although the fitness app was designed as a multicomponent program, it supported only selected capabilities relevant for independent living. The app-based physical activity program increased self-perceived physical functioning related to strength, endurance, and balance, but not to flexibility. This highlights a clear need for future apps and research to focus on all relevant areas, including flexibility and mobility, which are crucial for fully maintaining independence in older adults.