Effects of resistance training intensity and a dietary protein intervention on psychosocial outcomes, executive function, and quality of life in frail community-dwelling older adults

Abstract

Background: Psychosocial functioning, executive function, and quality of life are important contributors to resilience and daily functioning in frail older adults. Resistance training may improve these outcomes, but it remains unclear whether training intensity, with or without a dietary protein intervention, modifies these effects. We examined changes in these outcomes after 12 weeks of supervised resistance training to volitional muscular failure in frail community-dwelling older adults.

Methods: This secondary analysis of the TEAMS randomized controlled trial included 295 community-dwelling adults (mean age 74.0 ± 6.0; 69% female) who completed twice-weekly resistance training. Participants were randomized to training only or training plus a dietary protein intervention. Training intensity was randomized from 20% to 80% of one-repetition maximum (1-RM) in 5% increments. Psychosocial outcomes included depressive symptoms (Geriatric Depression Scale–15), anxiety (6-item State–Trait Anxiety Inventory), pain, fatigue, and fear of falling (Numeric Rating Scales), and sleep quality (Pittsburgh Sleep Quality Index). Executive function was assessed using the Trail Making Test (A and B), Stroop Color–Word Test, and Letter Fluency. Quality of life was measured with the 12-item Short Form Health Survey. Linear mixed models were applied, with

Significance: at P < 0.05.

Results: After twelve weeks, participants showed reduction in depressive symptoms (β = −0.167, 95% CI − 0.27 to − 0.06), executive function (TMT-A β = −4.71 s; TMT-B β = −12.11 s; SCWT log β = −0.091; LF β = +2.46 words), and improvement in quality of life (β = +1.26, 95% CI 0.62–1.91), regardless of training intensity. The dietary protein intervention led to a greater reduction in fear of falling compared with resistance training only (log β = −0.257, 95% CI − 0.491 to − 0.023), but showed no consistent additional effects on other outcomes.

Conclusion: In frail, community-dwelling older adults, twelve weeks of resistance training led to improvements in depressive symptoms, executive function, and quality of life. Training intensity did not consistently influence these improvements, and the protein intervention showed no additional benefits. These

results demonstrate that resistance training to failure is effective at different intensities, allowing programs to be tailored to individual needs. Trial registration : NL-OMON54919 (at ICTRP Search Portal), date of registration: 09-02-2021