Effects of Multicomponent Exercise on Immunity, Antibodies, and Physical Activity in Older Adults After COVID-19 Vaccination: An RCT-Feasibility Study

Background Immunosenescence contributes to reduced vaccine responsiveness and chronic low-grade inflammation in older adults. Although regular physical exercise has been associated with improved immune function, evidence regarding the feasibility and immunological effects of multicomponent exercise training (MET) following COVID-19 vaccination remains limited. This pilot randomized feasibility trial aimed to assess the feasibility of implementing a 10-week MET program and to explore its effects on functional fitness, physical activity, anthropometric measures, lipid profile, and immuno-inflammatory markers in community-dwelling older adults after COVID-19 vaccination. Methods Twenty-three community-dwelling older adults (≥60 years) completed this randomized pilot feasibility trial and were allocated to either a MET group (n = 10) or a Behavior Change Program (BCP) group (n = 13). Both interventions lasted 10 weeks. Pre- and post-intervention assessments included functional fitness (Short Physical Performance Battery), physical activity levels, anthropometric measures, lipid and protein profiles, immunoglobulins (IgA, IgM, IgG), and cytokines (IL-2, IL-6, IL-10, TNF-α, and IFN-γ). Results The intervention proved feasible, with satisfactory adherence among participants completing the program and no exercise-related adverse events. The MET group demonstrated significant improvements in functional fitness (p = 0.002; d=1.90). Although physical activity levels showed a positive trend, changes did not reach statistical significance. Significant reductions in IL-2, IL-6, and TNF-α were observed following MET (all p ≤ 0.05), whereas the BCP group exhibited increased IL-6 concentrations together with higher IL-2/IL-10 and IL-6/IL-10 ratios, suggesting a shift toward a more pro-inflammatory profile. Moderate-to-large effect sizes were also observed for improvements in selected lipid parameters, although most biochemical changes were not statistically significant. Conclusions This pilot feasibility trial demonstrated that a 10-week multicomponent exercise program can be safely implemented in community-dwelling older adults following COVID-19 vaccination and provides preliminary evidence of beneficial effects on functional fitness and selected immuno-inflammatory markers. Given the small sample size, these findings should be interpreted cautiously and confirmed in adequately powered randomized controlled trials.