Immunomodulatory, inflammatory, functional and biomechanical benefits of chronic exercise in physically active vs. insufficiently active older after fourth COVID-19 vaccine dose: nine months cohort.

INTRODUCTION

The vaccination against COVID-19 is being carried out, and observing the aging process and changes in the face of the pandemic in the older adults, studies are needed to better understand these changes. The purpose of this study was to compare immune response, inflammation, physical-functional performance, and gait at one and nine months after the fourth dose of the COVID-19 vaccine between physically active and insufficiently active older adults.

METHODS

Prospective cohort study. Thirty older adults were evaluated and divided into two groups: the Experimental Group ‒ physically active (EG, n = 15) and the Control Group ‒ insufficiently active (CG, n = 15). Assessments were baseline, one and nine months, post-vaccination and regular exercise practice.

MAIN OUTCOME MEASURES: Immunological and inflammatory markers and physical-functional variables: questionnaires (FRAQ, Baecke), physical tests (Step Test, Floor Transfer Test, Timed Up and Go, six-minute walk test, hand grip strength), and gait analysis using a pressure platform.

RESULTS

The EG showed increased IgA and decreased IgG levels over time. Regarding inflammation, EG demonstrated modulation of the inflammatory response, characterized by increased IL-10 levels, significant changes in IL-12p70 and IP-10 concentrations, and improved pro-/anti-inflammatory cytokine ratios (e.g., IL-6/IL-10), indicating a more regulated immune profile. Additionally, EG improved physical performance in the Step Test, Floor Transfer Test, and six-minute walking test, along with reduced plantar load in the midfoot and rearfoot regions. In contrast, the CG showed reductions in IL-10 and IP-10 levels over time, without consistent improvement in inflammatory modulation or physical-functional performance. In inter-group comparisons at nine months, EG exhibited higher IL-10 levels and a more favorable pro-/anti-inflammatory balance compared with CG, suggesting a controlled and effective immune activation following vaccination.

CONCLUSION

The practice of regular physical exercise was associated with more favorable immune, inflammatory, physical-functional, and gait outcomes at one and nine months after the fourth dose of the COVID-19 vaccine in physically active older adults compared with insufficiently active peers. These findings suggest that long-term regular physical exercise was associated with modulation of the immune-inflammatory profile, marked by a balanced increase in both Th1-associated cytokines (IL-12p70, IP-10) and the regulatory cytokine IL-10 and increased IgA levels and a reduction in IgG over time, suggesting a controlled and effective immune activation following vaccination against COVID-19 and regular exercise practice compared with CG (insufficiently active) and better physical-functional performance with reduction plantar overloading during gait.