Effects of Regular Physical Activity on the Immune System, Vaccination and Risk of Community-Acquired Infectious Disease in the General Population: Systematic Review and Meta-Analysis

Abstract

Background Regular physical activity is the prime modality for the prevention of numerous non-communicable diseases and has also been advocated for resilience against COVID-19 and other infectious diseases. However, there is currently no systematic and quantitative evidence synthesis of the association between physical activity and the strength of the immune system. Objective To examine the association between habitual physical activity and (1) the risk of community-acquired infectious disease, (2) laboratory‐assessed immune parameters, and (3) immune response to vaccination. Methods We conducted a systemic review and meta-analysis according to PRISMA guidelines. We searched seven databases (MEDLINE, Embase, Cochrane CENTRAL, Web of Science, CINAHL, PsycINFO, and SportDiscus) up to April 2020 for randomised controlled trials and prospective observational studies were included if they compared groups of adults with different levels of physical activity and reported immune system cell count, the concentration of antibody, risk of clinically diagnosed infections, risk of hospitalisation and mortality due to infectious disease. Studies involving elite athletes were excluded. The quality of the selected studies was critically examined following the Cochrane guidelines using ROB2 and ROBINS_E. Data were pooled using an inverse variance random-effects model. Results Higher level of habitual physical activity is associated with a 31% risk reduction (hazard ratio 0.69, 95% CI 0.61–0.78, 6 studies, N = 557,487 individuals) of community-acquired infectious disease and 37% risk reduction (hazard ratio 0.64, 95% CI 0.59–0.70, 4 studies, N = 422,813 individuals) of infectious disease mortality. Physical activity interventions resulted in increased CD4 cell counts (32 cells/µL, 95% CI 7–56 cells/µL, 24 studies, N = 1112 individuals) and salivary immunoglobulin IgA concentration (standardised mean difference 0.756, 95% CI 0.146–1.365, 7 studies, N = 435 individuals) and decreased neutrophil counts (704 cells/µL, 95% CI 68–1340, 6 studies, N = 704 individuals) compared to controls. Antibody concentration after vaccination is higher with an adjunct physical activity programme (standardised mean difference 0.142, 95% CI 0.021–0.262, 6 studies, N = 497 individuals). Conclusion Regular, moderate to vigorous physical activity is associated with reduced risk of community-acquired infectious diseases and infectious disease mortality, enhances the first line of defence of the immune system, and increases the potency of vaccination. Protocol registration The original protocol was prospectively registered with PROSPERO (CRD42020178825).

Vitamin D and Exercise Are Major Determinants of Natural Killer Cell Activity, Which Is Age- and Gender-Specific

“…Many studies reported that physical exercise improved health outcome of cancer patients and ameliorated immunosenescence in the elderly population (49)(50)(51)(52)(53). A metaanalysis demonstrated that higher level of habitual physical activity is associated with reduced risk of community-acquired infectious disease and mortality by it (54). Also, physical activity interventions resulted in improved state of immune markers: increased CD4 cell counts, increased salivary immunoglobulin IgA concentration, decreased neutrophil counts, and higher antibody concentration after vaccination (54).…”

“…A metaanalysis demonstrated that higher level of habitual physical activity is associated with reduced risk of community-acquired infectious disease and mortality by it (54). Also, physical activity interventions resulted in improved state of immune markers: increased CD4 cell counts, increased salivary immunoglobulin IgA concentration, decreased neutrophil counts, and higher antibody concentration after vaccination (54). One more important factor between the physical exercise and immune function is the intensity or duration of the exercise.…”

Post-COVID-19 Syndrome and the Potential Benefits of Exercise

“…Exercise attenuates immunosenescence by maintaining the peripheral T-cell pool and natural killer cell compartments, and it seems likely to improve the immune response to SARS-CoV-2 antigens [81]. In support of this argument, it has been recently demonstrated that regular, moderate to vigorous physical activity reduced the risk of community-acquired infectious diseases and infectious disease mortality [82]. All in all, it should be noted that exhaustive and excessive exercise training may cause mitochondrial functional impairment, inducing a dysregulated systemic inflammatory response, thus being detrimental for health [83][84][85].…”

Physical Activity Promotion and the United Nations Sustainable Development Goals: Building Synergies to Maximize Impact

“…[4][5][6] Recent findings have also unveiled physical activity's protective effects on infectious disease outcomes (including COVID-19). 7,8 Effective strategies to promote physical activity 9 can not only reduce disease burden and health care cost but could also offer untapped opportunities for achieving multiple SDGs. However, such synergy has not been explored systematically within a global context.…”