Dados do Trabalho

Título

Acute and chronic effects of physical exercise on IgA and IgG levels and susceptibility to URTI: a systematic review and meta-analysis.

Introdução e Objetivo

It is evident that immune changes are induced by physical exercise. However, there is a knowledge gap about the effects of acute exercise and exercise training on the immune system. Therefore, this systematic review and meta-analysis aimed at evaluating acute and chronic effects of physical exercise on immunoglobulin A (IgA) and immunoglobulin G (IgG) levels, as well as its relationship with the susceptibility to develop upper respiratory tract infection (URTI).

Casuística e Método

This systematic review and meta-analysis was conducted and reported in accordance with PRISMA statement. A systematic search of PubMed, Web of Science and EMBASE was performed in July 2020.This systematic review and meta-analysis included studies in which participants performed acute exercise or physical training and were subjected to analyses of URTI incidence and concentrations of IgA and IgG. The selected studies for systematic review were divided into the following three groups: (I) trials that evaluated the effects of acute exercise in sedentary subjects, (II) trials that evaluated the effects of acute exercise in athletes/ trained individuals, and (III) trials that evaluated the effects of exercise training on the incidence of URTI, as well as on the levels of IgA and IgG. In total, 2509 studies were identified through the database and reference searches. After removing the duplicates and excluding papers that did not meet the eligibility criteria following a review of their titles, abstracts and full texts, 43 studies (117 trials, n = 1176 individuals) were selected for inclusion in the systematic review.

Resultados

Twenty-nine studies (85 trials, n = 662 individuals) were included in the meta-analysis. Acute exercise increases the IgA levels in trained subjects (mean effect size (ES) = 0.68 (95% confidence interval (CI): 0.34 to 1.02) but does not affect its levels in untrained subjects (mean effect size (ES) = 0.16 (95% CI: -0.32 to 0.64). Such increase in IgA levels induced by acute exercise is greater in trained individual that performed ultramarathon (mean effect size (ES)=1.60 (95% CI: 0.20 to 3.01). On the other hand, physical training does not change IgG levels (mean effect size (ES)= -0.31 (95% CI: -1.49 to 0.88).

Discussão

The present systematic review and meta-analysis demonstrates that acute exercise increases the IgA levels in trained subjects, but does not affect its levels in untrained subjects. Such increase in IgA levels induced by acute exercise is greater in trained individual that performed ultramarathon in comparison with those that executed triathlon. Although, trained individuals present elevated IgA response to acute exercise, these individuals have decreased IgA baseline. On the other hand, the basal IgA levels were reduced by chronic physical training. In addition, physical training does not change IgG levels. These data indicate that acute exercise positively influences IgA levels in trained individuals, being this effect pronounced when a strenuous exercise such as ultramarathon is executed. Moreover, chronic physical training response over IgA levels seems to depend on the characteristics of the subject´s physical training since non-military personnel presented unchanged IgA levels. The present analysis brings important information for exercise practitioners and athletes and provide support for the better understanding of the beneficial effects of exercise in fighting infections such as URTI through modulation of immunoglobulin levels.

Conclusão

The present systematic review and meta-analysis indicates that acute exercise positively influences IgA levels in trained individuals, being this effect pronounced when a strenuous exercise such as ultramarathon is executed. Moreover, chronic physical training response over IgA levels seems to depend on the characteristics of the subject´s physical training since non-military personnel present unchanged IgA levels.