Exercise, inflammation and acute cardiovascular events.

Abstract

There is a knowledge gap regarding the consequences of exercise during acute infections in humans and contradictory findings in animal studies, compromising public health advice on the poten-tial benefits of physical activity for immunity. Here, we carried out a meta-analysis of studies of the effects of moderate exercise (ME) and exercise until fatigue (EF) on symptom severity, morbidity and mortality during viral infection in animal models. The sys-tematic review on PubMed, Scopus, Embase, Web of Science, Co-chrane and EBSCOhost (CINAHL and SPORT Discus) identified 8 controlled studies, with 15 subgroups within them. The studies exposed the animals (mice [7 studies] and monkeys [1 study]) to exercise immediately before or after viral inoculation (HSV-1, H1N1 influenza and B.K. virus) with follow-up for 21 days. ME significantly reduced morbidity (OR 0.43 [0.19; 0.98], P = 0.04) with no change for symptom severity (SMD-3.37 [-9.01; 2.28], P = 0.24) or mortality (OR 0.48 [0.08;3.03], P = 0.43). In con-trast, EF gave a trend towards increased symptom severity (SMD 0.96 [-0.06; 1.98], P = 0.07) and mortality (OR 1.47 [0.96;2.28], P =0.08) with no change in morbidity (OR 1.22 [0.60;2.5], P = 0.58). We conclude that in animals moderate exercise during in-fection is advantageous, whilst exercise until fatigue should be avoided. Further research is required to determine if moderate exercise may also be beneficial in humans during infection.