Exercise stress increases susceptibility to influenza infection

Physical Exercise Induces Specific Adaptations Resulting in Reduced Organ Injury and Mortality During Severe Polymicrobial Sepsis

“…Notably, there is overwhelming evidence that the beneficial effects induced by higher levels of physical activity for the risk of heart diseases and strokerelated deaths are independent from changes in body mass index (9). Although much is known about the relationship of physical exercise on the susceptibility to bacterial or viral infections (10)(11)(12)(13), only few experimental studies have investigated the effects of regular physical exercise on the survival probability and host response in severe infectious diseases. Mice subjected to regular exercise on a motorized treadmill displayed reduced symptoms, virus load, and levels of inflammatory cytokines after influenza infection compared with sedentary mice (14).…”

Interferon-beta, but not tumor necrosis factor-alpha, production in response to poly I:C is maintained despite exhaustive exercise in mice

“…In fact, we and other researchers have found that high concentrations of proinflammatory cytokines, for example tumor necrosis factor (TNF)-a, in plasma were strongly inhibited by exhaustive exercise before challenge of rodents with lipopolysaccharide (LPS), a gram-negative bacteria component [2][3][4]. In addition, it has been reported that exercise stress might be associated with increased susceptibility to viral infections [5,6]. However, changes in pathogen-induced type I interferons (IFN-a/b), which are very important in anti-virus response, after severe exercise are little known, although we reported that exhaustive exercise induced depression of IFN-a against injection of imidazoquinoline resiquimod (R-848), a ligand of the toll-like receptor (TLR)7 which responds to single-stranded (ss) RNA viruses to trigger IFN production in mice [7].…”

The suppression of tumor necrosis factor-alpha production in response to pathogen stimulation by strenuous exercise and underlying mechanisms

“…2). In fact, in animal experimental models, multiple laboratories reported that strenuous exercise induces increases in mortality, as well as worsening of infection with the influenza virus or herpes virus 9,10) . In contrast to these findings, exhaustive exercise markedly elevates the production of TNF-α in response to FG via TLR5 (unpublished data, Fig.…”

“…Indeed, innate immune functions are known to be transiently reduced by strenuous exercise [6][7][8][9] . In animal experimental models, strenuous exercise induces increases in mortality, as well as worsening of infection with the influenza virus or herpes virus 9,10) . Recently, the mechanisms underlying exercise-induced immunosuppression have been investigated.…”