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Moderate exercise protects mice from death due to influenza virus
Thomas Lowder1, David A Padgett, Jeffrey A Woods
1Department of Kinesiology, University of Illinois at Urbana-Champaign, 61801, USA.
Abstract:
We wanted to determine if different doses of exercise, performed in the initial days after infection when the host is mounting an immune response, altered mortality, and morbidity to influenza virus infection in mice. Forty hemagglutinating units of influenza virus (A/Puerto Rico/8/34) were administered intranasally to lightly anesthetized mice. Male Balb/cByJ mice were randomized to one of three groups: sedentary control (CON); moderate (MOD) exercise (20-30 min at 8-12 m/min); or prolonged (PRO) exercise (2.5 h at 8-12 m/min). Mice exercised on a treadmill 4 h post-infection and for three more consecutive days before symptom onset. Mortality, morbidity, bodyweight, and food intake were assessed. MOD had a significantly (p = .007) higher survival (18 of 22; 82%) rate when compared to CON (10 of 23; 43%). There was no difference in morbidity between MOD and CON, despite improved survival. PRO exhibited a survival rate of 30% (p = .29 vs. CON) and demonstrated significantly higher morbidity on several days. While all groups exhibited anorexia and significant body weight loss (approximately 30-35%) post-infection, exercise had little effect on these variables. We demonstrate that moderate exercise, performed in the initial days after influenza infection, significantly decreased mortality in mice. Prolonged exercise led to increased morbidity and tended to decrease survival.
Insights
Moderate exercise significantly improved survival rates in mice infected with influenza. However, prolonged exercise increased illness and tended to reduce survival, highlighting the importance of exercise intensity after infection.
Area of Science:
- Immunology
- Exercise Physiology
- Virology
Background:
- Influenza virus infection poses a significant global health threat.
- The host immune response plays a critical role in determining infection outcomes.
- The impact of exercise timing and intensity on influenza infection is not well understood.
Purpose of the Study:
- To investigate the effects of moderate and prolonged exercise doses on mortality and morbidity following influenza virus infection in mice.
- To determine if exercise initiated during the early immune response phase influences influenza infection outcomes.
Main Methods:
- Male Balb/cByJ mice were infected intranasally with influenza virus (A/Puerto Rico/8/34).
- Mice were randomized into sedentary control, moderate exercise, or prolonged exercise groups.
- Exercise interventions were performed starting 4 hours post-infection and continued for three consecutive days.
Main Results:
- Moderate exercise significantly increased survival rates (82%) compared to sedentary controls (43%).
- Prolonged exercise resulted in a lower survival rate (30%) and increased morbidity.
- Exercise had minimal impact on body weight loss and food intake, which were significant across all groups.
Conclusions:
- Moderate exercise initiated early in the immune response can significantly decrease mortality from influenza infection in mice.
- Prolonged or excessive exercise may be detrimental, increasing morbidity and potentially reducing survival.
- Exercise intensity is a critical factor to consider when examining its role in modulating host response to viral infections.
