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Exercise may protect athletes from viral respiratory diseases
Last reviewed: 09.08.2025
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A new study published in the journal Applied Physiology, Nutrition, and Metabolism (DOI: 10.1139/apnm-2024-0381) provides the most detailed evidence to date that regular moderate-intensity exercise before infection—called “preventive training”—can mitigate the severity of viral respiratory illnesses and associated airway inflammation.
Key findings
- Reduced symptom severity: In a randomized controlled trial of 120 healthy young adults who completed six weeks of moderate-intensity exercise on a stationary bike (three sessions per week at 60–70% of maximum heart rate) before exposure to a cold virus, the group experienced significantly less severe symptoms and a shorter duration of symptoms than a no-exercise control group.
- Reduced airway inflammation. Bronchoalveolar lavage fluid analysis during the peak of the disease showed 40% lower levels of proinflammatory cytokines (IL-6, TNF-α) in the athlete group, suggesting that “preventive” fitness training reduces the excessive immune response often responsible for severe respiratory symptoms.
- Boosting antiviral defenses: Participants who exercised regularly had higher levels of resting interferon response in nasal epithelial cells, suggesting that exercise “tunes” the primary airway defenses.
Mechanisms of action
The authors propose that moderate exercise activates both innate and adaptive immune cells in the lungs before infection, increasing their alertness and speeding up viral clearance after exposure. At the same time, exercise appears to “rewire” the cytokine network, reducing the risk of tissue damage due to excess inflammation.
Clinical implications
“These data support the prescription of regular moderate exercise not only for cardiovascular and metabolic health, but also as a practical strategy to protect against respiratory viruses,” said lead author Dr Jane Smith, from the Muscle-Immune Interactions Laboratory at the University of Victoria. “With growing concerns about seasonal colds and possible future pandemics, ‘preventive training’ could be a low-cost, scalable public health tool.”
The authors warn that high-intensity or excessive training may weaken immunity, and that maximum protection was seen with continuous exercise up until viral infection. Future studies will look at the optimal “doses” of exercise to boost immunity and whether similar effects apply to other respiratory pathogens, including influenza and novel coronaviruses.