Research
Hormonal
High-volume, intense exercise training and competition are associated with transient immune dysfunction and an increased risk of upper respiratory tract infections (URTI).
If you are training for a marathon or competing in endurance events, be aware that your risk of getting sick spikes in the days following the event. Prioritize recovery, sleep, and nutrition immediately after heavy exertion to mitigate this risk.
GoodSupportsHIGH confidence
Taken together, the best evidence supports that high exercise training workloads, competition events, and the associated physiological, metabolic, and psychological stress are linked to immune dysfunction, inflammation, oxidative stress, and muscle damage.
Why this rating
Supported by epidemiological data and immunological markers, though direct causation to infection is complex.
Source
The compelling link between physical activity and the body's defense system
David C. Nieman et al. · Journal of sport and health science/Journal of Sport and Health Science · 2018
DOI 10.1016/j.jshs.2018.09.009
narrative_reviewCited 1,299×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Moderate exercise training (≥5 days/week, 20+ min bouts) significantly reduces the incidence and duration of upper respiratory tract infections (URTI) compared to sedentary behavior.Good
- Carbohydrate ingestion (30-60 g/h) during prolonged endurance exercise attenuates post-exercise inflammation and stress hormone elevation.Good
- Polyphenol intake (specifically from fruits like bananas) during exercise provides anti-inflammatory and immune-protective benefits via gut-derived metabolites.Moderate
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