Exercise, immunology and upper respiratory tract infections.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing literature and mechanistic hypotheses without systematic review methods
PubMed 9129265 · doi:10.1055/s-2007-972702
What was done
This narrative review synthesized published epidemiological surveys, laboratory analyses, and nutritional intervention trials examining the effects of endurance exercise on immune function, the incidence of upper respiratory tract infection (URTI) symptoms after marathon and ultramarathon events, and the mechanistic role of vitamin C supplementation.
What was found
The abstract reports no quantitative values or statistical effect sizes. It notes that while regular long-term training stimulates host defenses, acute exhaustive endurance exercise causes transient immunosuppression. Epidemiological studies showed an increased incidence of URTI symptoms in the two weeks following competitive marathon and ultramarathon races, related to pre-race training status and race intensity. Vitamin C supplementation was reported to reduce post-race URTI symptoms, hypothesized to act by neutralizing phagocytic reactive oxygen species released during exercise-induced neuroendocrine stimulation.
Why it matters
It outlines a framework for understanding exercise-induced immune suppression and highlights antioxidant supplementation, specifically vitamin C, as a potential countermeasure for endurance athletes.
Limits
The abstract provides no specific numerical data, sample sizes, or formal search and selection criteria. As a narrative review, it relies on observational survey data susceptible to reporting bias for URTI symptoms and presents a theoretical physiological model that requires direct empirical validation.
Cited by
- supports Very high levels of exercise, such as marathon running or triathlon training, can cause immunosuppression.