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Exercise, immunology and upper respiratory tract infections
1Division of Physical Education, University of the Witwatersrand, Johannesburg, South Africa.
International Journal of Sports Medicine
|March 1, 1997
Summary
Intense endurance exercise can suppress immune function, increasing infection risk in athletes. Vitamin C supplementation may mitigate this by boosting antioxidant defenses, benefiting serious endurance athletes.
Area of Science:
- Exercise immunology
- Nutritional science
- Sports medicine
Background:
- Endurance exercise exhibits a dual effect on immune function: stimulation with regular training and suppression with acute exhaustive bouts.
- Epidemiological studies link marathon and ultramarathon running to increased upper respiratory tract infection (URTI) symptoms post-race.
- Training status and racing intensity correlate with URTI incidence in the fortnight following endurance events.
Purpose of the Study:
- To investigate the role of vitamin C in mitigating exercise-induced immunosuppression.
- To explore the hypothesis that vitamin C neutralizes exercise-induced reactive oxygen species.
- To assess the potential benefits of exogenous antioxidant intake for endurance athletes.
Main Methods:
- Review of epidemiological surveys on URTI incidence in endurance athletes.
- Analysis of nutritional intervention studies, particularly those involving vitamin C.
- Examination of laboratory studies on vitamin C's role in phagocyte function and oxidative stress.
Main Results:
- Vitamin C has demonstrated effectiveness in reducing URTI symptoms after competitive distance events.
- Laboratory findings indicate vitamin C as a primary defense against phagocyte auto-oxidative activity.
- It is hypothesized that exercise elevates reactive oxygen species, which are neutralized by plasma ascorbate.
Conclusions:
- Exercise-induced neuroendocrine responses may increase reactive oxygen species release from neutrophils.
- High plasma ascorbate levels can neutralize these exercise-induced reactive oxygen species.
- Supplementing with antioxidants like vitamin C may enhance intrinsic antioxidant defenses, benefiting athletes undergoing heavy training and competition.