Salivary IgA levels and infection risk in elite swimmers. Med. Sci. Sports Exerc., Vol. 31, No. 1, pp. 67-73, 1999. The effects of exercise on the immune system has been shown to be dependent on the level of fitness of the subjects, the degree of intensity, and the duration of the exercise. A reduction in salivary IgA levels occurs after individual sessions of exercise.
Purpose: The purpose of this study was to assess the relationship between changes in salivary IgA and training volume, psychological stress, and infection rates in a cohort of 26 elite swimmers over a 7-month training period and to compare the changes with a group of 12 moderately exercising controls.
Methods: Salivary IgA concentrations were measured by an electroimmunodiffusion. Exercise gradings were assessed by a standardized aerobic-anaerobic rating system. Psychological stress/anxiety was evaluated by the Spielberger State-Trait Anxiety Inventory. Infections were physician-verified.
Results: Salivary IgA levels showed an inverse correlation with the number of infections in both elite swimmers and moderately exercising control subjects. The pretraining salivary IgA levels in swimmers were 4.1% lower for each additional month of training and 5.8% lower for each additional infection. The posttraining salivary IgA levels in swimmers were not significantly correlated with infection rates but were 8.5% lower for each additional 1 km swum in a training session and 7.0% lower for each additional month of training. The number of infections observed in the elite swimmers was predicted from regression models by the preseason (P = 0.05) and the mean pretraining salivary IgA levels (P = 0.006). The trends in pretraining salivary IgA levels over the 7-month season, calculated as individual slopes of pretraining IgA levels over time, were also predictive of the number of infections (P = 0.03) in the swimmers.
Conclusions: These results indicate that measurement of salivary IgA levels over a training season may be predictive for athletes at risk of infection.
Hunter Immunology Unit, Hunter Area Pathology Service, Royal Newcastle Hospital, Newcastle NSW 2300, AUSTRALIA; Centre for Sports Science and Sports Medicine, Australian Institute of Sport, Canberra ACT 2616, AUSTRALIA; Faculty of Applied Science, University of Canberra, Belconnen ACT 2616, AUSTRALIA; and Faculty of Medicine and Health Sciences, University of Newcastle, Callaghan NSW 2308, AUSTRALIA
Submitted for publication July 1997.
Accepted for publication April 1998.
The authors wish to thank athletes and coaches of the AIS Swimming Team and the AIS staff who participated in this study, in particular Sr. Sue Beasley and Mr. Anthony Parker. The immunology tests were performed by the Hunter Immunology Unit by Ms. Sharron Hall. The assistance of Dr. John Wlodarczyk with establishing the database and initial data analysis (10) is gratefully acknowledged. This manuscript was typed by Ms. Kay Digby and Ms. Jennifer Hutchings. The project was funded by the Australian Sports Commission.
Address for correspondence: Dr. Maree Gleeson, Hunter Immunology Unit, Royal Newcastle Hospital, P.O. Box 664 J, Newcastle NSW 2300, Australia.