Salivary IgA levels and infection risk in elite swimmers

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 i ndividual sessions of exercise. Purpose: The purpose of this study was to a ssess 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 wer e measured by an electroimmunodiffusion. Exercise gradings were assessed by a standardized aerobic-anaerobic rating system. Psychological stress/anxie ty was evaluated by the Spielberger State-Trait Anxiety Inventory. Infectio ns were physician-verified. Results: Salivary IgA levels showed an inverse correlation with the number of infections in both elite swimmers and modera tely exercising control subjects. The pretraining salivary IgA levels in sw immers were 4.1% lower for each additional month of training and 5.8% lower for each additional infection. The posttraining salivary IgA levels in swi mmers were not significantly correlated with infection rates bur were 8.5% lower for each additional 1 km swum in a training session and 7.0% lower fo r each additional month of training. The number of infections observed in t he elite swimmers was predicted from regression models by the preseason (P = 0.05) and the mean pretraining salivary IgA levels (P = 0.006). The trend s in pretraining salivary IgA levels over the 7-month season, calculated as individual slopes of pretraining IgA levels over time, were also predictiv e of the number of infections (P = 0.03) in the swimmers. Conclusions: Thes e results indicate that measurement of salivary IgA levels over a training season may be predictive for athletes at risk of infection.