THE EFFECT ON IMMUNITY OF LONG-TERM INTENSIVE TRAINING IN ELITE SWIMMERS

The impact of long-term training on systemic and mucosal immunity was assessed prospectively in a cohort of elite swimmers over a 7-month tr aining season in preparation for national championships. The results i ndicated significant suppression (P < 0.05) of serum IgA, Ige and IgM and salivary IgA concentration in athletes associated with long-term t raining at an intensive level. There was also a trend towards lower Ig G2 subclass levels in serum in athletes compared with controls (P = 0. 07). There were no significant changes in numbers or percentages of B or T cell subsets, but there was a significant fall in natural killer (NK) cell numbers and percentages in athletes over the training season (P < 0.05). After individual training sessions there was a significan t decrease in salivary IgA levels for athletes compared with controls (P = 0.002). In athletes there was a downward trend in salivary IgA le vels over the 7-month training period in both the pre-exercise (P = 0. 06) and post-exercise samples (P = 0.04). There were no significant tr ends in salivary IgG levels over the study period in either athletes o r controls. The only significant change in salivary IgM levels was an increase in detection rate in the pre-competition phase in athletes (P = 0.03). The study suggests that training of elite athletes at an int ensive level over both short- and long-time frames suppresses both sys temic and mucosal immunity. Protracted immune suppression linked with prolonged training may determine susceptibility to infection, particul arly at times of major competitions.