Salivary IgA as a risk factor for upper respiratory infections in elite professional athletes

Med Sci Sports Exerc. 2008 Jul;40(7):1228-36. doi: 10.1249/MSS.0b013e31816be9c3.


The relationship between physiological and psychological stress and immune function is widely recognized; however, there is little evidence to confirm a direct link between depressed immune function and incidence of illness in athletes.

Purpose: To examine the relationship between salivary immunoglobulin A (s-IgA) and upper respiratory infections (URI) in a cohort of professional athletes over a prolonged period.

Methods: Thirty-eight elite America's Cup yacht racing athletes were studied over 50 wk of training. Resting, unstimulated saliva samples were collected weekly (38 h after exercise, consistent time of day, fasted) together with clinically confirmed URI, training load, and perceived fatigue rating.

Results: s-IgA was highly variable within (coefficients of variation [CV] = 48%) and between subjects (CV = 71%). No significant correlation was found between absolute s-IgA concentration and the incidence of URI among athletes (r = 0.11). However, a significant (28%, P < 0.005) reduction in s-IgA occurred during the 3 wk before URI episodes and returned to baseline by 2 wk after a URI. When an athlete did not have, or was not recovering from URI, a s-IgA value lower than 40% of their mean healthy s-IgA concentration indicated a one in two chance of contracting an URI within 3 wk.

Conclusion: On a group basis, relative s-IgA determined a substantial proportion of the variability in weekly URI incidence. The typical decline in an individual's relative s-IgA over the 3 wk before a URI appears to precede and contribute to URI risk, with the magnitude of the decrease related to the risk of URI, independent of the absolute s-IgA concentration. These findings have important implications for athletes and coaches in identifying periods of high URI risk.

MeSH terms

  • Acclimatization
  • Adaptation, Psychological
  • Adult
  • Cohort Studies
  • Exercise Tolerance
  • Health Status Indicators
  • Humans
  • Immunoglobulin A, Secretory / analysis*
  • Incidence
  • Male
  • Muscle Fatigue / immunology
  • Prospective Studies
  • Respiratory Tract Infections / epidemiology*
  • Respiratory Tract Infections / etiology
  • Respiratory Tract Infections / immunology
  • Risk Factors
  • Saliva / immunology*
  • Ships*
  • Sports / physiology*
  • Statistics as Topic
  • Stress, Physiological / immunology
  • Surveys and Questionnaires
  • Workload


  • Immunoglobulin A, Secretory