Int J Sports Med 2005; 26(10): 880-885
DOI: 10.1055/s-2005-837467

© Georg Thieme Verlag KG Stuttgart · New York

The Effects of a High Carbohydrate Diet on Cortisol and Salivary Immunoglobulin A (s-IgA) During a Period of Increase Exercise Workload Amongst Olympic and Ironman Triathletes

R. J. S. Costa1 , G. E. Jones1 , K. L. Lamb1 , R. Coleman1 , J. H. H. Williams1
  • 1Chester Centre for Stress Research, University College Chester, England
Further Information

Publication History

Accepted after revision: November 25, 2004

Publication Date:
11 April 2005 (online)


The present study observed the effects of a 6-day high carbohydrate (H-CHO) diet on salivary cortisol and IgA during a period of increased exercise workload. Thirty-two competitively trained male triathletes were randomly allocated into a self-selected (SS), or an H-CHO (12 g CHO kgbm-1 · day-1) dietary group. In addition to their training regimes, all subjects performed a 1-hour running exercise bout at 70 % V·O2max · d-1, for six days. Saliva samples were taken pre, immediately post, and morning post-exercise bout on days 1, 4, and 6. The concentrations of s-IgA and cortisol were determined by ELISA assays. There was a significant (p < 0.001) interaction between Group × Time for cortisol, with a marked increase in concentrations occurring in the SS dietary group pre to post exercise, and pre to morning post-exercise (p < 0.01). Conversely, a significant (p = 0.009) Group × Time interaction reflected higher post exercise s-IgA concentrations (p < 0.005) than pre exercise in the H-CHO diet group. Blood glucose concentration decreased pre to post exercise in the SS diet group (p < 0.01), whilst remaining stable in the H-CHO group. It is concluded that the consumption of a high CHO diet throughout a 6-day period of overtraining had a favourable effect on markers of immune activity and thereby reduced the susceptibility of these endurance athletes to upper respiratory tract infection URTI.


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K. L. Lamb

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