We are all aware of the need for carbohydrates for aerobic performance. Now it appears not only do carbohydrates aid endurance performance, but also help the immune response to exercise.
Triathletes ran or cycled for 2.5 hours at 75% of maximal aerobic capacity on two occasions. On one occasion they drank a carbohydrate drink and on another, a placebo containing no carbohydrate. When drinking the carbohydrate drink, the triathletes showed higher blood sugar and insulin levels, and lower blood cortisol and growth hormone levels. A lower cortisol level is an indicator of less stress. When drinking the carbohydrate drink they also showed lower white blood cell counts.
The authors conclude that carbohydrate ingestion during activity lessens hormonal responses indicative of stress and raises the immune response. The lowered immune response when not ingesting carbohydrates could result in an increased chance of infection.
Recommendations: Carbohydrate drinks consumed during exercise not only supply energy but help lower the major stress hormone during exercise.