Effects of Graded Carbohydrate Supplementation on the Immune Response in Cycling


Medicine & Science in Sports & Exercise:
doi: 10.1249/01.mss.0000191437.69493.d4
BASIC SCIENCES: Original Investigations

Purpose: This study examined the acute immune response after three standardized cycling sessions of 4-h duration in the field with varying carbohydrate (CHO) supplementation in a randomized, double-blind, placebo-controlled fashion. We hypothesized that the ingestion of carbohydrate (6 or 12% CHO beverages; placebo (P) without CHO) during exercise attenuates the exercise-induced immune response in a dose-dependent manner.

Methods: A total of 14 male competitive cyclists and triathletes (age: 25 ± 5 yr; height: 180 ± 7 cm; weight: 72 ± 9 kg; V̇O2max: 67 ± 6 mL·min−1·kg−1) cycled for 4 h on a 400-m track at a given workload of 70% of the individual anaerobic threshold (198 ± 21 W). Leukocyte and lymphocyte subpopulations were measured by flow cytometry before, immediately, and 1 and 19 h after exercise. In addition, C-reactive protein (CRP) interleukin 6 (IL-6), and cortisol were determined.

Results: The exercise-induced increase in leukocytes, neutrophils, and monocytes was significantly attenuated to the same extent by 6 and 12% CHO (P < 0.001). No differences could be demonstrated for lymphocytes and natural killer cells. The increase in CRP was attenuated significantly by 12% CHO only (P < 0.05), whereas the increase in cortisol and IL-6 was significantly reduced by 6 and 12% CHO (P < 0.001). The postexercise neutrophilia, which dominated the exercise-induced leukocytosis, was strongly related to the postexercise concentration of cortisol (r = 0.72; P < 0.001).

Conclusions: Because of the lacking dose-dependent difference, the ingestion of at least 6% CHO beverages can sufficiently attenuate the exercise-induced immune response and stress, especially in phagocytizing cells (neutrophils and monocytes) by the reduced release of cortisol.

Author Information

1Institute of Sports and Preventive Medicine, University of Saarland, Saarbrücken, GERMANY; and 2Department of Sports Medicine, Friedrich-Schiller-University, Jena, GERMANY

Address for correspondence: Jürgen Scharhag, MD, Institute of Sports and Preventive Medicine, University of Saarland, Building B8.2 66123 Saarbrücken, Germany; E-mail: j.scharhag@mx.uni-saarland.de.

Submitted for publication March 2005.

Accepted for publication August 2005.

©2006The American College of Sports Medicine