Purpose: The objective of this study is as follows: 1) to determine the effects of caffeine supplementation on the inflammatory response (IL-6 and IL-10 levels and leukocyte numbers) induced by a 15-km run competition and 2) to examine the effect of caffeine supplementation on the energetic metabolites as well as on the exercise-induced oxidative stress.
Methods: A double-blinded study of supplementation with caffeine was performed. Athletes participating in the study (n = 33) completed a 15-km run competition. Before competition, athletes took 6 mg·kg−1 body weight of caffeine (caffeine group, n = 17) or a placebo (placebo group, n = 16). Blood samples were taken before and after competition (immediately and after 2-h recovery). Leukocyte numbers were determined in blood. Concentrations of oxidative stress markers, antioxidants, interleukins (IL-6 and IL-10), caffeine, adrenaline, and energetic metabolites were measured in plasma or serum.
Results: Caffeine supplementation induced higher increases in circulating total leukocytes and neutrophils, with significant differences between groups after recovery. Adrenaline, glucose, and lactate levels increased after exercise, with higher increases in the caffeine group. Exercise induced significant increases in IL-6 and IL-10 plasma levels, with higher increases in the caffeine group. Caffeine supplementation induced higher increases in oxidative stress markers after the competition.
Conclusion: Caffeine supplementation induced higher levels of IL-6 and IL-10 in response to exercise, enhancing the anti-inflammatory response. The caffeine-induced increase in adrenaline could be responsible for the higher increase in IL-6 levels, as well as for the increased lactate levels. Furthermore, caffeine seems to enhance oxidative stress induced by exercise.
1Research Group on Evidence, Lifestyles and Health, Research Institute on Health Sciences (IUNICS), University of the Balearic Islands, Palma de Mallorca, SPAIN; and 2Group of Cell Therapy and Tissue Engineering, Research Institute on Health Sciences (IUNICS), University of the Balearic Islands, Palma de Mallorca, SPAIN
Address for correspondence: Pedro Tauler, Ph.D., Department of Fundamental Biology and Health Sciences, University of the Balearic Islands, 07122-Palma de Mallorca, Spain; E-mail: firstname.lastname@example.org.
Submitted for publication October 2012.
Accepted for publication December 2012.