Br J Sports Med. Published Online First: 1 May 2007. doi:10.1136/bjsm.2007.035147
Paper |
Effect of caffeine supplementation on hematological and biochemical parameters in elite soccer players under physical stress conditions
1 UFU, Brazil
2 UFRJ, Brazil
3 Botafogo de Futebol e Regatas, Brazil
4 Bittar Laboratory, Brazil
5 National Institute of Traumatic Orthopedic, Brazil
6 UNIRIO, UFU, UCB, Brazil
* To whom correspondence should be addressed. E-mail: cameron{at}unirio.br.
Accepted 6 March 2007
Abstract
Objective: We evaluated the effect of caffeine on white cell distribution and muscle injury markers in professional soccer players during exercise.
Methods: Male athletes (22) completed a placebo-controlled double-blind test protocol to simulate a soccer match followed to a Yo-Yo intermittent recovery test.
Results: Our data show an hematocrit increase that was enhanced by caffeine as a consequence of exercise. We found a synergic effect of caffeine in addition to exercise regarding blood leukocytes count that grew almost 5-fold more compared to the non-supplemented group. Exercise enhanced lymphocyte counts by about 38%, and when combined with caffeine, the count increased an additional 35%. The xanthine promoted a rise in circulating monocytes in an exercise-independent way, and a synergic action of exercise and caffeine was observed on segmented neutrophils. Caffeine promotes thrombocytosis in a greater way than exercise, because of muscle and vascular trauma. Plasma ADA, AST and LDH concentrations were enhanced in the groups due to exercise, and ALT concentration was also amplified in both groups with a synergism due to caffeine.
Conclusion: The present study suggests that the pronounced increase in white cell count in the group receiving caffeine was caused by higher muscle stress and consequently more intense endothelial and muscle injury, signifying the possibility that the use of caffeine can be one of the causes for the observed changes in the white cell response and, furthermore, that its use can augment the risk of muscle damage in athletes.
Key Words: Creatine kinase, Leukocytosis, Muscle damage markers, Soccer player, Thrombocytosis
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