CORRESPONDENCE: LETTER TO THE EDITOR
Reply
Philipp A. Kaufmann, MD*
* University Hospital Zurich, Cardiovascular Center, Nuclear Cardiology, Ramistrasse 100, NUK C 32, Zurich CH-8091, Switzerland (Email: pak{at}usz.ch).
Dr. McLellan points out that exercise has been shown to make subjects respond to subsequent exercise like caffeine-naïve subjects. We welcome this information, which seems to further strengthen our results (1), as it confirms that the sensitivity to caffeine is more pronounced during exercise.
However, based on our power calculation we cannot support the statement that increasing the study population and splitting it up into placebo and caffeine groups would have improved the quality of the study; as with the crossover design, each subject served as its own control, an advantage that would have been lost following the advice of Dr. McLellan.
Although some positive effects of caffeine on exercise performance might have been reported in studies more than 2 decades ago (as cited by Dr. McLellan), this seems to be challeneged by more recent experiences, which have led to removing caffeine from the doping list (2). We remain reluctant to comment on this, because this parameter was beyond the scope of our study, which was designed to assess the effect of caffeine on exercise-induced myocardial perfusion response.
Furthermore, it has been brought to our attention that the values for mean arterial pressure (MAP) in Table 1
of our report were regrettably incorrect. The correct values are given in the revised table (Table 1).
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References
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1. Namdar M, Koepfli P, Grathwohl R, et al. Caffeine decreases exercise-induced myocardial flow reserve J Am Coll Cardiol 2006;47:405-410.[Abstract/Free Full Text]2. World Anti-Doping Agency. Available at: http://www.wada-ama.org/en/. Accessed June 30, 2006.
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