In response to the comments by Fernandes et al

摘要

To the Editor of the Journal of Physiological Sciences, In the last issue (March 2013) of the Journal of Physiological Science Fernandes et al. [1] commented on our recent paper [2] published in the Journal of Physiological Sciences. We are glad that Fernandes and co-workers consider our paper as "an interesting study in the field of exercise physiology applied to swimming". However, they have also raised some concerns about our methodological approach. In detail: Fernandes et al. claimed that we did not provide the values of dead space. This is incorrect, as we clearly indicated that "athletes breathed through a low volume (about 200 ml), corrugate flexible plastic tube..." (see page 3 of the manuscript). The only information missing was the diameter of the tube, which was 25 mm, a value that should not impose a high internal resistance. They raised concerns about the fact that the gas analyser we used had only one breathing tube for inspiration and expiration, so that the possibility of mixing gases was not negligible. However, we validated the system by conducting incremental cycling tests with and without the adapted snorkel. The results, which are clearly described in the text, indicated that the system provided similar outcomes in terms of calculated oxygen uptake and carbon dioxide production, while pulmonary ventilation and heart rate was slightly increased at sub-maximal workloads with respect to free breathing ventilation. The gas analyzer employed assumes that the atmospheric inspired gas