Schoenhofer et al (June 2004)1brought an important contribution to the understanding of water immersion effects on respiratory parameters in subjects with severe diaphragm weakness. Seven patients with neuromuscular diseases and seven healthy control subjects were studied out of the water (sitting erect) and in the water (standing up at neck level) by spirometry, maximal static inspiratory pressure (Pimax), and mouth occlusion pressure measurements. The patients and control subjects showed mean drops in vital capacity of 30% and 3%, respectively, while showing mouth occlusion pressure increases of 191% and 29%, respectively. There is evidence that some factors not mentioned by the authors could have influenced the changes observed between the groups. Water temperature and time of immersion are examples. Specifically, a time of immersion between 20 and 30 min can minimize the enlarged plasma volume, which is the most important factor for the decrease in vital capacity.2 Thus, it would be important to know in the study of Schoenhofer et al1 the length of time of immersion, and whether this time was the same for both groups.