It has been well documented that endurance training induces numerous physiological adaptations that involve cardiovascular [1], metabolic [2], hormonal [3], or neurohumoral factors [4]. However, some controversy exists concerning the specific effects of physical conditioning on the respiratory function. Ramonatxo et al. have compared the breathing patterns in athletes of different fitness levels during exercise [5], and other cross-sectional reports have compared athletes to sedentary subjects

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... 6] [7] [8] . From some of these data, it appears that physical training causes tidal volume (VT) to increase and breathing frequency ( f b ) to decrease for a given level of minute ventilation (VE). For example, extremely fit oarswomen exhibit a slower, deeper breathing pattern than less-fit oarswomen or sedentary subjects [8]. Some other cross-sectional studies, however, provide no definitive evidence of a change toward a "slower deeper breathing" with endurance training [5, 7] . On the other hand, surprisingly little research has focused on analyzing the effects of training on breathing pattern by using a longitudinal design. In a prospective study, reported no significant effect of shortterm activity specific endurance training (five weekly sessions of 40 min each at ϳ75% VO 2 max ) on the breathing pattern of healthy, nontrained individuals. Comparable findings were obtained by Clark et al. [10] in nontrained subjects. Recently, Miyachi and Katayama reported that the hyperventilatory response of moderately trained subjects during heavy exercise