Brunani A, et al. - Obese men show higher O₂ consumption than lean men during physical exercise, with a trend toward higher peripheral O₂ extraction; possibly due to their larger muscle mass. In this study, endothelin-1 (ET-1) and nitric oxide (NO) were measured during a progressive submaximal exercise in obese and lean men. Findings revealed that obese and lean men exhibited different ET-1 and NO levels during physical exercise. This inference may support the hypothesis that increased O₂ consumption in obesity is due to different behaviors of the cardiorespiratory and circulatory systems.