Brunani A, et al. - A higher O₂ consumption and a trend toward higher peripheral O₂ extraction have been observed in obese men vs. lean men during physical exercise, probably due to their larger muscle mass. By measuring 2 vasoactive substances, endothelin-1 (ET-1) and nitric oxide (NO), during a progressive submaximal exercise in obese and lean men, researchers assessed this phenomenon in this study. Findings revealed that obese vs lean men had different ET-1 and NO levels during physical exercise. This finding may lend support to the hypothesis that increased O₂ consumption in obesity is due to different behaviors of the cardiorespiratory and circulatory systems.