Following thorough evaluation at rest, 265 of 400 current or ex-shipyard workers rode a cycle ergometer with equal work increments each minute to exhaustion while continuous multiple noninvasive cardiorespiratory measures and intermittent intra-arterial blood pressure and blood gas measures were made. Seventy-seven men, with a mean age of 54, including some who were smokers, obese, or hypertensive, were judged to have normal cardiorespiratory systems based on history, physical, electrocardiogram during rest and exercise, chest X-ray, pulmonary function tests, and exercise performance. Their responses to exercise are given. It was unusual to find at maximal exercise a breathing reserve less than 11 L/min, arterial PO2 less than 80 mm Hg, alveolar-arterial PO2 difference greater than 38 mm Hg, arterial-end tidal PCO2 difference greater than 1 mm Hg, respiratory frequency greater than 60, or a dead space/tidal volume ratio greater than 0.28. The normal anaerobic threshold/maximal O2 uptake ratio exceeded 40%. With maximal exercise, the intra-arterial systolic and diastolic pressures rose an average of 68 and 13 mm Hg, respectively. For predicting maximal oxygen uptake and oxygen pulse in an overweight man, we find it preferable to use age and height rather than age and weight.