Physiological responses to exercise in chronic cigarette and marijuana users.

Several physiologic responses to graded exercise were determined in four groups of young adult blue-collar workers identified as users of (1) marijuana, (2) cigarettes, (3) both marijuana and cigarettes, or (4) neither substance. Using covariate analysis of variance to control for race, age, height and weight, the groups did not differ in estimated percent fat, lean body mass, hematocrit levels, or blood hemoglobin values. Heart rate and oxygen consumption responses also were similar at all levels of exercise. The mean minute ventilation and perceived exertion were found to be higher in cigarette smokers than non-smokers of cigarettes but aerobic power and the physical work capacity did not differ. The differences in pulmonary function observed suggest the need for further study on older populations of chronic cigarette and marijuana users.