CIGARETTE-SMOKING AND SUBMAXIMAL EXERCISE TEST DURATION IN A BIRACIALPOPULATION OF YOUNG-ADULTS - THE CARDIA STUDY

Symptom-limited, graded exercise treadmill testing was performed by 4, 968 white and black adults, ages 18-30 yr, during the baseline examina tion for the Coronary Artery Risk Development in Young Adults (CARDIA) study. Compared with nonsmokers, the mean exercise test duration of s mokers was 29-64 s shorter depending on race/gender group (all P < 0.0 01), but mean duration to heart rate 130 (beats.min-1) ranged from 20- 50 s longer (P < 0.05). In each race/gender group, test duration to he art rates up to 150 was 15-35 s longer (P < 0.05) in smokers than in n onsmokers after adjustment for age, sum of skinfolds, hemoglobin, and physical activity score. The mean maximum heart rate was lower in smok ers than in nonsmokers (difference ranging from 6.7 beats.min-1 in whi te men to 11.2 beats.min-1 lower in black women, P < 0.001), although maximum rating of perceived exertion was nearly identical in smokers a nd nonsmokers. Chronic smoking appears to blunt the heart rate respons e to exercise, so that exercise duration to submaximal heart rates is increased even though maximal performance is impaired. This may result from downloading of beta-receptors caused by smoking. Smoking status should be considered in the evaluation of physical fitness data utiliz ing submaximal test protocols, or else the fitness of smokers relative to nonsmokers is likely to be overestimated.