A longitudinal study on smoking in relationship to fitness and heart rate response

Purpose: Smoking has been shown to be associated with impaired cardiovascular fitness and reduced heart rate response to exercise. It is not known whether these associations are present in adolescence and young adults, and whether they change over time. Methods: Maximal oxygen uptake ((V) over dot O-2max), maximum treadmill slope (Slope(max)), resting heart rate (HRrest), heart rate at submaximal exercise (HRsubmax), heart rate reserve (HRR), and maximum heart rate (HRmax) were measured one to nine times between ages 13 and 36 in 298 male and 334 female participants of the Amsterdam Growth and Health Longitudinal Study. Generalized estimating equation analyses were used to study the longitudinal relationship between smoking and cardiovascular fitness and heart rate response to exercise, whereas linear regression analyses were used to study the reversibility of smoking effects at age 36. Results: Moderate to heavy smoking (greater than or equal to 10 g of tobacco per day) was longitudinally and negatively related to (V) over dot O-2max, Slope(max), HRsubmax, and HRmax. With increasing age, the negative relationship between smoking and (V) over dot O-2max, Slope(max), and HRmax became stronger in males. Cross-sectional analyses suggested that the adverse effects of smoking were reversible in 36-yr-old males. Conclusion: Cardiovascular fitness and heart rate response to exercise are already reduced in young healthy smokers. In men, the adverse effects of smoking become stronger with increasing age but appear to be reversible at age 36.