Background: Research on smoking and physical activity provides strong evidence of smoking's negative impact and physical activity's positive impact on long-term health. However, evidence regarding the association between smoking and exercise activity and the independent effects of these factors on fitness is lacking.
Methods: The associations among exercise activity, smoking behavior, and physical fitness were examined in 3,045 Navy personnel. Exercise and smoking behaviors were measured using a lifestyle survey. Physical fitness was assessed using scores on the Navy's Physical Readiness Test. Analyses of variance were conducted to examine the relationships among smoking status, exercise activity, and PRT performance. Multiple regression procedures were used to examine the relationship between smoking and physical fitness after statistically controlling for the effects of exercise.
Results: Smoking was associated with lower exercise levels and lower physical endurance--both cardiorespiratory (1.5-mile run) and muscular (sit-ups). After controlling for exercise activity, smoking remained significantly associated with lower physical endurance but was not related to overall body strength (lean body mass) or percentage body fat.
Conclusion: Smoking is a detriment to physical fitness even among relatively young, fit individuals. Study findings suggest that smokers will have lower physical endurance than nonsmokers, even after differences in the average exercise levels of smokers and nonsmokers are taken into account. Cigarette smokers should be given strong encouragement to stop smoking as part of any effort to improve physical fitness.