The effect of habitual smoking on measured and predicted VO2(max).

Background: Nonexercise models were developed to predict maximal oxygen consumption (VO2(max)). While these models are accurate, they don't consider smoking, which negatively impacts measured VO2(max). The purpose of this study was to examine the effects of smoking on both measured and predicted VO2(max).

Methods: Indirect calorimetry was used to measure VO2(max) in 2,749 men and women. Physical activity using the NASA Physical Activity Status Scale (PASS), body mass index (BMI), and smoking (pack-y = packs.day * y of smoking) also were assessed. Pack-y groupings were Never (0 pack-y), Light (1-10), Moderate (11-20), and Heavy (> 20). Multiple regression analysis was used to examine the effect of smoking on VO2(max) predicted by PASS, age, BMI, and gender.

Results: Measured VO2(max) was significantly lower in the heavy smoking group compared with the other pack-y groups. The combined effects of PASS, age, BMI, and gender on measured VO2(max) were significant. With smoking in the model, the estimated effects on measured VO2(max) from Light, Moderate, and Heavy smoking were -0.83, -0.85, and -2.56 ml x kg(-1) x min(-1), respectively (P < .05).

Conclusions: Given that 21% of American adults smoke and 12% of them are heavy smokers, it is recommended that smoking be considered when using nonexercise models to predict VO2(max).