Nonexercise Estimated Cardiorespiratory Fitness and All-Cancer Mortality: the NHANES III Study

Objective: To examine the relationship between estimated cardiorespiratory fitness (eCRF) using nonexercise equations and all-cancer mortality in a representative sample of the US population.

Participants and methods: A total of 8506 study participants were derived from the Third National Health and Nutrition Examination Survey, conducted from October 18, 1988, to October 15, 1994. They were followed for all-cancer mortality. Participants' CRF was estimated from nonexercise models that were determined by age, body mass index, waist circumference, resting heart rate, physical activity status, and smoking status, and further grouped into quintiles. Hazard ratios (HRs) and 95% CIs were calculated from Cox proportional hazards models for the relationship between eCRF and all-cancer mortality.

Results: During a mean of 19.5 years of follow-up, 455 cancer deaths (263 men and 192 women) were registered. After adjustment for race/ethnicity, age, educational level, current smoking, hypertension, diabetes mellitus, and hypercholesterolemia, each 1-metabolic equivalent increase in eCRF was associated with 30% (95% CI, 24%-35%) and 27% (95% CI, 18%-36%) risk reduction for all-cancer mortality in men and women, respectively. When eCRF was categorized into quintiles, HRs (95% CIs) were 0.47 (0.24-0.95), 0.81 (0.46-1.44), 0.49 (0.26-0.93), and 0.57 (0.31-1.06) across incremental quintiles in women (quintile 1 was the reference group). However, none of the HRs reached statistical significance in men.

Conclusion: The eCRF was inversely associated with all-cancer mortality in quintiles 2 and 4 in women. More research is needed to further understand the association between eCRF and all-cancer mortality in men.