Objective: To determine whether, for a given body mass index (BMI), men and women with high cardiorespiratory fitness (HIGH CRF) have lower waist circumference (WC), sum of trunk skinfolds (SUM2) and sum of five skinfolds (SUM5), by comparison to those with LOW CRF.
Design: Observational cohort study.
Setting: 1981 Canada Fitness Survey (CFS).
Participants: A total of 3719 men and 3854 women 20-59 y of age from the 1981 CFS for whom anthropometric and physical fitness measures were available.
Main outcome measures: BMI, waist circumference, skinfolds, cardiorespiratory fitness.
Results: For a given BMI, men and women in the HIGH CRF group had lower WC, SUM2 and SUM5 by comparison to those with LOW CRF (P<0.001). A significant main effect for CRF group remained for SUM2 in both men (P=0.0001) and women (P=0.007), after statistical control for the effects of extremity fat. In women, but not men, there were significant interaction effects for WC (P=0.0023) and SUM5 (P=0.01), indicating that the difference between the LOW CRF and HIGH CRF groups increased with increasing BMI.
Conclusions: HIGH CRF is associated with lower levels of total and abdominal obesity for a given BMI by comparison to those with LOW CRF, independent of gender. This finding suggests a mechanism by which exercise attenuates the health risks attributed to obesity as measured by BMI. It is suggested that the routine measurement of WC and CRF would substantially improve the ability to identify those at health risk.