Cardiorespiratory fitness (CRF) is a strong, independent predictor of morbidity and mortality. Although the majority of adults who increase daily physical activity experience an increase in CRF (VO2 peak), about 10-15% of participants do not increase CRF despite participating in a standardized exercise program. In this study we sought to determine whether exercise combined with a healthy diet was associated with a corresponding improvement in cardiometabolic risk factors despite the absence of change in CRF. We studied 59 sedentary, abdominally obese (waist circumference: 104.6 ± 8.5cm) adults who participated in 3 (women) or 4 (men) months of supervised aerobic exercise. CRF was measured using a standard treadmill test. Cardiometabolic risk factors included fasting triglycerides, total cholesterol, HDL-C, LDL-C, insulin, glucose, systolic and diastolic blood pressure. Participants were asked to exercise 7 days per week for the time required to expend 500 kcals per session for women, and 700 kcals for men. The intensity of exercise was self-selected and ranged between 65-90% of VO2 peak. Men and women were combined for all analyses. To examine the relationship between corresponding changes in cardiometabolic risk factors and CRF, participants were divided into tertiles based on mean change in CRF. A linear trend test was used to characterize the change in cardiometabolic risk factors across CRF change tertiles. The volume (energy expenditure (kcal)) and intensity (%VO2 peak) of exercise performed across tertiles of change in CRF was not different (P>0.10). As expected a significant linear trend across tertiles was observed for change in CRF (P<0.001), however, the mean change in CRF within the lowest tertile was not significant (P>0.10). Without exception, no linear trend was observed for the change in cardiometabolic risk factors across tertiles of change in CRF (P>0.10). This was also true for change in waist circumference and visceral fat (P>0.10). Regression analysis using the total sample confirmed that, with the exception of glucose, the change score for each cardiometabolic risk factor was not related to the change in CRF (P>0.10). Our findings suggest that in abdominally obese adults, improvement in cardiometabolic risk profile is not associated with change in CRF and that increasing physical activity combined with a healthful diet is associated with substantial health benefit in the absence of change in CRF.
Effects of Diet and Physical Activity Interventions on Weight Loss and Cardiometabolic Risk Factors in Severely Obese Adults