Exercise dose-response of the V̇ E/V̇CO 2 slope in postmenopausal women in the DREW study

Purpose: Being overweight/ obese, having hypertension, and being postmenopausal are risk factors for the development of congestive heart failure (CHF). A characteristic of CHF is an abnormal V̇ ^E/V̇CO ² slope, which is predictive of mortality in patients with CHF. Although the V̇ ^E/V̇CO ² slope is well established in CHF patients, little is known regarding interventions for "at-risk" populations. Methods: We examined the V̇ ^E/V̇CO ² slope in 401 sedentary, overweight, moderately hypertensive women randomized to 6 m of nonexercise (control) or 4 kcal̇kg ^-1wk ^-1 (KKW), 8 KKW, or 12 KKW of exercise at an intensity corresponding to 50% of baseline V̇O ^2max. We examined trends in exercise treatment dose versus change in mean V̇ ^E/V̇CO ² slope using a linear regression model (KKW vs V̇ ^E/V̇CO ² slope) and a linear mixed model. Results: Regression analysis showed a significant trend for a reduction in the V̇ ^E/V̇CO ² slope from baseline (mean plusmn; SD: 32.6 plusmn; 6.3; P < 0.004). When expressed as mean change (95% confidence interval (CI)) from baseline, we observed significant reductions in the V̇ ^E/V̇CO ² slope for the 8-KKW (-1.14; 95% CI, -1.5 to -0.2) and 12-KKW (-1.67; 95% CI, -2.3 to -0.3) groups. No significant effect was noted for the 4-KKW (-0.4; 95% CI, -1.2 to 0.15) group. Conclusion: Moderate-intensity aerobic exercise at doses of 8 KKW or greater seems to present an adequate dose of exercise to promote small but significant reductions in the V?E/VCO2 slope in postmenopausal women who exhibit risk factors associated with the development of CHF.