Resumen de Volume of Exercise and Fitness Nonresponse in Sedentary, Postmenopausal Women
Susan B. Sisson, Peter T. Katzmarzyk, Conrad P. Earnest, Claude Bouchard, Steven N. Blair, Timothy S. Church
There is a wide individual heterogeneity in the maximal aerobic fitness (V[spacing dot above]O2max) response to exercise training.
Purpose: To examine predictors of V[spacing dot above]O2max nonresponse after aerobic exercise training in postmenopausal women.
Methods: The Dose Response to Exercise in Women (DREW) study was a randomized, controlled trial examining the effects of incremental training doses on sedentary postmenopausal women (45-75 yr). Participants were randomized to one of three exercise treatment groups (4, 8, or 12 kcal[middle dot]kg-1[middle dot]wk-1) for 6 months. Participants exercised 3-4 d[middle dot]wk-1 at 50% V[spacing dot above]O2max. Predictors of baseline V[spacing dot above]O2max were determined by ANOVA. We used a logistic regression analyses with categorical (ethnicity and treatment group) and standardized continuous variables (age, body mass index [BMI], and baseline V[spacing dot above]O2max) to determine predictors of nonresponse ([DELTA] <= 0 L[middle dot]min-1). Our analysis included 310 women because the control group was excluded.
Results: A total of 44.9%, 23.8%, and 19.3% of the 4-, the 8-, and the 12-kcal[middle dot]kg-1[middle dot]wk-1 treatment groups (P < 0.0001), respectively, were nonresponders. Maximal effort, BMI, age, and race significantly predicted baseline V[spacing dot above]O2max. Treatment group (8 and 12 kcal[middle dot]kg-1[middle dot]wk-1 vs 4 kcal[middle dot]kg-1[middle dot]wk-1; P = 0.0003), baseline V[spacing dot above]O2max (P < 0.0001), and age (P < 0.05) were significant predictors of nonresponse. Odds ratios and 95% confidence intervals were 2.13 (1.53-2.95) for baseline V[spacing dot above]O2max; 1.35 (1.00-1.83) for age; 0.45 (0.24-0.85) for the 8- versus the 4-kcal[middle dot]kg-1[middle dot]wk-1 group; and 0.27 (0.13-0.53) for the 12- versus the 4-kcal[middle dot]kg-1[middle dot]wk-1 group.
Conclusion: Women that were younger, less fit, or exercised more during the DREW trial had greater odds of improving their fitness with training. The most important finding of this study was that greater volumes of exercise were associated with a lower probability of being a nonresponder.
