PURPOSE: To investigate the relationship of total exercise volume in relation to the American College of Sports Medicine (ACSM) aerobic exercise guidelines on improving cardiovascular disease (CVD) risk factors and cardiorespiratory fitness (CRF).
METHODS: Ninety-two individuals (57.0±11.1 (28-79) years; 41% male, 59% female) in a self-referred exercise program completed a CVD risk factor assessment, body composition (iDXA), and maximal exercise testing pre- and post- 6 months of participation. All were provided an individualized exercise prescription based on ACSM aerobic exercise guidelines. Exercise volume (frequency, intensity, and duration) was recorded daily and subjects were stratified into three groups (HIGH, MODERATE, LOW) based on the total volume performed. A two factor (group x time) ANOVA with repeated measures on time was performed to assess differences between groups for resting hemodynamics, blood lipids, body composition, and CRF. Correlation analyses were used to examine the relationship between exercise volume, CVD risk factors, and CRF.
RESULTS: Exercise volume was higher (p<0.05) in HIGH compared to MODERATE and LOW, and MODERATE was higher (p<0.05) than LOW. A main effect for time (p<0.05) was present for resting heart rate, systolic/diastolic blood pressure, total cholesterol, triglycerides, LDL, body weight, waist circumference, BMI, CRF, body fat composition, and lean mass, independent of group. Exercise volume was correlated (p<0.05) with markers of aerobic fitness; resting heart rate (r=-0.236) and CRF (r=0.286). Improved plasma lipid profile was (p<0.05) correlated with exercise volume; total cholesterol (r=-0.287), LDL (r=-0.222), glucose (r=-0.247). Additionally, exercise volume was significantly correlated with markers of body composition, mainly fat distribution; body weight (r=-0.369), body mass index (r=-0.356), fat mass (r=-0.417).
CONCLUSION: Participation in a self-referred exercise program improves CRF and CVD risk factors regardless of exercise volume. Correlations between exercise volume and CVD risk factors (e.g. blood lipids, body composition) suggest a dose response relationship. Randomized control trials are warranted to assess the impact of exercise volume on CVD risk factors.