Exercise intensity: its effect on the high-density lipoprotein profile.

OBJECTIVE To determine the effect of aerobic exercise intensity on the active subfraction of serum high-density lipoprotein (HDL) concentration. DESIGN A randomized control, before-and-after investigation that tested the hypothesis that high-intensity exercise training would result in improvements in serum concentrations of HDL subfraction 2 (HDL2) greater than those accompanying moderate-intensity training. SETTING Exercise tests were completed in a hospital stress testing laboratory, and cholesterol analyses were performed in a university research laboratory. Exercise training was performed in the community at a site determined by the subject. SUBJECTS Subjects were 25 healthy female employees of a teaching hospital. INTERVENTION Maximum treadmill tests and serum cholesterol profiles were assessed in 25 women before and after a 12-week aerobic walking regimen; 12 women in a high-intensity exercise group (HIG) walked at a target heart rate of 80% and 13 women in a moderate-intensity exercise group (MIG) walked at a heart rate of 60% of their heart rate reserve for a distance of 2 miles three times weekly. MAIN OUTCOME MEASURES The main dependent variable was HDL2; other measures of the HDL profile were total HDL and HDL3. Peak oxygen uptake (VO2) was also evaluated as a dependent variable to ensure a general aerobic adaptation resulted from the exercise regimen. Measures were analyzed as pretraining to posttraining change scores and absolute values using independent and dependent t tests as appropriate. Statistical significance was assigned atp < .05. RESULTS Total HDL was 32.3+/-8.5mg/dL before and 40.3+/-10.6mg/dL after training in the MIG and 31.6+/-6.2mg/dL before and 38.2+/-12.0mg/dL after training in the HIG. HDL2 was 14.2+/-5.7mg/dL before and 18.5+/-6.9mg/dL after training in MIG. HDL2 was 13.0+/-6.2mg/dL before and 19.6+/-8.9mg/dL after training in the HIG. Total HDL and HDL2 increased significantly in both groups as a result of exercise training, and intragroup differences were not observed. HDL3 was not affected by exercise training. Training resulted in significant increases in peak VO2 in both MIG and HIG (29.0+/-5.0 to 31.9+/-5.4mL/kg/min in the MIG and 30.7+/-5.2 to 33.5+/-6.3mL/kg/min in the HIG). Intergroup differences in change scores for peak VO2, HDL, and HDL2 were not observed. CONCLUSION The results and analyses did not support the hypothesis that the HIG would acquire increases in HDL2 profile beyond those observed for the MIG. Moderate-intensity training was sufficient to improve the HDL profile, and high-intensity training appeared to be of no further advantage as long as total training volume (total walking distance per week) was constant.