Exercise intensity: Its effect on the high-density lipoprotein profile

Abstract

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 (HDL 2) 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 HDL 2 other measures of the HDL profile were total HDL and HDL 3. Peak oxygen uptake (V0 2) 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 at p < .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.Omg/dL after training in the HIG. HDL 2was 14.2 ± 5.7mg/dL before and 18.5 ± 6.9mg/dL after training in MIG. HDL 2 was 13.0 ± 6.2mg/dL before and 19.6 ± 8.9mg/dL after training in the HIG. Total HDL and HDL 2 increased significantly in both groups as a result of exercise training, and intragroup differences were not observed. HDL 3 was not affected by exercise training. Training resulted in significant increases in peak V0 2 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 V0 2, HDL, and HDL 2 were not observed. Conclusion: The results and analyses did not support the hypothesis that the HIG would acquire increases in HDL 2 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.