Effect of Repeated Exercise Bouts on High Density Lipoprotein-Cholesterol and its Subfractions HDL₂-C and HDL₃-C

 

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Abstract

Nine sedentary men (mean age, 22.8 yrs) were studied during and after treadmill exercise at 65% VChmax to determine the number of repeated exercise bouts required to bring about a sustained elevation in HDL-cholesterol and its subtraction HDL₂-C and HDL₃-C. A Latin square counterbalanced design was used. Thirty minute exercise sessions were undertaken in the following patterns: (1) single bout, (2) two bouts on alternate days, and (3) three bouts on alternate days. The exercise bouts in patterns 2 and 3 were separated by 48 h. Patterns 1, 2 and 3 were conducted 7 days apart. Blood samples were obtained prior to each pattern and at 5 min, 24 and 48 h after the last session within each pattern. There were no significant differences in triglycerides and total cholesterol between the selected blood sampling points for all patterns. Total HDL-C remained higher (p<0.05) than the pre-exercise level 5 min [pattern 1: 39.0 vs 41.2 mg·dl^-1, pattern 2: 37.1 vs 39.2 mg·dl^-1, pattern 3: 38.8 vs 42.7 mg·dl^-1] and 24 h [pattern 1: 39.0 vs 39.4 mg·dl^-1, pattern 2: 37.1 vs 39.1 mg·dl^-1, pattern 3: 38.8 vs 42.6 mg·dl^-1] post-exercise. Total HDL-C declined to pre-exercise values 48 h post-exercise in all patterns. HDL₂-C was lower (p<0.05) than pre-exercise 48 h for all exercise patterns. For all patterns, HDL₃-C levels were higher (p < 0.05) at the 5 min and 48 h post-exercise time points than at the pre-exercise. These data illustrate that exposure to repeated exercise sessions conducted on alternate days resulted in a prolonged (i.e., 24 h) elevation in HDL-C. This increase in HDL-C was primarily due to an increase in HDL₃-C. Three repeated exercise bouts (pattern 3) brought about a prolonged (i.e., 24h) and clinically significant (∼4.0 mg·dl^-1) elevation in HDL-C.