Initial Levels may Determine Small vs. Greater Increases in HDL-C in Exercising Population

Abstract

1103 PURPOSE: The purpose of this study was to determine changes in HDL-C in individuals with initially low levels of HDL-C (L-HDL-C) (1.0 mmol.l-1 or 38.7 mg.dl-1) compared to individuals with higher HDL-C (H-HDL-C) (1.2 mmol.l-1 or 46.4 mg.dl-1) concentrations utilizing meta-analytic technique. METHODS: We examined the effects of experimental design, duration and intensity of treatment, diet therapy, combination of diet and drug therapy, weight, age, sex and physical activity in adults. The data was generated via computer search and cross-checked. A library search was conducted through relevant journals. Three hundred sixty nine studies were identified and reviewed. From 369 studies, 53 studies were suitable to conduct a meta-analysis. Numerous studies revealed multiple effect sizes (ES) resulting in 198 ES and an N = 6382 subjects. RESULTS: For the purpose of statistical analysis we used the initial level of 1.0 mmol.l-1 (38.7 mg.dl-1) and below as a cut-off for the upper limit for L-HDL-C and 1.2 mmol.l-1 (46.4 mg.dl-1) and above as cut-off for the lower limit for H-HDL-C concentration. Although differences in HDL-C between the pre and the post treatment for both groups were significant, we also determined that subjects with L-HDL-C increased the HDL-C levels by a small margin only (mean difference of 0.06 mmol.l-1 or 2.3 mg.dl-1) compared to individuals in the H-HDL-C (mean difference of 0.12 mmol.l-1 or 4.6 mg.dl-1), twice the concentration compared to L-HDL-C, even though subjects adhered to the same treatment (age, sex, obesity, diet, exercise intensity, duration and volume, etc.). The differences were even greater when calculating the HDL-C concentration levels in the upper 25% of H-HDL-C compared to the lower 25% of L-HDL-C population in this study. CONCLUSION: We conclude that subjects with low initial values of HDL-C will respond less favorably to interventions of exercise, diet and various combinations of treatments compared to subjects who have higher levels of HDL-C.