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Does exercise increase HDL cholesterol in those who need it the most?

The Health, Risk Factors, Exercise, Training, and Genetics (HERITAGE) Family Study is a landmark multicenter trial designed to examine the physiological changes produced by exercise training and how genetics contributes to the variation in the response to exercise.1 Families underwent physiological and biochemical assessment before and after 5 months of supervised aerobic exercise training. This study is the largest intervention trial of the effects of exercise training on serum lipids, and the results for the entire cohort have been previously reported.2 In this issue of Arteriosclerosis, Thrombosis, and Vascular Biology , Couillard and colleagues3 present a detailed subgroup analysis of the lipid results for 200 white males that focuses on the effects of exercise on HDL cholesterol (HDL-C) levels. The results have important messages for both researchers and clinicians interested in the effects of exercise on lipid metabolism.

Coulliard and colleagues3 divided their subjects into 4 subgroups by using the 50th percentiles of plasma triglycerides (TGs) and HDL-C as cutpoints, 0.92 mmol/L (36 mg/dL) for HDL-C and 1.34 mmol/L (119 mg/dL) for TGs, thereby forming 4 subgroups: low TG/high HDL-C, high TG/high HDL-C, high TG/low HDL-C, and low TG/low HDL-C. The lattermost group is referred to as “isolated low HDL-C,” a common condition that is often, but not always, a risk factor for premature coronary disease. Interestingly, as expected, while the high TG/low HDL-C group had evidence of visceral obesity and insulin resistance, the isolated low HDL-C group did not. Both high-TG groups experienced a 13% to 15% decrease in TGs with exercise, which is consistent with multiple reports that exercise does effectively reduce TGs.4 The major question asked in this analysis was whether the HDL-C response to exercise was related to the baseline TG levels. HDL-C levels increased by an average of 4.9% in …