MORTON, A. R., P. R. STANFORTH, B. J. FREUND, M. J. JOYNER, S. M. JILKA, A. A. HARTZELL, G. A. EWY, and J. H. WILMORE. Alterations in plasma lipids consequent to endurance training and beta-blockade.Med. Sci. Sports Exerc., Vol. 21, No. 3, pp. 288–292, 1989. The chronic use of beta adrenergic blockers (BAB) has been associated with reductions in HDL-cholesterol (HDL-C) and increases in triglycerides (TG). This study evaluated the impact of concurrent endurance exercise training and chronic medication with BAB on plasma lipid and lipoprotein profiles in healthy young adult males. Changes in plasma lipids and lipoproteins were investigated while exercise training under the influence of one of two nonselective BAB [sotalol (320 mg·d-1) and propranolol (160 mg·d-1)], one β-1selective BAB [atenolol (100 mg·d-1)], or a placebo control. Total cholesterol (TC), HDL-C, LDL-cholesterol (LDL-C), TG, and the ratios of TC/HDL and LDL/HDL were determined before and after endurance training programs of either 14 (N=27, sotalol) or 15 (N=47, propranolol/atenolol) wk duration. The subjects exhibited increases in maximal oxygen uptake of 12–20%. Despite increased endurance capacity, the subjects in both BAB and placebo control groups failed to demonstrate the expected increase in HDL-C and decrease in TG. In fact, HDL-C was significantly decreased post-training in the propranolol group. The placebo groups did decrease TC, LDL-C and the TC/HDL and LDL/HDL ratios, improving their CHD risk profile. Similar changes were not observed in the groups on BAB. Thus, with respect to the present population, BAB does appear to interfere with the usual training-induced improvements in the lipid profile. Endurance training may, however, reduce the deterioration in the lipid profile known to occur with BAB.