GORDON, N. F., D. P. MYBURGH, M. P. SCHWELLNUS, and J. P. VAN RENSBURG. Effect of β-blockade on exercise core temperature in coronary artery disease patients.Med. Sci. Sports Exerc., Vol. 19, No. 6, pp. 591–596, 1987. The effect of pharmacologic blockade of β-adrenoceptors on the relationship between rectal (Tpa) and pulmonary artery (Tretemperatures was studied in six coronary artery disease patients during 30 min of exercise. Exercise was performed at a set work rate (120 W) on a cycle ergometer before and 2 h after the ingestion of 80 mg propranolol. The heart rate on completion of exercise was reduced (P< 0.001) from 140 ± 5 to 108 ± 3 beats.min-1by propranolol demonstrating a considerable degree of β-adrenoceptor blockade. At rest, neither Trenor Tpawere modified by propranolol. Likewise, propranolol failed to modify the Treresponse to exercise. However, propranolol induced an alteration of the normal relationship between Treand Tpaduring exercise. In particular, although Trewas essentially unchanged, propranolol accentuated both the initial fall (by 0.28°C,P< 0.001) and the subsequent rise (by 0.46°C,P< 0.01) in Tpaduring exercise. The present data therefore demonstrate a considerable limitation to the use of Trewhen assessing thermal homeostasis during acute β-adrenoceptor blockade. Furthermore, although research with more chronic therapy is warranted, our study suggests an accentuated risk of hyperthermia and, by implication, its adverse physiologic consequences during prolonged exercise performed by coronary artery disease patients treated with propranolol.