Calcium antagonists and exercise performance.

Abstract

Calcium antagonists lead to a relaxation of smooth vascular muscles and exert a cardiodepressive effect. They make up a heterogeneous group, with primarily substances of the nifedipine and verapamil type playing the most important role in the treatment of cardiocirculatory diseases. The principal indications include coronary heart disease and hypertension. During physical exercise, following the administration of calcium antagonists, VO2max and endurance performance are not impaired. The rate of perceived exertion does not increase to any greater extent in comparison with placebo. Nifedipine leads to an increase of noradrenaline (norepinephrine) as an expression of a reflex activation of the sympathetic system and to a slight increase in heart rate, while calcium antagonists of the verapamil type lower heart rate by 10 to 15 beats/min during physical exercise as a result of their intrinsic negative chronotropic effect. Cardiac output, in spite of the drop in heart rate, remains unchanged. Neither carbohydrate metabolism nor lipid metabolism, including lipolysis, which provide the essential energy-yielding substrates during exercise, are affected by calcium antagonists. Potassium likewise remains unchanged. The response of the hormones insulin, growth hormone and cortisol is the same with calcium antagonists both during incremental graded exercise and during prolonged exercise as with placebo. In comparison with the administration of only calcium antagonists, the combination of calcium antagonists and beta-blockers impairs physical performance. The diminishment in performance, however, is markedly less pronounced than with beta-blocker monotherapy. Unimpaired performance is crucial for physically active patients. Especially for patients performing regular physical activity who suffer from mild hypertension, calcium antagonists provide a viable therapeutic alternative to beta-blockers.