In opposite to β-agonists, the β-antagonists (beta-blockers) - acting through beta adrenergic receptors - have a depressive influence on sympathetic part of the central nervous system. Therapeutic properties of beta-blockers come from its binding effects to the β receptors dominating in the heart. Beta-blockers can act selective, on specific β receptors, (e.g. Atenolol, Acebutolol) or nonselective, on all β receptors (e.g. Propranolol, Penbutolol). Application of beta-blockers lead to cardiovascular inhibition resulting in a decreased heart rate, decreased contractility of cardiac muscle and decreased systolic blood pressure. Designed primarily as drugs improving cardiac function, under conditions of impaired cardiovascular system, the beta-blockers also exhibit calming neurological effects decreasing anxiety, nervousness and stabilizing motor performance. The improved psychomotor performance may be beneficial in sports requiring precision and accuracy such as shooting and archery. Prolonged use can cause bradycardia, heart blockage, hypotension, bronchial spasm, fatigue, and decreased motivation.