Exercise physiologists should not recommend the use of ephedrine and related compounds as ergogenic aids or stimulants for increased weight loss

摘要

Ephedra, or ma huang, refers to the above ground portion of the plants that comprise the genus ephedra. Although the species of ephedra differ in their chemical composition, the content of biologically active compounds in these plants is mainly due to ephedrine (other compounds being pseudoephedrine, norpseudoephedrine cathine, and norephedrine phenylpropanolamine). Ephedrine is similar in chemical structure and biological function to amphetamine, although having a 25-fold lower biological potency. Nonetheless, ephedrine is a potent central and peripheral nervous system stimulant, causing the stimulation of both α and β adrenergic receptors, and the release of dopamine within the brain and norepinephrine (noradrenaline) from sympathetic nerves within and external to the CNS. These mechanisms of action cause bronchial smooth muscle relaxation, increases in heart rate and blood pressure, variable peripheral vasculature constriction and dilation, general feelings of emotional and/or psychological arousal and increased alertness, and an accelerated metabolic rate. The biological responses to ephedrine have lead to its use as a stimulant in efforts to improve exercise performance, and assist in weight loss. It has been estimated that at least 3 billion doses of over-the-counter ephedrine or extracts from ephedra were ingested in the U.S. in 2000 for the purpose of stimulating increased weight loss. In addition, compounds high in ephedrine, such as over-the-counter medications to treat sinus congestion or symptoms of the common cold, can be and are used to synthesize the illegal drug metamphetamine. Intake of ephedrine exposes the user to unacceptable negative side effects, including mood disturbances, abnormal heart function, hypertension, gastrointestinal dysfunction and headache, while providing small amounts of added weight loss and/or central nervous system stimulation. Furthermore, individuals with underlying cardiovascular disease or other illnesses may be at more serious health risk when taking ephedrine. Individuals who need to lose weight (body fat) should rely on modifications to diet and increased daily physical activity and exercise. The need for body fat loss rather than gross weight loss should also be recommended and understood. Where additional assistance is needed in body fat reduction, individuals should consult a registered dietitian or their physician.