Although synthetic steroids aim to enhance their anabolic, or body-building properties and diminish their masculinizing, or anabolic properties, to date there is no exclusively anabolic steroid. Anabolic steroids that increase muscle strength have been taken by athletes who have trained in weightlifting, who continue intensive training while taking steroids, and who adhere to a diet high in protein and calories. While steroids are used to improve speed, endurance, and competitiveness as well as strength, the rapid consumption of calories in sports such as running and swimming may negate their action. However, athletes have reported that they feel less tired after taking steroids, enabling them to recover from workouts more quickly and train at high intensity for longer periods. Steroids may also promote aggressiveness in athletes. While taking steroids, men may experience a decrease in testosterone production, reduced sex drive, and overdevelopment of the mammary gland. Some women on steroids report increased sex drive, menstrual irregularities, and development of secondary male characteristics. Liver function tests can show abnormalities during a steroid regime; although these readings usually return to normal when steroids are discontinued, more serious and rarer problems are peliosis hepatitis, liver tumors, and a cancer of the kidneys. Because of their water-retaining properties, steroids have the potential for causing high blood pressure; they also reduce the level of HDL cholesterol with possible implications for coronary heart disease. Steroids can stunt growth by causing early fusion of cartilage plates. AIDS transmission can occur through sharing injection equipment. Although steroids are not physically addictive, athletes can become psychologically dependent on them; there have been a few case reports off other temporary psychiatric problems associated with these drugs.