Complex sentence: Athletes in many sports use Human growth hormone (HGH), also known as somatotropin, to enhance their athletic performance despite that recent studies have not been able to support claims that human growth hormone can improve the athletic performance of professional male athletes.
Split into simpler sentences: Athletes in many sports use Human growth hormone (HGH), also known as somatotropin, to enhance their athletic performance. Recent studies have not been able to support claims that human growth hormone can improve the athletic performance of professional male athletes.