What is the best performance enhancement drug?
Sleep is the greatest legal performance enhancement drug.
In sports, for example, you can get 20-30% better overnight by just getting enough sleep after a practice. Meanwhile, getting six hours of sleep or less will make your physically exhausted up to 30% faster.
Without good sleep, your lactic acid builds up quicker, and your ability of the lungs to actually expire carbon dioxide and inhale oxygen decreases too.