From a medical perspective:
Medical concerns about sex have less to do with male athletes breaking an ankle during an embarrassing sex swing accident and more to do with testosterone. It was once thought that sex weakened the male by causing him to lose testosterone, and therefore his masculine vitality and strength.
However, a Chinese study conducted in 2003 shows very little connection between testosterone levels and a man’s regular sexual activity. The study tested the testosterone levels of 28 men who abstained from sexual intercourse for different lengths of time. They found that a week of abstinence produced little to no fluctuations in testosterone levels. And on the seventh day, there was a great flood... sorry, a peak in testosterone levels, and then they went back to normal.
Which means that an athlete who ejaculated exactly seven days prior to competition would have just a little more testosterone than an opponent who is, presumably, not so regimented. However, waiting to have sex for any more than a week would offer no boost of testosterone to the athlete; his nights would just be lonelier.
But wait, there is some connection between a healthier male body and having sex on a regular basis. For instance, studies show that those who ejaculate more may be at less of a risk for prostate cancer, the reason being that ejaculation reportedly clears out prostate glands. And, well, anything that can keep an athlete healthy is obviously beneficial.