While many people hold their own views and opinions on this subject, I anticipate that most responses are based on mere opinions, gathered from personal experience or more likely superstition. Muhammad Ali, for example, was known to abstain from sex (or at least he said that he did) for several weeks before a big boxing fight believing that sexual intercourse zapped him of his energy and focus needed the day of the fight.
One argument for abstaining from sexual intercourse the night before an enduring athletic workout is that being sexually frustrated can lead to increased aggression. Evidence, however, suggests that sexual intercourse the night before an event does not alter physiological testing results, the latter of which was measured by strength and endurance of the palmar flexing muscles (1). Similarly, a randomized crossover study found that oxygen pulse, maximal aerobic power, and double product were not significantly affected by sexual intercourse 12 hours prior to the athletic performance (2). This should not come as a surprise given that the sexual intercourse only burns approximately 250 calories per hour, or a little over 4 calories per minute (3). So unless you are having sex that lasts for hours, the reality is that you are not burning a truckload of calories, contrary to what many people believe. Moreover, if you are having sex for hours on end, chances are your performance will be affected the next day - but by way of fatigue, and not the fact that you had sex the night before.
It is also possible that sexual activity the night before a major competition can be beneficial both psychologically and physiologically. If one has a tendency to be anxious, and thereby not be able to get a good night sleep the night before an event, sexual intercourse may help one relax, get a better night sleep, and therefore allow one to be more mentally and physically prepared the following day. It should also be noted that the linkage between sexual activity and athletic performance is not a clear one. For instance, other covariates such as diet and stress also factor into the equation with respect to athletic performance.
In short, little evidence exists that sexual intercourse the night before an event can produce negative outcomes in terms of one’s athletic performance the following day.
References
McGlone S, Shrier I. Does Sex the Night Before Competition Decrease Performance? Clinical Journal of Sport Medicine 2000; 10(4):233-4.
Boone T, Gilmore S. Effects of sexual intercourse on maximal aerobic power, oxygen pulse, and double product in male sedentary subjects. J Sports Med Phys Fitness 1995; 35:214–217.
Mirkin G. Sex before competition. Report #6750. Mar. 10, 1996. http://drmirkin.com/archive/6750.html
