Does fitness lead to better sex? Or does sex lead to better fitness?

There has been a lot of data showing that developing your physical fitness has beneficial side effects in the bedroom. In short, the most common male sexual dysfunctions are erectile dysfunction (ED) and premature ejaculation (PE). ED is fairly common ranging from 25/1000 - 50/1000 [e.g., 1]. It can be a result of poor circulation, which can be partially addressed with a  fitness regimen, especially aerobic training. Aerobic (cardiovascular) exercise can aid circulation [a, b, c]. In addition to fitness training a healthy diet full of anti-oxidants (e.g., blueberries, see also d, e) can also assist in circulatory function. Training also reduces stress and increases concentration and some even say heightens cognitive acuity/creativity.  Plus think of the kinds of diseases that are related to increased incidence of ED: obesity, cardiovascular disease, emphysema, etc. All diseases that in some, if not large, part are due to an unhealthy lifestyle. The latter (PE) is also common, affecting between 30-70% of all men at some point in their lifetime [e.g., 2]. A regiment of core training (short article here, see also f, and not for any particular scientific proof just nice to watch g, also see here) ought to increase a man's ability to control the pelvic muscles (kegel muscles, in particular) involved in inhibiting ejaculation and increase penile erectile rigidity. They even sell equipment designed to workout your 1st mate. Also, an increase in general fitness should increase a man's confidence in oneself so that PE related to self-esteem issues might also be quelled [3].  Most health professionals would recommend exercising about 3-5 times/week in order to reap the benefits for you and your member.

And, let's be honest, at the end of the day, looking good gets you laid [4].

OK, so being fit can increase your sex life, but is the opposite true? Can a good sex life increase your fitness? The discussion following will try to address this question empirically.

One of the earliest investigations of the role sex had on endogenous testosterone in humans was published under the name Anonymous [see 5] in the premier scientific journal Nature. The investigator measured the darkness of his "5 o'clock shadow" and weight of beard clippings on days after having had sex the previous night compared to nights when he was not so lucky. What he discovered was that his beard clippings were significantly heavier and his 5 o'clock shadow was significantly darker on days after he had gotten lucky the night before. This finding suggested that sex increased levels of circulating testosterone (& other sex steroids), which resulted in an increase in a secondary sexual characteristic - male typical facial hair.

Here's an experiment to try (and I would appreciate reports on your experiences if you choose to try it) systematically analyze the quality of your workout on a day after having had sex the night (or morning or afternoon, whichever you prefer or find a receptive female) before compared to a workout after a night when you were not so lucky (when comparing try to keep all other things equal; i.e. don't compare a night of binge drinking with sex to a night of TV watching without sex. If you drink and have sex, then compare next day workout to a prior night of drinking without sex). As a graduate student I did just this. I noticed that on nights after I went home with someone, I was significantly (5-10 lbs) stronger the next morning. Now this is far from scientific, but a similar effect can be noticed just by imaging sex (sexual body parts). Based on a number of findings that suggest that even fantasizing about sex can distract the mind, decrease perceptions of pain, etc., some of my colleagues at grad school and thought we'd take the technique to the gym. The "experiment" went something like this: for one week go about your normal workout. Then the next week during your heavy sets imagine your favorite sexual position or body part. We were to note whether the lift felt easier or if we were able to pump out a few more reps. Interestingly all 5 of us reported feeling an increase in strength and number of reps when imaging our favorite position or body part. As far as I know the effect has not been systematically studied and published, but it was pretty clear in our cases that something was going on. Were we simply distracted from the pain of the last rep? Were we tapping some primordial cave man instinct to show off (i.e. intra-sexual competition for access to mates)? Was our fantasizing during working out activating release of androgens in our blood stream? Well we never took it this far, but I am convinced that each of these may be the case.

With respect to pre-game banging, there are a few good studies that suggest the old age myth of no sex before the big game is just that: A myth (5, 6). 

So the moral of the story: Exercise 3-5 times/week in order to maintain a good sex life and I would recommend have sex 3-5 times/week to maintain a good fitness life!

--------For Females Only------

Other benefits of sex (for females only): The chemical composition of semen actually contains substances that produce antidepressant like effects in women. I am not, by any means, suggesting unprotected sex, but absorption of the chemicals in semen through the vaginal wall enters the bloodstream and produces biological effects in women. If you would like a copy of the paper demonstrating this effect please email me and you could also see the chapter dedicated to the chemical composition of semen in my book on female infidelity.