So his research team designed a study. They had 12 athletes do exercises (leg curls and extensions) in a gym. The researchers measured the kinetic energy and torque generated on days when the men reported they’d had sex the evening prior, and days they said they hadn’t. Their study, “Effect of Sexual Intercourse on Lower Extremity Muscle Force in Strength-Trained Men” found, contrary to what the title implies, no effect.
Read: How sex affects intelligence, and vice versa
At the risk of turning this into another “What is sex?” story, I had to ask how the terms were defined. “This was just college-aged men who were in a relationship with a woman,” Astorino told me, apologetically. Most research on this question has been done on (and by and from the perspective of) men. Astorino says he is trying to do better.
This limited definition of sex—as an act defined as completed whenever a male has an orgasm—was one of the problems that came up during the peer-review process. So was the question of sex positions. “One reviewer made the point that if the male was doing a lot of work, that might lead to more fatigue or muscle soreness than if he was playing a passive role,” Astorino said. And then there’s the question of duration. Sex can last anywhere from a few minutes to, I’ve heard, “all night long.” Most cases in Astorino’s study lasted less than 10 minutes. Only three fell in the 10–30 minute range. (Again, these were men in relationships, not living out the lyrics of a Boyz II Men song.)
Historians have traced the origin to archaic ideas about semen carrying testosterone out of the body. The first actual study of the idea, though, wasn’t until 1968. Warren Johnson set out “to test the traditional view of coaches and athletes that sexual release adversely affects motor performance.” He used a grip meter to assess the strength and endurance of the hand muscles in 10 married men on mornings after sex and mornings after no sex. There was no difference.
No further research was done on the topic for decades, even as coaches kept echoing the myth. A smattering of small studies in the 1990s found no effect of sex on subsequent performance. In a 2016 meta-analysis, researchers deemed the past studies universally weak and concluded “randomized controlled studies are urgently needed.” This has yet to happen. But at least in a relative way, the past two years have been a heyday for the field. Studies in 2018 included Astorino’s as well as another in which researchers measured strength, balance, agility, reaction time, and anaerobic power in 10 young men. Yet again, the studies found no difference based on night-prior sex.
Just this month, another study built in an even broader range of tests. Participants were evaluated on three separate occasions after having met one of three conditions on the previous night: sex, abstinence without other physical activity, and abstinence with physical activity. The third category involved “a 15-minute yoga exercise session intended to mimic the energetic cost of sexual activity.” The men then did tests of vertical jump, hand grip, and reaction time, among others. Nothing was affected.