Find a rival.

Competition against strangers or enemies—but not friends—can boost your testosterone levels if you come out on top, says a new study in Human Nature. Men’s T levels surged more than 30 percent when they won competitive domino matches. The researchers conducted similar experiments pitting friends against one another in different types of contests, but found that beating (or losing to) a buddy doesn’t affect your T levels.

Think of it as the hormonal thrill of victory. When your testosterone rises, your muscle tissues are stimulated, your coordination and mental ability improve, and you feel more self-confident—all things that will help you in a competitive setting, the study explains. And so your T levels may spike after a victory in order to prepare you for another challenger, the researchers speculate.

So why doesn’t your testosterone increase when you defeat a friend? Evolutionarily speaking, forming coalitions or partnerships was a good strategy for staying alive, explains study coauthor Mark Flinn, Ph.D., an anthropologist at the University of Missouri. If your T raged every time you faced off against an ally, that allegiance probably wouldn’t last long, he says. Although preliminary, Flinn’s research suggests playing (or even watching) sports that pit you or your team against strangers or rivals could up your T levels so long as your squad is victorious. Winning non-athletic competitions at work—say, beating out a competitor for a contract or job—could also increase testosterone, especially if women are present, the research shows. (T tends to spike when you’re competing for a woman’s attention, Flinn explains.)

So should you start challenging strangers at the gym? You could, but it won’t do you any lasting good, Flinn says. Any differences in T levels will be very short lived, he adds. So if you’re worried about low T, you’re better off losing weight and cutting back on alcohol.

Originally published on menshealth.com