Although you and your squad might not sync up on your menstrual cycles, some habits do naturally align among friends: When researchers looked at the running habits of 1.1 million runners around the world over a five-year period, as collected by an activity-monitoring company whose users track virtual friends' pace and mileage, they found that virtual friends followed similar training habits.
The results, published in Nature Communications, suggest that friends who push themselves to run faster and farther can motivate you to do the same—simply by doing their thing.
Because it's possible that people who train at the same pace happen to sync up due to their comparable running habits, researchers wanted to rule out coincidence: Knowing that bad weather can deter runners, they compared training habits of friend pairs in regions to see if weather patterns made a difference.
They found that friends of runners who clocked an extra 10 minutes on any given day ended up extending their own runs by about three minutes—regardless of bad weather in their 'hoods. Another cool outcome: When one friend goes faster, the study found, the other pal tends to follow suit.
The only thing that appeared to put a damper on these effects was gender: Men were affected by running habits of male and female friends (the data didn't speak to other genders), while women were only affected by female friends' running workouts.
Study authors didn't look into what triggers these effects, but they're confident that the results prove running is "socially contagious," according to study leader Sinan Aral, PhD, a professor at Massachusetts Institute of Technology's Sloan School of Management who spoke with the New York Times. That said, their learnings don't apply to non-runners trying to start up new habits from scratch, or friends who pursue other sports together, for which more research is needed.
As researchers delve into these unsolved mysteries, it pays to go for a jog, which obviously benefits you. Now get out there, and pound the pavement!
This article originally appeared on Cosmopolitan.com. Minor edits have been made by the Cosmo.ph editors.