Is joining a gym really better than going it alone? You bet—and astonishing new research proves it.

Despite the fact that “gym membership = better health” seems somewhat obvious (assuming, of course, you actually go to the gym where you pay dues), no one had ever conducted a study to test the theory—so exercise researchers at Iowa State University did exactly that.

In a study just out in the journal PLOS ONE, ISU scientists used data on more than 400 subjects ages 30 to 64 to compare those who belonged to a gym with those who didn’t. Result: 75% of gym-membership holders met the U.S. recommended physical activity guidelines—that is, at least 150 minutes of moderate exercise or 75 minutes of vigorous exercise each week—while only 18% of non-members met that standard.

To put a finer point on it: The gym rats actually worked out an average of 300-plus minutes each week. Talk about going above and beyond.

And it gets even better: “Gym members were 14 times more aerobically active than non-members, and 10 times more likely to meet muscle-strengthening guidelines, regardless of their age or weight,” said study author Duck-chul (DC) Lee, Ph.D. “It’s not surprising that people with a gym membership work out more, but the difference in our results is pretty dramatic.”

But wait, that’s not all: The researchers also discovered that gym-joiners had lower odds of being obese, a smaller waist circumference (about 1.5 inches less for men), a lower resting heart rate (by about five beats), and better cardiorespiratory fitness than the slackers.

Not a regular gym-goer? How about getting your ass over there and giving it a shot? Check out these tips for crushing it on your first day.