Powerlifters often jest that once you do more than 5 reps per set, you’re practically doing cardio.

Turns out, that might not be far from the truth.

In a recent study, scientists had 22 experienced weightlifters do five 10-rep sets of squats with 65% of their one-rep max and rest 3 minutes between sets. During each set, the researchers monitored the weightlifters’ oxygen consumption, heart rate, and overall aerobic output.

The findings?

High-rep squats pushed their cardiovascular systems hard enough to qualify as “vigorous” exercise. Basically, high-rep squats, especially when performed with heavy weights, give your heart and lungs a serious workout.

Are squats a cardio exercise, then?

Not quite.

Squats and other resistance exercises can increase your heart rate and burn calories, but they don’t deliver the same cardiovascular or metabolic benefits traditional cardio does. 

For instance, cardio enhances your body’s ability to use oxygen by increasing mitochondrial size and number and boosting capillary growth, which help your muscles use oxygen more efficiently.

While strength training can cause similar adaptations, they tend to be smaller than those gained from traditional cardio, and they depend heavily on the type of training—higher-rep bodybuilding routines are likely better than lower-rep powerlifting programs, for example. 

In other words, squats can feel like cardio, and they do provide some aerobic benefits, but they’re not a substitute for runs, rows, and rucks. To cover all your bases, doing regular cardio—even just walking—is a smart move for overall health.