Total-body workouts built around high-intensity interval training—which includes both resistance and cardio—are highly effective for building muscle, burning fat, and improving your cardiovascular endurance.

That's not "bro science" either—it's backed up by extensive physiological research. So why don't more people do it? Short answer: It's really demanding.

In a HIIT workout, you'll perform all-out, exhausting physical effort for a short time, followed by a short, sometimes active, recovery. If you're new to HIIT, your routine should involve working out hard for 60 seconds, and then breaks for 1-2 minutes, depending upon the exercise involved.

As you get accustomed to HIIT, you can lower the work-to-rest ratio from 3:1 to 2:1 and eventually even 1:1. During the high-intensity interval, your goal should be to get your heart pumping at 85% of its maximum rate. On a scale of 1-10, 10 being completely out of breath, your breathing should be at 8-9.

So yeah: It's tough. But there are plenty of benefits to HIIT, including increased metabolic rate, optimal muscle building and retention, fat loss, and increased calorie burn during and after the workout.

But there’s a lot more to HIIT that can benefit you as a physique-minded athlete. Check out this list to get the details on this essential workout method.