Exactly how many seconds to maintain your max heart rate for in a HIIT workout, according to trainers

Now that tracking your heart rate is as common as knowing how many steps you take each day, I always have my eye on how fast my heart is pumping—especially when I’m working out.

While my heart rate obviously reaches different levels during different types of workouts, it’s HIIT workouts where I really push myself. According to my tracker, I usually spend about a minute at max heart rate in a more intense workout. That might sound like a pretty short amount of time to be going as hard as you can, but trainers say that’s actually more than enough.

You can find your max heart rate by subtracting your age from 220 (so, if you’re 31, yours would be 189 beats per minute), and when you hit this number during your workout it should feel like “an all-out sprint, like you are being chased by a tiger,” says Joanna Stahl, trainer and founder of Go2Practice.

As for how long you should aim to hold that max heart rate for during HIIT? “Usually you should hold your max heart rate for 30 seconds, followed by 10 to 30 seconds for recovery,” says Phil Catudal, celebrity trainer and nutritionist. “Never hold it more than a minute though, unless you’re an elite athlete.” An example good use of your max heart rate is 30 seconds at 90 to 95 percent of your max, then 20 seconds at 65 percent of your max, then repeat, he says. “Work up to a minute. Some people can push for two minutes, but that’s far from normal and it’s not safe if you’re untrained.”

Getting to that super-high heart rate is actually the easy part: High intensity cardio-based exercises like sprinting or spinning will get you there in a flash. What makes it challenging is sustaining it. “Holding a higher heart rate allows your body to challenge and build the muscular and circulatory systems, making the body more proficient at utilizing oxygen throughout the body and building heart health as well as overall health,” says celebrity trainer and founder of Training Mate Luke Milton.

That said, you shouldn’t be aiming to hit your all-out max heart rate—Stahl recommends viewing it as a guideline for working out at levels based on that key data point. “Once you know your max heart rate, you play within the zones or percentages of effort based on your goals,” she says. “HIIT intervals, for example, are typically 10 to 30 seconds long of an all-out effort with heart rate above 85% of your max, and then recovery.” She suggests staying around 80 percent of your max for as long as you can, then throw in intervals at 75 percent to spice things up. Alternatively, likes to go all out at max heart rate for 30 to 40 seconds of a 45 second interval. So clearly it’s something you can play around with, but there is something satisfying about short bursts of your most badass effort when you’re working up a sweat.

After you go all out, here’s why you should also be tracking recovery. And here’s what it means if you have a low resting heart rate.