Why two 20-minute HIIT sessions per week is plenty

When it comes to fitness, it’s easy to fall into the more is more mentality. Ten push-ups is better than five, 26.2 miles is more impressive than 10K, and—yeah—that gal doing the splits in your hot yoga class makes you want to do the splits, too. Now that we’re living in the era of cortisol conscious workouts, gym-goers are conscious of how their sweat sessions affect their stress levels—including the bodily effects of a HIIT workout routine.

Cult on-demand fitness empire Les Mills just advised its digital trainees to cut weekly high-intensity interval training down to two sessions of 20 minutes. Why? Any more and your body simply doesn’t have ample time to reset from fight or flight mode. “We found their recovery was compromised and it was causing problems such as injuries, mood swings, fatigue and disrupted sleep,” Bryce Hastings, head of research for gym Les Mills told The Sun. And fam, this is a big deal coming from the brand that basically specializes in workouts that get your heart racing faster than you can say “gains.”

Fortunately, chill spinoffs of the beloved exercise style abound. High-intensity, low-impact (HILIT) workouts are on the rise, as well as cardio weightlifting and low-intensity steady state cardio (LISS) to keep your ticker closer to cruise control.

“Cortisol is not particularly a ‘bad’ hormone, it’s just that when it remains consistently high, then it’s sending a stress signal,” says Maillard Howell, owner of Dean CrossFit and founder of The Beta Way. “Hormones are chemical messengers.” Cortisol tells your nervous system, brain, and heart that you’re body is under attack, even if that “attack” is an intense workout.

“Cortisol is not particularly a ‘bad’ hormone, it’s just that when it remains consistently high, then it’s sending a stress signal.”

To Hasting’s point, this is NBD if your HIIT sessions fall a few days apart, enough time for your body to renegotiate its equilibrium, but if you’re testing your body with burpees, jump squats, and mountain climbers daily, you’re more prone to injury, fatigue, and stress.

As always, Howell emphasizes that everyone’s different. Maybe you can HIIT it three times a week, while your friend can do five—and that’s okay. “Everyone’s baseline is different. The human body reacts to stress by getting stronger, so someone who has been exposed to stress over a period of time through a form of sports or fitness, their baseline for cortisol response would be different from mine,” says the trainer. In this case, less is more. And “more” is what’s best for you.

If all the HIIT jargon has you scratching your head, bookmark this helpful guide. And don’t forget to stretch afterward.