Wellness TikTok Blamed HIIT for High Cortisol. A New Review of 44 Trials Says Yoga Wins, Not Walking

Search 'cortisol workout' on TikTok and you will find video after video telling you to trade your run for a walk, because sprinting supposedly floods the body with a stress hormone that stores belly fat and wrecks your sleep. CapCut, the editing app behind a lot of those videos, now hosts its own template page just for the trend. None of it mentions the exercise a new review of 44 clinical trials found actually lowers cortisol the most. It isn't walking. It's yoga.

The review, published in the journal Sports in 2025 by researchers Xiongjie Li, Jianping Huang, and Feilong Zhu, pooled 44 randomized controlled trials covering 3,284 people who had been diagnosed with some form of psychological distress. Yoga produced the largest average drop in cortisol, with qigong close behind. High intensity interval training, the exact workout wellness TikTok tells people to avoid, was the only category in the review that raised cortisol on average.

What cortisol is actually doing during a hard workout

Cortisol's job during exercise is to help the body meet a physical demand, not attack it. Martine Duclos, an endocrinologist and sports medicine physiologist at Universite Clermont Auvergne in France, says cortisol mobilizes stored energy so muscles have fuel to burn. Travis Anderson, a research scientist with the U.S. Olympic and Paralympic Committee, notes cortisol already follows a daily rhythm, peaking in the morning whether or not anyone exercises.

National Geographic reported on a study of 12 active men in which cycling at 60 percent and 80 percent of maximal oxygen uptake raised cortisol, cycling at 40 percent did not, and levels in both higher intensity groups had nearly returned to baseline within 90 minutes.

Where the wellness version of the story breaks down

Lena Fan, an endocrinologist and assistant professor at the Icahn School of Medicine at Mount Sinai, says the internet's cortisol panic mostly comes from a vocabulary problem.

“Social media is using cortisol synonymously with the word 'stress,' and cortisol doesn't always mean stress.”

Anthony Hackney, professor emeritus of exercise physiology at the University of North Carolina at Chapel Hill, adds the plain mechanical version: the harder the workout, the more cortisol gets released, and that is by design, not a malfunction. Marie Schaefer, a sports and exercise medicine physician at Cleveland Clinic, points to a different culprit for cortisol that stays elevated too long: skipped meals, short sleep, and skipped rest days, not exercise intensity by itself.

The pattern is bigger than one workout trend

This is not wellness TikTok's first cortisol misfire. In 2024, a wave of videos claimed everyday stress could visibly round out a healthy person's face, a claim that picked up the shorthand 'cortisol face.' Vijay Murthy, a functional medicine doctor, told Healthline the effect is real only in rare conditions like Cushing syndrome, not from ordinary stress. There is no running count of how often a real hormone gets recruited into an overstated wellness claim online, but cortisol specifically has now driven at least two separate viral cycles in under two years.

One limit worth stating plainly: the 2025 review's 3,284 participants had all been diagnosed with some form of psychological distress, not the general population doing the TikTok trend at home. The qigong result also carried a confidence interval wide enough to cross zero, meaning it was not statistically distinguishable from no effect at all. Yoga was the one category with a clear, consistent signal.

None of this makes cortisol fake or exercise dangerous. It makes cortisol the latest real hormone recruited to justify a workout choice people were already leaning toward for other reasons. The data does not reward the extreme in either direction. It rewards showing up for something like yoga or a brisk 20 minutes most days, then going home.