If you’ve been scrolling through fitness advice online, you’ve probably come across influencers talking about ‘low-cortisol workouts.’ Cortisol is, of course, most notoriously known as the stress hormone. So from the outside, this seems good. A low-stress workout.
But there’s more to it. How your body responds to exercise involves some slightly complicated mechanisms. And the truth is: For most people, spiking your cortisol levels during exercise isn’t a bad thing. In reality, it can paradoxically lead to healthier cortisol levels at your baseline.
To learn more about this topic and do some myth-busting, we reached out to obé’s director of programming, Melody D.
Cortisol: Friend or Foe?
Yes, cortisol is a stress hormone, but it’s not the villain it’s sometimes made out to be. “While exercise is a form of stress, it’s beneficial to our health because short-term stressors like exercise enhance our body’s ability to handle stress,” explains Melody.
Let’s backtrack. What is cortisol? “Cortisol is a hormone your body releases in response to stress, that’s why we call it the stress hormone,” says Melody. Let’s say you’re about to go into a job interview. As your mind perceives the stressor, it triggers your sympathetic nervous system. Your adrenal glands then release hormones like cortisol and adrenaline, as well as initiate other physiological changes like a faster heartbeat.
This is a helpful adaptation. It’s proven to enhance your focus and energy levels. So what’s the problem?
The problem arises when your stress response is consistently activated, aka chronic stress or ‘adrenal fatigue.’
Symptoms associated with chronic stress and adrenal fatigue:
- Persistent fatigue
- Difficulty getting out of bed
- Cravings for salty or sugary foods
- Weakened immune system
- Mood swings and irritability
- Brain fog
- Sleep disturbances
- Low energy
“When you exercise, especially during high-intensity workouts, cortisol levels temporarily spike to provide the energy your body needs,” explains Melody.
The theory put forward by many influencers online is that doing too many high-intensity workouts will keep your body in a state of chronic stress, even causing adrenal fatigue. And that leads to a whole array of negative side effects, from ‘cortisol face’ to hormone dysregulation and stagnated fitness gains.
Note: Adrenal fatigue, in theory, is when your adrenals get essentially ‘burned out’ from producing so much cortisol. (Spoiler: As outlined in a 2016 systematic review, there is no medical or substantiative basis that adrenal fatigue is a real thing.)
But here’s the thing that’s often left out of the conversation. “Exercise is a type of acute stress. This means that the increase in cortisol is brief. Once the exercise session ends, cortisol levels begin to drop and quickly return to normal,” says Melody.
In fact, a 2021 study found that cortisol increases during a HIIT workout and persists for 120 minutes after your workout. However, at the 120-minute mark, it drops to below baseline values.
Harnessing Cortisol for Enhanced Resilience to Stress
Here’s where things get really interesting: high-intensity workouts, the ones that spike your cortisol, actually help you handle stress better in the long run.
The brief increase in cortisol levels, followed by a sharp decrease, in a way, ‘trains’ your hormone system to become more efficient. This may sound paradoxical: How can spiking your stress hormone make you better able to handle stress?!
Melody explains: “Just as consistent training leads to increased strength and fitness, exposing our body to manageable stress helps it adapt, making us more resilient to future challenges.”
It’s the repeated cycle of stress and recovery that enhances your body’s ability to recover and adapt to stress over time. Recently we shared a blog about hypertrophy, explaining that to build muscle, you’ve got to damage the muscle. It’s during the recovery phase when your muscles grow bigger and stronger.
You can view stress resilience in the same way.
HIIT exercise → Cortisol spikes → Recovery → Cortisol drops = Enhanced capacity to handle stress, boosted stress resilience, and healthier cortisol regulation.
But we’re not here to discount anyone’s experience. If you’ve noticed some negative side effects from doing too many HIIT workouts, it’s worth addressing. While cortisol-spiking workouts are considered beneficial overall, there are caveats to this.
Too Much of a Good Thing?
As with everything in life, moderation is key. “It’s crucial to be aware of the risks of spending too much time in the moderately high-intensity zones, often referred to as Zone 3 or 4 training.”
“This type of exercise, which is common in boot camp or traditional group fitness classes, places the body under significant stress,” says Melody. If you’re so obsessed with the endorphin rush you get after a good HIIT workout, it can be tempting to fill up your schedule with a daily session. But your body needs recovery!
“Without the peaks and valleys of stress and recovery, cortisol remains elevated, leading to issues such as chronic fatigue, poor exercise recovery, and even unwanted changes in body composition,” explains Melody. And what’s worse: “These problems can occur despite the consistent effort put into workouts.”
Hard work deserves rewards, in the same way that your body deserves recovery.
Balance Your Workouts: Balance Your Cortisol
Before you sack off your beloved HIIT workouts, pause. Not only does research show that your cortisol levels drop below baseline 120 minutes after a HIIT workout, other studies also show that a regular exercise routine that combines low, moderate, and high-intensity exercise is optimal for healthy cortisol levels.
Here are some of Melody’s golden guidelines when it comes to cortisol balance:
1. When you go hard, go HARD: “To achieve the peak and valley of cortisol, you’ve really got to truly push yourself during your workout. Aim to reach a 9-10/10 on the Rate of Perceived Exertion (RPE) scale.”
2. Allow for sufficient recovery: “When you do push yourself to this level, take a day or two to prioritize recovery. Focus on your nutrition, water intake, and sleep.”
3. Take your symptoms seriously: “If you’re experiencing constant fatigue, persistent soreness, or unexplained weight gain despite being consistent in your workouts, it’s time to take a step back.”
4. Do what feels good!: “A lot of the information online about cortisol-spiking workouts comes from a place of (well-intentioned) misinformation. If your current workout routine feels good, keep it up.”
The Bottom Line: Don’t Fear the Spike
As Melody says, you’ve always got to do what feels good. If you’re currently crushing a 5-a-week HIIT workout routine and feeling on fire, there’s no reason to slow down now.
If you’re starting to feel drained, lethargic, or like you’re not progressing — take a break. Switch to some lower-intensity workouts like Yoga, Pilates, Barre, or even a walk outside listening to your favorite podcast.
The key here is balance. Melody concludes, “It’s crucial to understand the appropriate volume and level of stress to trigger a response that leads to adaptation without placing the body in a chronic stress state.” In other words, your body needs stress to grow stronger, but it’s all about finding that sweet spot.
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