Stressed out? This expert says it could be your workout

Woman sitting on a gym bench with her head in her hand looking stressed
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Exercise is considered one of the best ways to de-stress, but is your workout stressing you out? During Stress Awareness Week, we decided it is time to highlight the unique relationship between exercise and cortisol so that you can use exercise as a tool for your stress relief rather than against it.

There is an endless wealth of research — like this study published in the Journal of Clinical Psychiatry — that shows regular exercise reduces symptoms of anxiety, stress and depression, elevates mood and even improves sleep. But (surprisingly) there are times when your workout could raise your cortisol levels. Who knew? 

We spoke to Dr. Rami Hashish, body performance and injury expert, to discuss the relationship between cortisol and exercise and how exercise could be stressing you out. Find out how to sleep better naturally to reduce stress and the best fitness trackers for monitoring your health, or read on for the low down on cortisol and exercise.  

Image of Dr. Rami Hashish
Dr. Rami Hashish

Rami Hashish obtained his PhD in biomechanics from the university of Southern California. He has worked as a clinical instructor of physical therapy for several years before founding the national biomechanics institute. He is active on social media channels spreading the word on all things health.

What is cortisol? 

Cortisol has caught a bad rep, but it can be a helpful hormone. According to the Cleveland Clinic, cortisol is a hormone produced by your adrenal glands, and its many roles include regulating metabolism and blood pressure, suppressing inflammation and controlling your sleep-wake cycle. 

Dr. Hashish explains that despite its functions, cortisol is commonly known as the ‘stress hormone’ responsible for regulating your response to stress and producing the ‘fight-or-flight’ response. In the good old hunter-gatherer days, this was crucial for hitting the pause button on everything else and directing adrenalin to help you respond to danger. However, too much cortisol can negatively impact your health, increasing anxiety and blood pressure and disrupting your snooze (is 8 hours of sleep enough?)

Even though the days of being chased by a lion are over (we hope), your body can’t tell the difference between perceived and actual danger. So whether it’s relentless  emails or an overzealous driver on the car horn, your body is spending more time in a heightened ‘fight-or-flight’ state — and you might not even realize it.  

How does exercise reduce stress?

As we mentioned, a body of research exists showing that exercise reduces stress and anxiety and boosts mood. According to Dr. Hashish, the relationship between exercise and cortisol is often positive. “Exercise reduces cortisol levels and other stress hormones, like adrenaline, and stimulates endorphin hormones,” he says.

“This promotes a sense of relaxation and euphoria, such as the ‘runner’s high.’” Yep, that happy hit of dopamine is real.

Hashish explains that exercise causes a release of neurotransmitters throughout your nervous system, like endorphins, dopamine and endocannabinoids. These chemical messengers help regulate your sleep cycle and mood and promote improved attention, motivation and relaxation. 

Is HIIT exercise stressing you out? 

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While exercise is mostly a positive tool for stress management, some types of exercise could exacerbate your stress levels, like high-intensity training (HIIT).

HIIT (think CrossFit and boot camps, for example) certainly have a time and place and offer benefits like building lean muscle mass and torching calories. However, these intense bursts of exercise are designed to elevate your heart rate. And guess what? Your body senses this as danger and stress. 

Dr. Hasish explains that when the brain senses stress (remember, your body does not differentiate), it releases cortisol. “Cortisol provides your body with immediate energy by breaking down fats and carbohydrates and raising sugar levels,” he says. “This allows your body to perform in a fast and powerful manner. 

Man performing a snatch holding a barbell above his head in a squat

(Image credit: Getty images)

But the cortisol released in your bloodstream can cause negative changes to your immune system and sleeping pattern and induce fatigue and anxiety,” he says. When your cortisol levels rise, heart rate and blood pressure also elevate, which negatively impacts sleep as you feel more alert. 

We know that sleep and mood are closely related, with poor sleep contributing to high stress and anxiety levels. Prolonged states of stress have adverse effects like a slower metabolism and muscle repair, suppressed growth hormones, chronic pain and a higher likelihood of developing depression, according to the American Psychological Association (APA).  

How to prevent exercise from causing stress 

While you can’t exactly battle your body’s chemical response to exercise, there is an argument suggesting that this is the best time to exercise according to science. What’s more, the type and timing of exercise could improve your sleep and mood. 

Research, including this peer-reviewed article in News Medical, supports morning exercise to improve sleep quality later in the day. This could be a great way to slot high-intensity exercise into your routine without the impacts of elevated heart rate, temperature and metabolism close to bedtime. 

Another study published in the Journal of Health Psychology backs this up. It found that evening exercisers experienced delayed sleep and poorer sleep quality which could result in prolonged poor sleep hygiene and mood.

On the other hand, some research suggests that low-impact exercise reduces circulating cortisol levels, which could be the perfect option if you want to exercise close to bedtime. Yoga and Pilates are mind-body exercises forms helpful for reducing stress and anxiety. Try this bedtime yoga routine for better sleep and mood if you’re keen to give it a go (and if you need a new pad, check out our picks for the best yoga mats).

What’s more, mental health charity Mind strong recommends gentle exercise outdoors for stress relief and improving mood, so taking an evening walk could be the way to go if you’re feeling stressed or overwhelmed. Plus, you get your steps in, too. 

Woman meditating by the ocean on a mat

(Image credit: Getty images)

Benefits of recovery  

When in ‘fight-or-flight’, you sit in your sympathetic nervous system. But your parasympathetic nervous system signals your body to relax and repair. Overtraining and intense regular exercise limit the time your body can spend here, which means your body isn’t prioritizing recovery, further compounding those stress levels. 

Dialing back on the intensity using techniques like meditation and gentle exercise can help you prioritize recovery. The result? Your body gets to reap the rewards of your HIIT workouts  — think muscle repair and growth and increased energy levels, to name a few — rather than burnout. 

Up next: Why not give this deep sleep meditation a go? See what happened when our editor walked 10,000 steps a day for a month, and how to get a good night's sleep if you're stressed

Sam Hopes
Senior Staff Writer - Fitness

Sam Hopes is a level III fitness trainer, level II reiki practitioner, and senior fitness writer at Future PLC, the publisher of Tom's Guide. She is also about to undertake her Yoga For Athletes training course. Having trained to work with mind and body, Sam is a big advocate of using mindfulness techniques in sport and fitness, and their impact on performance. She’s also passionate about the fundamentals of training and building sustainable training methods.  When she's not writing up her experiences with the latest fitness tech and workouts, you’ll find her writing about nutrition, sleep, recovery, and wellness.