Cortisol has ominous connotations, after all, it’s a stress hormone, and one that can have a negative impact on your body. However, your body produces cortisol for a reason. It’s only when the stress hormone gets out of hand that it leads to problems. Your body releases more cortisol into your bloodstream during periods of mental or physical stress and when you’re fasting. The goal is to supply your body with more available energy. The way it does this is by stimulating gluconeogenesis, the conversion of amino acids from protein to glucose. Cells can then use glucose to make energy.
Since cortisol helps supply your body with energy, it has benefits, at least short term. But over time, it has negative effects. For example, having more cortisol circulating can, over time, lead to the loss of muscle and increase fat storage around the tummy. In addition, it reduces growth hormone and sex hormones. Therefore, it can contribute to infertility and bone loss. Therefore, you don’t want your cortisol level to be high all the time. Exercise, too, affects how much cortisol you have in your bloodstream. Let’s look at how each type of exercise impacts cortisol.
How Endurance Exercise Impacts Cortisol
People who do lots of endurance exercise, like cycling or running, can develop chronic elevations in cortisol. Running several times per week for 45 minutes at a time won’t do it, but if you’re clocking two-hour sessions several days per week, as some do when training for a marathon, it can raise your cortisol level and keep it at a higher level. Also, other factors like mental or physical stress combined with endurance exercise sessions can raise your cortisol level. That’s why you should scale back your workouts a bit if you’re mentally stressed, fatigued, or have other health issues that place added stress on your body.
Another factor is when you do your endurance exercise. If you take a long, hard run when in the evening, it deviates from what your internal biological clock dictates that you should be doing, winding down. Your cortisol level should come down at night, but if you’re doing long periods of endurance exercise, it can raise it. This can lead to sleep problems too. Exercise helps with sleep, but it’s most sleep-inducing when you work out in the morning.
High-Intensity Exercise and Cortisol
High-intensity exercise also increases cortisol. One study that compared the impact of different exercise intensities on cortisol found that working out at 80% of maximal oxygen uptake led to elevated cortisol while exercise at 40% and 60% of maximal oxygen uptake did not. In fact, studies suggest that low-intensity exercise lowers circulating cortisol and helps relieve stress. Think of how much less stressed you feel when you take a leisurely walk, stretch or do a relaxing yoga workout!
This doesn’t mean you shouldn’t do HIIT training, but it suggests you shouldn’t do it every time you work out and should give your body at least 48 hours of recovery between sessions. If you didn’t sleep well or are fatigued, it’s not a good day to tackle a high-intensity session. Save the drenching workout for a future training session after your body has had adequate time to recover. Overtraining, in general, can lead to spikes in cortisol.
Resistance Training
Although some studies show no significant rise in cortisol after resistance training, most research shows that how much cortisol rises depends on a person’s fitness level, the intensity of the training, the length of the training session, and the amount of rest between sets. Age is also a factor. As with endurance and HIIT training, you need more recovery time after intense workouts and those of long duration. Also, factor in more recovery time if you’re over the age of 50.
Other Tips for Controlling Cortisol
We mentioned the importance of getting adequate sleep and managing stress as both can increase cortisol but eating well and consuming enough calories matters too. One reason your adrenal glands release extra cortisol is to provide fuel for the body. When it senses starvation, your adrenal glands liberate more cortisol to allow glucose to enter the bloodstream. In response to cortisol, your liver converts amino acids from protein stores into glucose, a process called gluconeogenesis. The upside is your muscles have greater access to glucose for energy, but, over time, this can lead to an insulin resistance state. That’s one reason you don’t want chronically elevated cortisol. It’s bad for your metabolic health.
One way to reduce the release of cortisol during a workout is to eat enough calories and carbohydrates. Doing this ensures your cells have access to the glucose they need so you don’t have to call upon cortisol to help your body gain access to glucose. Also, lighten up on the caffeine. Caffeine in coffee and tea can boost cortisol, especially if you’re not accustomed to it, and the combination of caffeine and exercise is synergistic on cortisol release.
Don’t forget that a high cortisol level has other negative effects, depending upon how long it’s elevated. Short-term it has a negative effect on digestion and the immune system by suppressing the body’s immune response to viruses and other pathogens. If it stays high, it can trigger bone loss, weight gain, insulin resistance, depression, and infertility.
The Bottom Line
Exercise can affect cortisol in the short term and long-term too. The negative impact will be greater if you exercise at a high intensity without giving your body enough recovery time between sessions. After a workout, give your body at least 48 hours of rest between intense sessions and take a day from exercise each week to help your body bounce back. You won’t lose fitness benefits and you’ll come back stronger than ever. The best way to approach high-intensity exercise is in moderation and in a well-fueled state. Don’t forget about the importance of good hydration either. Not drinking enough fluids places additional stress on your body, not to mention how it impacts exercise performance. Give your body what it needs–hydration, nutrition, and rest–to get the most out of your workouts.
References:
- J Endocrinol Invest. 2008 Jul;31(7):587-91.
- Today’s Dietitian Vol. 11 No. 11 P. 38. November 2009.
- Pharmacology Biochemistry and Behavior. Volume 83, Issue 3, March 2006, Pages 441-447.
- 2012 May;37(5):611-7. doi: 10.1016/j.psyneuen.2011.09.001. Epub 2011 Sep 25.
- The Role of Cortisol in Concurrent Training. Rob Robergs, Ph.D. and Len Kravitz, Ph.D.
- Taha MM, Mounir KM. Acute response of serum cortisol to different intensities of resisted exercise in the elderly. Bull Fac Phys Ther 2019;24:20-5
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