Cortisol is the body’s primary stress hormone. It’s released whenever we feel or perceive a threat, be it mental, physical or emotional.
No doubt you’ve heard that cortisol is “bad” and something that can cause fat gain and/or muscle loss…but that’s not the whole truth.
Today, we’ll cover all things cortisol and how to optimize cortisol for exercise and recovery.
What is Cortisol and How Does it Work?
As mentioned above, cortisol is a hormone (chemical signaling molecule) that is primarily known for its role in the body’s stress response, but that’s just the beginning of cortisol’s many functions in the body.
It also influences metabolism, immune function and the inflammatory response.[1]
Let’s now take a closer look at how cortisol impacts our body’s more than just stress.
Increases Energy Availability
During periods of acute stress, our mind and muscles need an immediate source of energy to either fight or run away (“flight”). Cortisol stimulates the production of glucose by the liver, which increases blood glucose levels and provides a readily accessible supply of energy for our brain and muscles.
In the absence of glucose, cortisol can also stimulate the breakdown of protein in muscle tissue, which releases amino acids (including EAAs and BCAAs). The liver can convert these circulating amino acids into glucose, which can subsequently be used by the brain and muscles.
Cortisol also impacts fat cells in our adipose tissue. Specifically, it increases lipolysis -- the freeing of glycerol and fatty acids. These free fatty acids (FFAs) can then be oxidized (burned) for energy by other cells.[2] In a sense, cortisol can help you to burn body fat.
Affects Inflammation
Cortisol has a complex relationship with inflammation as it can both suppress and stimulate inflammation, depending on its concentration. Elevated levels of cortisol (such as those induced by a stressful encounter) suppress inflammation in the short term and prevent tissue injury from an excessive or prolonged inflammatory response. As such, it may be helpful since it helps our body’s not waste energy on an excessive inflammatory response.
Blood Pressure Regulation
Cortisol also impacts the cardiovascular system. It weakly mimics the effects of aldosterone -- a hormone that stimulates the reabsorption of sodium and water by the kidneys, which increases blood volume and blood pressure.
It also can make blood vessels more sensitive to the effects of noradrenaline -- a hormone/catecholamine that can cause blood vessels to constrict.[3,4]
Cortisol, Exercise, & Recovery
The relationship between cortisol, exercise, and recovery is complex. In the short term, cortisol can be beneficial as it heightens our awareness, focus, motivation, and energy levels -- all of this helps your body and mind to perform at a high level during your workouts.
After exercise, cortisol levels typically return to baseline. In the hours and days following your workout, you still need to prioritize recovery so that cortisol levels stay in their normal range and do not remain chronically elevated as this can lead to decreased recovery, impaired sleep, muscle breakdown and fat gain.
In the short term, the amount of cortisol released in response to exercise depends on several factors, including:
- intensity of exercise
- duration of exercise
- training experience
- time of day
Let’s now take a look at the factors that influence whether cortisol is helping or hurting your workouts and recovery.
Exercise Intensity
As you might expect the more intensely you exercise (stress your nervous system and muscles), the larger the increase there will be in cortisol levels.[5]
Research demonstrates that exercising at above 60% of VO2 max (maximum rate of oxygen consumption) significantly elevates cortisol while training at a much lower intensity (<40% of VO2max) produces very modest increases in cortisol.
Exercise Duration
Unsurprisingly, the longer you exercise at a moderate to intense level, the greater your cortisol levels will rise.
Studies show that training longer than 90-120 minutes may cause significant increases in cortisol.[6] This means that individuals who favor endurance training activities may be at a greater risk for chronically elevated cortisol levels, especially when coupled with insufficient rest, recovery and nutrition between workouts.
Training Experience
Individuals who have been training for some time will be more used to the rigors and stress of training compared to untrained individuals or novices. Still, the more experienced you are, the better you know your body and you may be able to push even harder (which would induce greater overall stress to your system).
So, while you may be more used to hard training compared to inexperienced lifters or “casual” gym goers, you also know how to push past the point of comfort, which may or may not lead to greater increases in cortisol.
Time of Day
Like other hormones of the body, including testosterone, estrogen, and melatonin, cortisol levels naturally fluctuate over a 24-hour cycle. Outside of exercise, cortisol levels are naturally at their highest first thing in the morning -- this is to assist with helping you wake up and get moving in the morning.
Over the course of the day, they naturally decline, so that you can get ready for bed. Unfortunately, modern living interferes with natural cortisol fluctuations. Evening/late-night scrolling through texts, emails, and social media along with increased TV/movie watching can increase cortisol levels and suppress melatonin, which can adversely impact sleep quality.
Intense workouts right before bed have been found to disrupt sleep patterns, in part to elevations in cortisol. However, if you enjoy or need to exercise in the evening (due to your personal schedule), try to do it at least 1-2 hours before bed, so that cortisol levels can return to baseline and you can have a great night’s sleep.
Pro tip: Having a carbohydrate-rich meal (such as a serving of oats + protein powder) after your evening/nighttime training session can help to lower cortisol, support muscle recovery, and improve your ability to get quality sleep.
The Bottom Line: Is Cortisol Good or Bad for Exercise & Recovery?
Like most things in life, cortisol is neither good nor bad. It serves a vital role as part of the body’s stress response where it helps increase alertness, motivation, and energy production. However, when chronically elevated, cortisol can have negative effects on the body, including muscle breakdown, fat storage, impaired recovery, decreased immune function, and metabolic dysfunction, which negatively impact muscle gains and exercise performance.
The trick to keeping cortisol in check is to manage your personal stress to recovery ratio. While stress comes in different forms (physical, mental, and emotional), you can only recover from so much. With that in mind, it’s critical to do what you can to limit lifestyle stress and take adequate rest and recovery -- the foundation of which is proper diet, regular physical activity, and quality sleep.
For added cortisol and stress support, certain supplements, including Super Magnesium and nighttime recovery aids, such as1UP Beauty Dream and 1UP Recharge PM, can help you to calm down, relax, and get the recovery you need to feel refreshed, energized, and ready to tackle whatever life has in store for you!
References
- Oakley RH, Cidlowski JA. The biology of the glucocorticoid receptor: new signaling mechanisms in health and disease. J Allergy Clin Immunol. 2013 Nov;132(5):1033-44.
- Thau L, Gandhi J, Sharma S. Physiology, Cortisol. [Updated 2023 Aug 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538239/
- https://www.sciencedirect.com/science/article/abs/pii/B978145570760700019X
- Yang S, Zhang L. Glucocorticoids and vascular reactivity. Curr Vasc Pharmacol. 2004 Jan;2(1):1-12. doi: 10.2174/1570161043476483. PMID: 15320828.
- Hill EE, Zack E, Battaglini C, Viru M, Viru A, Hackney AC. Exercise and circulating cortisol levels: the intensity threshold effect. J Endocrinol Invest. 2008 Jul;31(7):587-91. doi: 10.1007/BF03345606. PMID: 18787373
