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Improve Athletic Performance by Measuring Your Cortisol

Did You Know Cortisol Testing Can Help Optimize Recovery and  Establish Preparedness for Training and Competition?

Improve Athletic Performance by Measuring Your Cortisol

Did You Know Cortisol Testing Can Help Optimize Recovery and  Establish Preparedness for Training and Competition?

Here’s a surprising fact: Sometimes, training more can actually make you weaker. It sounds counterintuitive, but overtraining can set you back and increases the risk of injuries. Sometimes, it’s better to take a break and allow your body to recover. Sometimes, less really is more.

But how can you tell exactly when you need to rest and when you’re ready to train again? How can you prevent overreaching and start performing better? Many elite athletes, whose livelihood and professional careers depend on the quality of their training, can give you the answer: By measuring your cortisol.

When you put your body under too much pressure for too long, the main stress hormone cortisol surges in your system. And it puts you at greater risk of fatigue, fractures and even sickness.

In fact, one study found that an increase in cortisol prior to a competition may be detrimental to athletic performance.

So if you want to train better, to perform better and avoid injuries, you need to know what high cortisol is doing to you. You need to know how to measure it. And you need to know how to beat it.

What Intense Training and Cortisol Do to Your Body

You can find the full story about cortisol here. But for now, know that cortisol is normally good. In fact, your body produces cortisol every morning as part of your daily hormone cycle. It regulates a wide range of vital functions, such as your metabolism and immune system. And it’s an essential part of your body’s flight-or-fight-or-freeze response.

That’s why, when you encounter a stressful situation, your body produces more cortisol to help. In the same way that coffee makes you more alert in the morning, cortisol can help you focus and stay energized over the short term. But if you’re stressed for long periods — mentally or physically — you maintain high levels of cortisol, and your body goes into overdrive.

That’s when you’re in danger of overreaching and then overtraining. It doesn’t matter what physical shape you’re in, any athlete who doesn’t allow time for adequate recovery can suffer the consequence. In fact, that’s why the most diligent and committed ones often suffer.

For example: In June 2021, Olympic gold medalist swimmer Simone Manuel announced she’d been diagnosed with overtraining syndrome. It’s why she failed to qualify for the 100-meter freestyle finals at the U.S. Olympic swimming trials.

When she was training, exercises that used to be a breeze left her winded. Muscles ached. She seemed to be putting in more effort, yet she saw diminished results. That can be thanks, in part, to high cortisol. In fact, high cortisol is linked to three key signs of training too hard:

1. Muscle Soreness:

To start, high cortisol can cause your muscles to stay tense. Think of it as a constant state of readiness because your body can’t tell when a threat has passed. Pair that with reduced blood flow and a build-up of lactic acid (another side-effect of high cortisol). And overall, muscle movements can be limited.

It’s also worth noting that general chronic pain has also been linked to high cortisol levels. In one study, 16 people with chronic back pain were compared to a control group. Those in pain had higher levels of cortisol.

So keep this in mind: Unusual muscle pain that persists after training is one big sign of training too hard.

2. More Injuries, Slower Recoveries:

High cortisol also decreases your white blood platelet cells. These are your immunity cells. They flow through your bloodstream fighting off viruses, bacteria and any other invaders. A lower amount hurts your recovery and your immunity in general.

In one study, 235 adults were grouped into either those with high or low stress. Over the course of six months, those with high stress suffered from 70% more respiratory infections and had nearly 61% more days of symptoms than those with low stress.

To top it off, high cortisol can also blunt the bone-formation process. In fact, high stress levels are associated with lower bone mineral density and weaker bones. And if you break a bone? Well, cortisol can also reduce inflammation, an essential part of healing.

That’s why another big sign of overreaching is any delays in your recovery.

3. Energy Loss and Lack of Focus:

Overreaching may also make you feel fatigued. Depressed. Unfocused. It may sound odd. Cortisol is supposed to keep you alert, right? Well cortisol regulates your sleep-wake cycle by waking you up when levels naturally increase every morning and allowing you to fall (and stay) asleep when levels drop at night.

When your levels are chronically high, this can cause insomnia or restless sleep. One study of 2,316 people revealed that those suffering from a higher number of stressful incidents were at a significantly higher risk of insomnia. Sleeplessness, in turn, can lead to a host of issues, such as fatigue, mood swings and lack of focus.

But sleep isn’t the only casualty. Chronic stress has also been linked to brain shrinkage and memory loss. In one study, high cortisol levels were linked to smaller total brain volumes, changes in the brain white matter, and substandard performance on some memory and cognitive assignments. In another study, researchers looked at 1,225 individuals and found those with higher cortisol levels had a more difficult time remembering specific events.

All of this and more is why you need to watch your training regimen and avoid overdoing it. Remember, studies have already found links between high cortisol and poorer athletic performance.

By measuring your cortisol in real time, you can maintain a normal cortisol profile and track it. That's how you can reduce your risks, and perform better. To start controlling your cortisol, request access to's breakthrough technology.

As Professor Chris McLellan, who has tested the cortisol levels of thousands of elite athletes, says: “Cortisol testing provides coaches, trainers and health & fitness professionals with increased capacity in conjunction with existing performance monitoring methods to establish preparedness for training and competition and optimize recovery. With cortisol, what gets measured, gets managed.”

Reduce Cortisol and Prevent Overtraining

Sometimes training more means training less. When you’re overloading your body, the best thing you can do is take a break. Let your body repair itself.

We know waiting can be hard. But creating a training schedule with recovery periods built in will allow you to perform better in the short term and stay healthy in the long term.

Once you’ve tackled that, there are a number of small lifestyle changes you can start making today that will help you continue to control your cortisol levels. Read about some scientifically backed stress-reduction techniques here.

Before you go, we have one more question for you: How can we get better? Here at, our goal is to gather the best information to help you understand the science of stress. If you think we missed anything in our research, please let us know here.


  1. Nature: Status, Stress and Performance in Track and Field Athletes during the European Games in Baku (Azerbaijan)

  2. Redox Biology: Intramuscular mechanisms of overtraining

  3. American Psychological Association: Stress effects on the body

  4. Brain (A Journal of Neurology): The stress model of chronic pain: evidence from basal cortisol and hippocampal structure and function in humans

  5. American Journal of Epidemiology: Stress and acute respiratory infection

  6. Frontiers in Endocrinology: Stress and Alterations in Bones (An Interdisciplinary Perspective)

  7. Sleep: Stress and Sleep Reactivity: A Prospective Investigation of the Stress-Diathesis Model of Insomnia

  8. Neurology: Circulating cortisol and cognitive and structural brain measures

  9. Journal of Cognitive Neuroscience: Associations between Basal Cortisol Levels and Memory Retrieval in Healthy Young Individuals

Improve Athletic Performance by Measuring Your Cortisol

Here’s a surprising fact: Sometimes, training more can actually make you weaker. It sounds counterintuitive, but overtraining can set you back and increases the risk of injuries. Sometimes, it’s better to take a break and allow your body to recover. Sometimes, less really is more.

Take Your Training to the Next Level With These Tools

It's time to dig into the best tools for improving your training. Let's look behind the science of two well-established markers of training readiness and recovery: HRV and cortisol.

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When you think about stress, what comes to mind? Looming work deadlines, financial worries, feeling overwhelmed? In today’s world, stress can take on countless forms. Sometimes, it’s even a force of good. But a key reason behind it all is often overlooked. In this article we’ll explain everything: the good, the bad, the ugly, and why controlling your stress can be a matter of life or death.

Join the waitlist has developed a rapid test to measure cortisol at home, without the need for a lab. Be the first to know!

Jessica Cohn-Kleinberg

Written by

Jessica Cohn-Kleinberg

Written on:

November 19, 2021 at 3:36:37 PM


April 7, 2022 at 2:25:10 PM

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