Informational Posts

Can You Over Exercise and Worsen Your Thyroid Health?

Are You Over Exercising and Worsening Your Thyroid Health?
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Originally published on 18th March 2017
Last updated on 3rd April 2019

Whilst exercising is well known to be beneficial and in fact crucial for good health, there is such a thing as over exercising.

Could you be pushing your body too far and causing more harm than good?

Do you ever feel flarey, dizzy or lightheaded with exercise? Or as if you have poor stamina or poor ability to withstand much exercise? Do your arms ever feel like dead weights after exercising? Or do you experience frequent shin splints when you attempt exercise?

These are common complaints from those with hypothyroidism.

A photo of Rachel in sportswear

Related Post: 5 Do’s and Dont’s for Exercising With Hypothyroidism and Hashimoto’s

Exercise and Hypothyroidism: A Caution 

Great care should be taken with physical activity when you live with endocrine issues such as thyroid disease or adrenal dysfunction (though it is more accurately referred to as hypothalamic-pituitary axis dysfunction), as too much exercise can exacerbate these conditions and actually cause us to feel worse.

The thyroid gland regulates the body’s metabolism (this is its most important job) and impacts every cell and function in the body. When it doesn’t work properly, e.g. underperforms, this causes hypothyroidism – a slowing down of many bodily processes.

However, repeatedly engaging in overly demanding exercise can cause a surge of biochemical imbalances to occur within the body, including the disruption of the hypothalamus-pituitary axis, which can reduce thyroid function. Intense cardio, marathon running and training, obsessive weight lifting etc. with little to no recovery time can all cause extreme stress to the body, particularly the thyroid.

Too Much Stress On The Body Isn’t Good 

When the body is under stress – emotional stress, mental stress, as well as physical stress – it responds by producing cortisol, a stress hormone produced by the adrenal glands.

Many of us with hypothyroidism already have stressed-out and overworked adrenal glands, due to the stress of having (often undiagnosed or under-treated) hypothyroidism, even without knowing. This means that we could have high cortisol levels almost constantly, where our body is in a constant stressed-out mode, and producing more cortisol by over exercising adds to this vicious cycle.

When cortisol is overly produced, it can inhibit thyroid function and cause adrenal dysfunction, where, even if our thyroid test results look OK, we still feel rubbish. Or we ‘pool‘ T3, where we have on-going issues and symptoms.

You can check your cortisol levels with a 24 hour, four point saliva test to confirm. If your doctor won’t check your adrenals, you can very simply order testing yourself here and here.

Signs of Stressed Out Adrenal Glands 

Sara Gottfried also explains in her book that a sign of adrenal issues can include trying to exercise, only to find you crash, feeling light-headed and faint. This is due to cortisol being part of the glucocorticoid family, a substance that raises your glucose level. It is cortisol’s job to give you the energy you need.

When you have this reaction to exercise, it’s a sign you’ve used up your main energy supply as you’re perhaps low on cortisol and so don’t have enough ready to use.

I have read in several books, including Dr Skinner’s and Sara Gottfried’s, that they’re unsurprised by marathon runners who eventually get struck down with endocrine issues such as thyroid and adrenal dysfunction, due to the intense and unneeded stress this puts on the body.

As someone who witnessed their husband train and complete a marathon a few of years ago, I’m not surprised! It’s crazily demanding on the body and I wonder if we get to a certain point with marathon and long distance running, where it’s actually no more beneficial to the body and is instead just harmful. After all, how can 20+ miles not be a huge stress to the body?

Listen To Your Body

You may think you are following a perfectly healthy workout routine, when in reality you could actually be causing some serious damage to your body. It is important for us to know therefore when enough is enough and when we need to slow things down. Listening to our bodies is crucial and taking things at our own pace will help us avoid causing any issues with over exercising.

However, it is obviously crucial to mention here that every person (and every thyroid patient) will be different. We will all have different needs when it comes to exercise, from type of exercise to frequency and intensity. You may well need to experiment with different types and frequencies to see what does and does not work for your body.

As thyroid conditions affect people on a scale, no two experiences are the same and no two bodies will be able to handle the exact same exercise routine. Comments suggesting that we could all manage the same level of exercise “if only we tried hard enough” are unhelpful, as are suggestions that none of us can handle any exercise at all. So please do not take this article as saying the latter, either!

Although there are benefits to higher intensity training, such as improving overall health and building lean muscle, without maintaining a good balance of exercising, resting and recuperating, along with proper nutrition, setbacks in our health and symptoms can plague us.

Signs that you need to take things slower and reevaluate your exercise regimen include:

Adding to that, you can also explore the full list of adrenal fatigue symptoms here.

Activities that tend to be popular among thyroid patients include: yoga, pilates, swimming, walking and even dancing. Anything that can be done in the comfort of your own home and at your own pace is a big plus and if you can add a social aspect into it too – perhaps getting friends to support you – even better! Read about how to find the best exercise for your hypothyroid body here.

The time of day can also impact when you exercise. If you find that your blood sugar levels are affected or you have cortisol issues (many of us feel at our worst in the morning), you may find it better to exercise later on in the day, such as at lunchtime or in the afternoon.

After a thyroid disease diagnosis, you may need to rediscover which exercises you can safely do without taking your health backwards.

Has your exercise been affected with a thyroid diagnosis?

You can click on the hyperlinks in the above post to learn more and see references to information given.

About Author

Rachel Hill is the highly ranked and multi-award winning thyroid patient advocate, writer, speaker and author behind The Invisible Hypothyroidism. Her thyroid advocacy work includes writing articles, authoring books, producing her Thyroid Family email newsletters and speaking on podcasts and at events about the many aspects thyroid disease affects and how to overcome these. She is well-recognised as a crucial and influential contributor to the thyroid community and has a large social media presence. Her bestselling books include "Be Your Own Thyroid Advocate" and "You, Me and Hypothyroidism".


  • Adele Firth
    September 26, 2021 at 1:09 pm

    Hi Rachel, I was diagnosed hypothyroid 3 years ago. A year and a half on my treatment I went into thyrotoxicosis and was taken off levothyroxine. I have since found out that I have Graves’ and Hashimoto’s antibodies present in my recent bloods. I am starting to block with Carbimazole and replace with thyroxine. I was once healthy and very active loved walking and going to the gym etc. now I get out of breath and palpitations just walking up the stairs. 🤞Hoping I am on the right path for recovery now.

  • Misty Whitehead
    March 16, 2021 at 2:21 am

    I’m a runner with all of the classic hypothyroidism symptoms listed but I’ve had my blood tested three times with normal levels. Is it possible to have thyroid problems with normal blood tests?

    • Rachel Hill
      March 21, 2021 at 9:37 am

      It depends on what you’re having tested really and the way the results are read. Are you having the full thyroid panel tested? Many doctors only check TSH which can come back normal while the other parts of the thyroid panel would look abnormal or suboptimal.

      There is also a difference between ‘falling in range’ and being ‘optimal’.

  • Katchen
    August 25, 2020 at 8:14 pm

    Hi Rachel,

    How many days of exercise per week do you find works best for you? What sort of work outs do you like? I am newly diagnosed with Hashi’s and hypothyroidism and I’m trying to find the correct balance.

    Thank you 🙂

    • Rachel Hill
      August 26, 2020 at 6:45 pm

      Currently, I walk daily (an hour or more) and do yoga twice a week. Before the pandemic I also did swimming. And before I got pregnant, I did dance aerobic classes and salsa too. I adapt my exercise depending on where I am in life and health!


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