Raina Kranz C. P. T.,
Thyroid Nation

The CONNECTION between over-training in athletes and those with hypothyroid who exercise.

We all know how challenging exercise can be with chronic disease, especially hypothyroidism/hypothyroid. It is also compounded by the autoimmune disease Hashimoto’s Thyroiditis. There are many physiological changes that occur at the cellular level that alters the metabolism with thyroid disease and there is a correlation between over training syndrome (OTS) in athletes and people with hypothyroid.

First let’s address what Over Training Syndrome (OTS) is; it is a maladaptive response to excessive exercise without adequate rest. This results in a disturbance in multiple body systems, such as (Neurological, Endocrine and immunological) as well as, mood changes. Terminology used for (OTS) in the past included; burnout, staleness, failure, adaptation, under-recovery, training stress syndrome and chronic fatigue.

We know, the longer hypothyroid goes untreated there is an increase of damage that occurs to the muscles and once treatment is started with Levothyroxine, that process is halted. What we do not know is how much is reversible. There is also an issue with metabolism and how the body converts fuel from stored glycogen in the muscle tissue for muscle contraction. Simply put..those with hypothyroid and/or hashimoto’s have a malfunction in this process leading to muscle fatigue very quickly. Weakness and lack or endurance is the biggest complaint and the exhaustion after training that day or days after can be discouraging. With OTS in athletes this is a similar situation.

The Glycogen Hypothesis (the cellular synthesis); low muscle glycogen can impair performance due to inadequate fuel for the workload

Low muscle glycogen also results in increased oxidation and decreased concentrations of Branch Chain Amino Acids (BCAA), these play a key role in using muscle tissue, building muscle tissue and maintaining muscle tissue. Decreased muscle glycogen will alter the central neurotransmitter’s involved with muscle fatigue. This is the very same process that happens to those with hypothyroid/hashimoto’s.


The Central Fatigue Hypothesis (the neurological synthesis); this includes disruptive mood, sleep & behavior

The neurotransmitter known as serotonin (5-HT) is responsible for the regulation of these functions.
With normal exercise, there is an increase in unbound tryptophan (an essential amino acid, essential for human life and is the building block of protein bio-synthesis) with that increase, it competes with the branch chain amino acids (BCAA) for entry in the brain. Exercise decreases the levels of (BCAA) due to the increased oxidation favoring tryptophan’s entry into the brain and the conversion into serotonin (5-HT). Increases in unbound tryptophan entry into the brain has been directly correlated with fatigue, due to increased serotonin synthesis in the brain. Athletes given serotonin re-uptake inhibitors has artificially increased (5-HT) in the brain and reduced performance. To reverse this in athletes supplementation with BCAA’s has resulted in more energy and mental clarity, possibly due to the dampened serotonin (5-HT) synthesis.

In my opinion, this is also happening to thyroid patients with exercise. Since we may already be in a fatigued state we are inducing depression after training, possibly lasting for days. In some cases, this can become chronic cycle as we try to continue an exercise program.

Another, connection with over training in athletes and thyroid disease is the sensitivity factor. Once an athlete is over fatigued, they may be over sensitive to serotonin (5-HT) …meaning they are in chronic fatigue and more exercise also re-creates the cycle. Since regular normal exercise increases the unbound tryptophan to compete with BCAA for entry into the brain…well-trained, well rested athletes recover from this process and will be able to resume normal training after a period of recovery. Where over trained athletes are more sensitive to this process and do not recover. There is this lingering effect of tryptophan and the constant denial of BCAA getting into the brain, allowing for chronic fatigue and depression. I am theorizing that people with hashimoto’s and hypothyroid are already starting in the depleted state, therefore causing all of issues with stating and maintaining an exercise program that does not result in enhanced performance and weight loss.

Exercise-Revolution-Thyroid-Nation-Ad3The Glutamine hypothesis (glutamine is integral for immune cell function)

Glutamine plays a key role in DNA/RNA synthesis and decreased glutamine after exercise, may be the reason for increased incidences of upper respiratory tract infections in athletes.

Prolonged exercise greater than 2 hours or repeated bouts of high intensity can decrease plasma concentrations of glutamine. Low plasma glutamine has been found in over trained athletes, due to over utilization and/or decreased production by over worked muscles.

In vitro, immune cell function can be compromised when glutamine concentrations are below physiologic levels. Despite the decrease after exercise, the amount of glutamine available to immune cells do not change necessarily. Glutamine supplementation can restore physiological levels but will not improve post exercise immune impairment of immune cells. Although, supplementation may decrease early rates of infection in athletes. What does this mean for those of us with autoimmune disease, we already have a decreased amount of glutamine in our body. When we exercise we are decreasing glutamine in an already depleted state, setting ourselves up for infection(s).

Oxidative Stress hypothesis (muscle damage and repair)

This is a normal process that occurs when training. When exercising microscopic muscle tearing occurs within the fibers to allow for strength, endurance and muscle hypertrophy. This is actual damage to the muscle and then it goes through a healing process at a cellular level and netting positive results. When oxidative stress becomes pathologic, inflammation, muscle fatigue and soreness leads to poor physical performance. Again, for the over trained athlete this is a negative side effect of excessive exercise, but for thyroid disease it is almost a constant state of affairs.

Hypothalamus hypothesis (changes in the hypothalamic-pituitary-adrenal HPA)

There are subtle changes in function of the HPA axis in endurance athletes and over trained individuals can cause serious changes in their cortisol levels and andrenocorticotropic hormone, testosterone and other hormone levels. Andrenocorticotropic (ACTH) also known as corticotropin, produced by the anterior pituitary gland and a very important component of the (HPA) axis. This hormone is produced in response to biological stress, along with its precursor corticotropin-releasing hormone from the hypothalamus. Its principal effects are to increase the production and release of corticosteroids. Addison’s disease ( Primary Adrenal Insufficiency) , occurs when adrenal gland production of cortisol is chronically deficient, resulting in chronically elevated ACTH levels; when a pituitary tumor is the cause of elevated ACTH (from the anterior pituitary) this is known as Cushing’s Disease and the signs and symptoms of the excess cortisol (hypercortisolism) is known as Cushing’s syndrome. A deficiency of ACTH is a cause of secondary adrenal insufficiency.

Alterations in the (HPA) are very specific to the individual and other factors are involved including; exercise capacity, inherent vulnerability to stressors, diet and other hormonal levels. Exercise does not cause adrenal insufficiency, but it can cause the lowering or elevating of cortisol levels that can cause adrenal fatigue.
As many thyroid patients have issues with high or low cortisol due to adrenal fatigue, it is a wonder that we can ever start an exercise program at all. While researching for this article I found many correlations to diet and its effects on exercise in healthy people as well as, how it effects those with thyroid disease. I will share that with all of you, in part two of this segment. It is an article in itself.


In conclusion, there are many things to consider in the body systems when taking on training; your current fitness level, your current health status, your stress level, your fitness capacity and how not to overdo it. There are also many options for pre and post exercise supplementation to assist with recovery and repair of the immune system and muscle tissues. All can be implemented in a customized program created for you….we are all unique in our chemical make-up and what works for one may not work for another….so all aspects of your life need to be taken into account to assure you the ability to reach your goals.

This article is offered under Creative Commons license. It’s okay to republish it anywhere as long as attribution bio is included and all links remain intact.

About the Author

Radiant-Raina-KranzRaina Kranz, C.P.T. attended and is certified from the American College of Sports Medicine. She studied Kinesiology/Biomechanics. Living in Hollywood, Florida she is a full time personal trainer and coach. Find her at her website, Personal Fitness Training Florida. and wonderful online Facebook Group, Thyroid Discussion Group. Click to schedule an appointment or to learn more about Raina’s Customized Thyroid Exercise Training Program at Thyroid Trainer.

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