The thyroid is an important gland in the endocrine system. Most people don’t pay attention to thyroid function until they’re experiencing some of the side-effects of a thyroid disorder, which can influence everything from metabolic rate to mental health.
As is the case with most chronic health conditions, exercise can play an important role in helping a person to maintain their quality of life, but only if understood and applied correctly.
Below is a very brief overview of common thyroid conditions, their causes, symptoms, and the implications that they can have for exercise.
What Does The Thyroid Do?
The thyroid is a gland in the throat which is responsible for regulating metabolism. It determines how the body’s cells use energy, through the release of the hormone levothyroxine (T4) which is converted as needed to the more active triiodothyroxine (T3). Thyroid function influences Base Metabolic Rate, heart rate and rhythm, blood pressure, mood, cognitive function, appetite, digestion, and tolerance to heat and cold.
There are many different types of thyroid diseases and disorders, with different causes, symptoms and implications for exercise.
Hypothyroidism: Underactive Thyroid
Causes Include: autoimmune disease (Hashimoto’s); thyroid cancer; iodine deficiency; over-training/stress; chronic illness; very low carbohydrate diets.
Symptoms Include: not refreshed after sleep; fatigue; depression, apathy and mood changes; “brain fog” – short-term attention deficit and memory problems; confusion; weight gain; constipation.
Implications for Exercise: If the person is treated with correct dosages of thyroid hormones, there should be no significant change to their response to exercise.
Without treatment and/or management, their exercise tolerance will be affected.
The hypothyroid person may experience hypoglycaemia due to low levels of TH; fatigue more quickly and have slower recovery rates. Low TH levels result in reduced rates of respiration, heart rate and blood pressure, which can result in dizziness and fatigue. Breathing can be affected if they have a goitre, and because all of the muscles, including the diaphragm, become weaker.
They can regain their previous levels of strength and cardiovascular fitness once their hypothyroidism is cured, reversed or managed.
Incorrect dosages of thyroid hormones can also produce symptoms such as increased sweating and heart rate, chest pains and heart palpitations, which mimic the symptoms of hyperthyroid disease.
Hyperthyroidism: Overactive Thyroid
Causes Include: autoimmune diseases (Graves’ Disease, Hashimoto’s Disease), excess iodine consumption; thyroiditis (inflammation of the thyroid); cancers of the pituitary, reproductive or thyroid gland; incorrect dosages of thyroid hormone in the treatment of hypothyroidism.
Symptoms Include: difficulty sleeping; frequent bowel movements or diarrhoea; elevated heart rate and blood pressure; heart palpitations and chest pains; hyper-activity (which can manifest in socially commended “workaholism”); weakness; tremors; weight loss or gain; amenorrhoea (absence of a menstrual cycle) or dysmenorrhoea (irregular menstrual cycle).
Implications for Exercise: Although the hyperthyroid person may appear to be someone with a lot of energy, they are prone to fatigue as their elevated metabolic rate pushes them past their own limits, and means that they are “burning out” even while at rest. Elevated metabolic rate means that they are breaking down fat and protein faster, leading to a build-up of ketone bodies in the blood. These factors, combined with the fact that they have trouble sleeping, can reduce their exercise tolerance and impair their recovery.
Hyperthyroid people are also at risk of developing chronic fatigue syndrome or heart failure.
Hyperthyroid women of reproductive age who experience amenorrhoea may also be at risk of fractures if the condition has persisted for long enough to result in a decrease in bone density.
Treatments include dietary interventions; thyroid-blocking medications; surgery and radiation “therapy” to remove or kill part of the thyroid. Like their hypothyroid counterparts, these clients can be trained normally once their disease is cured or controlled.
People with thyroid problems experience a variety of symptoms, and may fluctuate between hypo- and hyperthyroid. Thyroid problems can be temporary or permanent, and symptoms can vary from day to day and differ greatly between individuals.
If you have a thyroid disorder, it is important to develop good rapport with your personal trainer and to inform them of your symptoms from session to session, as well as of your body’s reactions post-exercise. Thyroid problems are real, so don’t let anyone immediately dismiss them as an excuse for weight issues. The effects that hypo- and hyperthyroidism have on the metabolism of energy means that care must be taken not to push yourself beyond their limitations. Results will come from your ability to manage their disease with your medical or allied health practitioners. An exercise specialist or personal trainer can perform a valuable role in helping you to exercise safely within your limitations, which may vary from session to session depending on their symptoms, diet, lifestyle, stress levels and medications.
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