# Exercise as it relates to Disease/The effect of hypothyroidism on exercise
### What is the thyroid gland

The thyroid is a butterfly shaped gland located low on the inside the neck, lying just below your Adam’s apple as seen in figure 1. It produces the hormones triiodothyronine (T3) and thyroxine (T4), which regulate the body’s metabolism. The release of these hormones rely on and are controlled by the anterior pituitary through thyroid stimulating hormone (TSH).

### What is hypothyroidism

Hypothyroidism also known as an ‘underactive thyroid’ is when there is an insufficient secretion of the thyroid hormones T3 and T4. This causes the slowing of the body’s metabolism. Hypothyroidism generally originates from sub-clinical hypothyroidism meaning a raised serum thyrotropin (TSH) but a normal triiodothyronine (T3) and thyroxine (T4) concentration.

### Prevelance

The usual cause of thyroid disorders worldwide is iodine deficiency. Population samples in the USA and Europe display that in populations with high iodine, the prevalence of spontaneous hypothyroidism is between 1 and 2%, and it is more common in older women and 10 times more common in women than in men. Research in Northern Europe, Japan and the USA have found the prevalence to be between 0.6 and 12 per 1000 women and between 1.3 and 4.0 per 1000 in men examined. The prevalence is much greater in elderly in the community with hypothyroidism found in 7% of 558 subjects aged between 85 and 89 years in the Netherlands.

### Risk Factors

The risk factors include; age (risk greatest after the age of 50), family history (genetics playing a big part in developing hypothyroidism), lifestyle (smoking affects thyroid function and hence greatly increases the risks of hypothyroidism. Smoking also increases hypothyroidism’s negative effects on the arteries and heart) and other conditions such as type 1 diabetes, rheumatoid arthritisceliac disease, addison’s disease, down syndrome, turner syndrome, bulimia and anorexia.

## Signs and symptoms

The signs and symptoms of hypothyroidism can be very subtle at first but will become more noticeable as the sufferers metabolism continues to slow. The symptoms also vary from person to person and depend on the severity of the condition. Signs and symptoms may include all seen in figure 2 and the following:
* Fatigue, loss of energy, lethargy
* Weight gain
* Decreased appetite
* Cold intolerance
* Dry skin
* Hair loss
* Sleepiness
* Muscle pain, joint pain, weakness in the extremities
* Depression
* Emotional lability, mental impairment
* Forgetfulness, impaired memory, inability to concentrate
* Constipation
* Menstrual disturbances, impaired fertility
* Decreased perspiration
* Paresthesia and nerve entrapment syndromes
* Fullness in the throat, hoarseness
* Decreased hearing
* Blurred vision

## Hypothyroidism as it relates to exercise
### Detrimental effects on exercise

The many symptoms of hypothyroidism coincide with one another, increasing the extent of one another and the effect they have on exercise.
| Symptom of hypothyroidism | Potential effects on exercise |
| Fatigue | Fatigue is reported in approximately 21% of hypothyroidism patients. These patients who are 'feeling tired' may experience cognitive dysfunction, diminished energy and their the overall ability to carry out physical activity may be diminished. |
| Weight Gain | As hypothyroidism goes undetected gradual weight gain will occur. Even once diagnosed and treatment occurs many patients report inability to lose the weight, even through regular exercise. This can have a serious impact on a patients willpower to continue exercising as there are no visible benefits. |
| Decreased Appetite | Hypothyroidism can have clinically significant consequences on appetite. Hypothyroidism classically causes reduced basal energy expenditure and hence along with appetite. This coincides with fatigue as the energy to exercise decreases. |
| Cold Intolerance | Cold intolerance is an abnormal sensitivity to a cold environment or cold temperatures. Patients suffering from this symptom find it difficult to participant in exercise during cold conditions. In colder climates this may seriously limit the time a person can spend exercising. |
| Sleepiness | From a behavioral perspective, those suffering from sleepiness/drowsiness may be less motivated to diet or exercise. Daytime sleepiness lowers their energy levels and makes it difficult to commit to an exercise |
| Muscle/Joint Pain | In a particular study (Golding, 1970) pain and aching in muscles or joints sometimes described as fibrositis, was common to all participants. Participants with untreated hypothyroidism seemed very sluggish and exhibited slow joint movements when exercising. |
| Depression | Depression has a massive effect on the amount of exercise a hypothyroid patient takes part in. Depression causes sufferers to stay secluded, keep indoors and not participate in activities. |

### Recommendations

One of the biggest problems with hypothyroidism is it's difficulty to diagnose. Symptoms creep in slowly and sufferers are unable to feel any sudden changes. Paying attention to the signs and symptoms and diagnosing the disease is the first and foremost important part on the road to recovery. Once diagnosed, T4 medication needs to be taken daily and regular blood tests need to be done until T3 and T4 levels become stable.
Although almost all of the symptoms affect exercise, working out is still highly recommended in combating a large majority of the symptoms. The best types of exercise include a combination of both aerobic exercise and weight training. Aerobic training is recommended for around 30 minutes per day, 4 to 5 days a week. Weight training is highly recommended as it builds up muscle mass and keeps the basal metabolism active. Starting slow is crucial and as the symptoms begin to subside more vigorous activities can be undertaken. If fatigue is viewed as a major symptom it is recommended patients use progressive relaxation training as treatment instead of exercise, at least until fatigue improves.
A specific study (Ciloglu et al., 2005) displayed that 70% intensity exercise (moderate activity) causes the most prominent changes in thyroid hormone values and is the recommended intensity to keep the thyroid at its most active.
To conclude it appears the most beneficial way to alleviate and eradicate symptoms of hypothyroidism is through a combination of thyroid medicine and healthy lifestyle choices. Exercise plays a major role in preventing hypothyroidism, prolonging the development of overt hypothyroidism in sub-clinical patients and in controlling the symptoms of overt hypothyroidism.

## Further reading

Assessment of left ventricular diastolic function by radionuclide ventriculography at rest and exercise in subclinical hypothyroidism, and its response to l-thyroxine therapy
Cardiac Systolic and Diastolic Function at Rest and Exercise in Subclinical Hypothyroidism: Effect of Thyroid Hormone Therapy
Cardiovascular Hemodynamics and Exercise Tolerance in Thyroid Disease
Cellular energetics in hypothyroid muscle

## References

* ↑ Cooper, D., McDermott, M. and Wartofsky, L. (2004). Hypothyroidism. The Journal of Clinical Endocrinology & Metabolism, [online] 89(11), pp.0-0. Available at: http://dx.doi.org/10.1210/jcem.89.11.9990
* ↑ Mason, R. and Wilkinson, J. (1973). THE THYROID GLAND — A REVIEW. Australian Veterinary Journal, [online] 49(1), pp.44-49. Available at: http://dx.doi.org/10.1111/j.1751-0813.1973.tb14680.x
* ↑ Khandelwal, D. and Tandon, N. (2012). Overt and Subclinical Hypothyroidism. Drugs, [online] 72(1), pp.17-33. Available at: http://dx.doi.org/10.2165/11598070-000000000-00000
* 1 2 Vanderpump, M. (2011). The epidemiology of thyroid disease. British Medical Bulletin, [online] 99(1), pp.39-51. Available at: http://dx.doi.org/10.1093/bmb/ldr030
* ↑ Gussekloo, J. (2004). Thyroid Status, Disability and Cognitive Function, and Survival in Old Age. JAMA, [online] 292(21), p.2591. Available at: http://dx.doi.org/10.1001/jama.292.21.2591
* ↑ Azizi, F. (2004). Age as a predictor of recurrent hypothyroidism in patients with post-partum thyroid dysfunction. Journal of Endocrinological Investigation, [online] 27(11), pp.996-1002. Available at: http://dx.doi.org/10.1007/bf03345300.
* ↑ Park, S. (2005). Genetics of congenital hypothyroidism. Journal of Medical Genetics, [online] 42(5), pp.379-389. Available at: http://dx.doi.org/10.1136/jmg.2004.024158
* ↑ Nyström, E., Bengtsson, C., Lapidus, L., Petersen, K. and Lindstedt, G. (1993). Smoking — A risk factor for hypothyroidism. Journal of Endocrinological Investigation, [online] 16(2), pp.129-131. Available at: http://dx.doi.org/10.1007/bf03347665
* ↑ Glinoer, D., Riahi, M., Grün, J. and Kinthaert, J. (1994). Risk of subclinical hypothyroidism in pregnant women with asymptomatic autoimmune thyroid disorders. The Journal of Clinical Endocrinology & Metabolism, [online] 79(1), pp.197-204. Available at: http://dx.doi.org/10.1210/jcem.79.1.8027226
* ↑ Prasher, V. (1999). Down Syndrome and Thyroid Disorders: A Review. Downs Syndr. Res. Pract., [online] 6(1), pp.25-42. Available at: http://dx.doi.org/10.3104/reviews.95
* ↑ CROXSON, M. and IBBERTSON, H. (1977). Low Serum Triiodothyronine (T 3 ) and Hypothyroidism in Anorexia Nervosa. The Journal of Clinical Endocrinology & Metabolism, [online] 44(1), pp.167-174. Available at: http://dx.doi.org/10.1210/jcem-44-1-167
* ↑ Orlander, P., Griffing, G., Varghese, J. and Freeman, L. (2014). Hypothyroidism. [online] Emedicine.medscape.com. Available at: http://emedicine.medscape.com/article/122393-overview
* ↑ El-Haddad, B., El Bizri, I., Kallail, K., Zackula, R. and Hoffman, J. (2012). Fatigue and TSH Levels in Hypothyroid Patients.
* 1 2 Dimeo, F., Thomas, F., Raabe-Menssen, C., Prepper, F. and Mathias, M. (2004). Effect of aerobic exercise and relaxation training on fatigue and physical performance of cancer patients after surgery. A randomised controlled trial. Supportive Care in Cancer, [online] 12(11), pp.774-779. Available at: http://dx.doi.org/10.1007/s00520-004-0676-4
* ↑ Shomon, M. (2014). Losing Weight with Hypothyroidism. [online] About Health. Available at: http://thyroid.about.com/cs/dietweightloss/a/losingweight.htm
* ↑ http://www.hindawi.com/journals/jtr/2011/306510/
* ↑ Pietrangelo, A. (2014). Cold Intolerance: Causes, Diagnosis & Treatments. [online] Healthline.com. Available at: http://www.healthline.com/symptom/cold-intolerance
* ↑ Davila, D. (2014). Diet, Exercise and Sleep. [online] Sleepfoundation.org. Available at: http://sleepfoundation.org/sleep-topics/diet-exercise-and-sleep/page/0%2C1/
* ↑ Golding, D. (1970). Hypothyroidism presenting with musculoskeletal symptoms. Annals of the rheumatic diseases, 29(1), p.10.
* ↑ Bowers, E. and Jones, N. (2014). Working Out With Hypothyroidism. [online] EverydayHealth.com. Available at: http://www.everydayhealth.com/thyroid-conditions/working-out-with-hypothyroidism.aspx
* ↑ Ciloglu, F., Peker, I., Pehlivan, A., Karacabey, K., \.Ilhan, N., Saygin, O. and Ozmerdivenli, R. (2005). Exercise intensity and its effects on thyroid hormones. Neuroendocrinology Letters, 26(6), pp.830--834.