The Dangers of Thyroid use in Bodybuilding Contest Prep Weight Loss

Dangers of Thyroid Drugs

Reaching for the Greatest Physique Holds Many Potential Dangers

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Thyroid hormone can profoundly increase the body's metabolic rate - a very attractive prospect for a variety of athletes. From track and field to boxing, thyroid medications are widely used by athletes hoping to lose weight.

Unfortunately, there's a lot of misinformation circulating about thyroid drugs. I recently overheard just a sample of this ignorance while I was at a bar. Two bodybuilders were standing next to me discussing their drug use. One mentioned that he used T3 to build muscle while coming off steroids. If he was taking T3 for this purpose, then he could not have been more wrong about its effect on skeletal muscle. I was amazed at his lack of knowledge about this drug, especially given that he was using scientific jargon in speaking to his friend. So, for those two guys and for other bodybuilders as well, I am going to set the record straight on T3.

The thyroid - an endocrine gland, which secretes hormones directly into the bloodstream - is located in the lower part of the neck, right in front of the windpipe. A normal thyroid is shaped like a butterfly - it has two lobes joined by a narrower portion, called the isthmus. The gland produces two iodine-containing compounds: liothyronine (T3), also known as triiodothyronine, and thyroxine (T"). Both are very potent at stimulating the metabolic processes in your body. Because of its structure and higher dissociation constant (i.e., it does not bind to certain carrier proteins and is easily released), T, is more metabolically active than T.. The relatively weak binding properties of T3 account for a rapid onset and offset of action. This means that T, is strong stuff.

Thyroid hormones enhance the ability of tissues in the body to use oxygen, producing a general increase in the basal metabolic rate. They also augment the metabolism of carbohydrates, lipids and proteins. In fact, the thyroid affects al-most every organ system in the body, including skeletal muscle. These actions shaped like a butterfly - it has two lobes joined by a narrower portion, called the isthmus. The gland produces two iodine-containing compounds: liothyronine (T3), also known as triiodothyronine, and thyroxine (T"). Both are very potent at stimulating the metabolic processes in your body. Because of its structure and higher dissociation constant (i.e., it does not bind to certain carrier proteins and is easily released), T, is more metabolically active than T.. The relatively weak binding properties of T3 account for a rapid onset and offset of action. This means that T, is strong stuff.

Thyroid hormones enhance the ability of tissues in the body to use oxygen, producing a general increase in the basal metabolic rate. They also augment the metabolism of carbohydrates, lipids and proteins. In fact, the thyroid affects al-most every organ system in the body, including skeletal muscle. These actions may explain the weakness you are experiencing.

When athletes take exogenous thyroid, they're essentially making them-selves hyperthyroid during the period of administration. This subjects them to many of the same symptoms as someone who has the medical condition of an overactive thyroid gland (e.g., Graves' disease). The big difference is that an athlete generally cycles thyroid hormone for very brief periods (four to eight weeks), while a diseased individual often displays the effects of years of suffering with a malfunctioning thyroid gland.

One prominent feature of Graves disease is muscle dysfunction, manifesting itself in decreased strength and general feelings of tiredness. The cause of this, and possibly your feelings of weakness in your arms and legs, can be found at the cellular level. Several scientific studies on humans and on animals have demonstrated that high thyroid levels are associated with lower glycogen content, decreased activity of certain oxidative enzymes, changes in the composition of muscle fibers (fibers shift toward fast-twitch, though these particular changes are relatively small and most likely don't influence performance), more pronounced phosphocreatine depletion and a decrease in pH during various muscle contractions. Also interesting to note is that muscle atrophy, or a decrease in muscle mass, is a component of the myopathy associated with the hyperthyroid state. What all this means to you is that if you have a normal thyroid gland, taking exogenous thyroid hormones can decrease your performance in the gym and cause muscle weakness or even result in muscle loss.

It's known that athletes, relying on word of mouth and anecdotal evidence regarding dosages and efficacy, use varying amounts of T3. The side effects from the misuse of thyroid drugs include tremors, headaches, profound weight loss, fever, nervousness, insomnia, heart palpitations, tachycardia (rapid heart rate), cardiac arrhythmia and even cardiac arrest. In addition, women using T3 can sometimes experience disturbances in their menstrual cycles. The extent of complications from using and abusing T3 depend largely on biologic variability and genetic factors, as well as eating habits, level of cardiovascular activity and current lifting program. Some athletes can take very low dosages and experience serious side effects, while others at the same dose will experience no side effects.

Another very important factor in discussing T3 usage is the administration of androgens or other anabolic agents that often accompanies it. Taking androgens, growth hormone and/or a selective B2-agonist will, in theory, potentiate the lipolytic effects of T3. It is known that metabolic rate is increased with high-dose thyroid use and a protein breakdown can occur. It is suspected, but not yet demonstrated in the scientific or medical literature, that simultaneous use with anabolics may prevent the catabolism of skeletal muscle during a cycle of thyroid.

There is very little in the scientific literature on the athletic use of thyroid hormones, although one recent study, published in Medicine and Science in Sports and Exercise (29:175-80, 1997), showed that hyperthyroid individuals (people with overactive thyroid glands) experienced increases in muscle mass after treatment with antithyroid drugs. No scientific queries have been conducted on the physiologic effects of thyroid drugs on healthy resistance-trained athletes.




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