Testosterone, growth hormone, and insulin-like growth factor (IGF-1) play a critical role in bodybuilding and strength training.
They increase strength and stimulate muscle growth.
Other hormones, such as cortisol, epinephrine, norepinephrine, and glucagon, increase the availability of glucose, your body’s primary source of fuel. Insulin facilitates the storage of glucose in muscles for future use.
All of these hormones are part of the body’s natural endocrine response.
Key Hormones in Bodybuilding
Hormones influence muscle growth and strength in different ways. Some specifically promote muscle growth, while others influence the way we use and store glucose for training and competition.
Testosterone is a male hormone produced mainly by the testicles but also by the adrenal glands, which are situated on top of the kidneys. Testosterone is responsible for the development of male physical characteristics, muscle mass, strength, fat distribution, and sex drive. In women, testosterone is produced by the ovaries and adrenal glands, albeit in lower quantities.
Testosterone is classified as both an androgenic and anabolic steroid hormone. Androgenic refers to male characteristics, while the term anabolic refers to the growth of body tissue. Testosterone is arguably the most important hormone for bodybuilding. The amount the body produces gradually wanes with age.
The use of supplementary anabolic steroids to build muscle has been popular for decades. They work very well, but also carry potentially serious health risks. It is for this reason that any form of testosterone supplementation is banned in sports.
Growth Hormone and IGF-1
Growth hormone is produced by the pituitary gland and stimulates the liver to produce IGF-1, the hormone ultimately responsible for anabolic muscle growth. As with testosterone, the production of GH declines with age. Both hormones have an inverse relationship to body fat, meaning that the less GH and IGF-1 you produce, the more body fat you will accumulate.
Insulin is the storage hormone produced by the pancreas in response to food. When food is eaten, it is broken down into glucose, fatty acids, amino acids, vitamins, and minerals. Insulin warehouses the stored form of glucose, known as glycogen, in muscles and the liver. It also enables amino acids to repair damaged tissues and build muscle mass.
These effects are considered anabolic. Insulin production is largely influenced by exercise and diet, especially the consumption of carbohydrates and protein.
Cortisol is produced by the adrenal glands. It is often called the “stress hormone,” because physical and/or emotional stress triggers its release. Hydrocortisone and cortisone are the manufactured forms of cortisol.
Cortisol is a catabolic hormone, meaning that it breaks down tissue. In addition to controlling inflammation, cortisol makes glucose available by breaking down muscle whenever the blood sugar is low. This commonly occurs during endurance sports when the circulating glucose supply has been used up.
Epinephrine (adrenaline) is called the “fight or flight” hormone because it acts quickly at times of stress to constrict arteries and raise blood pressure. This increases the heart rate to deliver oxygen more effectively. Epinephrine also constricts airways so that respiration is more efficient.
On top of this, epinephrine directs the muscles and liver to surrender their glucose stores during strenuous activity. In this sense, epinephrine is a catabolic hormone like cortisol.
Glucagon acts like a mirror hormone of insulin. When you fast or eat a low-carb diet, glucagon responds more efficiently than insulin to replenish low glucose supplies.
Glucagon works by instructing the liver to give up its glucose stores. It also breaks down muscles to increase cortisol, which stimulates the production of glucose. If insulin is anabolic, then glucagon is catabolic.
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