Hormones Control Cellular Function
Hormones are chemicals that control how cells function in your body. Hormones only influence cells with specific receptor sites. Hormones can either be anabolic meaning they help build new tissue, or catabolic because they play a role in breaking tissue down meaning they are responsible for both building new muscle and burning fat, therefore to get the results you want from your workouts, it is important to know which ones are influenced by exercise as well as understanding the functions they influence.
3 Categories of Hormones
There are three major classifications of hormones: steroid, peptide and amines (modified amino acid hormones) with each one having a unique chemical structure that determines how it interacts with receptors in cells. Steroid hormones interact with receptors in the nucleus of a cell, peptide hormones are comprised of amino acids and work with specific receptors sites on the cell membrane and amines contain nitrogen and influence the sympathetic nervous system.
A peptide hormone produced by the pancreas insulin regulates carbohydrate and fat metabolism. When blood sugar is elevated insulin is released to promote the storage and absorption of glycogen and glucose. Insulin helps reduce levels of glucose in the blood by promoting its absorption from the bloodstream to skeletal muscles or fat tissues. As it relates to physical activity it is important to know that insulin can cause fat to be stored in adipose tissue instead of being used to fuel muscle activity. When exercise starts the sympathetic nervous system suppresses the release of insulin, consequently it is important to avoid foods with high levels of sugar (including sports drinks) before exercise because it can elevate insulin levels and promote glycogen storage instead of allowing it to be used to fuel physical activity. Wait until the body has started sweating before using any sports drinks or energy gels.
Cortisol is a catabolic steroid hormone produced by the adrenal gland in response to stress, low blood sugar and exercise. Cortisol supports energy metabolism during long periods of exercise by facilitating the breakdown of triglyceride and protein to create the glucose necessary to help fuel exercise. Cortisol is released when the body experiences too much physical stress or is not sufficiently recovered from a previous workout. While cortisol helps promote fat metabolism exercising for too long can elevate levels of cortisol to catabolize muscle protein for fuel instead of conserving it to be used to repair damaged tissues.
Epinephrine and Norepinephrine
These amine hormones play an important role in helping the sympathetic nervous system (SNS) produce energy and regulating the body’s function during cardiorespiratory function during exercise. Classified as catecholamines epinephrine and norepinephrine are separate but related hormones; epinephrine is often referred to as adrenaline because it is produced by the adrenal gland. Epinephrine elevates cardiac output, increases blood sugar (to help fuel exercise), promotes the breakdown of glycogen for energy and supports fat metabolism. Norepinephrine performs a number of the same functions as epinephrine as well as constricting blood vessels in parts of the body not involved in exercise.
A steroid hormone produces by the Leydig cells of the testes in males and the ovaries of females with small amounts produced by the adrenal glands of both genders. Testosterone is responsible for muscle protein re-synthesis, the repair of muscle proteins damaged by exercise, and plays a significant role in helping grow skeletal muscle. Testosterone works with specific receptor sights and is produced in response to exercise that damages muscle proteins.
Somatotropin (Human Growth Hormone aka GH)
GH is an anabolic peptide hormone secreted by the anterior pituitary gland that stimulates cellular growth. Like all hormones GH works with specific receptor sites and can produce a number of responses including increasing muscle protein synthesis responsible for muscle growth, increasing bone mineralization, supporting immune system function and promoting lipolysis – fat metabolism. The body produces GH during the REM cycles of sleep and is stimulated by high intensity exercise such as heavy strength training, explosive power training or cardiorespiratory exercise at or above the onset of blood lactate (OBLA, the second ventilatory threshold).
Insulin-like Growth Factor (IGF-1)
Given the name IGF because it has a similar molecular structure to insulin this is an important hormone stimulated by the same mechanisms that produce GH. IGF is a peptide hormone produced in the liver and supports the function of GH to repair protein damaged during exercise making it an important hormone for promoting muscle growth.
Brain-derived Neurotrophic Factor (BDNF)
BDNF is a protein that stimulates the production of new cells in the brain. The production of BDNF is closely related to the production of GH and IGF, the same exercises which elevate levels of those hormones also increases amounts of BDNF. High intensity exercise can stimulate anabolic hormones for muscle growth while elevating levels of BDNF which can help improve cognitive function.
Learn how exercise influences hormone production
Live virtual workshop with Tricia Murphy Madden and Pete McCall on Thursday, May 13 at 1pm pacific / 4pm eastern.
Make sure your workouts deliver the results you want! Exercise influences the endocrine system to produce the hormones that control cellular functions. The nervous system controls how muscles function and works the same regardless of gender. However, primary sexual characteristics do influence how the endocrine system, which produces the hormones that control how cells function, responds to exercise. Hormones can have either a catabolic (breakdown) or an anabolic (growth) response on muscles and will change based on age and exercise experience. This informative session will cover how gender, age and exercise influence the hormones in your body.
Exercise and Hormone Production
Want muscle? T, GH and IGF are produced in response to the amount of mechanical stress created during resistance training exercises. Moderate to heavy loads performed until momentary fatigue generate high levels of mechanical force, which creates more damage to muscle protein signaling the production of T, GH and IGF to repair protein resulting in muscle growth.
T and GH are produced during the REM cycles of sleep, meaning that a full night’s rest is critical for promoting muscle growth after a hard strength workout. Insufficient rest and recovery does not allow for optimal muscle protein synthesis and could lead to an accumulation of energy producing hormones like epinephrine and cortisol, which can reduce the ability to generate new muscle tissue. Loss of sleep, loss of appetite, lingering illness and cessation of gains from exercise are all symptoms of overtraining, which means time to step away from the gym and spend a few days on the couch with the remote. Yes, that sounds lazy, but adequate rest is the only way to properly recover from overtraining and reset the endocrine system.
You Have Anabolic Steroids in Your Body Right Now
The term ‘anabolic steroids’ is often referred to as a method of cheating used by athletes who want to improve performance, however they are simply natural chemicals produced by the body responsible for promoting tissue growth.
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