Exercise Can Slow Down Aging:
Those of us who make a living teaching exercise science know a little secret – it’s the hormones that change the body, not just exercise. Hormones are chemicals produced by the body that control how cells function. Exercise can elevate levels of muscle-building hormones and to do that, focus on movements that involved multiple muscles as opposed to wasting time on exercises that only use one muscle at a time. Here’s another secret: when exercise elevates levels of muscle-building hormones, it CAN slow down the effects of aging.
Every hormone has a job
Certain hormones help build new muscle while others stimulate energy production, i.e. fat burning; if you understand what hormones do as well as which ones are released in relation to exercise then you can identify the best workouts for your goals.
The Role of Hormones
Hormones are the product of the body’s endocrine system. Hormones can affect a number of different cellular functions, however they only influence cells with specific receptor sites. Hormones control physiological functions including: energy metabolism – how the food we eat gets turned into muscle activity, reproductive processes, mood (and overall mental state) and muscle growth, specifically the process of muscle protein synthesis.
3 types 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 specific receptors. 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.
Hormones can either be anabolic meaning they help build new tissue, or catabolic because they play a role in breaking tissue down. 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.
Important Exercise-related Hormones:
Listed below are some important hormones involved in exercise along with the physiological functions they control.
Having a sugary snack or drink too close to the start of exercise could increase insulin levels and reduce the amount of fat you’ll burn while you sweat. Insulin is a peptide hormone produced by the pancreas and regulates carbohydrate and fat metabolism. When blood sugar is elevated after ingesting carbohydrates, insulin is released to promote the storage and absorption of those carbs. Insulin helps reduce levels of glucose in the blood by promoting its absorption from the bloodstream to skeletal muscles or fat tissues. When it comes to exercise, it is important to know that insulin can cause fat to be stored in adipose tissue instead of being used to fuel muscle activity. As you start exercising your 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. Avoid any high carbohydrate food or drinks for 45-minutes before exercise and wait until you have started sweating before using any sports drinks or energy gels once you do start working out.
To borrow from Sex in the City, consider cortisol your ‘friendemy’ because it can both help you and hurt you. It a catabolic steroid hormone produced by the adrenal gland in response to stress, low blood sugar and exercise. Cortisol supports energy metabolism during the start of exercise by facilitating the breakdown of free fatty acids to be used for fuel (this is how fasted cardio works for fat burning and why it is important that it be low-intensity; cortisol levels are highest in the morning and exercising at a low intensity will ensure that fats are used for fuel before carbs). However, when moderate-to-high intensity exercise lasts longer than 45-60 minutes, glycogen (how carbohydrates are stored in muscle) will deplete causing the release of cortisol which will convert amino acids into the glycogen needed to 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. Want to become “skinny fat?” Then perform long periods of high intensity exercise to ensure that proteins are used for fuel instead of fats or carbs.
Epinephrine and Norepinephrine
Commonly called adrenaline because they are produced by the adrenal gland; epinephrine is an amine hormone while norepinephrine is a neurotransmitter. Both work together to 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 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.
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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. Exercises that involve large amounts of muscle mass like squats, deadlifts, push presses, barbell bent over rows, kettlebell swings, snatches and power cleans can help elevate T, especially when combined with shorter rest intervals. There is research that suggests that waiting too long between sets or exercising for longer than an hour could actually lower T levels; therefore when it comes to elevating T workouts should be fast paced and be over in about 30-45 minutes (not including warm-up and cool-down). To learn a little more about T, read THIS BLOG POST I wrote for the American Council on Exercise. Good news for women, they produce MUCH less T then men; muscle growth in women is much more of a function of HGH and insulin-like growth factors (see below).
Somatotropin (Human Growth Hormone aka HGH)
HGH is an anabolic peptide hormone secreted by the anterior pituitary gland that stimulates cellular growth. Like all hormones, HGH 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 HGH during stage 3 of non-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). On those days when you do your harder, more intense workouts you want to make sure that you can get a good night’s sleep so that your body has the time to produce the anabolic hormones that help your muscles repair themselves.
Insulin-like Growth Factor (IGF, aka Mechano Growth Factor)
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 HGH. IGF is a peptide hormone produced in the liver and supports the function of HGH to repair protein damaged during exercise making it an important hormone for promoting muscle growth. IGF is released in response to carbohydrates ingested after a workout which helps explain why a post-exercise shake or snack can help promote recovery while enhancing muscle growth.
Brain-derived Neurotrophic Factor (BDNF)
BDNF is a protein that helps stimulate the production of new cells in the brain. The production of BDNF is closely related to the production of HGH and IGF, the same exercises which elevate levels of those hormones also increases amounts of BDNF. The same types of high intensity exercise that can stimulate anabolic hormones for muscle growth can also help elevate levels of BDNF. This means that the hard workouts responsible for making you sweaty and the good sore can also help to smarten you up.
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While there are a myriad of hormones responsible for an almost infinite number of physiological functions the hormones listed above are directly influenced by physical activity and play important roles in helping the body adapt to the imposed physical demands of exercise. Understanding how exercise influences the hormones that control physiological functions can help you identify the best exercises for your goals. Hormones have both short and long-term responses to exercise. In the acute phase immediately post-exercise, T, HGH and IGF are produced to repair damaged tissue. Over the long-term there is an increase in the receptor sites and binding proteins, which allow T, HGH and IGF-1 to be used more effectively for tissue repair and muscle growth.
This e-book explains how exercise can slow the aging process and provides examples of workouts that can help to extend your lifespan.
If you want muscle growth: Moderate to heavy loads performed until momentary fatigue can create the mechanical stress necessary to signal the production of T, GH and IGF to repair and grow muscle proteins resulting in overall muscle growth.
Inducing metabolic and mechanical stress in the gym will only go so far in promoting muscle growth. T and HGH are produced during sleep, meaning that a full night’s rest is critical for promoting muscle growth after strength training. 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 can significantly affect your ability to achieve your fitness goals.
Proper recovery is essential for getting results from your workouts – READ THIS BLOG to learn 6 recovery strategies that you should be doing
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Like heavy resistance training, HIIT stimulates an increased production of the anabolic hormones T, HGH and IGF-1, which are responsible for muscle growth and fat metabolism. Research by Linnam and colleagues (2005) indicated that “hormonal changes appear to be related to the amount of muscle mass activated and to the metabolic response caused by the exercise.” Likewise, in their research on sprint interval training, Meckel et al. (2011) found that to stimulate an anabolic response, “input should be sufficient to cause a sizable metabolic effect.” Intense exercise produces results; however, to reduce the risk of an overuse injury it is important to take the time to properly rest and recover between high intensity workouts. A good schedule would have you doing 2-3 days of full-body strength or power training workouts a week with the other days focused on lower intensity mobility or metabolic conditioning workouts.
For a deep dive on the topic of muscle growth, FOLLOW THIS LINK to a full-length article I wrote for the American Council on Exercise