Exposing your muscles to progressive overload through weight training is the stimulus that causes them to grow, but there are a number of “key players” behind the scenes that influence how much return you get on your weight training investment. These anabolic and catabolic hormones can make it easier or harder to build lean body mass. Here are some of those hormonal players and what they do.
Hormones That Impact Muscle Growth #1: Insulin
Insulin is a hormone released after a meal that helps your cells take up glucose. Not only does it open up the channels for cells to take up glucose, but it also delivers amino acids to muscle cells so they can use them for growth and repair. Here’s the kicker. You don’t want too much insulin hanging around in your system because it blocks fat breakdown. On the other hand, you do want enough after a workout to help muscle cells get the amino acids they need.
To give your muscles the short-term benefits of insulin after a workout, eat a snack that contains 30 grams of protein and 30 grams of carbs after your workout. It’s the best time to consume simple carbs. Doing so boosts muscle protein synthesis and prevents muscle breakdown. What you don’t want to do is spike insulin levels throughout the day when you’re not working out.
Insulin can be your friend if you’re trying to build muscle, or your worst enemy when you’re trying to lose fat. You can take advantage of its anabolic effects by consuming simple carbs after weight training and eat fiber-rich, low-glycemic carbs the rest of the day to avoid its negative effects.
Hormones That Impact Muscle Growth #2: Testosterone
Testosterone is another anabolic hormone that boosts muscle protein synthesis – yet women have 15 to 20 times less testosterone compared to men. That’s why the average woman with normal testosterone levels doesn’t have to worry about “bulking up. “ In fact, they’ll find it significantly more challenging to build lean body mass relative to men. On the other hand, by progressively overloading muscle tissue, women CAN build lean body mass. This shows that other anabolic hormones play a role in muscle growth.
There are some studies showing that weight training increases post-exercise testosterone levels in women. Fortunately, women aren’t dependent upon testosterone to build strength and lean body mass. Other anabolic hormones have a greater impact, especially growth hormone.
Hormones That Impact Muscle Growth #3: Growth Hormone
Unlike testosterone, women naturally have higher levels of growth hormone relative to men. In addition, intense resistance training boosts growth hormone levels. Compound strength exercises that use large muscle groups trigger the most growth hormone release. Multiple sets also cause a greater rise in growth hormone levels than single sets. On the other hand, high-rep training with lighter weights (less than 70% of one-rep max) doesn’t elicit the same growth hormone response as heavier weight training.
How can you maximize the benefits? Minimizing rest periods between sets will enhance growth hormone release. Another way to boost growth hormone release is with high-intensity aerobic training. The key to maximizing growth hormone release during exercise is to move out of your comfort zone and limit rest periods between sets.
Hormones That Impact Muscle Growth #4: Cortisol
Unlike the muscle-friendly hormones we’ve discussed, cortisol thwarts your efforts to get stronger and more defined. That’s because this hormone produced by the adrenal cortex is catabolic. Cortisol is released in response to mental or physical stress, and its goal is to give you the additional energy you need to respond to a threat. One way it does this is by breaking down muscle tissue so your liver can use the amino acids to make glucose through gluconeogenesis. There go your hard-earned muscle gains!
The key is to keep cortisol in check by not doing long periods of moderate-intensity cardio, getting enough sleep at night, reducing mental stress in your life and not starving yourself. No starvation diets! Going on a very low-carb or calorie-restricted diet can send your cortisol level into orbit. This causes muscle wasting and makes it easier to store belly fat. Stick with shorter, high-intensity interval workouts to minimize cortisol release and maximize growth hormone if you’re trying to build or preserve lean body mass.
Hormones That Impact Muscle Growth #5: IGF-1
IGF-1 is short for insulin-like growth factor one. It’s an insulin-like hormone produced by the liver in response to growth hormone. Research suggests that IGF-1 mediates the anabolic effects of growth hormone on muscle tissue. Like insulin, it helps to transport amino acids into cells so muscle cells can use them to build muscle. Plus, it stimulates bone growth and has a growth-promoting effect on most tissues.
The composition of your diet has some effect on IGF-1 levels. Dietary protein and dairy products have a stimulatory effect, and IGF-1 levels decline with calorie restriction. As might be expected, people who eat a vegetarian or vegan diet usually have lower levels of IGF-1. T
The problem with IGF-1 is its anabolic nature has also been linked with proliferation of cells, including cancer cells. Some studies suggest that higher levels of IGF-1 are associated with a greater risk for pre-menopausal breast cancer, colon cancer, and prostate cancer. That’s why it’s not a good idea to take any of the IGF-1 supplements available in health food stores to boost muscle growth.
The Bottom Line?
These are some of the “behind the scenes” players that make it harder or easier to build muscle. You can subtly alter levels of these hormones by the intensity of your workouts, your diet, and sleep patterns. Use this to your advantage – to get the lean, firm physique you’re looking for.
References:
Med Sci Sports Exerc, 33 (4) p. 635-643.
J Appl Physiol, 75(2) p. 594-604.
Br J Sports Med 2009;43:7 521-525.
Harvard University Gazette. “Growth Factor Raises Cancer Risk”
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What Role Does Growth Hormone Play in Building Lean Body Mass?
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