Does Human Growth Hormone (HGH) Build Muscle?

Growth hormone, or human growth hormone ("HGH" for short), is often associated with performance-enhancing drugs and athletes or bodybuilders from (ostensibly) yesteryear. However, it is not some rare synthetic compound or new peptide — it’s a naturally occurring hormone produced by your body.

Growth hormone plays an important role in growth and development in children, and helps control metabolism and "tissue" growth (which includes muscle). But its role in stimulating muscle growth is more complex than the name might suggest. So does growth hormone really live up to its name and build muscle?

What is Human Growth Hormone?

Growth hormone is secreted from the "anterior pituitary" gland in the brain. The levels of growth hormone in your body are very small but rise and fall throughout the day. Several factors influence its release, which include sleep, exercise, stress, and nutrition. The largest spikes in growth hormone often occur during deep sleep and after intense exercise, when it can increase 2- to 6-fold from normal concentrations.^[1][2]

One of growth hormone's most influential jobs is to stimulate the liver and other tissues to produce another hormone, Insulin-like growth factor 1 ("IGF-1"). IGF-1 does support muscle growth, and just like growth hormone itself, it can be taken as a performance-enhancing (or muscle-enhancing) drug.^[3]

But despite its reputation, growth hormone does not directly (by itself) stimulate muscle, at least not to the same extent as hormones like testosterone. Instead, growth hormone appears to play a more passive role by increasing fat loss and helping maintain muscle mass (rather than increasing it).^[3]

Growth hormone also seems to help repair connective tissues in your joints and ligaments. So it may help with recovery and reinforce structural support for your body during exercise. This may support recovery and reduce injury risk, which could indirectly benefit muscle growth by allowing more consistent, intense training.^[4]

This may support recovery and reduce injury risk, which could indirectly benefit muscle growth by allowing more consistent, intense training.

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Effects of Exercise on Growth Hormone Levels

Resistance training is one of the most effective methods to naturally increase your growth hormone levels, and some exercises produce greater amounts of it. High-volume, moderate-to-high-intensity resistance exercise using large muscle groups produces the biggest increases in growth hormone.^[2]

However, the increase in growth hormone after exercise is short-lived. It peaks after about 15–30 minutes and then returns to baseline within an hour. So can this short-lived spike in growth hormone stimulate muscle growth?

The consensus appears to suggest not. Or at least it's not the primary driver of growth anyway. But as we said earlier, it still plays meaningful roles in body composition and tissue repair.^[5]

More specifically, it mobilises fat for energy if (or when) you are in a caloric deficit, when maintaining muscle mass becomes more difficult. It also supports cartilage and tendon recovery, which may help reduce injury risk as you train. This may indirectly support muscle growth and athletic development in people who are training at high intensities and undertaking fat loss exercise programmes.

Natural vs Synthetic HGH: What’s the Difference?

There is a lot of confusion around the role that certain hormones play in muscle growth. This comes from the potent effects that very high ("supraphysiological") doses achieve. However, these levels can rarely be reached naturally, no matter how optimal your lifestyle is.

Doping with HGH involves injecting doses far exceeding natural physiological levels (by 2-5 fold). At these levels, synthetic human growth hormone drugs have been shown to increase fat loss, IGF-1 production, collagen synthesis and muscle repair beyond what can be achieved naturally.^[1]

Injecting these large amounts of specially designed hormones also means they stay in your system longer, giving them more time to exert their physiological effects. Yet, surprisingly, the evidence for performance-enhancing effects of HGH in healthy athletes is limited.

This is probably because clinical studies use lower doses than athletes actually take, and in real life HGH is often ‘stacked’ with other drugs, which studies can’t easily replicate.^[6]

Chronic misuse (and abuse) of HGH has been linked to several health problems: insulin resistance, joint swelling, carpal tunnel syndrome, and increased risk of "acromegaly" (enlarged hands, feet, facial features and organs), to name a few. 

Growth Hormone and Healthy Ageing

As people age, their growth hormone production naturally declines. This decrease is associated with shrinking muscles, lower bone density, and increased body fat (including visceral fat). Increasing growth hormone naturally may not directly build muscle. But the natural decline with age may make it harder to maintain muscle mass.^[7]

Some clinical studies have explored the use of growth hormone replacement therapy (somatropin) for people who are deficient, with some positive effects. Its use in healthy people is controversial and not recommended due to limited benefits and potential risks. It is also prescription-only in most of the world and banned in competitive sport.^[8][9]

From a training and recovery perspective, there are many natural ways to support healthy growth hormone production (without the risks of injecting it). Getting enough high-quality sleep is arguably the most effective (natural) way to increase it, as most growth hormone is released during deep sleep.^[10]

Bottom Line

Growth hormone is a vital hormone that supports recovery, fat metabolism, and structural support of the connective tissue in the body. But its direct contribution to muscle growth is more limited than commonly believed, or than its name suggests.

There is some evidence that growth hormone supports repair of connective tissue and may therefore indirectly help muscle growth. But good sleep, regular exercise and strategic recovery are likely to support healthy natural levels in young and middle-aged adults.

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