An Update on the Science of Saunas for Growth Hormone (GH) Release

So guys, I thought I’d do a post about how regular sauna use can actually be incredibly anabolic and help you increase muscle mass.

There are heaps of studies on saunas and hormone changes, but what I was specifically interested in was looking at the influence of saunas on modulating growth hormone levels.

Why growth hormone?

GH is anabolic and one of 3 main drivers of mTOR, which is the regulatory protein that controls heaps of things in our body (everything from cell growth and division to its role in cancer when it goes wrong), but for the purposes of this post; its control of skeletal muscle growth and hypertrophy. GH fits into the category of being a ‘growth factor’ as seen below, ultimately facilitating protein synthesis by ‘activating’ mTORC1:

AAs is the other category and obviously we know steroids work.

But, what if you could increase the growth factor vector without having to spend exorbitant amounts of money on GH.

There is a way you can do it, and it’s utilising the sauna.

Scientific Studies on Growth Hormone and Saunas:

The following 3 studies looked at this issue specifically, and quickly summarised:

Study 1: Heat Exposure Elevates Plasma Immunoreactive Growth Hormone-Releasing Hormone Levels in Man

• Participants: 12 men, aged 31-66.
• GH Measurement: GH levels were measured before and after 15 minutes of sauna exposure at 72°C.
• Findings: In younger men (31-46 years), GH levels increased from 2 to 5 µg/L at 30 minutes post-exposure. In older men (49-66 years), there was no significant increase in GH levels .

Study 2: Haemodynamic and Hormonal Responses to Heat Exposure in a Finnish Sauna Bath

• Participants: 8 healthy young men.
• GH Measurement: GH levels were measured before, during, and after sauna exposure at different temperatures (80°C dry heat, 100°C dry heat, and 80°C dry and humid heat).
• Findings: At 100°C dry heat, GH levels increased from a baseline of 3.5 µg/L to 17.3 µg/L. At 80°C dry and humid heat, GH levels increased from 8.8 µg/L to 16.3 µg/L during the sauna session .

Study 3: Plasma ACTH, Beta-Endorphin, Prolactin, Growth Hormone, and Luteinizing Hormone Levels After Thermal Stress, Heat and Cold

• Participants: 8 young healthy subjects.
• GH Measurement: GH levels were measured before and after exposure to a sauna at 90°C.
• Findings: GH levels showed a significant rise at the end of the sauna exposure, increasing from 3.8 ng/ml to 8.8 ng/ml .

So to conclude and put these numbers into perspective, the increases in GH levels in each study compared to baseline are as follows:

1. Study 1: In younger men (31-46 years), the GH level increased to 2.5 times the baseline level.
2. Study 2:

• In the 100°C dry sauna, the GH level increased to approximately 4.94 times the baseline level.
• In the 80°C dry and humid sauna, the GH level increased to about 1.85 times the baseline level.

1. Study 3: The GH level increased to around 2.32 times the baseline level.

So basically, anywhere from a 1.85x to a whopping 4.94x baseline. Not only this, but GH levels remained elevated for at least 45 minutes in Study 1, meaning you’re getting a large ‘window’ of stimulus which is beneficial from a muscle building point of view - mTOR activation for longer = more potential muscle protein synthesis.

But why does the sauna, of all things, increase GH?

If the fact that saunas increase GH is all you wanted to know, feel free to stop reading here. But, if you’re anything like me and like to understand the mechanisms of action behind physiological responses, the researchers across these studies hypothesised a few reasons as to why saunas seem to increase GH levels:

Heat Stress as a Trigger: 

Sauna exposure induces a state of hyperthermia, a form of physical stress, which stimulates the hypothalamus and pituitary gland. This stimulation leads to the release of GH. Heat stress via heat-shock proteins (HSPs) is a well-known activator of the hypothalamic-pituitary-adrenal (HPA) axis, which plays a crucial role in stress response mechanisms. In fact, multiple studies have shown that during times of stress (not just heat stress), the hypothalamic-pituitary axis is upregulated. The body's response to heat is similar to its response to other stressors, wherein GH release is a part of the overall adaptation process.

Role of Growth Hormone-Releasing Hormone (GHRH): 

In the first study, it was observed that the increase in plasma GH levels in younger men following sauna exposure was preceded by an increase in plasma immunoreactive GHRH levels. This suggests that the mechanism of GH release in response to sauna exposure involves the stimulation of GHRH release. GHRH is a key hormone that signals the anterior pituitary gland to secrete GH, so this makes sense. More GHRH = more circulating GH.

Age-Related Differences: 

The first study also highlighted that older men did not exhibit a significant increase in GH levels following sauna exposure, which could be due to age-related decline in the responsiveness of the GH axis. This suggests that the sensitivity of the GH response mechanism to heat stress may diminish with age.

Hyperthermia-induced Physiological Changes: 

Hyperthermia caused by sauna exposure can lead to changes in blood flow, metabolism, and neuroendocrine functions. These changes can stimulate the pituitary gland to release GH as part of the body's effort to regulate internal temperature and respond to the physiological challenges posed by the heat. Again, this is along the ‘I recognise your body is under stress so I am going to activate your HPA to try and combat this’ vector.

Role of Endogenous Opioids: 

The third study mentions that heat exposure could activate the endogenous opioid system, which might play a role in the neuroendocrine response, including the secretion of GH. Endogenous opioids like beta-endorphins can influence the secretion of several hormones, including GH. And, studies have shown that sauna exposure can significantly increase beta-endorphin levels, as seen below:

In summary, the increase in GH levels following sauna exposure is a multifactorial process involving a heat-induced stress response, activation of the HPA axis, stimulation of GHRH secretion, and possibly the involvement of the endogenous opioid system. The precise mechanisms may vary based on individual factors like age and the specific conditions of the sauna exposure (temperature and humidity levels), but the overall idea is there: if you are a young male and wanting to get an extra anabolic stimulus, you can directly influence your growth hormone levels by getting in the sauna.

Maybe Derek was onto something. Maybe he never worked out, maybe it was all a lie. Maybe it was just the anabolic stimulus from being in a sauna whenever he filmed.

Thanks so much for reading guys, see you next post.