Training, recovery, sleep and growth hormone

Training produces tissue damage and improved fitness is the result of the way the body compensates for that damage.  This simple fact implies that promoting effective compensation is at least as important as the training itself.  Yet much of our attention in planning a training program is directed at determining how we can adjust the content of our training achieve the maximum tissue damage and yet still recover.  Most of us devote less attention to optimizing the process of recovery. 

Usually our body reminds us we need to re-hydrate, and we would be foolish to ignore that need.  Some of us give thought to post-training nutrition, and many dietitians recommend strategies such as consuming carbohydrate and protein in the ratio of 3:1  or 4:1 but the scientific evidence supporting such strategies is controversial.  Similarly some of us engage in post-run stretching but there is less convincing evidence that post-run stretching makes a great deal of difference.  Perhaps those of us with time and money get a regular post-exercise massage but there even less evidence that this leads to improved performance.  I do not discount the possible value of any of these post-run rituals – nutrition, stretching or massage – but on the whole, as far as I am aware, the quality of the evidence for their benefit is relatively limited.

What do Africans do?

In the absence of good scientific evidence, perhaps the most sensible approach is to look at what successful athletes do.  In my post on 27 April ‘How fast should the long run be’, I quoted from a magazine article by Hilary Stellingwerff, a Canadian runner who had spent some time training in Ethiopia at the invitation of Haile Gebrselassie.  She said:  “Athletics comes number one for African athletes; there is nothing else. They train very hard and sleep the rest of the day to recover.’ [1].  Plentiful sleep also features in the recovery strategy of Paula Radcliffe.  In an interview with Rachel Cooke for Observer Sport Monthly several years ago, she made it clear that, like the Africans, she spends a lot of time sleeping.  ‘I’m usually in bed by ten and I don’t get up until around nine,’ Paula reports. ‘Then I have another two hours sleep in the afternoon. You really need that sleep when you train as hard as I do.’  [2]

What does science tell us?

There is in fact a small amount of scientific evidence supporting the hypothesis that extra sleep improves athletic performance.  Cheri Mah and colleagues at Stanford University carried out a study in which 6 basket-ball players from the Stanford team maintained their typical sleep-wake patterns for a two-week baseline followed by a period in which they obtained as much extra sleep as possible. Significant improvements in athletic performance, including faster sprint time and increased free-throws, were observed [3].  

It is likely that one of the major physiological process by which sleep promotes recovery is the release of growth hormone.  Growth hormone is an anabolic hormone that is released from the pituitary gland in a pulsatile manner, typically in four of five bursts per 24 hours.  The most substantial burst occurs during the first two hours of sleep, though several smaller pulses are released at later stages during sleep.  A young adult typically secretes a total of around 400 micrograms (0.4 mg) per day.

Many features of the physiology of growth hormone relevant to runners were discussed in a  review by Widdowson and colleagues [4].  Growth hormone promotes the mobilization of fatty acids and would be expected to promote the use of fat as fuel when running.  Exercise itself, especially anaerobic exercise and resistance training, promotes the release of growth hormone.  In the context of recovery, the most relevant of the many actions of growth hormone is the promotion of muscle development. 

Does additional GH enhance performance?

The evidence for beneficial effect of injections growth hormone on athletic performance has hitherto been equivocal, but a recent large and rigorous study by Ken Ho and colleagues at St Vincent’s Hospital in Sydney, funded by the World Anti-doping Agency, has provided striking evidence of benefit, though also an indication of some risks [5].  96 healthy, young recreational athletes (average age of 27) took part in the eight week study. The 63 male athletes were randomly assigned to one of four regimens: 2 mg per day of growth hormone (about 5 times the amount typically released daily from the pituitary in young adults); 250 milligrams per week of testosterone; both growth hormone and testosterone; or placebo injections. The 33 female athletes received either growth hormone (2 mg) or placebo injections.   The allocation to treatment groups was double blind so neither the athletes nor the investigators knew who was receiving hormones and who was receiving the placebo.

After eight weeks, sprint capacity had shown an improvement that was 3.9% greater in the group receiving growth hormone than in the group receiving placebo injections.  A 3.9% improvement would reduce a 100 metre sprint time of 10 seconds to 9.61 seconds, enough to convert an ‘also ran’ to a medal winner in many races.  The male athletes who received both growth hormone and testosterone had an 8.3% average increase in sprint capacity.   However the sprinting performance returned to normal six weeks after the growth hormone injections stopped. Somewhat surprisingly, the improved sprint performances were not accompanied by increased strength or power.

Consistent with the known effect of growth hormone on fat metabolism, growth hormone reduced body fat and increased lean body mass.  However, consistent with the observation of the adverse effects in the disorder, acromegaly, in which the pituitary gland produces excessive growth hormone, the athletes receiving growth hormone also reported swelling and joint pain.   On balance this study by Ho and colleagues demonstrates that the World Anti-doping Agency should put more effort into testing for abuse of growth hormone.  From the perspective of the athlete who wishes to optimize both performance and health, the evident conclusion is that optimizing natural release of growth hormone release is likely to be worthwhile.  So perhaps the focus on sleep in the recovery stagy of both Paula Radcliffe and the African runners described by Hilary Stellingwerff appears very sound. 

There is only the fragmentary evidence such as that from the study by Cheri Mah at Stanford that increasing sleep might produce a large enough increase in growth hormone to affect athletic performance.  However, our understanding of the nature of the training effect suggests that when an athlete has reached a plateau where performance no longer improves despite regular training, perhaps the most rational approach is to devote at least as much attention to facilitating recovery as to adjusting the content of training sessions.  Getting enough sleep might well be the best place to start.


[1] Hilary Stellingwerff   ‘Living the High Life.’  Canadian Runner, Issue 2.4, 2009.

[2] Rachel Cooke   ‘In it for the long run’ Observer Sport Monthly, Sunday 1 December, 2002.  (,,849746,00.html)

[3] Mah C . presented at SLEEP 2007, the 21st Annual Meeting of the Associated Professional Sleep Societies (APSS). (Reported in: American Academy of Sleep Medicine. ‘Extra Sleep Improves Athletes’ Performance.’ ScienceDaily, June  2007)

[4] Widdowson WM, Healy M-L, Sonksen PH, and Gibney J.  The physiology of growth hormone and sport.  Growth Hormone & IGF Research 19 308–319, 2009

[5] Meinhardt U, Nelson AE, Hansen JL, Birzniece V, Clifford D, Leung K-C, Graham K, and Ho KYY. The Effects of Growth Hormone on Body Composition and Physical Performance in Recreational Athletes: A Randomized Trial.  Annals of Internal Medicine, 152 (9): 568-577, 2010.


9 Responses to “Training, recovery, sleep and growth hormone”

  1. Ewen Says:

    Thanks for a timely post Canute. I suspect insufficient sleep is partly to blame for my current form slump.

    Kara Goucher said in that podcast Rick linked to that she is always sleeping. I remember reading that Gabriela Szabo slept 14-16 (!) hours a day when in heavy training.

    • canute1 Says:

      Thanks for the additional examples of elites who sleep a lot.

      I suppose for many of us, getting 8 hours in 24 would be better than we usually mange. In fact I like the idea of 6 hours at night and a 2 hour siesta. Since GH release is greatest in the first two hours of sleep, perhaps this woudl maximise GH release. But I fear that the siesta will have to wait until after I have retired

  2. Mystery Coach Says:

    As a side note the late running guru George Sheehan used to say when you had reached your peak and started coming down from it that instead of training an hour a day you should sleep that hour instead.

  3. Mystery Coach Says:

    Looking back for the article by Sheehan on sleep I came across his notes in his book Dr. George Sheehan’s Medical Advice for Runners. (pg 56)

    “Research has shown that sleep replenishes certain essential substances in the brain. Depletion of these substances seems to have a causal relation with depressed states.”

    This would seem to follow the discussion earlier about Salazar’s use of Prozac.

    The chemical health of the brain may be a bigger factor in peaking than the condition of the muscles themselves.

  4. Sleep, Drugs and Alcohol « Exercise for Geeks Says:

    […] Elite athletes spend a lot of time sleeping, and for good reason. Marathoner Paula Radcliffe spends about 11 hours per day asleep, 9 at night and a futher 2 in the afternoon. The International Olympic Committee placed HGH on the list of banned substances over 20 years ago. It has been demonstrated that HGH has a positive impact on sporting performance, whether it be via i…. […]

  5. Bifiwndm Says:

    I’ll call back later elweb bbs links the question is… how is he able to get that thing so hard without losing all the blood in his brain?

  6. Muscle ZX90 Says:

    magnificent post, very informative. I’m wondering why the other experts of this sector do not realize this. You should proceed your writing. I’m sure, you’ve a huge readers’ base already!

  7. vitamins and minerals Says:

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  8. Balance and Recovery Says:

    […] body is different but minimum 7 hours a night is needed to allow your muscles to recover and maximize growth hormone throughout your sleep […]

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