Monday, January 14, 2008

Growth Hormone - New Research

Blogging on Peer-Reviewed ResearchI have had a couple of posts before on Growth Hormone and how to increase your production of it:

So if you are interested in maximising your GH, practice IF, get enough sleep in the dark and work out intensely with short rests between sets.

Here are a couple of new bits of research on GH and exercise, to think about in developing your training and indeed lifestyle.

The growth hormone response to repeated bouts of sprint exercise with and without suppression of lipolysis in men.
A single 30-s sprint is a potent physiological stimulus for growth hormone (GH) release. However, repeated bouts of sprinting attenuates the GH response, possibly due to negative feedback via elevated systemic free fatty acids (FFA). The aim of the study was to use nicotinic acid (NA) to suppress lipolysis in order to investigate whether serum FFA can modulate the GH response to exercise. Seven non-obese, healthy men performed two trials, consisting of two maximal 30-s cycle ergometer sprints separated by 4 h of recovery. In one trial (NA), participants ingested NA (1 g 60 min before, and 0.5 g 60 and 180 min after, sprint 1); the other was a control (Con) trial. Serum FFA was not significantly different between trials prior to sprint 1, but was significantly lower in the NA trial immediately before sprint 2 (NA vs. Con; mean (SD); 0.08 (0.05) vs. 0.75 (0.34) mmol/l, P<0.05). Peak and integrated GH were significantly greater following sprint 2 compared to sprint 1 in the NA trial (peak GH, 23.3 (7.0) vs. 7.7 (11.9) µg/l, P<0.05; integrated GH, 1076 (350) vs. 316 (527) µg/l/60 min, P<0.05) and compared to sprint 2 in the Con trial (peak GH, 23.3 (7.0) vs. 5.2 (2.3) µg/l, P<0.05; integrated GH, 1076 (350) vs. 206 (118) µg/l/60 min, P<0.05). In conclusion, suppressing lipolysis resulted in a significantly greater GH response to the second of two sprints, suggesting a potential role for serum FFA in negative feedback control of the GH response to repeated exercise.

The role of lactate in the exercise-induced human growth hormone response: evidence from McArdle's disease.

Purpose: Increased blood lactate concentration has been suggested as a primary stimulus for the exercise-induced growth hormone response (EIGR). Patients with McArdle's disease are unable to produce lactate in response to exercise and thus offer a unique model to assess the role of lactate in the EIGR. Accordingly, McArdle's patients were exercised to test the hypothesis that lactate is a major stimulus of the EIGR.
. Eleven patients with McArdle's disease (3 male, 8 female; age: 35.5 +/- 13.9 years, height: 166 +/- 8 cm, body mass: 75.2 +/- 13.1 kg) were recruited for the study. The patients walked initially at 0.42 m/s, increasing by 0.14 m/s per 3 min stage. Exercise was terminated when participants completed 3-minutes at 1.80 m/s or when a Borg CR10 pain scale rating of "4" was reached. Stages were separated by 60 s for capillary blood sampling for analysis of hGH and blood lactate concentration.
Results. McArdle's patients' blood lactate levels remained at resting levels (0.3 - 1.2 mM) as exercise intensity increased. Nine out of eleven participants failed to demonstrate an EIGR obtaining hGH values below the clinical definition of a response (>3 microg/L).
Conclusion. The absence of an EIGR in nine out of eleven participants suggests that lactate could play a major role in the EIGR in humans.

So where do these 2 new studies take us?

  • A single 30-s sprint is a potent physiological stimulus for growth hormone (GH) release;
  • Increased blood lactate seems to be a primary stimulus for exercise induced GH release....
    • so to promote GH release you must train such as to increase blood lactate....i.e. beyond your lactate threshold this is not gentle jogging but hard work or intervals;
  • In repeated intervals the the second (third, fourth etc) elicit a lower GH response, probably due to lipolysis (fat burning) and therefore elevated systemic free fatty acids (FFA)
Anyone out there have any bright ideas about these bits of research and how we can use them?


Mark Reifkind said...

yet another reason I like the low rep, multi set, hi force methods of also increases test levels I beleive.
the kb is a natural for this type of training; Hardstyle of course!

freemymac said...
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Anonymous said...

I heard that the current issue of OnFitness magazine talked about "burst training", basically a 1 minute max effort burst spread out through the day, with presumably ample rest in between. Seems to jibe with your post.

Anonymous said...

Would it be correct to draw the conclusion that exercisers who want to shed excess body fat should not take large doses of vitamin B-3 (niacin, a.k.a. nicotinic acid)?

Chris said...


avoid large doses of nicotinic acid? Maybe if you are trying to max GH?

Phillip said...

Not sure if you have covered this yet.... Wonder how much duration is too much? 10 to 30 seconds seems ideal. Can you actually decrease GH by training too hard, too long, too often? This report seems to indicate diminishing returns beyond the first 30 sec effort.

Chris said...

Good point Philip - definitely appears to be something of diminishing returns. I suppose there are complexities here - training isn't all about GH. There are other things we are wanting to promote too - e.g. VO2 max

Still another reason to think short and intense rather than long and easy.

Chris said...
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