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Life Extension Magazine

Life Extension Magazine March 2009
Reports

Enhancing Growth Hormone Naturally

Glycine Supports Healthy Sleep, GH Release

Glycine Supports Healthy Sleep, GH Release

Since GH secretion occurs primarily at night, ensuring good sleeping habits is essential for individuals seeking to optimize their natural levels of GH. Unfortunately, one-third of adults report at least occasional bouts of insomnia, and about one-third of them suffer from sleeplessness or disturbed sleep on a more chronic basis, to the point that it regularly impairs daytime functioning. For the millions of sleepless among us, there may be good news—in the form of an inexpensive, naturally occurring amino acid known as glycine.

Within the central nervous system, glycine functions as an inhibitory neurotransmitter, playing a well-documented and critical role in initiating normal patterns of REM sleep.51 Now, a new study of chronic insomniacs demonstrates that glycine administered orally just prior to bedtime significantly improves sleep quality, shortening the latency between sleep onset and initiation of slow-wave (deep) sleep as measured by polysomnography. Volunteers also reported less daytime sleepiness, a subjective finding that was objectively corroborated by improved performance on cognitive tasks testing memory recognition.52

Declining GH Levels and Poor Health

There are a number of lifestyle factors that lead to decreased GH and IGF-1 secretion. For example, multiple studies indicate that central adiposity (the accumulation of central body fat) accurately predicts GH decline.65-68 In addition, it is well established that poor nutritional status, inadequate sleep, and lack of physical fitness can all contribute to decreases in circulating GH and IGF-1, regardless of age.60

Individually or in combination, poor nutritional status, inadequate sleep, and lack of physical fitness negatively impact body composition, bone strength, athletic conditioning, and cognition—independent of their effects on serum GH levels.42

It seems clear that an unhealthy lifestyle contributes to somatopause both directly, by causing profound reductions in GH secretion, as well as indirectly, by promoting the physical and psychological symptoms of accelerated aging.

These findings build on previous work showing that a supplement cocktail containing glycine, glutamine, and niacin (vitamin B3) significantly increases endogenous GH secretion in healthy, middle-aged men and women. Individual test subjects in the study who demonstrated a concomitant increase in IGF-1 also exhibited improved memory and vigor.53

Lifestyle Techniques to Naturally Boost Endogenous GH Secretion

Healthy lifestyle practices are an essential component of a program to enhance endogenous GH production. The most important techniques for optimizing GH levels include:

1. Deflate the spare tire. If you happen to suffer from fat stores concentrated centrally around the organs of the abdominal region, GH secretion will be even more impaired. Fortunately, research indicates that declining GH due to body fat gain is partially reversible with weight loss.54 Unfortunately, visceral adiposity is often an indicator of both insulin and leptin resistance and, as a result, can be very difficult to shed permanently. Fortunately recent work has led to the discovery of effective, natural methods for combating leptin resistance.55-58 For more information, see: “Deflating your spare tire for a longer, leaner life…Understanding the risks of leptin resistance” Life Extension, February 2009,58 and “Vindication” (How correcting a testosterone deficit can reduce abdominal adiposity), Life Extension, December 2008.59

2. Avoid high-glycemic-load carbohydrates. Insulin is a powerful, direct inhibitor of GH secretion.42,60 To prevent the unhealthy surges of insulin or “insulin spikes” that decrease endogenous GH levels and increase your risk for type 2 diabetes, avoid highly processed carbohydrates like refined white bread and sugary cereal, as well as high-glycemic-load foods such as white rice, potato chips, cookies, soda, and commercially processed fruit juices (high in fructose and devoid of fiber). Instead, emphasize nutrient and fiber-rich whole fruits, vegetables, nuts, and legumes (beans).61

3. Insist on a good night’s sleep. The majority of GH secretion occurs at night during slow-wave (deep) sleep. Along with high-intensity exercise, another natural stimulus of endogenous GH secretion is sleep itself. It is well documented that inadequate sleep, irregular sleeping patterns, and poor quality sleep can substantially inhibit GH secretion.1,42 To optimize sleep, maintain good sleep hygiene habits: keep to a regular bedtime and wake up time; do not consume alcohol or caffeine 4-6 hours before bedtime; and keep excess light and noise out of the bedroom.

4. Plan your last meal of the day carefully. Your last meal of the day is the most important for maintaining a robust GH/IGF-1 axis. A high-protein, low-carbohydrate snack before bedtime serves a dual purpose. First, it helps minimize insulin release and allows for maximum endogenous GH secretion. Second, important essential and conditionally essential amino acids found in protein assist endogenous GH secretion.42-44

Harnessing Your Lactate Threshold

At some point, depending on exercise duration and intensity, the rate of lactic acid formation in your muscles becomes greater than the rate of dispersion. This is known as the lactate threshold, and can usually be elicited at activity levels that demand between 80% and 90% of a trained athlete’s maximum heart rate.

One of the easiest ways to surpass your lactate threshold is through resistance training, but you do not have to lift heavy weights to take advantage of increased endogenous GH. Several studies have shown that circuit training, which utilizes relatively light resistances, can be just as effective at driving GH release as a more strenuous workout.64,69,70 Intuitively, circuit training might seem less intense than power training. However, circuit training calls for an increased number of repetitions per set and the rest periods between consecutive sets are often considerably shorter, typically on the order of zero to 30 seconds, versus a minute or two for heavier lifting.

If longer-duration, lower-intensity “cardio”-type activities such as running, cycling, or swimming are more your cup of tea, you may need to enhance your workouts to generate optimal GH secretion during exercise. Punctuating your usual, lower-intensity cardio routine with brief, all-out sprints every three to five minutes will rapidly push you to your lactate threshold.

5. Stay active! Exercise is a significant, natural optimizer of GH secretion.62 The type of exercise you do, as well the intensity and duration of your workouts, all play an important role in determining to what degree your training regimen contributes to GH secretion. A number of studies have suggested that the intensity necessary to trigger exercise-induced GH release corresponds to the lactate threshold—the exercise intensity at which lactic acid accumulates in the blood.63 Exercise training above the lactate threshold appears to amplify the pulsatile release of endogenous GH at rest, increasing total secretion for at least 24 hours.64

Conclusion

The plentiful growth hormone levels of youth are associated with strength, good health, and vitality. However, given the high cost and mixed study results associated with recombinant GH injections, optimizing lifestyle choices to enhance endogenous GH production may represent the most intelligent way to benefit from this youthful hormone. Through weight management, exercise, healthy sleep habits, minimizing intake of high-glycemic-load carbohydrates, and consuming targeted nutrients such as CDP-choline, niacin, glycine, glutamine, arginine, and ornithine, you may safely and cost-effectively capture the many benefits of naturally high GH levels.

If you have any questions on the scientific content of this article, please call a Life Extension Health Advisor at 1-800-226-2370.

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