As you are probably aware, the first step in muscle growth is an increase in protein synthesis and a decrease in protein breakdown. Our hormones are directly involved with both protein synthesis and breakdown and in fact, play a major role. The hormonal system supports normal function of the body and helps it respond to external stimuli such as heavy resistance training. Hormones are chemical messengers that are made, stored and then released into the blood by different endocrine glands, such as pituitary, thyroid, adrenal etc.

The aim of any serious resistance training is to promote tissue growth by increasing the amount of anabolic hormones released into the body. These include: testosterone, insulin, growth hormone and IGF (Insulin-Like Growth Factors). Catabolic hormones on the other hand, are the enemy of resistance training. These types of hormones include: cortisol and progesterone, which contribute to the breakdown of muscle protein, to be used for glucose (energy) synthesis. (1)

Hormones are secreted during and after resistance training. Muscle remodeling takes place due to these hormonal secretions, and our aim is for these hormonal changes to be of the anabolic variety. In the situation where you had a heavy training session, catabolic actions in the muscles may occur as a result of the inability of anabolic hormones to bind to the receptors.(2)

Examination of the main hormones involved in resistance training and the ways in which to increase their anabolic output, while also limiting the role of catabolic hormones, will help when determining the appropriate training program.

TESTOSTERONE (Anabolic)
Testosterone is the primary hormone that interacts with skeletal muscle tissue. Testosterone's role is paramount in muscular development. Most research has been undertaken on male subjects and although there are variations between the different genders, similar training protocols can be followed, even though women have 15-20 times lower testosterone concentrations than men.

To increase testosterone levels, the following NSCA (National Strength and Conditioning Association, USA) suggestions should be incorporated into your training program.

-Testosterone levels are typically highest in the morning and drop with time during the day. This makes gains in the morning easier, but if you train in the afternoon your total testosterone levels will be higher throughout the entire day, since resistance training according to the below guidelines actually increase testosterone output.
-Undertake training using predominantly large-muscle group exercises such as squats, deadlifts, pull-ups/chins, etc
-Perform high intensity, heavy resistance (85%-95% of 1RM) OR combine high volume, multiple sets of an exercise with short rest periods (30sec-1min).

GROWTH HORMONE (Anabolic)
Growth Hormone (GH) also known as somatotropin is naturally secreted by the pituitary gland. GH is vital in the normal development of children, but it is also a major link in adapting muscles to resistance training. There are many synthetic GH supplements on the market today and some do hold some value, however exercise-induced GH secretion is very different from GH injections. The hypertrophy (muscle building) seen from exercise induced GH shows a much higher force production (ability to lift heavier weight) than synthetic GH.(3)

The major physiological uses of Growth Hormone are:
-decreased use of glucose and an increased use fat breakdown (lipolysis)
-increased protein synthesis and enhanced immune function
-increased use of fats

The largest increases in GH levels are seen while undertaking the following training guidelines. (4)
- 10 repetitions at heavy resistance
- 3 sets of each exercise
- 1 min rest intervals
- Consume both carbohydrates and protein before and after workouts.
- Perform interval type of cardiovascular exercise at high intensity, as detailed scientifically in the comprehensive book - Ready, Set, Go, Synergy Fitness for Time-Crunched Adults, by Phil Campbell, MS, MA . (Available exclusively in Australia through our online Health Fitness Shop)

INSULIN-LIKE GROWTH FACTORS, IGFs (Anabolic)
Many of the GH effects are transported through IGFs. IGF-1 is the primary IGF involved with respect to exercise. IGF has a major role in protein synthesis. Responses of IGF-1 to heavy resistance training, however, remain unclear and are currently being investigated by researchers worldwide.

EPINEPHRINE (Anabolic)
Epinephrine is a catecholamine that is secreted by the adrenal medulla and is important in strength and power activities. It is usually one of the first endocrine functions to occur in response to resistance exercise. This hormone acts as the central motor stimulator, peripheral vascular dilator, and enhances enzyme system in muscle. (6)

Some of the physiological functions of epinephrine include:
-increased muscle contraction rate -increased Blood Pressure
-increased energy availability -increased blood flow
-augments the secretion rates of other hormones, such as testosterone.
-Heavy resistance training has been shown to increase epinephrine levels during maximal exercise. (7)

CORTISOL (Catabolic)
Cortisol can be thought of as enemy number one in high intensity training, and thus needs to be avoided. Cortisol also plays a role in suppressing the immune system, which has a negative effect on the recovery and remodeling of muscle.(5) The reason is that cortisol is an extremely catabolic hormone that helps convert amino acids to carbohydrates when glycogen levels in the muscle are low. It is vitally important for survival circumstances, but for resistance training it limits muscle protein synthesis and therefore muscle growth. The major problem with limiting cortisol is that the same resistance training protocols, short rest periods and high training volume, that promote GH release, also increases cortisol. This is like giving four quarters and receiving a dollar. The preliminary conclusion is that you have not gained on the original situation. This paradox can be alleviated substantially by consuming a higher protein diet, as well as obtaining sufficient rest between training sessions. This rest should include at least eight hours of restful or uninterrupted sleep per night.

As you can see it is not easy to obtain an anabolic state while limiting cortisol. To reduce the release of cortisol a quality diet of carbohydrates and protein before and after each workout is essential to help promote testosterone, GH, IGF and Epinephrine levels. Always remember to vary your workout routine in order to prevent the chronic catabolic responses that can occur when too much cortisol is released, often in an overtraining state.

Want to know more about exercising effectively, whilst increasing your Growth Hormone levels naturally?

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References:

1) Baechle T.R., & Earle R.W., eds. Essentials of Strength Training and Conditioning, 2nd Ed. Human Kinetics. 2000. p.95
2) Deschenes M.R. et al. Endurance and resistance exercise induce muscle fiber type specific responses in androgen binding capacity. J. Steroid Biochem. Mol. Biol. 50(3/4):175-179, 1994
3) Goldberg A.L., & Goodman H. Relationship between growth hormone and muscular work in determining muscle size. J. App. Physiol. 200:655-666. 1969
4) Kraemer, W.J., et al. Hormonal and growth factor responses to heavy resistance exercise. J.Appl. Physiol. 69(4): 1442-1450. 1990.
5) Baechle T.R., & Earle R.W., eds. Essentials of Strength Training and Conditioning, 2nd Ed. Human Kinetics. 2000. p.112
6) Kramer, W.J. et al. The effects of high intensity cycle exercise on sympatho-adrenal medullary response pattern. J. Appl. Physiol. 70:8-14, 1991
7)Kramer, W.J. et al. Changes in plasma proenkephalin peptide F and catecholamine levels during graded exercise in men. Proc. Nat. Acad. Sci. USA 82:6349-6351. 1985