Strength Research Tid Bits Vol II - Hormones

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Strength Research Tid Bits Vol II - Hormones

Postby Canuck Singh » Tue Jul 08, 2008 6:23 pm

GH, IGF
To grow muscle, growth hormone (GH) is needed to produce insulin-like growth factor (IGF). The GH/IGF pathway is stimulated by intense resistance training and is thought to be at least partially responsible for gains in muscle mass. This study determined the effects of resistance training on circulating IGF-1 levels and compared single-set and multi-set training.

Thirty-one men and women completed 25-weeks of weight training (three sessions a week). One group performed a single-set of each exercise, another group performed three sets of each exercise each training session. The rest of the subjects served as a control group. Before and after 13 and 25-weeks of training, blood hormones and strength were assessed.

Results showed that during the first 13-weeks of training, circulating IGF-1 increased by approximately 20% in both the one and three-set groups, but no further increases were seen after that. Increases in strength occurred concurrently within the first 13-weeks of training and were significantly higher in the group performing three sets compared to the group performing single set training.

These findings indicate that circulating IGF-1 increases may occur during the initial stages of a strength training program. These increases in IGF probably mediate some of the gains in strength witnessed. Increases in this growth factor seemed to plateau after 13-weeks of training.

Ref: Med. Sci. Sports Exerc. 33;4:648-653, 2001
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Re: Strength Research Tid Bits Vol II - Hormones

Postby Canuck Singh » Fri Jul 18, 2008 2:12 pm

One or more sets for optimal Growth?

Single set training or multiple set training—which is more effective? Recent research on experienced lifters gives further insights into this question.

In this research, two groups of trainees participated in either a low-volume (one set with heavy weight) or higher-volume (three sets with heavy weight) strength training program for 25-weeks. The aim of the research was to investigate the effects of these training volumes on muscle strength gains, insulin-like growth factor-1 (IGF-I) and its two major binding proteins, IGFBP-1 and IGFBP-3.

IGF-1 is the growth factor that builds big muscle. A combination of intense weight training and a diet rich in protein and carbs after training prolong its potent effects. In the results from this research, both groups showed a 20% increase in IGF-I levels during the first 13-weeks of training. However, after this, no further increases were noted by the researchers.

Interestingly, the three-set training group showed a 20% decrease in IGFBP-3 binding protein, and significantly better strength gains. The decrease in binding protein means more bioactive IGF circulating in the system. Maybe this is why the three-set group produced better gains from training than the single set group.

These findings indicate that multiple sets are required to promote a high secretion of active IGF. It also appears that a short break from training is required after 10 or so weeks to restore peak IGF-1 secretion.

Borst, S.E., et al. Med. Sci. Sports Exerc. 33(4):648–653, 2001.
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Re: Strength Research Tid Bits Vol II - Hormones

Postby Canuck Singh » Fri Jul 18, 2008 7:39 pm

Most athletes know that intense exercise triggers the release of growth hormone (GH) and anabolic growth factors such as IGF-1 within the body. Now research shows that men with high fitness levels secrete more of these potent anabolic hormones in response to exercise, and they have higher resting levels compared to sedentary men.

In this study, seven men who perform regular, intense exercise were compared with seven age-matched sedentary men during two exercise trials (cycling 60 minutes) at varying intensities. Circulating GH, IGF-1, insulin and glucose levels were monitored during and after the workouts.

Results showed that the men who perform regular, intense exercise had greater insulin sensitivity and glucose regulation. These men also exhibited higher levels of GH and IGF-1 in response to the bout of exercise. Consequently, these men also showed higher resting concentrations of these hormones compared to males who didn’t exercise regularly. The scientists concluded that exercise training increased the activity of the GH/IGF-I system in men and this results in greater GH/IGF-1 output.

Although this study was performed on older men (mean age 51), I see no reason why these results would not apply to men aged in their 40s or even 30s - the age when circulating levels of these anabolic hormones start to decline. The fit men in this study performed regular intense cardio work.

Ref: American Journal of Physiology. 283 5 E929-E936 2002.
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Re: Strength Research Tid Bits Vol II - Hormones

Postby Canuck Singh » Sat Nov 01, 2008 3:43 pm

Science is making great inroads regarding understanding the mechanisms that directly increase muscle mass and enhance athletic performance. We now know to gain muscle mass it is a case of maximizing the positive factors that increase protein synthesis while minimizing those that influence protein breakdown.

According to a recent review (Houston 1999) the positive factors are: testosterone, growth hormone, insulin, IGF-1,a positive energy balance, post exercise carb/protein meals, intense resistance training and adequate recovery from it. The negative factors that must be minimized for any growth to occur are: cortisol, a negative energy balance, not eating after exercise, too much exercise and inadequate recovery between workouts.

* The resistance training should directly stress the major muscles of the body. The majority of weight training research suggests the programs that stress muscle energy systems most severely, producing the ‘greatest displacement from the resting state’ are the most effective. (Fleck & Kraemer 1997)

* The stimulus of weight training sets the stage for your body to produce an optimal hormone profile for growing muscle. However a post training high protein and carbohydrate meal potentiates the muscle building effects of weight training even further. A high protein/carbohydrate meal consumed directly after training is proven to directly counteract the catabolic effects of training and optimize the levels of all anabolic hormones including the most anabolic hormone of all - insulin.(Chandler et al. 1994)

* A positive energy balance is required to produce gains in lean body mass. It also promotes muscle protein synthesis. The athlete must take in more food energy than is needed to maintain energy balance. (Houston 1999)

* A lot of protein is needed, every day. Forslund et al.(1998) demonstrated that for physically active men, more than 3 times the RDA for protein resulted in a significantly greater stimulus to muscle protein turnover (the prerequisite mechanism of building muscle) than the meager recommended dietary allowances.

* Protein synthesis rates and amino acid transport rates after training are dramatically stimulated for up to 48hrs after one hard session with the weights. If an abundant, external supply of amino acids is present during this time frame, dramatic increases in protein synthesis rates and muscle amino acid uptake are witnessed. This ensures muscle protein is being deposited. (Bolio et al.1997) Therefore small frequent meals of easily assimilated protein throughout the day and night are a necessity. They maintain high blood levels of amino acids that maximize the effect of this anabolic mechanism.

* Adequate recovery between training sessions is extremely important. The damaging effects of intense resistance training on muscle persist for 5 days or more.(Stauber and Smith 1998.) Be aware of how much work smaller muscles like front deltoids and rotator cuff muscles have to contend with during a full week's training. You may actually be hitting these muscles 3 or 4 times a week!

Bolio G et al. Am.J.Physiol.273:E122-E129,1997
Chandler RM et al. J.Appl.Physiol.76:839-845,1994.
Fleck SJ & Kraemer WJ. Human Kinetics. 1997.
Forslund AH et al. Am.J.Physiol.275:E310-E320
Houston ME. Can.J.Appl.Physiol.24(4):305-316, 1999.
Jebb SA et al. Am.J.Clin.Nutri.64:259-266,1996
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Re: Strength Research Tid Bits Vol II - Hormones

Postby Canuck Singh » Sat Nov 15, 2008 12:35 pm

Research does show that the magnitude of the hormonal response (that is the secretion of testosterone, GH and IGF) from training depends upon;

1. The amount of muscle stimulated and the degree of repair and remodeling of muscle fibers induced by the exercise program (1).

2. The amount of high threshold motor units activated and the recruitment of type II muscle fibers (the ones that grow the biggest), to produce the greatest amount of force(2,3).

3. Use of only heavy external loads to activate the high threshold motor units, which in turn stresses the sarcolemma, consequently, increasing anabolic hormone levels (4,5).

4. Finally, muscle hypertrophy is seen only by utilization of progressive, heavy resistance overload (6).

5. Much of the research regarding males and strength training show higher concentrations of testosterone are synonymous with the development of muscle strength and hypertrophy(7).

Equally as important, is diet pre and post training. Diet appears to make or break any hormonal response from weight training. Pre and post training nutrition has a profound impact on the anabolic hormone profile of building muscle. It prolongs the effect of some hormones and manipulates other hormones crucial to muscle growth such as insulin and cortisol(8).

The bottom line; the degree of intensity and overload used is the overriding factor in activation of the entire anabolic hormone milieu. However, if your dietary approach is not optimal, even the most demanding session will amount to nothing!
1. Kraemer WJ. Essentials of Strength and Conditioning. Pages 86-107. Human Kinetics, 1994.

2. Staron RS, Leonardi MJ, et al. J.Appl.Physiol.70(2):631-640,1991.

3. Staron RS, Malicky ES, et al. Eur.J.Appl.Physiol.60:71-79,1989.

4. Kraemer WJ, Fleck SJ, etal. J.Appl.Physiol.75(2):594-604,1993.

5. Kraemer WJ, Gordon SE, et al. Int.J.Sports Med. 12(2):228-235,1991.

6. Cureton KJ, et al. Med. Sci. Sports Exerc.20(4):338-344.1998.

7. Taylor JM, et al. J. Strength & Condit. Res.14(2):220-227,2000.

8. Kraemer WJ, etal. J.Appl.Physiol.85(4):1544-1555,1998
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