Zma Info

[blaxican25]

ZMA: Is This Prohormone Alternative Worth it?

Edmund R. Burke, Ph.D.

Many strength and power athletes are taking notice of a supplement called ZMA, a patented, trademarked product sold as a natural alternative to prohormones such as androstenedione and androstenediol. These prohormones, used to add lean body mass and increase strength, are banned by many sports organizations. ZMA combines zinc monomethionine aspartate (30 mg), magnesium aspartate (450 mg), and vitamin B6 (10.5 mg) in a formula designed to enhance muscle strength, endurance, healing, and recovery. To date, however, only one published abstract supports these claims. Furthermore, published studies suggest that magnesium alone may generate similar results as those claimed by this product.

Essential Zinc and Magnesium
Zinc is an anabolic mineral required for production of growth hormone and testosterone, which promote tissue repair, healing, and muscle growth. Magnesium helps transport oxygen to muscle tissue, thereby promoting strength, endurance, and relaxation. Magnesium also activates enzymes necessary for metabolism of carbohydrates and amino acids. In vitro, vitamin B6 potentiates zinc's inhibitory effect on the enzyme 5A-reductase, which converts testoerone to dihydrotesterone. This conversion interferes with testosterone's anabolic effects in the body, so the combined supplements keep testosterone around longer.1

Researchers have examined the effects of zinc supplementation on muscle strength and endurance using isometric and isokinetic tests in the knee extensor and flexor muscle groups. In a 14-day, double-blind, placebo-controlled study of 16 female volunteers, 135 mg/day zinc significantly increased muscle strength and endurance compared to placebo.2 However, this is an enormous and potentially unsafe dose of zinc, although no adverse effects were reported.

Magnesium is essential for energy production by both aerobic and anaerobic metabolism, as well as muscle-protein formation and regulation. A magnesium deficiency can cause muscle weakness and cramps. Magnesium supplementation, on the other hand, also has been shown to increase muscle strength.

In a 1992 double-blind, placebo-controlled study in the exercise and sport science laboratory at Western Washington University in Bellingham, researchers first analyzed three-day diet records of 26 college students and then calculated their magnesium intake. One group of 12 supplemented with magnesium oxide to bring their magnesium intake, including diet, to 8 mg/kg body weight/day. The remainder received placebo. During the seven-week trial, subjects participated in a strength-training program. Results showed that the supplemented group significantly increased peak quadriceps torque, measured by leg presses, by 26 percent compared to 10 percent for the placebo group.3 Furthermore, German researchers have found that 300 mg/day magnesium enhances sleep efficiency, at least in those older than 50.4

These results indicate that even simple magnesium oxide can be absorbed and produce a positive effect. The results suggest that this form of magnesium could perform just as well as ZMA.

Why ZMA?
ZMA?as well as zinc alone?has been shown to increase anabolic hormone levels, including free testosterone and IGF-1 (insulinlike growth factor), hormones that may be suppressed in hard-training athletes.

The ZMA study most often cited as evidence of efficacy was co-investigated by Lorrie Brilla, Ph.D., at Western Washington University, and Victor Conte of Balco Labs in Burlingame, Calif. Conte is the inventor and patent owner of ZMA. Brilla and Conte studied 12 NCAA division II football players who took ZMA nightly during an eight-week spring training program. A separate group of 15 took placebo.

In the athletes taking ZMA, researchers measured a 30-percent increase in both free and total testosterone. (Free testosterone exists in blood; total includes levels in blood and in cells.) Testosterone levels in the placebo group declined by 10 percent, a result of hard training. The placebo group displayed a 21.5 percent decline in blood IGF-1 levels, while there was no significant change in the ZMA group.

In addition to improvements reported in anabolic hormone levels and sleep quality, the athletes made significantly greater gains in muscle strength and power. After eight weeks of training, the ZMA group experienced an 11.6 percent increase, compared to a 4.6 percent increase in the placebo group.5

The muscle-strength increase may have been mediated by the anabolic hormone increases in the ZMA group, or could have been mediated by the magnesium- improving muscle energetics, neural signaling, or both.6

Ultimately, the anabolic hormone increases are not important to athletes if they do not get more muscular. There were no changes in body weight in either the ZMA or placebo groups, suggesting that ZMA has no effect on muscle mass. However, there was a notable increase in strength and power. Thus, the observed increases with ZMA are no more striking than the increases observed with magnesium oxide. Clearly, more research is needed before trumpeting the effectiveness of ZMA.

Exercise Caution
Because calcium interferes with zinc and magnesium absorption, no ZMA, zinc, or magnesium supplements should be taken with dairy products or other calcium-containing foods or supplements. In addition, it is important to avoid high doses of zinc; several studies indicate that 50 mg zinc or more per day may reduce levels of copper, HDL (good) cholesterol, and even the antioxidant enzyme superoxide dismutase (SOD) in as few as 14 days. Magnesium has a low order of toxicity, although excessive intake may lead to diarrhea.

The results of the limited, preliminary research on ZMA offers evidence that magnesium supplementation may help healthy young men enhance their athletic performance. The research linking zinc to performance is tenuous. Zinc depletion appears to reduce muscle endurance (but not peak strength/force), and unsafe doses of zinc after depletion do not reinvigorate lost muscle endurance despite correcting blood-zinc concentrations.7

ZMA is marketed as a natural testosterone-boosting supplement for athletes, an alternative to androstenedione. Because ZMA is not a prohormone or hormone precursor, it does not adversely affect blood hormone levels. Certainly ZMA costs less than androstenedione, but whether it is more beneficial than magnesium is still uncertain.

[Illadelphia]

not sure what the point of this thread is, hines ward?

[MikeCellucor]

Libido and Sleep are improved for me. Two essential mineral in decent forms. If you get it cheap...its worth it. Dont buy into the MASS game....its just icing on the cake, especially since most elite athletes are found zinc deficient even while taking supplemental zinc.

[BigPumpinJoe]

It can be a very useful supplement for some but for me all it did was wake me up in the middle of the night and give me the wierdest dreams at times. ZMA is usually cheap anyway so I guess give it a try.

[Speedbuff]

RESEARCH SUPPORTIVE OF ZMA SUPPLEMENTATION

1. The effect of zinc depletion on muscle function was tested in 8 male subjects. After receiving 12 mg Zn/day for 17 days, the subjects received 0.3 mg Zn/day for either 33 or 41 days. The subjects were then divided into two groups for zinc repletion. Group A subjects received overnight infusion of 66 mg of Zn on Day 1 and 10 and then were fed 12 mg Zn/day for another 16 days. Group B subjects were fed 12 mg Zn/day for 21 days. Peak force and total work capacity of the knee and shoulder extensor and flexor muscle groups were assessed using an isokinetic dynamometer at baseline, at two points during depletion, and at repletion. Plasma zinc levels decreased by an average of 67% during depletion and remained 9% below baseline after repletion. The peak force of the muscle groups was not found to be significantly affected by acute zinc depletion, however, shoulder peak force (strength) was found to be reduced by 9.2% in the extensor muscles. Total work capacity (muscle endurance) for the knee extensor muscles and shoulder extensor and flexor muscles declined significantly by 28.1%, 24.1% and 26.4%, respectively. This study demonstrates that muscle endurance, or total work capacity, declines rapidly with acute zinc depletion and the degree of the decline was correlated with the reduction in plasma zinc concentration.

Van Loan, MD, et al. The Effects of Zinc Depletion on Peak Force and Total Work of Knee and Shoulder Extensor and Flexor Muscles. Int J of Sport Nutr, June 1999, Vol. 9, No. 2, 125-135.

2. A study was conducted to determine the effects of magnesium supplementation on strength development during a double-blind, 7-week strength training program in 26 untrained subjects (14=placebo, 12= Mg), 18-30 years old. Pre and post peak quadriceps torque (leg press) measurements were made using an isokinetic dynamometer. The leg muscle strength of the magnesium supplemented group significantly increased by 26%, compared to only 10% for the placebo group.

Brilla, LR, et al. Effect of Magnesium Supplementation on Strength Training in Humans. J Am Coll Nutr, July 1992, Vol 11, No. 3, 326-329

3. Serum zinc levels were determined in 160 training athletes (103 males and 57 females). In 23.3% of male and 43% of female athletes, serum zinc was significantly below the "normal range".

Haralambie, G. Serum zinc in athletes in training. Int J Sports Med 2 (1981) 135-138.

4. Magnesium, zinc and copper status of 270 US Navy Sea, Air and Land (SEAL) trainees was determined from dietary intakes and biochemical profiles. The dietary intakes of 34% and 44% of the trainees were below the RDA for Mg and Zn, respectively. The blood plasma concentrations of Mg and Zn were significantly below the "normal range" for 23% and 24% of the trainees, respectively.

Sing A, et al. Magnesium, Zinc and Copper status of US Navy SEAL trainees. Am J Clin Nutr 1989;49:695-700.

5. Serum zinc levels were measured in 20 adolescent gymnasts (9 boys, 11 girls, age 12-15). They had 26% lower serum zinc levels (0.599 +/- 0.026 mg/l) when compared to 118 matched controls (0.810 +/- 0.014, p < 0.001). The gymnasts serum zinc levels were positively correlated with adductor strength (r=0.468, p < 0.05). The 11 of 20 gymnasts with serum zinc < 0.6 mg/L had lower insulin-like growth factor binding protein 3 levels than the others (2.326 +/- 0.064 vs 2.699 +/- 0.12, p < 0.01). This protein is supposed to reflect growth hormone activity. Thus, zinc is lowered in trained adolescent gymnasts and this reduction could play a role in abnormalities of growth or muscular performance.

Brun J, et al. Serum zinc in highly trained adolescent gymnasts. Bio Trac Elem Res, 1995, Vol. 47, 273-278.

6. Twenty-one professional football (soccer) players underwent a maximal exercise test on a cycloergometer, with progressively increasing workloads until VO2max. On the whole these subjects had low serum zinc because nine (43%) of them had a hypozincemia (0.54 +/- 0.01 mg/L) which suggested a zinc deficiency. The subjects with low serum zinc had a 26% lower power output (123 +/- 8.71 vs. 166.27 +/- 14.84 watts, p = 0.029) and exhibited a 35% higher increase in blood lactate (lactic acid) during exercise (7.51 +/- 0.81 vs. 5.57 +/- 0.33 mmol/L, p <0.04) resulting in a 24% lower 2 mmol lactate threshold (44.7 +/- 3.9% vs. 58.9 +/- 4.8% of maximal power output p < 0.04). In conclusion, this study suggests that zinc status may influence blood rheology (flow) during exercise by an effect related to lactate accumulation.

Khaled S, et al. Serum zinc and blood rheology in sportsmen (football players. Clin Hemo and Micro 17 (1997) 47-48.

7. Ten collegiate basketball players serum mineral levels were measured before official practice began and immediately following the competitive season. Diets were monitored and remained the same throughout the four month period. Mean serum values for Mg and Zn decreased pre-season to post- season by 16% and 41%, respectively.

Lefavi RG, et al. Reduced serum mineral levels in basketball players after season. Med and Sci in Sports and Exer. Vol. 27, No. 5, May 1995

8. Twelve professional volleyball players and 12 control subjects were studied to determine the effects of daily physical training on serum, sweat and urine zinc concentrations. The professional athletes trained every day in two sessions, one in the morning (work in the gym for 2 hours) and another in the afternoon (specific work on the sports field for 3 hours). Simultaneously, 12 male volunteer university students, who were moderately trained, participated as the control group. The study was conducted over a period of 10 weeks. Pre-post tests were made using a progressive bicycle ergometer (increasing 30 W every 3 minutes to reach a maximum tolerated power). Pre-post blood samples were obtained at rest and immediately following exercise. After ten weeks of training, the professional athletes showed a significant increase in 24 hour urinary zinc excretion (22% greater losses), in contrast to a slight decrease (2% less) in the controls. The athletes also showed a very significant increase in the zinc loses in sweat compared to the controls. The athletes sweat zinc concentrations increased by an astounding 300%, compared to only 30% increases in the control group. The athletes serum zinc levels decreased by 4%, compared to a 2% decrease in the control group. Finally, the post exercise cortisol levels of the athletes significantly increased by 93%, compared to only an 18% increase in the controls. The authors stated that the athletes "cortisol levels increased in response to the exercise work load stress, and this behavior seems to be related to muscular damage". The authors went on to say that "It seems that the changes in zinc metabolism found in the study may be damage, increased protein turnover and increased zinc excretion (via sweat and urine). Because strenuous exercise during a period of competition can induce a "catabolic state" and has been shown to increase skeletal muscle protein turnover, it is likely that urine zinc is derived from muscle tissue". The authors concluded by saying that "Zinc supplementation and/or stress control appear to be indicated in athletes. In our practical opinion, we think that alterations in zinc metabolism with increases in zinc excretion and stress levels lead to a situation of latent fatigue with a decrease of endurance".

Cordova A, et al. Effect of training on zinc metabolism: changes in serum and sweat concentrations in sportsmen. Ann Nutr Metab, 1998 42:5, 274-82.

9. Plasma zinc, iron, copper and selenium levels were measured in 66 Navy SEAL trainees before and after a 5 day period of sustained physical and psychological stress called "Hell Week". The trainees pre-post plasma zinc levels decreased by 33%.

Singh A, et al. Biochemical indices of selected trace minerals in men: effect of stress. Am J Clin Nutrition 1991; 53:126-31.

10. Nine healthy, male subjects (18-40 years) were supplemented daily with 365 mg of magnesium as aspartate for 14 days. Before and after the supplementation period each subject performed a rigorously identical one hour ergometer exercise. The magnesium supplementation significantly reduced the subjects plasma levels of the catabolic "stress" hormone cortisol by an average of 25% (P < 0.025), which remained decreased during the exercise. The magnesium also significantly lowered the subjects' heart rates throughout the exercise period by an average of 8% (P < 0.03). Golf SW, et al. Plasma aldosterone, cortisol and electrolyte concentrations in physical exercise after magnesium supplementation. Clin Chem Clen Biochem, 1984, Vol. 22, pp. 717-721.

11. Medical students were tested to determine the acute effect of zinc supplementation on cortisol levels. The test was started at 7:00 AM after a 12 hour fast. Serial blood samples were collected from an experimental zinc group and controls at 30 minute intervals for 240 minutes. A subgroup of 7 subjects (3 men, 4 women) ingested 25 mg of zinc immediately after the baseline collection and their cortisol levels were compared to 8 matched controls who received a placebo. The control group started out with an average cortisol level of 11 mcg/dL and fell to 9 mcg/dL at 240 minutes, which is an 18% reduction. The zinc supplemented group started out with an average cortisol level of 16 mcg/dL and significantly dropped to 6.5 mcg/dL, which is a 59% reduction. In summary, the zinc supplemented group had a 41% greater reduction in cortisol levels compared to controls. The fact that zinc inhibits basal cortisol secretion in humans may be related to a direct blockade of cortisol synthesis and secretion in the adrenal cortex.

Brandao-Neto J, et al. Zinc acutely and temporarily inhibits adrenal cortisol secretion in humans. Bio Trace Elem Res, 1990, Vol. 24, 83-89.

12. Nine men participated in an 85 day zinc depletion/repletion study divided into 3 metabolic periods: 18 day baseline, a 44 day depletion, and a 23 day repletion. 12 mg of zinc per day was fed to the men during baseline and were held constant after adjustments during the baseline period. Plasma zinc declined from 77.1 +/- 0.03 mcg/dl at baseline to 28.1 +/- 0.07 mcg/dl at depletion; concentrations returned to 77.9 +/- 0.03 mcg/dl at repletion. Total body weight, fat, fat-free mass (FFM), and bone mineral did not change during depletion, but total body water increased 5.3% +/- 1.9%, or about 2 kg or 4.4 lbs (P <0.05) by the end of the depletion and returned to baseline values at the end of repletion. The percent water in FFM increased from 71% +/- 1 to 75% +/- (P <0.05) at the end of depletion and was associated with a small decrease in body protein. The data suggest that zinc depletion impairs water balance.

Sutherland B, et al, Effect of experimental zinc depletion on body composition and basal metabolism in men. The FASEB Journal, Mar. 10, 1995, Volume 9, Number 4.
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