Directions For ZMA: Take 3 capsules daily for men and 2 capsules daily for women, preferably on an empty stomach, 30-60 minutes prior to bedtime. For best results, avoid taking with foods or supplements containing calcium.
Does exercise effect sleep?
Studies involving the effects of different types and duration of exercise on sleep efficiency have yielded conflicting results. However, in a study of the effects of power exercise on the sleep of a group of trained power lifters, the tendency was for this type of more strenuous exercise to affect sleep adversely (3).* Excessive training has also been reported to cause sleep disturbances as well as mood changes, and the sleep disruption was greater at higher training volumes (4).* In addition, long duration daytime exercise of moderate intensity has been shown to decrease GH and testosterone production during nighttime sleep (5).*
Does age effect sleep?
Sleep quality declines with age, with progressively less time in deep or slow wave sleep (SWS), which occurs during the initial part of sleep. Age related declines also occur in lean body mass, growth hormone (GH) and insulin-like growth factor 1 (IGF-1)(6).* In normal young adults, a major burst of growth hormone occurs shortly after sleep onset, in association with the first period of slow wave sleep. In men, approximately 70% of the daily GH output occurs during this period of early sleep throughout adulthood (7).* Extensive evidence also indicates the existence of a consistent relationship between increased SW sleep (stages 3 and 4) and increased GH secretion and, conversely, between awakenings and decreased GH release. Pharmacological stimulation of SW sleep results in increased GH release, and compounds which increase SW sleep represent a new class of GH secretion stimulators.
How does ZMA effect sleep?
In a study of patients with mild or moderate sleep problems, it was suggested that sleep efficiency was significantly improved with oral magnesium therapy (8).* Researchers have also suggested that chronic sleep deprivation causes magnesium deficiency as well as decreased exercise tolerance. However, these researchers also suggested that that the decreased exercise tolerance observed as a result of sleep deprivation could be significantly improved by oral magnesium administration (9).* ZMA contains magnesium aspartate, which is highly bioavailable, and studies have shown this form to have a superior rate of absorption compared to other forms (10).*
Does exercise effect testosterone levels?
First of all, it's a widely held misconception that exercise increases testosterone levels. In fact, prolonged exercise decreases the production of testosterone by approximately 10% (11). Many studies have reported post-exercise increases in serum testosterone levels, however, what they're measuring is only a temporary false elevation. This is because exercise causes significant decreases in plasma volume, hepatic plasma flow and the metabolic clearance rate of testosterone. This is the reason it's extremely important to measure testosterone levels in a rested state during the early morning as opposed to post exercise. A large percentage of the testosterone secreted daily occurs during sleep and levels peak during the early morning and decrease throughout the day by 25% to an evening minimum (12).
The following analogy may be helpful in explaining the effect of exercise on testosterone levels. Imagine that there's a hose bringing testosterone into a bathtub, which represents testosterone production, and you decrease the flow of the hose by 10%, which represents the effects of exercise. If you restrict the drain flow at the same time by 30%-a reduction in metabolic clearance rate of testosterone-the level of testosterone will briefly appear to be elevated. However, this is only a short-term effect of exercise and clearly represents a false elevation.
Does age effect testosterone levels?
Testosterone levels significantly decline with age. Serum testosterone concentrations were examined from over 4,000 military veterans and their testosterone levels dropped by more than 30% from age 32 to age 44 (13). In another study of over 1,400 men aged 20-60 years old, testosterone levels showed a significant stepwise decrease with age (p < 0.001) starting with the early adult years (14).
How does ZMA effect testosterone levels?
The connection between zinc and testosterone has been known for more than 15 years now. For example, in a study published back in 1982, kidney failure patients, who are typically zinc deficient, were supplemented with zinc for a period of six months, and their testosterone levels increased (15).* In a more recent study conducted in 1996 called "Zinc Status and Serum Testosterone Levels of Healthy Adults", the researchers suggested that 30 mg per day of zinc supplemented to the diets of healthy American men experiencing moderate zinc deficiencies doubled their testosterone levels in 6 months (16).*
An independent study of ZMA was recently conducted at Western Washington University under the direction of sports performance researcher, Lorrie Brilla, Ph.D. A group of 12 competitive NCAA football players who took ZMA nightly during an 8 week spring training program had increases in free and total testosterone levels (1).* How does ZMA effect muscle strength?
In addition to measuring the anabolic hormone increases in the football players, Dr. Brilla measured their muscle strength and functional power increases. Pre and post leg strength and power measurements were made using a Biodex isokinetic dynamometer. The players who took ZMA nightly during the 8 week period of intensive training had greater strength gains than the placebo group.* The ZMA group also had two times greater functional power gains compared to the placebo group (1,2).*
How prevalent are zinc and magnesium deficiencies in athletes?
Zinc and magnesium deficiencies are common in the general population and even more prevalent in athletes. Through an extensive search of worldwide medical research data, we discovered that rigorous exercise and stress results in bodily losses of zinc and magnesium (24).*
In addition, in a study called "Biochemical Indices of Selected Trace Minerals in Men: Effect of Stress," blood (plasma) levels of zinc and other trace minerals were determined in 66 men before and after a 5 day period of sustained physical and psychological stress. Zinc levels decreased by 33% (25)!* In another study called "Magnesium, Zinc and Copper status of 270 US Navy Sea, Air and Land (SEAL) trainees" conducted by the US Department of Military Medicine, it was shown that the blood concentrations of magnesium and zinc were significantly below the "normal range" for 23% and 24% of the trainees, respectively (26).*
Don't athletes get enough zinc and magnesium from foods?
The main reason for baseline deficiencies in the both the general population and in serious athletes is that it's difficult to get proper amounts solely through the intake of whole foods. USDA studies show that 68% of self-selected diets contain less than two thirds of the RDA for zinc (27) and 39% contain less than two-thirds of the RDA for magnesium (28).* While zinc and magnesium are contained in a wide variety of foods, it's been our experience that athletes don't acquire sufficient quantities through their normal diets. One reason may be that foods high in these minerals aren't necessarily the most desirable.* For example, the best food sources for zinc include oysters and beef liver. These foods just aren't consumed by most athletes, nor should they be.
Don't athletes get sufficient zinc and magnesium from their multiple vitamin/mineral supplements?
In a study called "The effect of 7 to 8 months of vitamin/mineral supplementation on the vitamin and mineral status of athletes," blood indicators of eight vitamins (B1, B2, B6, C, E, A, B12, folate) and six minerals (Cu, Mg, Zn, Ca, P) were measured in 86 athletes before and after a 7-to 8 month period of training (29). During this period, half consumed a multi-vitamin/mineral supplement and a matched group took a placebo. Following the supplementation period, blood indicators of B1, B6, B12 and folate status all increased, but there were no effects of supplementation on the blood levels of any of the minerals.* Zero effect! This is may be due to the competitive and antagonistic interactions that prevented absorption.* The authors suggested that "7 to 8 months of multi-vitamin/mineral supplementation did not effect any of the blood mineral levels".*