The Original Muscle Mineral - Magnesium: Magnesium Effects on Exercise
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If you were to ask the average bodybuilder which nutrient was most vital to promoting muscular growth, he or she would likely
answer, "Protein." indeed, the literal translation of the word protein means "of first importance." Few would argue the necessity
of optimal protein intake in the quest for a more muscular body. Truth is, though, that protein, while important, is only part of
the bodybuilding-nutrition equation. You need all the required nutrients to make training progress. That means an array of essential
nutrients other than protein, such as vitamins and minerals.
Some vitamins and minerals are directly linked to building muscle. Most vitamins are coenzymes, meaning that they're part of the
enzyme structure. Minerals, meanwhile, are enzyme activators, which means vitamins without mineral support can be useless. Of the
minerals most linked to building muscle, two stand out. One is zinc; the other is magnesium.
Zinc activates some 200 enzymes in the body, and magnesium more than 300. Many of them are related to magnesium's active role in
the physiology of adenosine triphosphate, or ATE the most elemental energy source. All foods are eventually converted into ATE but
without magnesium ATP activity would be inhibited, leading to a number of possible complications.
Magnesium stabilizes the phosphate bonds in ATEP enabling enzymes that break those bonds to work more efficiently and thus release
actual energy. Any enzyme reaction in the body that requires ATP also requires magnesium.
ATP helps deliver phosphates to other enzymes. Creatine kinase is the enzyme that adds phosphate to creatine, thereby activating it
in muscle. The metabolite AMP, which is made from ATE requires magnesium and is involved not only in hormone release, but also in the
series of reactions that result in fat release from fat cells.
Magnesium acts as a natural calcium regulator in the body and is often called a natural calcium channel blocker because it competes
with calcium for entry into cells. As a result, it's implicated in everything from muscle relaxation to antagonizing calcium's role
in blood clotting.
Magnesium has a close relationship with potassium. Without magnesium, potassium cannot be retained in cells and is excreted from the
body. That's why taking potassium without magnesium doesn't make physiological sense. Magnesium regulates intracellular potassium and
keeps blood potassium within the normal range. Together magnesium and potassium regulate the cellular sodiumpotassium pump and are
involved in creatine uptake in muscle.
Magnesium regulation of calcium and potassium also affects heart function and blood pressure. It influences the stability of cellular
membranes, which are prone to oxidation because of their fat content. Many cardiovascular problems are related to oxidation; magnesium
is an indirect antioxidant. Animals deficient in it show signs of pro- oxidant activity, such as lipoprotein oxidation and a proinflammatory
state linked to many diseases.
Magnesium in the Body
The body's total stores of magnesium are between 21 and 28 grams, about one ounce, in a 150-pound adult. Most of the stored magnesium
is in bones (50 percent), with the remainder in soft tissue. Muscle contains a fourth of the body's magnesium, and a small amount
circulates in the blood. The kidneys control magnesium retention and excrete excess amounts.
The more magnesium you take in at one time, the less your body absorbs. When your body stores of magnesium are low, you absorb considerably
more; the usual absorption rate is 30 percent of the dose. One study found that with an intake of 36 milligrams a day of magnesium, 65
percent was absorbed. When the daily intake increased to 973 milligrams, the absorption rate dropped to only 11 percent.
Several substances are known to favor or hinder magnesium absorption. Fructose and fermentable carbohydrates favor magnesium uptake, and
excessive fiber intake may slightly blunt absorption. Natural food elements, such as phytates from wheat and oxalates from vegetables,
could impair magnesium uptake by forming an insoluble complex with the mineral, but the chlorophyll in many vegetables forms its own complex
with magnesium, favoring absorption. Too much zinc also may interfere with magnesium uptake. Moderate protein intake boosts magnesium uptake,
while getting more than that impairs it.
Excess intake of fat, refined sugars and alcohol, as well as the use of diuretics, can promote magnesium excretion. Many bodybuilders have
experienced painful muscle cramps after taking diuretic drugs, such as Lasix. That's because the drugs trigger the excretion of sodium, water,
magnesium and potassium, and mineral loss is what causes muscle cramps. Use of high-dose thyroid drugs, such as Cytomel, also promotes
magnesium losses. When magnesium is deficient, the body secretes more aldosterone, an adrenal hormone that encourages sodium retention along
with potassium and magnesium excretion- leading to a vicious metabolic cycle. A high insulin release causes a shift of magnesium from blood
into cells, lowering blood levels. Recent evidence shows that magnesium plays an essential role in both preventing diabetes and controlling
insulin levels.23 The good effects of magnesium on blood fats and insulin also mean that it may help prevent the metabolic syndrome.
Calcium promotes muscular contraction, and magnesium helps to temper that activity. That may be helpful in situations where excessive contraction
maybe a problem; for example, in the case of the hyperactivity of the smooth muscle in bronchial tubes that occurs with asthmatic attacks,
magnesium can help relieve bronchial constriction. Because magnesium is a natural antihistamine, it may also help prevent the allergic onset
of the disease.
Another mineral that reacts with magnesium is phosphorus. Excess consumption of phosphorus leads to magnesium excretion, which explains why
drinking a lot of cola lowers magnesium levels, since carbonated drinks are high in phosphorus. Conversely, a high magnesium intake results
in phosphorus excretion-no problem, as phosphorus is ubiquitous in all proteins.
Natural Mineral Facts
Stress is an important cause of many types of disease. It affects bodybuilding negatively, due to higher cortisol release and loss of vital
nutrients. Research shows that magnesium helps blunt its negative effects in the body. When magnesium is deficient, stress-related cardiovascular
damage is increased during heart attacks. Even the release of fat from cells lowers blood magnesium because the liberated fat bonds with
magnesium in the blood, resulting in magnesium losses. Catecholamines, such as epinephrine, stimulate the release of fat, but they also
overstimulate the heart. The body releases more catecholamines- which are considered stress hormones-when magnesium levels are low.
A lack of magnesium increases aggressive behavior, which you can reverse with magnesium supplementation. Magnesium helps promote the sleep you
need to break down accumulated stress hormones. Studies show that magnesium may reverse age-related sleep problems.
Cancer usually involves cellular mutations that result in damage to DNA, and magnesium is involved in DNA repair. It activates enzymes that
are required for DNA repair. Magnesium's antioxidant activity, control of resting insulin levels and role in DNA repair explain recent findings
showing that a high magnesium intake helps prevent colon cancer. Cancer also involves elements of the immune system and out-of-control inflammation;
studies show that lower blood magnesium leads to a greater release of inflammatory mediators in the body. Another mineral, selenium, is linked to
lower cancer rates, but without magnesium, the body doesn't absorb or retain selenium.
Magnesium intake may be even more vital as you age. A recent study of 1,138 men and women, average age 67, showed that older people with higher
magnesium levels also have stronger muscles. Think about that in light of the main reason people end up in nursing homes: frailty. Another study
found that magnesium helps reverse memory loss in middle-aged people through its interactions with the NMDA receptor in the brain.
Magnesium and Exercise
Since muscle stores a fourth of the body's magnesium, it seems that magnesium must play a vital role in exercise. Magnesium regulates neuromuscular
activity, excitation and muscular contraction, and it promotes the activity of enzymes that participate in muscle protein synthesis. Thanks to its
role in ATP physiology, it's essential for muscle energy. Its antioxidant and anti- inflammatory activities help delay fatigue and boost muscle
recovery Magnesium is needed for the synthesis of insulinlike growth-hormone-1 (IGF-1), which is anabolic.
That's why it's included in a food supplement that also contains zinc, which is involved in the activity of such anabolic hormones as testosterone,
growth hormone and insulin. Since magnesium promotes the synthesis of prostacyclin and nitric oxide, it facilitates vasodilation in muscle, which
increases muscle pump during training and oxygen delivery to muscles. Magnesium further aids muscle endurance by helping to boost production of 2,3
DPG, a substance in red blood cells that helps release oxygen.
The short, intense exercise that characterizes bodybuilding helps increase blood magnesium levels, probably due to dehydration and the movement
of magnesium from muscle into blood. On the other hand, overtraining lowers magnesium levels, probably related to the increase in stress hormones,
such as cortisol and the catecholamines, which trigger the mineral's excretion. Studies show blood level reductions of magnesium ranging from 5
percent to 25 percent following long-distance running and after 90 minutes on a treadmill. You also lose magnesium in hot weather.
High-intensity exercise may increase magnesium excretion for several reasons. During intense training the kidneys' ability to conserve magnesium
is temporarily impaired, leading to magnesium excretion, an effect amplified by the rise of several hormones that occurs during hard exercise:
aldosterone, antidiuretic hormone and thyroid hormones. They can remain elevated for as long as 14 hours after intense training. The rise in blood
lactic acid during hard exercise can elevate plasma phosphate (to buffer the excess acid), and phosphate pushes magnesium out of the body.
A big debate is whether the drop in blood magnesium represents an actual loss or a redistribution of the mineral from blood to muscle. The latter
implies that when the exercise session ends, magnesium levels return to normal. But some scientists think the return-to-normal process isn't efficient
in many people, leading to lower magnesium levels. In addition, the acidosis that results from high-intensity training causes magnesium to be excreted.
Mag Scientists
The results of studies that have looked at magnesium in athletes have been contradictory, some showing beneficial effects and others no effect.
Athletes with full stores would show no effects from added magnesium intake. On the other hand, many athletes avoid the best food sources of magnesium
(legumes, dark green vegetables, seafood, grains and nuts). They may take in substances that lead to magnesium losses, such as caffeine, fats and
phosphate (from soda and other sources). So-no surprise- many athletes come up short on magnesium. That's especially true in sports that have weight
limits, where diets are often restricted. Drinking hard water adds magnesium to the diet (9 to 27 percent).
Studies show that most Americans get about 76 percent of the suggested daily dose of magnesium; deficiency begins when you get 70 percent or less.
Studies of strength- trained athletes show that most average about 135 percent of the RDA for the mineral. But since a high-protein diet uses up
magnesium and popular low-carb, high-fat diets often don't include magnesium-rich foods, bodybuilders and other strength athletes are still more prone
to marginal deficiency. Food processing and the depletion of magnesium in farm soils also limits access to the mineral.
One study examined the effects of supplemental magnesium during strength training. For seven weeks, young men received either a placebo or a magnesium
supplement at a dose of eight milligrams per kilogram of bodyweight. The placebo group got an average of 250 milligrams a day of magnesium from food,
while the supplement group averaged 507 milligrams daily. Peak-torque leg extension levels increased by 20 percent in the supplement group, while those
in the placebo group gained by 11 percent.
Even those taking food supplements may not have optimal blood magnesium. About a quarter of all athletes show magnesium intake below the RDA. A dietary
limit for magnesium saturation may exist. The suggested dose of magnesium for a hard-training athlete is estimated at eight milligrams per Kilogram of
bodyweight daily, or 720 milligrams for a 200-pound athlete, taken in divided doses. The dosage includes food intake; taking more than 350 milligrams
at once gives you diarrhea.
Excess magnesium is an issue mainly for those with renal failure, since the kidneys regulate magnesium retention and excretion. Some people experience
excess magnesium levels when they take over-the-counter medications that contain magnesium, such as Epsom salts or antacids. Magnesium is also elevated
in some medical conditions, such as low thyroid and viral hepatitis, and in those taking lithium. In extreme cases, excess magnesium can cause death by
stopping the heart. The treatment for excess magnesium involves forced diuresis and administering intravenous calcium.
Supplement Issues
Some magnesium supplements are better than others. Organic forms, such as citrate, aspartate and fumarate, are better absorbed than inorganic forms,
such as magnesium oxide and hydroxide. Unless it's finely ground, magnesium oxide has low water solubility and thus lower bioavailability than, say,
magnesium citrate, which is absorbed 4.5 times better than oxide. Magnesium carbonate is chalk, has a low absorption rate and can lower plasma magnesium.
Magnesium sulfate, better known as Epsom salts, has more use as a relaxing bath soak. Magnesium hydroxide is sold as Maalox, an antacid; long-term use is
linked to heart problems in some Magnesium chloride is sold as a timed-release drug called Slow-Mag, but less of it is absorbed than from food sources,
such as almonds. For maximum absorption rates, it's best to take smaller doses. The larger the dose, the less absorption and the greater the chance of
the primary side effect, diarrhea.
One newer form combines magnesium with creatine-very sensible, as magnesium activates the enzymes required for storing creatine in muscle as well as
the sodium-potassium pump mechanism that pushes creatine into muscle. One study showed improved bench press numbers after subjects used a magnesium-creatine
supplement, but the same effect occurred with creatine alone. In another study the mag-creatine supplement increased intracellular water content, which acts
as an anabolic signal in muscle.
Then there's ZMA, which combines magnesium, zinc and vitamin B6. That combination is touted as a potent anabolic complex; both magnesium and zinc are
involved in anabolic hormone function. The originator of the supplement (who later achieved notoriety by distributing designer steroids to athletes)
maintains that nearly all athletes are deficient in those nutrients. Studies that have evaluated ZMA have found no anabolic effect, though one experiment
detected an increase in IGF-1 in football players who took the supplement. If your diet is low in those nutrients, you'd benefit from the supplement.
Since the recommendation was to take it before sleep, the magnesium content would help with relaxation and sleep. Sleep itself breaks down accumulated
stress hormone levels while promoting growth hormone release.
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