Dehydration & Muscle Cramps Part 2 – Nerves, Muscles, & Magnesium

13 Weird Facts About Magnesium

by | Jul 29, 2021 | 8 comments


In the previous blog on cramping and dehydration, Dr. Bucci explained the prevailing schools of thought on what causes cramping during exercise, ending with a potential solution to both theories: magnesium.

In this blog, Dr. Bucci explains how magnesium – when combined with the correct balance of other electrolytes and conditions – provides that solution. He also explains how EFS and EFSPRO take advantage of this research to help prevent cramping during exercise.

Recap on EAMC Research

The previous blog on cramping & dehydration introduced the modern term Exercise-Associated Muscle Cramping (EAMC) during or after endurance exercise. Currently, the world of sports research is trying to figure out if muscle cramps are because of electrolyte losses/imbalances (along with dehydration) or because of nerves causing muscles to misfire (neuromuscular incoordination).

Both hypotheses have findings from human studies to support their cases, but neither camp has provided a definitive final answer on what causes muscle cramps. Knowing what causes cramps means they can be dealt with and hopefully, greatly reduced or even eliminated.

As I noted in the previous blog, there’s evidence that both hypotheses are partially right, because there is a unifying cause common to all cramps – specific, local muscle fatigue after repetitive, long-term, short-term, and/or very intense resistance exercise. Everyone agrees on that.

OK, everyone is right. Now what?

Regardless of which side of the debate you fall on, there’s good news: Magnesium loss or redistribution from endurance exercise can explain both kinds of muscle cramps. There is evidence that magnesium during exercise is the best way to reduce muscle cramps, regardless of how they start, along with proper hydration and other electrolytes. We’ve seen it work too many times and there is a massive amount of support from a wide range of sports nutrition and magnesium research.

Scientists used to believe that taking additional sodium during exercise was the best way to keep cramps at bay. New research, however, shows you need the right amount and type of magnesium to stop nerves from causing muscles to misfire and prevent cramping.

Given the above, all we need to do is load up on magnesium before and during exercise and we’re good, right? Not so fast, nothing’s ever that simple in the human body. The solution to using magnesium to prevent EAMC lies in tying together that wide range of findings. To help do that, I’ve assembled a body of “weird facts” about magnesium that are gleaned from research and ultimately paint a broader picture of why both nerves and muscles need the right amount and kind of magnesium during long-term exercise to prevent cramping in a way that satisfies both theories of EAMC.

Weird Magnesium Facts

Weird Fact #1: More exercise means more ATP generation, which means more magnesium is needed. Why? As soon as ATP forms, the available magnesium stash (hanging out with taurine, actually) inside of cells is used to stabilize ATP when it is moved from its generation point to muscle contractile structures inside muscle cells. Magnesium needs to be shuttled back and forth inside of intracellular areas to keep your muscles contracting. Not to mention continuing to run and ramp up all those membrane receptors and enzymes. Some magnesium will get lost from its intracellular places in working muscles during long-term exercise. This is why magnesium uptake and maintenance is important for endurance athletics.

Weird Fact #2: Long-term exercise induces a sort of “spring tetany,” which is seen frequently in livestock and provides a clue that magnesium deficiency is a key primary contributor to misfires and cramping. This is also called “grass staggers,” “grass tetany” or “lactation tetany.” Tetany is muscle spasms (i.e., continuous cramps) from hypomagnesia (low serum/cellular magnesium). To quote one reference: “The tetany characteristic of hypomagnesemic disorders is the result of intracellular, cellular membrane, and extracellular metabolic effects of magnesium” (Goff, p.138). Meaning that the most-used muscles are the first ones to show cramps from not having enough intracellular magnesium in muscles. Sounds like EAMC, right?

The good news is that cramping and dehydration are easily preventable by making a few minor tweaks to your hydration strategy.

Weird Fact #3: The key to magnesium nutriture is not simply giving more – than can backfire and cause mineral imbalances. This immediately refutes most human clinical studies on magnesium, since they’re administering high doses of magnesium by itself, and those doses aren’t balanced with hydration and/or other electrolytes. That approach just begs for hit-or-miss science (mostly miss), and it explains why many magnesium studies do not find benefits for sports nutrition or human health – even when other evidence says they should.

Weird Fact #4: During long-term exercise (two hours or more), you are running primarily on your intracellular magnesium stash. Magnesium supplementation during exercise can maintain this stash IF the right amount and kind of magnesium is given, along with other electrolytes. Sodium (and chloride) is one prerequisite, along with a little – but not a lot – of potassium. Calcium, the counterpart to magnesium, is also a prerequisite. In other words, you need all the electrolytes for magnesium to have a chance to work during exercise. Deficits of any other electrolyte will imbalance magnesium, delaying uptake and thus, cell entry.

Weird Fact #5: It’s not easy for your body to get magnesium into the right cells at the right times. Or not even get past the gut. So how do we do magnesium right? Again, a deep understanding of magnesium helps figure it out. It’s really simple once you know what your body is really doing, and the answer is partially informed by facts 6 – 11.

Weird Fact #6: Magnesium does not have hormonal controls like calcium, sodium (chloride) and potassium. That means there is not a ready pool of magnesium in the body that can be quickly mobilized and sent where needed most. Instead, magnesium must be continuously ingested to keep feeding tissues. This was easy from traditional diets we evolved on, but not from a modern, magnesium-eviscerated diet. The corollary to this fact is that magnesium absorption into the gut is slow and metered, the weak link in the chain of magnesium status, which brings us to

Weird Fact #7: Magnesium absorption into the gut is tricky and unlike other electrolytes. Why? Each magnesium ion is actually surrounded by a shell of water molecules that are stripped off by specialized proteins in between intestinal cells (called claudins). This is the rate-limiting step for magnesium uptake into the gut lining cells. Kinda like a drip coffee maker instead of a coffee press. And you need to have the right kind of claudins specific for magnesium – another step ripe for monkey-wrenching. A diet adequate in magnesium (around 400 mg daily from foods and chelated supplements) builds up magnesium-specific claudins over time, but not all of us eat a diet adequate in magnesium. Another reason to use magnesium chelates that interchange with sodium chloride in the gut. This is why high doses of magnesium do not help raise intracellular magnesium – the uptake into the gut is spacetime-limited, and cannot be upregulated in a day or during a long-term event.

Weird Fact #8: Despite the limiting effect of claudins, having an adequate Vitamin D status helps magnesium absorption from the gut, but many athletes are not sufficient in vitamin D function, and the cycle time of vitamin D repletion is way too long for immediate help adding Vitamin D during exercise. Sunshine and daily intakes of 1000-5000 IU/day – that’s 25-125mcg using the new units for Supplement Facts panels – should be enough.

Weird Fact #9: Chloride also helps magnesium absorption in the gut. When consumed at intestinal pH levels, sodium chloride and some chelated magnesium forms (like dimagnesium malate) exchange magnesium for sodium to form magnesium chloride and sodium malate, both of which are rapidly absorbed. There’s no stomach acid needed for magnesium absorption from non-chelated sources like oxide, hydroxide, carbonate or some chelated forms. Other magnesium forms, especially magnesium oxide, cannot do this trick unless there is a lot of stomach acid, which is shut down during long-term exercise. Dimagnesium malate has human studies showing best possible uptake, and it also has a higher percentage of magnesium than other well-absorbed chelates like bisglycinate, making it the preferred choice for a magnesium chelate to use during exercise.

Weird Fact #10: Magnesium uptake from blood to cells is as tricky as into the gut – same issues. You need claudins and specific receptors to get magnesium from blood into cells. This is why blood levels of magnesium do not give accurate information on what is going on in the cells, misleading many researchers into disregarding magnesium supplementation. Human studies in endurance exercisers found it took weeks to months for supplemental magnesium to saturate intracellular magnesium (but they were using the wrong kind of magnesium without the correct balance of other electrolytes and factors explored here).

Weird Fact #11: Once magnesium is inside cells, keeping it there depends on having sufficient sodium, chloride, potassium and calcium, taurine, and a steady magnesium supply – further reinforcing the point that all five electrolytes are crucial to endurance athletics, not just sodium and potassium.

Weird Fact #12: The nervous system includes neurons zapping muscles with contract/relax signals, and those signals are carried by leg-length axons. Proportionally, that’s like us humans having one arm reaching coast-to-coast across America, giving sign language and registering feelings through touch. The scale is daunting, but every time we walk or run we prove it’s normal. This isn’t specifically related to magnesium, but it is a weird fact.

Weird Fact #13: We are not even going to get into the large literature on medical magnesium use for preventing and relieving life-threatening cramps in important arteries and uterine muscle/blood vessels. Long story short: intravenous, soluble magnesium works better than any oral form of magnesium, but is still not perfectly effective for these extreme medical conditions. Even iv magnesium has to deal with all the Weird Facts listed above. But this world-wide practice is effective enough to support all the Weird Facts about magnesium (#s 1 – 11).

The First Endurance Solution

All five electrolytes (calcium, magnesium, sodium, chloride, and potassium) are essential for cramp prevention.

Taken together, these findings explain why EFS & EFS-PRO supply plenty of each of the five electrolytes. Including all five helps your body sort out what it really wants and needs to prevent cramping, and then helps it get everything to the right places during exercise – inside cells, especially muscle and nerve cells. The answer, it turns out, is simple; it just requires looking beyond established sports nutrition practices (such as providing only sodium and maybe potassium) to find better, more effective solutions.

In closing, I should note that EFS and EFS-PRO provide a LOT of electrolytes, which may be a concern to some athletes. Fortunately, your body has efficient ways to dispose of excess dietary electrolytes – most notably via urine and sweat outputs during exercise. Over-consuming gives you the best chance to stay flush with electrolytes, supporting those muscles and nerves working the hardest to prevent muscle cramps, but doesn’t pose any risk in terms of actually taking too many electrolytes on board.


Goff, JP. Ruminant hypomagnesemic tetanies, Ch 35 in Current Veterinary Therapy – E-Book: Food Animal Practice, Anderson DE, Riggs DM, Eds., Saunders Elsevier, St. Louis, MO, 2008, pp. 137-40.

Luke Bucci PhD

Luke Bucci PhD

Chief Scientific Officer

Dr. Bucci is the industry leader in sports nutrition. He’s also an accomplished author and lecturer and holds multiple patents and patent applications on clinical laboratory testing methods and nutritional supplements.
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