Magnesium – which type should you choose?

Everybody knows the name, but what magnesium really is and especially, what its essential actions are is not that well known. Of course, telling you that it’s responsible for over 300 chemical processes in our body is still pretty large to really understand its utility.

Not only it is the fourth most common element we can find on earth, it’s also the fourth most common mineral in our body. It leads approximatively 350 enzyme reactions. Knowing this, you know you need to make sure you are not magnesium deficient.

To make it clear, you need ample amounts of magnesium in your system for energy production, muscle contraction, heart beat, communication between neurons and the whole nervous system and much more.

Energy production would be non-existent without magnesium. Our muscles would be firing all the time, like a never-ending state of contraction. You know the feeling when your calves get cramped hard? Imagine this all over your body, constantly.

Better be dead, I know. Cholesterol would be released in the blood stream uncontrollably, probably making you die of a heart attack in a very short time.

Ok, horror story aside, what I mean is that magnesium is really important for our body to function properly. With that many functions, deficiency can lead to many health problems.

Now as a hard trainees, why do you need to consider it more than other people?

Intense physical activities deplete magnesium

By working out hard, you can be sure you are depleting magnesium every time. A study published by the American Physiology Society measured the urinary excretion of magnesium pre and post workout and compared the results. The depleting effect was as much as 21% more following the workout compared to the pre-workout values.

It’s no surprise, because magnesium is involved in so many processes that influence muscle contraction, oxygen uptake, energy production and electrolyte balance. All of those process are heavily used when training hard.

This decrease in magnesium is largely attributed to the intense muscle contraction but also the increased excretion through sweat and urine. Even slight decreases in plasma magnesium may impair performance and amplify the oxidative stress from a hard workout.

Other functions not related to working out include:

  • Energy production and glucose control
  • Dilation and contraction of blood vessels, electrolyte control
  • Neuromuscular control, lipid metabolism, electrolyte control, anti-inflammatory action
  • Neuronal transmission, neuroplasticity

So, we now know some of its roles and how important it is, but what if someone is deficient in magnesium? What could the symptoms be?

Fatigue and Weakness
Poor muscle contraction, force leaks during lifting, impaired recovery between workout sessions

Trouble Focusing
Low focus when training, brain fog, difficulty organizing your thoughts

Poor Sleep Quality
Magnesium plays a major role in the production of GABA, a neurotransmitter responsible for calm and relaxation. This impairs sleep and recovery.

Some recent studies even link low magnesium to signs of depression.

Is food enough?

  • It is very difficult to get enough magnesium from food even if you eat very healthy. Today’s foods are not that rich in vitamins and minerals as they were some time ago, because intensive farming practices deplete soils.
  • Purification processes deplete the amount of magnesium available in drinking water
  • People in general are more stressed than ever, which depletes magnesium reserves

Now, there are so many types and forms of magnesium that it can be hard to know which is best for you. If you go buy a supplement, you will often see that the magnesium is bound to another substance, usually an amino acid. The reason is that when used as a supplement, magnesium has to be attached to an acid (or other substance) or your body won’t be able to absorb it.

The acid to which the magnesium is bound determines how much of it is absorbed by the body as well as its bioavailability. Each acid will also influence a different therapeutic reaction in the body. Some will create a relaxing effect while others will help with focus or relieve symptoms and inflammation.

To help find your way through all those different magnesium products, here’s list of different magnesium forms and how they can be used to get maximal benefits.

Magnesium Citrate

  • Relatively cheap and popular in most pre and intra workout supplements
  • Mixes pretty well in water-
  • High bioavailability and easily absorbed in the digestive tract
  • Can cause gastrointestinal issues, cramp, diarrhea, etc…
  • In low dosed, it can be ok if mixed with food
  • Use in intra workout to help with muscle contraction
  • Best timing: intra workout with low doses and other amino acids

Magnesium Oxide

  • Used to treat acid reflux or as a laxative
  • Low bioavailability, poor absorption (+/- 4%)
  • Most of it is excreted
  • Don’t supplement with it as it causes gastrointestinal issues
  • Best timing: there is no best timing unless you have severe heartburn of acid reflux issues.

Magnesium Sulfate

  • Also know as Epsom salt
  • Low bioavailability orally but well absorbed through skin
  • Good to treat inflammation, swelling, muscle aches
  • Best timing: in hot bath, evening to promote relaxation, replenish magnesium and lower inflammation

Magnesium Chloride

  • Naturally occurring form of magnesium
  • Very well absorbed through skin
  • Available in sprays, gel or cream
  • Used for severe magnesium deficiency as it replenishes magnesium more quickly
  • Use peri workout to increase ROM of muscles and joints that will be worked
  • Ideal for those who suffer from loose stools with magnesium use
  • Best timing: pre-workout / post-workout


  • Stabilizes and improves heart function
  • Contributes to an increase in ATP production
  • Lowers blood pressure and reduces blood clotting
  • Improves insulin sensitivity
  • Has a calming effect on the nervous system and can provide relief for muscle twitches and spasms as well as anxiety
  • Best timing: Post workout and pre bed


  • Increases synapse density and improves cognition, learning and memory
  • Promotes relaxation and sleep
  • May cause headaches or a feeling of increased blood flow to the head, which usually goes away after about a week, but this is something that as been reported for first timer
  • Improves your overall mental health and well-being
  • Greatly increases the concentration of magnesium in the brain and spinal column
  • Best timing: Post workout or pre bed, can be used in low doses if you have to work hard with your brain


  • Absorbed quickly and effectively
  • Gentle on the stomach
  • Good at lowering cortisol
  • Passes the blood-brain barrier where it has a calming effect on the nervous system
  • Is the best option if you suffer from chronic muscular pain or muscle tightness, spasms and cramps.
  • Best timing: post workout and pre bed


The RDA recommendationsss are 320 to 360mg for female and 400 to 420mg for male. Those are recommendations for sedentary people. If you are working out hard, you can be sure you need much more since you are depleting a lot more every day.

I find that most people benefit from supplementing with 500mg of magnesium daily, and that’s a minimum. Heavier individuals can increase dosage up to 1000mg spread into post workout and pre-bed. 

Hopefully, you can now make a clearer choice to replenish magnesium and also choose which therapeutic effect you are looking for.


Stéphane Aubé

Written by Stéphane Aubé

Stéphane Aubé has worked in the fitness industry for more than 12 years. He works as a trainer and advisor for Hungry For Victory, a company he founded which specializes in nutrition and physical development for athletes of all disciplines. He has wo…