Most people don’t give much thought to the inner workings of electrolytes – except perhaps the headline-grabbing sodium.

But if you’re into serious fitness, it’s a good idea to get familiar with magnesium, especially if you constantly battle with muscle cramps after intense training or find it hard to recover from prolonged exercise.

Magnesium is required for more than 300 biological reactions in the body, including those involved in the synthesis of protein, muscle contraction, cardiac activity and energy metabolism. So it’s a busy little electrolyte. Even more important for athletes is magnesium’s pivotal role in energy production, particularly in the metabolism of adenosine triphosphate (ATP), the ‘energy currency’ for hardworking muscles.

Because of these roles, you can see why the proper magnesium level is essential for peak physical performance. If you don’t get enough through food, and your absorption is reduced or excretion is excessive, you can end up with a magnesium imbalance. However endurance athletes, who sweat at a rate of 1-1.5 litres or more per hour, seem to be at a greater risk of a magnesium deficiency, and the health and performance problems that follow.

How much is enough?

The recommended daily intake (RDI) of magnesium for the general population is a minimum of 300mg for women and 400mg for men, which is easy to achieve if you’re eating well.

There is no established RDI for the athletic population but emerging evidence suggests that magnesium requirements are significantly elevated in athletes because of depletion of magnesium stores during endurance training.

Athletes can safely take up to 500 to 800 mg of magnesium daily, and magnesium supplements may benefit the hard exercisers out there, especially those who are predisposed to muscle cramping and fatigue and/or those with poor dietary intake.

Too much of a good thing

Eating magnesium-rich foods such as whole grain cereals, leafy greens, nuts and seeds will help to achieve recommended levels, however excessive supplementation can lead to gastrointestinal upsets, such as diarrhoea. As always, it’s important to talk to your doctor before taking any supplementation.

Kathleen Alleaume


Kathleen Alleaume is an accredited exercise physiologist and nutritionist and founder of The Right Balance