Magnesium: An Important but Often Forgotten Electrolyte

 Magnesium: An Important but Often Forgotten Electrolyte

By Todd Parker, MA, MS

Todd Parker - Photo Shoot Nov 2011 4Magnesium is a mineral, like sodium, calcium, and potassium, which all are important to maintaining electrolyte balance in our bodies. Magnesium, however, is often overlooked as a mineral which plays critical role in cramp prevention. In fact, muscular contractions could not consistently occur without magnesium’s presence. Because it plays such an important role as our bodies produce energy, it is important to work toward maintaining healthy levels of magnesium.

Magnesium imbalances can be caused by things such as diuretics (e.g., caffeine) and alcohol consumption.  As with most endurance exercise, longer and more intense exercise can deplete magnesium levels, which can lead to cramping.

Biochemically speaking, as we exercise, magnesium aids our bodies to utilize oxygen. Therefore when magnesium gets depleted through exercise, electrolytes must be replenished for the body to produce the energy which fuels us during intense exercise.

For athletes, especially those training and racing in endurance sports, magnesium deficiency indicators can include one or more of the following:

  • abnormal muscular weakness
  • muscular cramping and “locking”
  • muscular spasms
  • impaired glucose breakdown (for ATP/energy production)
  • inability to sustain exercise intensity for extended periods
  • irregular heartbeat (e.g., elevated performance heart rate)
  • disorientation and confusion

You can get magnesium into your diet with unrefined whole grain breads and cereals, green leafy vegetables, lentils, peas, beans, nuts, and seeds. Meat, fish, fruit, dairy products, and processed foods are poor sources of magnesium.

Magnesium is excreted primarily through sweat and urine; therefore, cold fluids (which empty out of the gut faster) are the preferred choice for replenishment during exercise. Conversely, excess magnesium is filtered by the kidneys; however, if overly excessive, kidney function is adversely affected. When this occurs, just as with a deficiency, side effects may surface in the form of muscular spasms, and as I call it, muscular “locking”. Through proper monitoring, athletes can supplement with 300-900 mg per day without contraindications. Larger dosages, as in 700-900mg, should be broken up into 2-3 doses throughout the day with food. Female athletes should supplement at the lower end of this range, and don’t normally require any dosage above 300-400mg. Increases in oxygen uptake, no matter how minor, could (for example) improve a cyclist’s sustained power output, which can facilitate improved performances.

If you’re an endurance athlete or you exercise for long periods or with extremely high intensity, look for beverages that not only have calcium, potassium, and sodium, but also contain magnesium. If you’re cramping during longer training sessions or races and have ensured that the other three minerals are being replenished, there’s a good chance what you’re experiencing is attributable to low magnesium levels.

Todd Parker is a former Professional Triathlete and holds a Masters in Exercise Physiology from San Jose State University. He is an exercise physiologist, certified cycling and endurance sports coach, strength coach, and personal trainer. You can reach Todd at