Magnesium for Sports & Fitness

What is it?

Magnesium is an essential mineral to the human body. It is needed for bone, protein, and fatty acid formation, making new cells, activating B vitamins, relaxing muscles, clotting blood, and forming adenosine triphosphate (ATP; the energy the body runs on). The secretion and action of insulin also require magnesium.

Where is it found?

Nuts and grains are good sources of magnesium. Beans, dark green vegetables, fish, and meat also contain significant amounts.

Why do athletes use it?*

Some athletes say that magnesium

helps curb dehydration.
helps prevent muscle cramping.

What do the advocates say?*

People who are doing “heavy-duty” exercise lose a lot of magnesium through urination and sweat, so it’s important that it’s replaced. To keep water in the blood vessels, electrolytes, such as magnesium, need to be replaced. Therefore, to curb dehydration, electrolyte drinks are more effective than plain water.

Magnesium helps to prevent muscle cramping after exercise, too.

How much is usually taken by athletes?

Magnesium deficiency can reduce exercise performance and contribute to muscle cramps, but sub-optimal intake does not appear to be a problem among most groups of athletes.¹ ² Controlled trials suggest that magnesium supplementation might improve some aspects of physiology important to sports performance in some athletes,³ ⁴ but controlled and double-blind trials focusing on performance benefits of 212 to 500 mg per day of magnesium have been inconsistent.⁵ ⁶ ⁷ ⁸ ⁹ ¹⁰ It is possible that magnesium supplementation benefits only those who are deficient or who are not highly trained athletes. ¹¹ ¹²

Are there any side effects or interactions?

Comments in this section are limited to effects from taking oral magnesium. Side effects from intravenous use of magnesium are not discussed.

Taking too much magnesium often leads to diarrhoea. For some people this can happen with amounts as low as 350–500 mg per day. More serious problems can develop with excessive magnesium intake from magnesium-containing laxatives. However, the amounts of magnesium found in nutritional supplements are unlikely to cause such problems. People with kidney disease should not take magnesium supplements without consulting a doctor.

Vitamin B6 increases the amount of magnesium that can enter cells. As a result, these two nutrients are often taken together. Magnesium may compete for absorption with other minerals, particularly calcium. Taking a multimineral supplement avoids this potential problem.

Are there any drug interactions?
Certain medicines may interact with magnesium. Refer to drug interactions for a list of those medicines.

Resources

See a list of books, periodicals, and other resources for this and related topics.

*Athletes and fitness advocates may claim benefits for magnesium based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on magnesium. For more complete and detailed information, including references and safety information, see Magnesium as a nutritional supplement.

References

1. McDonald R, Keen CL. Iron, zinc and magnesium nutrition and athletic performance. Sports Med 1988;5:171–84 [review].

2. Lukaski HC. Magnesium, zinc, and chromium nutriture and physical activity. Am J Clin Nutr 2000;72:585S–93S [review].

3. Golf SW, Bohmer D, Nowacki PE. Is magnesium a limiting factor in competitive exercise? A summary of relevant scientific data. In: Golf S, Dralle D, Vecchiet L, eds. Magnesium 1993. London: John Libbey & Company, 1993:209–20.

4. Ripari P, Pieralisi G, Giamberardino MA, Vecchiet L. Effects of magnesium picolinate on some cardiorespiratory submaximal effort parameters. Magnes Res 1989;2:70–4.

5. Weller E, Bachert P, Meinck HM, et al. Lack of effect of oral Mg-supplementation on Mg in serum, blood cells, and calf muscle. Med Sci Sports Exerc 1998;30:1584–91.

6. Brilla LR, Haley TF. Effect of magnesium supplementation on strength training in humans. J Am Coll Nutr 1992;11:326–9.

7. Golf SW, Bender S, Gruttner J. On the significance of magnesium in extreme physical stress. Cardiovasc Drugs Ther 1998;12(Suppl 2):197–202.

8. Manore M, Merkel J, Helleksen JM, et al. Longitudinal changes in magnesium status in untrained males: effect of two different 12-week exercise training programs and magnesium supplementation. In: Kies CV, Driskell JA, eds. Sports nutrition: minerals and electrolytes. Boca Raton, FL: CRC Press, 1995:179–87.

9. Brilla LR, Gunter KB. Effect of magnesium supplementation on exercise time to exhaustion. Med Exer Nutr Health 1995;4:230–3.

10. Finstad EW, Newhouse IJ, Lukaski HC, et al. The effects of magnesium supplementation on exercise performance. Med Sci Sports Exerc 2001;33:493–8.

11. Finstad EW, Newhouse IJ, Lukaski HC, et al. The effects of magnesium supplementation on exercise performance. Med Sci Sports Exerc 2001;33:493–8.

12. Lukaski HC. Magnesium, zinc, and chromium nutriture and physical activity. Am J Clin Nutr 2000;72:585S–93S [review].

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires August 2007.