Plasma magnesium losses following exercise have been reported in the nutritional literature. The exact reason for this loss is not known, but may result from mineral losses in sweat and urine or redistribution of magnesium between the tissues of the body. Estimates for post-exercise plasma magnesium losses range from around 2% to up to 15% following strenuous exercise, with the degree of loss depending on the intensity and duration of exercise performed. Generally, the more demanding the exercise, the greater the loss of magnesium. Magnesium losses in the plasma occur immediately following exercise and levels can remain depleted for up to 24 hour post-exercise. Magnesium supplements appear not to provide short-term ergogenic benefits to healthy individual, suggesting that the losses of magnesium do not impair performance. However, that is not to say that the losses of magnesium might not impair post-exercise metabolic regulation, particularly if initial plasma magnesium levels are low. Those engaged in strenuous exercise should therefore ensure that plasma magnesium is at optimal levels prior to exercise.
Those engaged in strenuous exercise should therefore ensure that plasma magnesium is at optimal levels prior to exercise. This may minimise the metabolic fall out from either magnesium losses or its redistribution to other tissues. In particular, magnesium losses from plasma might amplify the exercise induces oxidative stress of intense exercise. It has been estimated that exercise might increase the magnesium required from the diet by around 10 to 20 %. Therefore if this extra magnesium is not ingested a deficiency state can develop. Although short term magnesium losses through exercise might not impair performance, the deficiencies caused by persistently low intakes during periods of physical activity might cause poor performance through a general magnesium deficient state. Because magnesium intakes have been reported to be low in developed nations, a large number of athletes may be exercising with low magnesium plasma levels and this may be impairing their performance. Supplemental magnesium may have performance enhancing effects in such individuals.
