Vigorous activity can influence nutritional magnesium status, and magnesium status can influence physical performance as well as dictate whether vigorous physical activity is healthy or dangerous. This is true whether the runner is fit or unfit, trained or untrained.
Nutritional magnesium is deeply involved in ATP (energy) production, oxygen uptake, central
nervous function, electrolyte balance, glucose metabolism and muscle contraction, including the
all important muscles—the heart plus all its blood vessels.
During both a race and training, vigorous exercise ups the body’s requirement for nutritional
magnesium—not only because of the higher metabolism and muscle contraction where
magnesium plays crucial roles, but also because of increased magnesium loss in sweat and urine.
It has been estimated that athletes’ general requirement for nutritional magnesium is easily 10 –
20% higher than the general population. At the same time, nutritional magnesium can be low in
modern, processed food diets. Without a reliable, widely available marker for clinical
magnesium status (widely used serum magnesium reference ranges do not adequately reflect
body magnesium status), the combination of increased magnesium need for racing/training plus
marginal magnesium intake can make the seemingly healthy choice of running just the opposite
by depleting an already low body magnesium.
When magnesium status is healthy and adequate, blood magnesium shows large swings during
exercise, more than 10 times larger than when exercising in a marginal or deficient magnesium
state. This wide range of blood magnesium inflow and outflow enables the healthy body to fully
function during the high magnesium need of vigorous exercise. Healthy magnesium stores allow
for the large excretions of magnesium in urine and sweat that occur when the body is performing
at peak capacity–without danger of going into a depleted magnesium state. These magnesium
changes in blood and urine normalize within 24 hours after vigorous exercise in runners adequate
in magnesium, unless a deficit has been induced by the exercise bout. In runners with marginal
or deficit magnesium status, the blood levels do not show such wide swings of magnesium
during performance, and urine losses are smaller. It is as if the body is conserving its precious
store of magnesium by limiting the body’s ability to perform at its peak. Thus, it has been shown
that supplemental magnesium given to deficient and marginally deficient runners allows
measurably increased performance during athletic events, while those who are magnesium
adequate are already performing at peak ability which magnesium supplements do not enhance.
Reference: Nielsen FH, Lukaski HC. Update on the relationship between magnesium and exercise. Magnes Res 2006;19(3):180-9.http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=17172008
Source: CMER Center for Magnesium Education and Research
Contact: A. Rosanoff, Ph.D., Director of Research and Information Outreach