magnesium loss and exercise
Magnesium is involved in numerous processes that affect muscle function including oxygen uptake, energy production and electrolyte balance. Thus, the relationship between magnesium status and exercise has received significant research attention. This research has shown that exercise induces a redistribution of magnesium in the body to accommodate metabolic needs. There is evidence that marginal magnesium deficiency impairs exercise performance and amplifies the negative consequences of strenuous exercise (e.g., oxidative stress). Strenuous exercise apparently increases urinary and sweat losses that may increase magnesium requirements by 10-20%.* Based on dietary surveys and recent human experiments, a magnesium intake less than 260 mg/day for male and 220 mg/day for female athletes may result in a magnesium-deficient status**. Recent surveys also indicate that a significant number of individuals routinely have magnesium intakes that may result in a deficient status ***. Athletes participating in sports requiring weight control (e.g., wrestling, gymnastics) are apparently especially vulnerable to an inadequate magnesium status. Magnesium supplementation or increased dietary intake of magnesium will have beneficial effects on exercise performance in magnesium-deficient individuals. Magnesium supplementation of physically active individuals with adequate magnesium status has not been shown to enhance physical performance **** . An activity-linked RNI or RDA based on long-term balance data from well-controlled human experiments should be determined so that physically active individuals can ascertain whether they have a magnesium intake that may affect their performance or enhance their risk to adverse health consequences (e.g., immunosuppression, oxidative damage, arrhythmias).
* long history on this site re healthy physically active folks coming down with neuro symptoms
** um yeah, esp considering daily amounts (per mainstream sources) for healthy average joe are more like 320 (F) - 420 (M) mg/day
http://www.hc-sc.gc.ca/fn-an/nutrition/ ... bl-eng.php
if it takes intakes around 70-75% of RDA in an athlete no less to flag deficient on a blood test, that highlights the known issues with the so-called 'normal' range in serum
**** yup no fun. the runs if you take too much of a poorly absorbed form, muscle weakness with too much of a properly absorbed form
from Consolazio et al 1963 https://www.ncbi.nlm.nih.gov/pubmed/14022653 "The results of this study show that a considerable quantity of sodium, potassium, magnesium and iron are lost in sweat of men during 16 consecutive days' exposure to environmental temperatures of 100°F. During a 7.5-hour collection period, the sweat excretions averaged 0.601 gm/hour for sodium, 0.125 gm/hour for potassium, 2.3 mg/hour for magnesium and 0.13 mg/hour for iron..." "...when the overnight sweat losses are included, this excretion could account for 25% of the total."
Rose, L. I., Carroll, D. R., Lowe, S. L., Peterson, E. W., & Cooper, K. H. (1970). Serum electrolyte changes after marathon running. Journal of applied physiology, 29(4), 449-451.
Beller, G. A., Maher, J. T., Hartley, L. H., Bass, D. E., & Wacker, W. E. (1975). Changes in serum and sweat magnesium levels during work in the heat. Aviation, space, and environmental medicine, 46(5), 709-712.
Liu, L., Borowski, G., & Rose, L. I. (1983). Hypomagnesemia in a tennis player. The Physician and Sportsmedicine, 11(5), 79-80.
http://www.tandfonline.com/doi/abs/10.1 ... 6.11708536
lots more where those came from, but no more time at present