Magnesium & Exercise

1. Magnesium & Exercise Sarah Renaghan

2. Magnesium (Mg2+) • Abundant in Earth’s crust, salt water, vegetation • Most commonly in a 2+ oxidation state • Interactions with other elements/ ions • In nature • In the body

3. In the Human Body • Required for over 300 enzymatic reactions • Energy metabolism • Glycolytic pathway, beta oxidation • ATP hydrolysis, Phosphocreatine system • Ion/ electrolyte balance • Muscle contraction • Bone health • Heart rhythm

4. Mg2+ distribution in the body • Blood levels maintained constant • Using blood levels to determine total body magnesium status only reflects 1% of body stores

5. RDA: Magnesium • Exercise cause needs to ↑ 10-20%?

6. Dietary Sources • Vegetables • Especially green & leafy • Legumes • Fish • Nuts • Whole grains • Refining process strips ~85% • Drinking Water • Especially “Hard Water” Chlorophyll-α Magnesium-poor foods -Refined carbohydrates -Eggs, Dairy -Meats

7. Supplemental Sources • IV, Topical, or Oral Supplements • Absorption differences • Best when chelated with amino acid or compounded with salt • Side effect: GI issues UL = 350mg/day (adults 19 years or older)

8. Effects of Exercise • Exercise = ↑ metabolism/ ATP production • As cofactor, lack of Mg2+ may be rate-limiting • Exercise causes • ↑ Mg2+ loss through ↑ sweat/ urine production • Redistribution of Mg2+ between body stores

9. Model: Changes DURING Exercise

10. Model: Changes FOLLOWING Exercise

11. Research • Variety of research with differing exercise mode, intensity, form of supplementation, time course, measurements, • Lit Review: No effect of Mg supplementation, regardless of whether the performance outcome was strength, anaerobic-lactic acid, or aerobic (Newhouse, 2000) • In state of deficiency, exercise capacity and performance may be impaired • Increased Mg2+ intake through diet or supplementation may improve performance (Nielsen, 2006)

12. Magnesium Deficiency • Difficult to assess deficiency • Assess dietary intake • Not uncommon in U.S. (according to NHANES) • Associated with hypocalcemia, hypokalemia • Symptoms: • Muscle weakness • Neuromuscular dysfunction • Muscle cramping/ spasms • Decreased immune function • Impaired response to oxidative damage and stress • Common in weight-class sports with strict diets (i.e. wrestling) • Dietary Mg2+ intake may be a strong, independent predictor of BMD even in athletes (Matias, 2012) • Toxicity rare • Symptoms similar to those of deficiency + GI issues

13. Magnesium Deficiency & Performance • Reduced dietary intake associated with impaired performance • Reduced exercise capacity and endurance • Increased heart rate and oxygen uptake during submaximal exercise • Impaired neuromuscular function • Fatigue and cramping • Impaired immune function and recovery • Supplementation has been shown to restore performance in magnesium-deficient athletes

14. In conclusion… • If magnesium intake is adequate, supplementation does NOT enhance performance • If magnesium intake is deficient, supplementation may restore impaired performance • But not beyond that of adequate dietary intake • May be achieved through dietary Mg2+ or supplemental form • Exercise may increase needs ~10-20% • Food First Approach • No UL for Mg2+ from food-sources • Mg2+-rich foods rich in other micronutrients • Benefits of consuming minerals in combinations • Awareness of other interactions

15. Deep ocean mineral water as recovery beverage..? Deep ocean mineral water accelerates recovery from physical fatigue Hou et al. Journal of the International Society of Sports Nutrition 2013, 10:7