Magnesium is an essential element found in food. It is important for cellular functions in cardiac tissue and muscles, particularly. Magnesium in the medical setting has been used for replacement for hypomagnesemia and important to maintain for cardiac health. to prevent and even treat arrhythmias. It has also been used for use in preeclampsia to prevent seizures in pregnancy. We have also used it clinically for asthma exacerbations and headache prevention. But what is the utility outside the hospital? Can CrossFit athletes benefit from magnesium supplementation?
Do I have a Magnesium Deficiency?
First, finding out if you are deficient in magnesium is probably not worth the testing. Serum magnesium does not reflect total body stores, since a lot of it is stored in bones. RBC magnesium is supposed to be the more accurate measure of total body magnesium, but in my experience I don’t find utility in testing for it, period. Unless you are chronically deficient due to malnourishment or drink excess alcohol, testing would not be meaningful. Magnesium can be found in such as nuts and seeds (almonds, pumpkin seeds), salmon, avocados, spinach and other greens etc.) and it is unknown who’s walking around with magnesium deficiency. However,one study estimated that up to 48% of all US adults do not meet the recommended daily intake.
Should I take Magnesium supplements?
First, everyone should eat more nuts, seeds, salmon and green leafy vegetables. CrossFit athletes should stick to eating meats and vegetables, nuts and seeds, little starch, some fruit and no sugar, as Greg Glassman stated. So, as a CrossFit athlete if you are dialed in with your nutrition and you are the other 52% without a magnesium deficiency, should you supplement with magnesium? In my opinion, give it a try. Based on recent studies on muscle recovery and pain, I do think that there’s emerging evidence for performance and more importantly, muscle recovery.
Muscles and Magnesium
Muscles need magnesium for their cellular function. In this systematic review, the authors found that magnesium supplementation “reduced muscle soreness, improved performance, recovery and induced a protective effect on muscle damage.” While the evidence is promising, this was based on just 4 studies and therefore we should be cautious in applying this conclusion for all our CrossFit athletes. Muscle soreness (delayed onset muscle soreness) and rate of perceived exertion was lower on those supplemented with magnesium glycinate 350mg vs. those with placebo. Another small study in runners demonstrated reduced levels of IL-6 (inflammation) and improved glucose recovery and less muscle soreness. So while these are small studies, they are promising!
What type of Magnesium should I take?
There are a dizzying number of magnesium supplements on the market and caution must be taken when buying magnesium products over the counter. If at all possible see if the supplement has third party verification by NSF or USP. These labels ensure that what the label claims to have is actually what’s in the pills.
Magnesium Citrate
Magnesium Glycinate
Magnesium Sulfate
Magnesium Oxide
All of the above works fine, but most say that Mag Citrate and Mag Glycinate are the best tolerated. Magnesium in high doses can cause diarrhea. It is recommended that supplementation does not exceed 350mg a day. I like Costco brands, and they do have a USP certified Magnesium Citrate version that has 250mg in 2 (huge) pills.
Summary
Magnesium is important for heart and muscle function and many US adults do not consume enough magnesium through diet. Eating foods rich in magnesium (fish, nuts, seeds, leafy greens, etc) is important for health. For CrossFit athletes – additional magnesium supplementation (up to 350mg a day) may help reduce muscle pain after exercise and may help feel better during intense workouts. Give it a try, and tell me what you think!
REFERENCES
- Magnesium: Fact Sheet for Health Professionals – https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional
- 2. U.S. Department of Agriculture, Agricultural Research Service. Usual Nutrient Intake from Food and Beverages, by Gender and Age, What We Eat in America, NHANES 2013-2016; 2019.
- Tarsitano MG, Quinzi F, Folino K, Greco F, Oranges FP, Cerulli C, Emerenziani GP. Effects of magnesium supplementation on muscle soreness in different type of physical activities: a systematic review. J Transl Med. 2024 Jul 5;22(1):629. doi: 10.1186/s12967-024-05434-x. PMID: 38970118; PMCID: PMC11227245.
Robert Oh, MD, MPH 