The short answer
Magnesium is essential for normal muscle and nerve function, so getting enough matters for training. But reviews find little evidence that supplements improve strength or performance in people who already get enough, and a Cochrane review found magnesium is unlikely to prevent ordinary leg cramps in older adults. Drug-tested athletes should prioritize a certified product.
What physiology tells us
Magnesium helps regulate muscle contraction and relaxation, nerve signaling, protein synthesis and energy metabolism. Someone with low intake has a reason to fix it. Before blaming cramps or soreness on magnesium, consider total food intake, hydration, training load, sleep, electrolytes and any health conditions.
Does magnesium prevent cramps?
A Cochrane review of 11 trials found magnesium is unlikely to provide clinically meaningful cramp prevention for older adults with nighttime leg cramps (moderate-certainty evidence). Results in pregnancy were inconsistent, and the review found no randomized trials of magnesium for exercise-associated cramps (Garrison, 2020). That doesn't support marketing that says magnesium glycinate prevents workout cramps.
Can it improve performance or recovery?
A meta-analysis of randomized trials found no significant improvement in muscle strength, power or peak torque with magnesium in athletes and active people, who tend to have good magnesium status. Benefits appeared mainly in older adults and people likely to be deficient (Wang, 2017).
A 2024 systematic review reported less muscle soreness with magnesium in some studies, but the trials were small and varied in dose, form and exercise type (Tarsitano, 2024). It's fair to say magnesium supports normal muscle function. It isn't fair to say a glycinate capsule speeds recovery or builds muscle.
Choosing a product as an athlete
If you're drug tested, banned-substance screening matters more than any recovery claim. In our comparison, Momentous Magnesium Bisglycinate and Thorne's Magnesium Bisglycinate powder are NSF Certified for Sport. Check the exact product in the NSF directory, since certification doesn't carry over to a brand's other products.
If you aren't tested, weigh testing evidence, dose, price and convenience. Transparent Labs offers 300 mg with linked reports, Nootropics Depot links lot-matched reports, and EO VITA offers 275 mg in three capsules. A bigger number isn't automatically better.
Ready to compare labels rather than marketing? See eight magnesium glycinate supplements side by side, with elemental dose, cost per 100 mg and evidence tiers.
Frequently asked questions
Should I take magnesium after lifting?
Timing matters less than total intake. No strong evidence supports a post-workout window.
Does magnesium prevent leg cramps?
Evidence in older adults is generally negative, and there are no randomized trials for exercise cramps.
Is an NSF mark worth paying for?
For drug-tested athletes, yes. It screens for banned substances; it doesn't prove better recovery.
Should I take it with electrolytes?
Check what your electrolyte mix already contains. Combining products can push you over 350 mg of supplemental magnesium.
Sources
- Garrison SR, et al. Magnesium for skeletal muscle cramps. Cochrane Database of Systematic Reviews, 2020.
- Wang R, et al. The effect of magnesium supplementation on muscle fitness: a meta-analysis and systematic review. Magnesium Research, 2017.
- Tarsitano MG, et al. Effects of magnesium supplementation on muscle soreness in different type of physical activities: a systematic review. Journal of Translational Medicine, 2024.
- NIH Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals.
This guide summarizes published research for general information. It is not medical advice. Reviewed by Doug Phitzinger, MS, Sports Medicine, on November 10, 2026.