Yes, supplemental magnesium may improve exercise performance but only in individuals that are magnesium deficient [1, 2]. Magnesium is involved in energy metabolism, cardiorespiratory function, and muscle actions, and when we don’t get enough of it, sports performance suffers accordingly [1, 2]. Additionally, athletes who engage in more intense exercises may require 10-20% more magnesium than the general population due to higher urinary and sweat losses . Magnesium has not been shown to prevent or relieve exercise-related muscle cramps .
 Garrison, S. R., Korownyk, C. S., Kolber, M. R., Allan, G. M., Musini, V. M., Sekhon, R. K., & Dugré, N. (2020). Magnesium for skeletal muscle cramps. The Cochrane database of systematic reviews, 9(9), CD009402. https://doi.org/10.1002/14651858.CD009402.pub3