I've never seen Mg Carbonate in a sport supplement but I usually look for the highest bio-availability and the least laxative effect. Hence, Bisglycinate is my

I've never seen Mg Carbonate in a sport supplement but I usually look for the highest bio-availability and the least laxative effect. Hence, Bisglycinate is my best choice. Usually comes in pills and rarely also (expensive) in liquid shots w/ sweeteners.