Thoughts on Magnesium Supplements

<p>Anyone use them? I had major cramping during last OLY tri and a friend suggested sport legs suppliments.  My hydration was OK and I had an electrolyte replacement drink on the bike (hammer HEED).  In spite of that, i had cramps in both calfs during the very end of swim and throughout T1 and had hamstring cramps out of T2 that plagued me through first 2 mi of the run. </p>
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<p>I also heard benefits of magnesium supplements before bed to aid recovery... worth a try?</p>