Howdy! Long time mostly lurker here.
In addition to my day job, I'm a part-time professional musician. I was playing the third hour of a three hour set last Saturday when my fretting hand completely cramped up. It locked in an unnatural and unusable position. Not good for business, let me tell ya.
I supplement with 600 mg of magnesium glycinate every evening. I also drink reverse osmosis filter water daily, spiked with ConcenTrace Trace Mineral Drops. And I always have a couple bananas for potassium the meal before every show.
So, what else should I look out and try?