I cannot comment on the exact physiology which leads to muscle cramps, but I
can give you one observer's 'cause'. In my case, when I am lacking calcium
(either when I run out of milk and don't get to the store or simply do not
drink enough) I can be almost guaranteed to have leg cramps that or the next
evening.
Someone else here should be able to provide you with the smaller details of
the cramps.
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