Muscle cramps are the body's way of reminding you to take care of nutrition and hydration before a workout.
What everyone else said. Remember that coffee can act as a diureticc depending on the type and amount of caffeine in it. Which can increase your urine output while the also burning extra calories. All this combined can dehydrate you. A couple cups in the morning then followed by lots of water during the day will probably solve your problem. Throw potassium in the mix and you are golden.
Assuming you don't have intermittent claudication due to heart issues. ;)
http://www.bullshido.net/forums/show...?t=2127&page=1 was a similar question that I asked many years ago. Bananas, water, and Fingermoon suggested suppliments cal/mag and zinc. I got some and after pumping pills, water, and bananas went to burn on leg presses at 310 3x reps, which for sure would have me cramping at 2AM like a jackknife. Worked.
So I got pills and when working out hard take 'em. Also a good diet helps. Potassium is in potato and sweet potato skins, magnesium is in fish, squash, beans and such. Lately at night if I'm feeling cramps I gobble Emergen-C electrolite fizzy drink powder, it works fast.
Like everyone else has already said, water and potassium, and be proactive. Hydration in particular should be an ongoing thing rather than a pre-training thing.
Also, I learned the hard way that the worst thing to do for a seized calf is to try to stretch it out by putting weight on it. Ouch.
Coconut water is full of potassium. I find that if I drink it before a work out I stay much better hydrated than with anything else thus far.
You're not overdoing it. It's what you didn't do right 24-48 hours beforehand (a.k.a all the time) that caught up with you. Hydrate, you don't need to chug down Gatorade but do ensure you replace what your body loses through sweating.
SCREW the bananas. It's not potassium you're missing, it's Zinc and Magnesium. Trust me on this one.
I've had the calf cramps since I was a teen running long distance and training, get it so often at night, jolts you awake with pain and have to scoot down and shove my foot against the bedboard to alleviate the cramp.
I'm surprised no one has said cancer yet. I must have been on Sociocide for too long.