Heat Lightning Cramps — What Causes Them?

I recognize that this isn’t the place to get medical advice, so this is more a question of, ‘Has anyone had this happen to them?”

I’m 52 and live in flat Florida. I started riding in February and in seven months have ridden about 2,300 miles. I do a 12-mile ride almost every weeknight and then ride one or both weekend days for 25 to 65 miles. I ride a Trek Navigator 300 and average about 14 mph with a fairly high cadence. I carry a 100-oz Camelbak and am religious about hydration (a kidney stone will do that). Following the advice of this group, I drink before I’m thirsty and eat about half a power bar every 30 minutes. On long rides, I’ll add bananas.

I have never had any problems with muscle cramps. Every once in a while, I’ll have something that I describe as “heat lightning” cramps: just a flicker of discomfort that warns me to change pedal position or something before the muscle does cramp.

Earlier this month I went back to my home state of Missouri to see if I could ride the hills on my old newspaper route. It felt really good to get off flat land:

  • Day One, 32 miles of hills
  • Day Two, 37 miles of hills
  • Day Three, 68 miles of flats and hills
  • Day Five, 92 miles of mostly flats

None of those rides caused me any problems. I wasn’t even very sore the next day.

I had planned to do an unsupported century the next week, but I had to bail out early to come home for Hurricane Floyd.

Because of bad weather and work, I didn’t have a chance to get back on my bike for about four days. I started on my normal 12-mile ride and started experiencing the “heat lightning” in my left calf after about four miles, so I changed position slightly. At the half-way point, I got off and walked for a few minutes and tried to stretch it out, but it was still tight.

The next day was still sore, so I went to a chiropractor who specializes in sports injuries. He chewed me out for not stretching enough when I start out, treated it with ultrasound and told me to take it easy for a day and use moist heat on it. He also recommended calcium supplements.

Two days later, on Sunday, I went riding with a newbie and did 16 miles at an excruciatingly slow 10 mph. Felt fine. A thunderstorm and problems at work kept me off the road until Wednesday night, when I stretched with no pain for about five minutes and then took off at about 12 mph.

Bingo! Same as the other night. Left calf knotted up again. Made it home, but it wasn’t fun.

Here’s the question: what would cause this all of a sudden? I’ve ridden longer, harder, faster in hotter weather with no problem. Now, on a couple of short, slow rides, I’m dying.

My doctor has suggested a more neutral riding position.

I haven’t made the transition to clipless yet. I’m still using clips, not that I would think that would make much difference.

And, as far as I know, I haven’t made any drastic changes to any part of the bike over the last couple of weeks. Same shoes, same pedals, no change in handlebar height, saddle position is the same, although I may have changed seat height by no more than 3/8 inch up or down.

That’s what’s got me confused. Can’t figure out what’s different, except that I’m a couple of weeks older. (And, as the old saw goes, my right calf is the same age as the left one.)