So, I got a question from one of my athletes about a weird cramp in a race. Then, I got an email question about cramping. And, a comment in a blog post about cramping. So, I thought that I'd post up some of what I've read (by experts), some of the things that I've had conversations about (with experts), and some of my personal experiences. No science references or anything...and you'll see why. If you see the word expert...take it with a grain of salt so to speak as some are definitely more versed in science than others.
Some experts say that cramps are b/c of electrolyte imbalances. The focus has generally been on sodium loss, but the human body is complex. In addition to sodium, we lose potassium, magnesium, calcium, and others. The focus has been on sodium b/c that's easy to measure and it's generally what you 'taste' when you sweat. But, some research has pointed to the others having just as much of a role. So, electrolyte losses is one theory. That might be some of the reason why salt tabs or electrolyte tabs seem to help in racing and hot training. And, it could be that dehydration contributes to this...more on that later.
Other experts seem to think that electrolyte imbalances aren't the cause and that you really don't lose enough to make a difference. In other words, you already have so much sodium, potassium, calcium, magnesium, etc. in your system that the amount you lose in sweat really won't matter. They argue that salt supplementation is not necessary. But, trying to sell that to someone who has been doubled over with some kind of cramps up one minute and then are fine 5 minutes after taking a salt tablet is a really tough.
Dehydration is also thought to be a cause of cramping. Really these all get lumped together b/c once you are dehydrated, you can argue that your electrolytes are 'off'. It is very difficult to recover from dehydration, so try to keep the fluid imbalance in check. That's not to say go overboard either as you can overhydrate. That brings with it a host of other problems, and that is the reason why some marathons have aid stations placed every 1.5-2 miles instead of every mile. What research has shown is that the front runners tend to slightly dehydrate while the back of the packers tend to over hydrate. But, hydration is another topic all together...so what you have above is the 'nickle' tour so to speak.
Conclusion #1: An electrolyte or mineral imbalance and/or hydration probably plays some role.
Probably one of the primary causes of cramping is simply over exertion. That's why they typically occur during races and not in training. The only way to mitigate this or remedy is to make sure that you are doing some race efforts in your training. These should take the form of race effort swims, bikes, and runs...and race effort bricks. They don't need to be 100% race distance, especially when you consider the run. But, it's not too difficult to put out the same energy expenditure on the bike (it will take a longer time/distance unless it is all race effort) and then run to see how you handle it.
Conclusion #2: Overexertion probably has as much to do with cramping as electrolyte/mineral concentration and dehydration.
What are the solutions. The best 'solution' is to race as you train and train as you race. Put simply, if you are training for an Ironman, every long session is a race rehearsal for hydration, electrolytes, and calories. If you are doing Olympic distance races, definitely do some hard bike/runs to see how you respond.
So, by race rehearsal, it comes down to effort, hydration, electrolytes, calories, even the position that you are going to be riding in as most times it's the bike that seems to set people up for cramping on the run. If you live in a hilly area (like Austin) and are racing flat (like New Orleans or Galveston or Florida) then it would probably pay to either find some seriously flat roads, or sit on the trainer and get used to the sameness.
If you commonly cramp up in a swim workout (Feet/calves), then my experience is that it is one of a few things. First, inadequate hydration and electrolytes. Put a NUUN tablet in a water bottle and drink that before and during your workout. Second, for me it has typically come AFTER a run, and the run combined with inadequate hydration is likely the cause. Thirdly, it happens a lot when people use fins and aren't used to the added plantar flexion (pointed toe) that they put the foot in when kicking.
Hopefully that at least provided some info...useful info. And again, I try to keep things pretty general and provide more of an overview since there are so many differing 'expert' opinions about it and since many of those 'experts' see things in a black/white king of way.
Sources: I said I wasn't going to but...20 years of racing, Optimum Sports Nutrition by Colgan, Tim Noakes via book at web posting, Joe Friel via book and web posting, Peak Performance by Hawley and Burke, a friend of mine at UT who is getting his PhD in the subject, and Assorted other web postings. I try to read most we posting stuff with a somewhat skeptical eye.