I’ve been a coach now for 30 years and I’ve yet to see scientific proof as to the cause of cramps. There have been lots of studies and plenty of theory backed by studies, but no actual physical proof that I have seen. If there was, I guarantee you the professional teams would be all over it.
Here are some of the causes of cramps that I have seen over the years.
1. People with higher fast twitch muscle fibers tend to be more susceptible to cramps. What I mean is that people that are genetically predisposed to be sprinters are far more likely to get cramps then people who are genetically predisposed to be distance runners.
2. Conditioning. People who are out of shape are far more likely to get cramps, especially when doing extreme exercising.
3. Tight fitting clothing, wet suits or spandex appears to increase the risk of cramps.
4. Heat. Muscle cramps appear far more often on hot days.
5. Hydration. Caused by #1. It’s not just hydration, but what you hydrate with. Soda’s lead to cramps.
You need to get in better shape if you are going to do 4-5 hour sessions overpowered. You may need to take more breaks and drink more water or gatorade type drinks.