This year I did run two marathons and had to deal with the same problem after about 30 km.
Muscle cramp in such a way I could only(hardly) walk the rest of the marathon, because I never give up.
My max heart rate is about 170. After analysing this marathons I think my problem is that I want to run to fast from the start of a marathon.
My heart rate was about 150, and I think I have to run on a heart rate of about 130 max.
My age is 62 and I have to deal with a marathon time of about 4 hours.
Is my heart rate causing the muscle cramp?????
Personally I don't think it has to do with drinking and fueling.
Does anyone has suggestions on this.
Which muscles are cramping?
Have you done your long runs enough?
Was the course hilly?
I think more info is needed to help answering your questoins.
The marathon was starting in the evening, and the temperature went down during the race. The course was flat, and around a lake. More runners were dealing with cramp that evening.
Two weeks before I did my last long trainingrun of 32 km.
Mostly training three ore four times a week, but before a marathon slow down.
This morning again the 32 km with a heartrate of 140. My pace was 9.5min/mile.
This felt good, just tired afterwards.
From my own experiance I can say that my first marathon ended up with cramping thighs after 35k. I managed to finish by shortening my step and increasing my cadence. That course was also flat. I got rid of that problem by doing more longruns over time and up to 3 hours. Just to get my legs to get used to the tirering of putting the feet on the ground step by step for 42 k. If the course is hilly the downhills also tend to get my thighs to cramp if I get tired. I now try do RUN downhill as a rest when I do my hill repeats and that has helped alot. I think the best way of making sure not to cramp is of course to make sure you are hydrated and energized but to do what Eric says: a lot of running in HRZ 2 over a prolonged time. Definately more than the regular 20 week marathon programs. Then work on the hills to get strong.
Hope this will help,