Fighting Fatigue and Dehydration During Marathons

Question
Hi Nick - I just completed my second marathon.  In my first marathon, I did not have any fatigue problems till about mile 23 when I hit the wall.  During the last one I completed about 3 weeks ago, I had a much different result.  I was keeping my pace I had trained for till about mile 12, then had to start walking due to dehydration and fatigue.  Most of this was due to the climate - it was a very warm muggy day in Texas and I'm a big sweater.  

I relied only on water stations, and I'll not make that mistake again if it's going to be a warm day (I'll take a bottle with me to begin with).  However, I didn't know how to work in walking.  Once I began to have problems at mile 12, I started by walking 30 seconds at every mile marker and then running to the next mile marker before walking again.  I didn't know if my technique was best, if I should have walked a mile to regain strength and hydration, or what.  In the end, I was walk/running as best I could so I did not have to post a DNF.  

Then, I began getting terrible cramps at mile 20 in my legs I hadn't gotten in my previous race, which I also blame partly on the dehydration and fatigue.  I ran through the cramps as best I could, but should I have stopped and stretched?  Would that have helped me more through the rest of the race?  

I had a time goal of 3:45 I'd trained appropriately for at the start, but at the end the goal became to just finish.  I have started training for my next marathon in February, and am going to try to get a 3:45 finish this time as well.  I just didn't know how to handle the effects of early fatigue in a race, as I did not have that problem in my first marathon.  My goal is to post an optimal time without hurting myself as opposed to just being a finisher.  Thanks for the help.

Answer
Jeff, first of all, great job on working so hard. That is very admirable.

1) Stretching will only help if it is not related to dehydration. I suggest stretching and intense self-massaging to decrease the cramp because it can't hurt. If it is solely related to dehydration then it won't help much.

2) Make sure to do sprint intervals of 30-120 seconds each 1-2 times a week to help decrease chances of cramping. This will help your muscles learn to clear the blood lactate (commonly referred to as lactic acid) out of the muscles.

3) Make sure to drink a sports drink with salt and potassium during the race and to make sure you have at least 5000 mg of salt the day before the race.  

4) I'm sure you know this, but I would like to reinforce the importance of constantly drinking small amounts so as not to irritate your stomach during the race.  

Since the race is in February you shouldn't have as much problem with heat.

Please let me know if you have any other questions. Good luck preparing for February!