Leg cramps

Our marathon training group ran 9 miles on Saturday morning.  I ran my usual 2 minute intervals most of the time - 2 minutes running,  2 minutes walking, although there were several times in the middle of it that I ran 6 minutes because I was feeling good.  Anyway, whenever I walk I drink the water that I am carrying in the containers in my fuel belt.  When I empty one of them, I fill it with Gatorade at the nex****er stop, so have been sipping that as well, although I don't drink as much of it as I do water.  Also during the run I ate a few protein/carb snack-size bars.  Anyway, I finished without problems, did some stretching, ate an orange slice and a small bagel, then went home and iced down my legs.   Ok, long story short, I sat for awhile at my computer, then got up to walk, and my legs started feeling crampy.  They never cramped completely, but felt like they were going to any minute.  I stretched them out,  had some orange juice, ate lunch.  It wasn't until I had my shower, and went to do some shopping and go to my Mom's - in other words moving instead of sitting - that it finally cleared up. Any suggestions other than not sitting down for any length of time?  Do I need more Gatorade?  More water?  More stretching?  So far, knock on wood, I haven't dumped from drinking Gatorade, but I might not have had enough to cause me to dump. Thanks, guys.  I appreciate any advice.

My suggestion would be more water and salt.  I am not sure why salt but it made me feel a million times better after my last marathon.  They also say that bananas help.

Bananas, salt, and water - that's a combination of potassium and sodium as well as the water.   (I'm a little afraid of Gatorade...)  Thanks.  I'll try that.  Marcia