Question about leg cramping

Steve's Question

 Hi Lee,

Just a question if you could help me.
Yesterday I suffered extreme cramping in one leg around the 24km mark. I had not had experienced any cramping throughout training program.
I paced myself yesterday to not go out to hard. Would there be a reason and is there a way of preventing in the future.

Lee's Response

Hi Steve,

In relation to your cramping, it seems that it was mainly due to the extreme heat and combine that with the tough physical exertion of running and you became severely dehydrated.
Drinking water and electrolyte drinks are good for hydration before, during and after your event but you need to have an electrolyte drink that is high in sodium (salt) for warm weather races.
When you start to sweat and especially when it is hot, your body loses alot of fluid and cramps occur because the body requires sodium to perform some very specific functions.
1) The maintenance of fluid levels, particularly blood volume throughout the body.
2) The ability of the nervous system to transmit the nerve impulses that are required to initiate the muscular contraction necessary to produce movement. 
When sodium to your body fluid is too low, the body will resist the absorption of further water or other fluids and this seems to be evident from your race.
The fact that you also had significant cramping in one leg may also suggest that you are not structurally sound and favour one side more than the other and as you are fatiguing and dehydrating, the stress and work load is far greater.
I hope this answers your question for you.