Cramps during long events

Quoted message said:

Hi, I finished a 50k trailrun recently (palo duro, ~7 hours), but as in
every marathon-length event for years, I got cramps around the 20mile
point and had to powerwalk the rest of the distance. Mentally I felt
fine, but, cramps in the hamstring and later in the lower leg and foot
muscles.

Hi rms,

I've quoted what I've learned about cramping from a reply I wrote to someone
else a while ago. Ignore the parts that don't apply to you...

Cramping during long races bothered me for years until I figured it out.
Everyone said it was electrolytes. They were wrong. They would often
strike when I was running well, with lots of gas in the tank. At the Baldy
Peaks 50k, in '01 I was in solid 2nd place at 20 miles (just before the long
descent) when they struck, and it was very frustrating and extremely painful
to struggle through and hold off the sharks.

In brief, it's likely to be dehydration. Here's the long version:
=====
If your cramps were affecting more than a single muscle (eg, both sides, if
you stop and stretch, something else cramps, if you feel funny pre-cramp
twinges in other places, etc), then you are dehydrated.

It took me a couple of years to figure it out. I would cramp on longer
races typically after 3.5 - 5 hours, especially in hot or humid conditions.
After one particularly bad race, I weighed myself after I had to walk in
because of cramps. I had lost about 8 lbs (and I started at 152 lbs).

You say you stayed hydrated, but did you weigh yourself before and after the
race? I have downed quarts of liquid in long races and still have come up
5-8 lbs light at the end.

The proof that it is hydration is this (if this sounds too simple to be
true):

Next time it happens, stop and drink 20-20 ounces of fluid. Take a couple
of salt tablets (I use succeed brand), too. Start walking. If you can
begin
to jog again without cramps, that was it. When this has happened to me in
races, as little as 20oz chugged quickly with salt has stopped them cold
within 2-3
minutes. Don't try and jog through the cramps -- that causes muscle damage.
If you rip yourself up, the water will stop the cramps, but not the pain
from running on shredded muscles.

You are a big guy, with a high BMI (look it up). The higher the BMI, the
higher the heat load (less surface area per weight). So you run hotter than
the skinny ones. So you sweat more. In addition, you may have a high sweat
rate to boot.

Next race, weigh yourself before and after, take into account how much you
drank during, and determine your sweating rate (under that set of
conditions -- temp, humdity). I need about 40oz/hour when racing in 65
degrees when its humid, for example.

Finally, you need to replace salt if you're going to be drinking more than a
quart or two of fluid in a race. To the tune of 1 gram of sodium/liter
(about 2/3 tsp of pure salt per quart). This is the amount of salt in your
sweat. Without salt replacement, your sodium concentration declines. When
that happens:

You sweat less (and overheat).

You drink and the fluid sloshes around in your stomach instead of being
absorbed.
(it sloshes around because you need to pump sodium into your stomach in
order to absorb water. When your body is low on it, it suppresses this
process to conserve your plasma sodium concentration)

You feel queasy, and may not even want to drink.

In extreme cases you can get Hyponatremia and it will kill you. (rare).

So you get a vicious cycle of your body needing water, yet you feel queasy
and it won't absorb. The solution is to take a Succeed tablet for every
pint or two you drink during a long race. Salt with water enables your
stomach to absorb a 20 oz bottle in 2-4 minutes.

NFI in Succeed, salt, or water...

-- Dan