Phil M. wrote in message ...
Quoted message said:Quoted message said:I ran a trail 1/2 M today (13.4 miles per GPS, 1800' of climb).
Before I left, I weighed myself on my digital scale: 153 lbs.
During the race I drank a 20 oz bottle of Cytomax (wt: 1.25 lbs).
After the race I drank a 16 oz bottle of water (1.0 lb)
After the race I ate a 6oz cookie (choc chip, of course). (.375 lbs)
I weighed myself right after the drive home: 148.5 lbs
So: I lost 4.5 lbs -- after eating 2.6 lbs of water and food, in a
race that took 1:44:00 to run.
You probably shouldn't add in the weight of the cookie as it's not fluid?
But it would count to counter glycogen burned, hmm.
Quoted message said:Quoted message said:This implies that during the race I lost about 7 lbs in under 2 hours!
Conditions were mid 60's, foggy (therefore fairly muggy for L.A.), no
sun.
I know I have a fairly high sweat rate, usually 40+ oz per hour when
racing at slower ultra speeds.
One possibility is that I burned through 2.5 lbs of glycogen stores,
and the other 4.5 lbs represents a sweat rate of 41 oz/hr.
This is a really interesting observation because water is stored with
glycogen also. Since it can take longer than 24 hours to fully restore
glycogen, one would expect to remain a bit lighter until this happens. But
how is the water stored with the glycogen used? Is it used metabolically?
If so how much is used this way? Is some of it available for sweating?
An aside is that on severe low-carb diet one strives to go without glycogen,
thus emptying their stores in the first week of the induction phase of the
diet. This can lead to water (and glycogen) loss of about 6-7 pounds. After
this happens you're not dehydrated. If you lose that all at once from
exercise, instead of over a week, I guess it throws the body out of balance
too much and causes problems.
I know for one thing that my legs scream at me until I feed them back all
their glycogen after hard exercise. When I experiemented with low-carb for a
year, I didn't have this problem because I found it very difficult to do any
hard exercise. Now my #1 priority after exercise is to eat a generous amount
of carbs and hydrate within 30 mins after exercise.
Quoted message said:Did you check your urine color to see how dehydrated you were? Here's a
color chart - http://tinyurl.com/co5ah
lol interesting chart Phil. Mine was about a 5 or 6 after today's long run
and I was down 3 pounds (about 2%), though I'd consider a 4 on that scale a
sign of dehydration, not the 7 they suggest.
Quoted message said:7 pounds seems like a lot for just 13 miles, especially for someone
weighing 153 pounds. That's about 4.5%. I believe that at the WS100 they
can withdraw you from the race if you have a 7% loss of weight.
From a book I am currently reading, "Performing In Extreme Environments"
(thanks Dot), here's how the author describes finding your sweat rate:
1. Record body weight before and after 1 h of exercise or rest in heat.
2. Calculate the difference (D) between these rates.
3. If clothing is wet, the increase in clothing weight should be noted by
weighing it before and after heat exposure. This increase in weight
represents sweat that was produced but remained in the fabric, and should
be added to D (step 2 above). If nude body weight is taken, this step can
be ignored.
4. The weight of fluid consumed during step 1 should be added to D.
5. The weight of urine lost during step 1 should be subracted from D.
6. Your hourly sweat rate (in kg/h) equals D (step 2), after correcting for
the items in steps 3-5.
7. Weight loss should be replaced by consuming 1 L of fluid for each
kilogram of body weight that was lost.
This is basically the the formula I used today when figuring out my sweat
rate, though I used 4 hours as the time period. For a long mostly easy run
on an extremely humid day my sweat rate came out to about 40oz per hour.
(Consumed (4) 20oz bottles + (1) 1 liter bottle = 113 oz over 4 hours, and
lost 3 pounds = 48oz (~16 fluid ounces per pound). So 161oz over 4 hours,
40oz per hour). Also took 4-5 s-caps to be able to absorb 28oz per hour.
-T
Quoted message said:Again, according to the book, the typical water loss for a marathoner
(5:00-10:00 pace) is 1-1.5 L/h. So your 40 oz is about 1.2 L/h, so it's
right in the normal range. For 100 mile ultra runners (12:00-18:00 pace)
it's .7-1.2 L/h. So you're at the top of the normal range.
--
Phil M.
