Wednesday, April 15, 2015

Race Report : EPIC AR50 DNF at mile 40 with hydration rate discussion

I learned alot about running while completing four 50k trail races and three marathons last year (2014) and was able to apply tweaks, tips and lessons learned on AR50. Many things worked just perfectly on Saturday, April 4th.  However, near mile 37 nausea started in and by mile 40 I was done. Not "ohh you're just uncomfortable you just need to push through it" but done done. Not being able to hold down any water for 30 min sucks.

Illustration by Daniel Yagmin




Why the epic bonk at mile 40?  Why did I start dry heaving around 37 then couldn't keep any fluids down no matter what my pacer and I tried?

Was it hot? No, morning started in the 50s and warmed to 65 with slight breeze.

Did I eat the wrong foods for breakfast or somewhere along the way?  Maybe.  I ate a bagel with tea/water for breakfast three hours before race start just to top things off.  The first 25 miles from start to major aid state at Beals (mile ~25) went fine. I ate three honey stingers (160 calories each), some GU Chomps (40 calories each) and drank ~35 oz of tailwind (5 scopes '100 calories per scope in 45 oz). However, at Beals AS I changed shoes then ate an entire Snickers Bar plus 20 oz Gatorade. It was a mental treat I gave myself as I normally would but those 380 calories when I was used to processing only ~150 per hour was probably a shock to my gut.

Was my pace too great?   25 miles in 5 hours = 12:21 min/mile? Gosh I hope not. That was about as slow as I could 'run' on mostly flat terrain employing frequent walk breaks.

Fluid by mile 25: 35 oz  / 5 hours = 7 oz/hr
Fuel by mile 25:  35 oz (500 calories / 45 oz) + 3 honey stingers (160 cal) + 4 blocks (40 cal) = 1068 calories or 214 calories / hr.
Beals Sugar Spike : 20 oz of Gatorade (130 cal), plus Snickers bar (250 cal).

Fluid from 25-40: 20 oz water in (many oz out!), mouthfuls of coke, ginger ale.
Fuel from 25-40: one honey stinger (160 cal), two chomps (80 cal?), some tailwind (10oz maybe) = ~300 cal? Several Ginger Chews, a couple of pepmo bismo antacids.

Was I dehydrated and/or glucose depleted. Probably.  I was most likely dehydrated and possibly glucose depleted by mile 40. Look at 'How to calculate sweat rate below'.

Didn't you notice you started to feel queasy and didn't you do something about it?  Yes, as my pacer told me. I was lucid and chatty at Beals, was OK at 31miles, then started to miss jokes, less chatty soon after. That was when my pacer really started reminding me to drink fluids, take pepmo  bismo antacids, ginger snaps, take shorter steps, take rest breaks, etc.  Honestly, I did try to drink but the sweet taste of the tailwind turned my stomach even more upset, ginger snaps did alleviate some of the nausea but not enough for me to drink much fluid.

Was I under-trained for the effort. Maybe. My longer run ever was 31 miles (50k).  Some of those races where over technical terrain and over steep hills (North Face Endurance Challenge) but ultimately the longest I've even been on my feet running was 7 hours.  So, with an estimated 50 mile finish of 12 hours you could say I wasn't really trained to run 50.

What went wrong? How can one run several 50k/marathons successfully and not a 50 mile race?  That is a big question and my answer is that I didn't finish all the 50ks successfully.  On two (Overlook 50k and WTC50k) I had nausea as well.  Severely on Overlook 50k but that was most likely to the 100 deg canyon we went through.  On WTC50k the weather was perfect, I did go out too fast and had slight nausea at finish.  So, looking back I didn't finish all 50ks well. The writing was on the wall and I was just too stubborn to read it.  Something was off, probably fluid intake and I didn't correct it.


[How to calculate sweat rate]

1) Weigh yourself while dry before exercise (Naked) 
2) Exercise, keeping track of how much you drink in ounces and how long you exercise. 
3) Weight yourself while dry after exercise. (Naked). If you need to urinate then do so before you weigh yourself.  
4) Use the calculations below to determine your sweat rate.
 

Your change in weight in ounces will be:
[ (Pre-exercise wt #) - (Post-exercise wt #) ] x 16 oz/# ] = (Wt Change in Ozs)

 
But you need to account for the weight "gained" back from drinking, so add the amount you drank to get your total sweat loss:


(Wt Change in Ozs) + (Fluid Consumed in Ozs) = (Sweat Loss in Ozs)

 
Now divide by the number of hours you exercised to get your sweat rate:
 

(Sweat Loss in Ozs) / (Hours Exercised) = (Sweat Rate Ozs/Hr)
 

Here is an example:
 

Ran for two hrs, consumed two 20 oz bottles tailwind. Weather was 65 with wind at 9.5 min/mile pace on flat, paved road.

Wt Change in Ozs = [ ( 156.8 # - 153.8 # ) ] x 16 oz/# = 48 oz

Sweat Loss in Ozs = 48 oz + ( 2 x 20 oz bottles ) = 40 oz 

Sweat Rate Ozs/Hr = 88 oz / 2 hr = 44 oz / hr

My bottles are '23' oz but after I filled to the usual fill line I poured into a measuring cup and read 20 oz.

There has been alot of discussion about over hydration if you follow this procedure because:
a) glycogyn has weight and when its near depleated you don't gain it back and it doesn't make sense to replace it with fluid.
b) you do burn some fat and the amount is a function of your metobolic efficiency and your pace.
 
Generally speaking about one pound of body mass is burned up per hour of exercise so if we take that into account then a corrected sweat loss could be:


Adjusted sweat rate = (44 - 16) oz / hr = 28 oz / hr.

Conclusion

What a learning experience!  Dehydration plus sugar spike at Beals probably lead to nausea that lead to DNF at mile 40.  My hydration rate of 7 oz / hr for the first 25 miles was woefully inadequate as was my ability to 'listen to my thirst / body'.  Moreover, I spiked my gut at Beals with too many calories and failed to keep up even with my own fluid/fuel rate from 25-36.  I clearly need more training at a more realistic fluid rate of 1 to 1.5 20 oz bottles per hour; no sugar spikes and probably should take a couple of tums/ginger snaps at mile 20. A longer training run past 7 hours is probably needed as well.

Additional Reading

Some good reading on the causes, how to prevent and treating stomach issues:
IRunFar -> Dreaded Stomach Issues.  Link here
TrainRunning Magazine -> Nagging Nausea. Link here

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