DaveLeeNC

I am a high sweating kind of guy, even though I am of average size (5'10" and 155 pounds). I have mostly dealt with this by avoiding heat of the day long rides. But there are lots of folks who do stuff like the Hotter N' Hell ride soon coming up. My question is 'how do people like me take something like that on'. FWIW, I have no intention of riding this event, but trying to do longer rides here in south-central NC is a similar issue.

For me I routinely sweat 4-5 pounds an hour in hot weather. I have run more carefully controlled experiments in the past, but today's (miserable) ride is a good example. It was only 90 minutes and no water as my brand new bike's water cages do not get here until tomorrow (just didn't bother taking the old cages off - only 90 minutes so). It was hard at the end but nothing surprising or anything that presented symptoms other than being more tired than the pace says I should have been.

When I got up this morning I weighed 156.5 pounds (immediately after a quick stop at the toilet). I drank a couple cups of coffee while doing some home admin work and then off on the ride. Nothing else went in or out, as I recall (OK - I did not hold my breath the whole time). When I got back I stripped and got back on the scales. I weighed 148.6 pounds. I seemed to have lost 8 pounds of water in 90 minutes. And the temp during the ride was between 86 and 90 degrees. This is consistent with 'better' experiments that I have done in the past.

From what I have read of water absorption rates, 1.5 pounds an hour is probably the best that you can do. So if I were to take on Hotter N' Hell at an easy 5.5 hour pace, I lose around 27 pounds of water. During this time I could absorb maybe 8-9 pounds of water, probably leaving me comatose if I actually did this.

How do folks like me deal with such rides?

Thanks.

dave

illdrag0n

I'f you lose 27 pounds in 6 hours of riding i'll eat my hat

DaveLeeNC

Your hat is safe as I would be comatose before that would happen (obviously).

dave

Gconan

Camelbac. Coconut water also. Drink.

Seattle Forrest

I sweat a lot, and my sweat is salty. My cat wants to lick my arms when I get back from riding.

Electrolytes are hugely important for me.

DaveLeeNC

The issue isn't access to water in my case. Even if I could get the requisite 20'some pounds of water down my throat over a 5.5 hour period, less than half that (from what I understand) would actually get into my system.

Or does coconut water have some exceptional absorption properties.

dave

SashaSolitaire

Dave, you are assuming that you'll lose moisture from your body at the same rate "through out the duration" of your ride. Your body cannot afford to lose ~20% of it's weight in an outing. I would assume that at some point during the ride, your body will stop sweating and your core temp will start climbing.

As you are aware, sweating is a mechanism of the body to stabilize temperature. If the body is unable to stabilize the temperature through sweating, it'll stop doing so. I sweat heavily too, and in the humid Hudson valley region, the heat coupled with the available moisture in the air make it really icky. In my case, after a while, I stop sweating, and my body temp starts going up. I usually carry both bottles on my bike, one for drinking and the other for dunking my head to cool me down.

Gconan

I just recommended it for electrolytes and it does hydrate really well.

DrIsotope

As the OP has mentioned losing significant water weight over the course of a short-ish ride, they really need to watch for signs of overheating. It can come on relatively suddenly, and it's no fun.

It just takes a couple of times of overheating your core and you'll know the signs-- I get black dots in my peripheral vision (I call 'em black sparkles,) shaky hands, and elevated heart rate that will not recover. The HR is easy to spot-- when you have to stop at a light or intersection, heart rate recovery should drop by 10+ beats (unless you're barely working.) So if you're ticking along at say 150bpm, stop for 30 seconds, and it's still 150bpm, more water, more shade, less effort.

I've never lost more than 7lbs over the course of a ride... but on that same ride I drank over 11lbs of water, so the total production of sweat would have been 17-18lbs. This was in about 4.5 hours of moving time, ~175oz of water and/or Gatorade.

I didn't weigh myself after finishing my most recent descent into near-heat exhaustion, but I drank 2.5 gallons over the course of 9.5 hours, all but 3 quarts of it straight water. But I was still sweating (heavily, I might add) so I kept going.

At least in my case, when I get to where it's ~1oz/minute intake, it's just about dialing back intensity and trying to make it home as thoughtfully as possible, because my electrolyte balance is pretty much out the window, and I'm going to feel worse the following day than I do at that moment. The last 11 miles of the ride I mentioned last, I took in two full 25oz bottles-- one water, one full-strength Gatorade.

MoAlpha

This is a legitimate concern and the answer is that your performance is going to be limited in time and/or intensity by the rate at which you can replace sweat losses. Helpful things include drinking an appropriately constituted glucose and sodium and potassium salt solution to replace losses and, importantly, to aid in absorption. Water follows sodium, which is actively transported across the cells of the gut, and several electrolyte absorption and conservation processes are insulin dependent, hence the importance of sugar.

I can’t find anything authoritative-looking on the maximum water absorption rate, but I think your estimate is low, based on my own experience. And I’m not sure the numbers I’m seeing are based on properly constituted rehydration solutions.

Sweat rate is controlled to some extent by hydration status and a decrease can signal relative dehydration. This impairs thermoregulation and can spiral into hyperthermia, which always accompanies significant dehydration. If you notice your sweat decreasing it’s time to stop and seek relief.



I am 5’9” and 145 lbs and I sweat in your league. Very good for cooling while it lasts!

Abe_Froman

Yea I dont buy the 1.5 lbs per hour number. I dont sweat a ton, but I routinely take in 2 20oz bottles per hour(or more) on long, hot rides. Thats close to 3 lbs an hour, and I'm sure I could drink more. Its not like I'm peeing it out on a hot day, so its either being absorbed, or creating some mutant evil water baby inside me.

DaveLeeNC

Abe, I hope that you are right. And I will be finding out.

dave

Doge

I road across the Mojave 120 solo about 150 miles that day.. Both kids have had to deal with heat. Things you can do/not do:
-Avoid alcohol and coffee - both diuretics.
-Find an electrolyte drink low in sugar and use it.
-Eat some real food, low carbs. Carbs are fuel, but hard to control. When you are out, you are out. That you are asking suggest you should go lower carbs. Save the sugar for the home stretch.
-Warm up/sweat before you start
-Think of long sleeves. I was in long sleeve yellow wool. There is better stuff now.
-Carry water to pour OVER you.
-Don't use external ice first time out. Ice can cause pores to close. However if you have time to try it ahead the ice socks work well. Just you want it cooling, not freezing you shutting down your cooling system.

MoAlpha

Another problem with estimates of maximal water absorption rate is that hydration status has a big influence on it. A number from a study in well hydrated individuals is irrelevant.

Let me also say that caffeine is a weak diuretic, which loses its effect in the face of even mild dehydration. I once had to sit through a few hours of caffeine talk from people at the Army’s Soldier Systems Center in Natick, MA. They field trialed the hell out of it in elite operators doing terrible things for days on end and it increased performance with no effect on hydration.

DaveLeeNC

FWIW, Haile Gebrselassie won a marathon in Dubai (2:05) while losing 9.8% of his body weight.

https://www.precisionhydration.com/b...rmance-suffers

Lots of variables here. LONG/LONG ago I lost 8% of my body weight in a marathon. Those last 6 miles were pretty ugly. I was pretty new to running at the time and had no idea what was happening (an 80+ degree day popped up in late November in Kentucky). I was extremely uncomfortable and my legs just would not do what they had been doing earlier. I didn't show any of the other 'traditional' symptoms of dehydration - dizziness, dry skin, cramps, excessive thirst, etc. And I was NOT thirsty during the run (but could suck a firehose dry after it was over).

dave

Seattle Forrest

I was thinking the same thing. Experiment with them before the day, see how you respond.

They'll keep the sun off of you, help with evaporative cooling, and they'll trap the sweat that would have fallen to the ground, helping you stay cooler maybe. I personally seem to sweat less after my clothes wet out from my sweat.

Best tops I've found for this are Craft Extreme 2.0 and Arc'teryx Phasic SL. The latter is heavenly comfortable. Wool is good too.

MoAlpha

Good article. Leaves the “metabolic” water gained from conversion of carbohydrate to CO2 and water, a minor mitigator of sweat losses.

shelbyfv

I recently began using this "Liquid IV." Despite the name, it's a powder. It seems to work well for me. Big bag at Costco.

MoAlpha

I'm sure it does! From their web site: SODIUM + POTASSIUM + GLUCOSE + WATER = CTT. Hope it tastes better than Gatorade®

shelbyfv

They only stock Passion Fruit flavor at Costco. Very light, easy to chug.

JasonD67

One thing that really helps me in the heat is to take salt licks every few miles in addition to a sport drink. It's made all the difference for my physiology while biking in the heat and humidity around here.

downhillmaster

I’m sorry but you lost me after you stated that you did a 90 minute ride with absolutely no water and the only issue you experienced was being a little more tired at the end.
Do you think that maybe you are blowing this way out of proportion?
I don’t know for sure though so maybe you should continue with your water absorption experiments

indyfabz

My poor departed boy would sometimes lick my legs after I came home from a particularly sweaty ride.

indyfabz

It's a hydration multiplier, silly.

FIFY

WhyFi

That's not a very high bar. When I set out on long rides, one of my two bottles usually contains an electrolyte mix. On really long rides, I'll pick up a Gatorade when the electrolyte mix runs out. Even the more lightly flavored Gatorade varieties are just gross and sticky-sweet.

My departed dog would do that, too. It would gross me out, but after particularly tiring rides I just couldn't be bothered to shoo her away.