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Print Story Let's talk about sweat, shall we?
Cycling
By ObviousTroll (Sat Jun 27, 2009 at 07:44:46 PM EST) cycling, family (all tags)
I made an interesting physiological discovery about myself today.

Weighed myself this morning. Came in at 241 pounds. Then I went and did some chores at the church, then embarked on a 40 mile bike ride in the July sun. During and after the ride, I consumed ~ 1 gallon of liquids. Then I went to get a shower.

Before the shower, I weighed myself. Came in at 236 pounds.

Including the liquids I drank, that means that I lost 13 pounds of water during my bike ride.

Admittedly, some of that was lost through respiration, but still. That's a lot of sweat.

Inside: More about the bike ride but, fortunately, nothing else about how much I sweat.


I've been trying to get out to Lancaster to ride ever since SWHTL and I spent the weekend there a few months ago. Every week, something comes up to make it impossible. Sometimes it was the weather. Usually it was a scheduling conflict, which was starting to make me quite cranky.

This week, though, was shaping up differently (I thought). Did a "I wonder where that road goes" ride on Sunday. Took Monday off and spent the day riding with my baby sister - who had just ridden her first century (she wanted me to go with her, but I bailed). We had a great ride, puttering along at low speeds and catching up on each other - we haven't actually had a real conversation in years - although I blew it when I promised her we'd stop at an ice cream parlor I knew of - I had just been there the week before, but this time we couldn't find it.

Shrug. It was still a great way to spend the day.

Anyway, about the Lancaster ride - I could spend paragraphs about how long I've been trying to get out there to ride and all the obstacles people have put in my way about getting an entire day by myself, but I won't - and I didn't get a whole day this time, either, but SWTHL helped out by taking my cooking chores for the day.

Overall, it was a spectacular day. Hot and sunny (I had to stop and buy sunblock from a mini-mart for $10 ($10!!!) bucks) but with enough wind to keep me from feeling it too much. I also got some nice pictures, although the cheap P&S I had brought actually corrupted some of the ones I took - I'm going to have to replace it.

But, most of the ones I got were nice. I even got one for Hulver.
< "Looking Out the Window" (June 2009) | record heat >
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Let's talk about sweat, shall we? | 28 comments (28 topical, 1 hidden)
I rode to the library and Y today by georgeha (4.00 / 1) #1 Sat Jun 27, 2009 at 08:09:25 PM EST
and back, maybe two miles.

I probably sweated a few pounds later, cutting the grass, transplanting irises and some gardening and de-pooping.


I sweated horribly today. by ambrosen (4.00 / 1) #2 Sat Jun 27, 2009 at 08:15:16 PM EST
I'm even more worried about how I'll sweat tomorrow when I'm out on a ride with Herring.

My money is on by Herring (2.00 / 0) #9 Sun Jun 28, 2009 at 11:47:26 AM EST
quite a lot.

And now I must bathe.

You can't inspire people with facts
- Small Gods

[ Parent ]
Me too. by ambrosen (2.00 / 0) #12 Sun Jun 28, 2009 at 02:31:48 PM EST
I had a nap at Leigh Delamere's on the way home but I'll be in the bath soon. Cheers for a great ride. Hope my fading at the end didn't bother you too much. One day I'll sort out the old fuel pump issue my engine's got.

[ Parent ]
It was good fun by Herring (2.00 / 0) #13 Sun Jun 28, 2009 at 02:43:30 PM EST
I think I was close to fading too by the end.

Early night tonight I think.

You can't inspire people with facts
- Small Gods

[ Parent ]
Goodness by sugar spun (4.00 / 1) #6 Sun Jun 28, 2009 at 06:59:32 AM EST
I couldn't cycle 40 miles, not even if I were sitting on a stationary bike with airconditioners firing from all sides.

I'm not sure if I'm more impressed with you or disturbed by the thought of all that sweat. It might be a tie. I'm pretty disturbed by the sweating, it has to be said.

Me, too, truth be told. by ObviousTroll (2.00 / 0) #16 Sun Jun 28, 2009 at 07:27:21 PM EST
but it was worth it, I think.

An Angry and Flatulent Pig, Trying to Tie Balloon Animals
[ Parent ]
Fat by kwsNI (2.00 / 0) #8 Sun Jun 28, 2009 at 09:03:13 AM EST
It's not just water you're losing there.  Unless you're loading up on carbs right before you leave and keeping more coming in every hour or so, you're body has to start burning fat just to power yourself.  At 240lbs, it wouldn't be unheard of to lose 2-3lbs of fat over 40 miles, especially since you ride often enough that your body becomes fairly proficient at tapping fat reserves for energy. 

Yes, it would be. by ni (4.00 / 1) #10 Sun Jun 28, 2009 at 12:44:57 PM EST
At 240lbs, it wouldn't be unheard of to lose 2-3lbs of fat over 40 miles, especially since you ride often enough that your body becomes fairly proficient at tapping fat reserves for energy.

Let's ignore, for the moment, the significant time delay required before lipid catabolism occurs (longer, in nearly every case, than an hour in humans). Let us also pretend that he had no glycogen in his body (we'll assume ObviousTroll to be some beyond-the-grave zombie sort), and no carbohydrates available for catabolism in his body.

Let's say he was biking at a "moderate pace" -- around 13 mph. This means he would have completed his 40 mile bike trip in marginally over three hours. Three hours of bike riding at this pace while weighing 240lb would burn, depending slightly on just which questionable internet source one relies on, around 2,100 calories (rounding up). There are around 3,500 calories per stored pound of body fat.

So, assuming he burned nothing but fat (which surely isn't the case), and that he started burning this fat immediately (I'd be unsurprised if he didn't start until after he was home, although he might have begun in the last hour or something), he still would have only burned a half pound of fat.


"These days it seems like sometimes dreams of Italian hyper-gonadism are all a man's got to keep him going." -- CRwM

[ Parent ]
Losing battles number 3271 in a series: by ambrosen (4.00 / 1) #11 Sun Jun 28, 2009 at 02:26:37 PM EST
Attempting to bring science into a discussion about weight loss. Still, at least we can be thankful that more of the journalism on this subject seems to be discussing satiation.

[ Parent ]
satiation by ObviousTroll (2.00 / 0) #20 Sun Jun 28, 2009 at 07:36:13 PM EST
Indeed - I long ago realized that my need to eat is driven by things other than actual hunger.

Unfortunately, that doesn't make them any easier to ignore.

I've been trying to wean myself off the carbohydrate merry-go-round, but with limited success.

An Angry and Flatulent Pig, Trying to Tie Balloon Animals
[ Parent ]
Glycogen by ucblockhead (2.00 / 0) #15 Sun Jun 28, 2009 at 06:54:35 PM EST
You are ignoring the weight of glycogen itself...also, in practice the body will replenish this from fat stores (at least I think it does that if you don't eat right away) which means that you essentially can just ignore how much glycogen he has at the outset.

Even if he does eat immediately afterwords, a glycogen deficit will mean that his body will be building glycogen stores before going to fat.  It's all a zero sum game.

But yeah, if he lost 13 lbs, most likely 12 was water.  (If we don't reflect on his potty habits during the ride.)
---
[ucblockhead is] useless and subhuman

[ Parent ]
No, I'm not. by ni (2.00 / 0) #17 Sun Jun 28, 2009 at 07:28:25 PM EST
a) Yes, glycogen will ultimately be replaced from fat stores (assuming no simpler sources of energy are available).
b) The claim made was about fat. Yes, his body definitely lost (very significant amounts of) other energy sources, but that's not really the issue at hand.
c) Yes, it's zero-sum in some sense. The lipid catabolism will be offset compared to glycogen use, though. A hormone signaling pathway needs to be activated for lipid catabolism to begin, and it's fairly slow. If he'd been running a marathon or something it could play a big role, but in three hours of biking it's probably not kicking in until he gets home, or near there. That it's ultimately zero-sum isn't significant, because he weighed himself when he got home. Most of the glycogen synthesis has yet to take place at this point.


"These days it seems like sometimes dreams of Italian hyper-gonadism are all a man's got to keep him going." -- CRwM
[ Parent ]
My point by ucblockhead (2.00 / 0) #22 Sun Jun 28, 2009 at 08:31:27 PM EST
There's not much different between fat actually lost during the ride and fat that almost certainly will be lost immediately following the ride from a "how do I lose weight" perspective.  From the "end user perspective" (as it were) losses from exercise are either ultimately water or fat.

In other words, if I write the check, I "paid" the bill even if the bank hasn't gotten around to transferring funds.
---
[ucblockhead is] useless and subhuman

[ Parent ]
Of course, by ni (2.00 / 0) #24 Sun Jun 28, 2009 at 09:59:31 PM EST
but I think you need to reread the parents. Whether he'll ultimately lose fat isn't the issue -- yes, of course he will, but the question is whether his weight loss immediately upon returning from bicycling can credibly be attributed to fat loss. In this case there's all the difference between fat loss that has taken place and fat loss that will take place, in that one can contribute to a weight loss and the other can't (being in the future and all).


"These days it seems like sometimes dreams of Italian hyper-gonadism are all a man's got to keep him going." -- CRwM
[ Parent ]
I wouldn't call it "loading" up on carbs by ObviousTroll (2.00 / 0) #18 Sun Jun 28, 2009 at 07:31:23 PM EST
ni's estimates on the calorie burn rate are similar to my own, but I've noticed a marked improvement in my mood and energy levels if I eat a 100 calorie granola bar every hour or so during the ride - so I did bring a stash with me to eat.

On the other hand, it's also pretty established that once your metabolism gets jacked up by heavy exercise, it stays elevated for several hours afterwards, so it's possible you're right and I did burn a couple of pounds of fat overall.


An Angry and Flatulent Pig, Trying to Tie Balloon Animals
[ Parent ]
It's not unusual by Herring (2.00 / 0) #14 Sun Jun 28, 2009 at 02:45:47 PM EST
for pro cyclists to lose 5% of their bodyweight on a stage (as water). Much more than that and it wont be doing you good though.

I need to do a 60+mile ride before this sportive in August. Maybe next weekend. I wish I didn't live on a hill.

You can't inspire people with facts
- Small Gods

Good luck. by ObviousTroll (2.00 / 0) #21 Sun Jun 28, 2009 at 07:42:25 PM EST
I added elevation charts to my riding log because I wanted to know if how my hill riding was doing. Interestingly, a 40 mile ride with a total of 1400 feet up/down left me more tired than a 30 mile ride with 2800 feet of up/down - but the second ride made me much more miserable while I was doing it.

The main reason the water loss surprised me is that I wondered if it puts a kind of cap on how long/far I can ride - if it explains why I run out of gas after a couple of hours.

An Angry and Flatulent Pig, Trying to Tie Balloon Animals
[ Parent ]
It's the salts that will do you in by ucblockhead (2.00 / 0) #23 Sun Jun 28, 2009 at 08:33:53 PM EST
I did a long hike last year...20 miles on a hot day, and by the end I was about ready to lose it.  Water was doing nothing and food seemed to turn to paste in my mouth.  When I hit the car, I immediately went to Safeway and bought three fruit-juice drinks.
---
[ucblockhead is] useless and subhuman
[ Parent ]
Yeah, I learned that lesson the hard way by ObviousTroll (2.00 / 0) #25 Sun Jun 28, 2009 at 10:03:35 PM EST
Last summer, after my first 50 mile ride, I got horrendous cramps. Now I make sure to carry some "energy tablets" with me - the stuff I buy basically turns the water into sugar-free gatorade.

An Angry and Flatulent Pig, Trying to Tie Balloon Animals
[ Parent ]
you should try by garlic (4.00 / 1) #27 Mon Jun 29, 2009 at 07:03:03 PM EST
an evening before bed weigh in, and a morning weigh in. That'll give you an 8 hour resting water loss guideline.


Let's talk about sweat, shall we? | 28 comments (28 topical, 1 hidden)

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