It was pretty muggy here in Phoenix this morning and I had a hard 40 minute run planned. I decided to check my sweat rate on a day like this as this type of weather doesn’t come around very often. It is usually warmer, but much dryer. I weighed myself right before I left the house (167.5 lbs on the scale naked) and proceeded with my run. I knew I was sweating a lot because I threw my shirt on the ground about halfway through my run because it was soaked and irritating my skin (read: nipples). Got home after running just over 43 minutes, toweled off, stripped and hopped back on the scale. This time it read 164.4 lbs. Doesn’t 3.1 lbs seem like an extreme amount of water weight to lose on such a short run? What does your sweat rate look like on days like this?
Seems fairly typical - especially on those hot days. If anything, it may be a little much (I loose about that much on hour long runs, but I weigh closer to 190 - 195). Just rehydrate.
I did this as an experiment last summer…measuring fluid loss in all three disciplines.
Here’s what I came up with.
Swim - 2.0 lbs (16 oz)/hr Bike - 3.5 lbs (56 oz)/hr Run - 2.5 lbs (40 oz)/hr
Weighed myself before and after, took the difference.
Swim conditions were a normal outdoor pool (roughly 78-80 F)
bike was on an indoor trainer, 72-76 degrees (took three measurements in three separate sessions, took the average)
run was on a treadmill, ambiant temp of 70-72 (what they keep my local YMCA at), again took 3 measurements, took the average.
On a hot day (80 degree plus), I’ll lose more like 3.5 lbs an hour in water weight. The most I’ve ever lost was 5 lbs on a hot 90 minute run.
Three days ago I lost 4-4.5 lbs in just over an hour of easy running. Of course, it’s been ridiculously hot in Atlanta lately, and running in near 80 degree temperatures with a humidity rate that’s just as high is what passes for moderate right now. From what I’ve been able to find online, my number is at the high end of normal, but doesn’t seem excessive.
My records are a pound a mile running (that’s ~9 lbs/hour, if I could do that before getting heat stroke), and 1oz/minute biking (that’s ~4lbs/hour). Hell, I lost 2 lbs last week doing 3000yds in the pool! This past weekend I did 53 miles in 2:45, and net loss was about 8.5lbs (~3lbs/hour).
Oh here I’m thinkin’ this thread would be ugly…like a little story about a guy (at band camp…) who collected his stationary trainer-evoked sweat in a bucket, to see for real if one would/could ever truly “sweat buckets”. He figured his basement and a Trainer was the place he thought it most likely to happen.
He diddn’t empty it after each ride, once he found out it took many rides to sweat even one bucket. He let it fill over weeks.
He is an outstanding cyclist, and let’s just say ya can’t gross him out.
When I was in New Orleans (Tulane), I used to get a warm up and one set of (very vigorous) singles and be soaked and soak a very large bath towel. I was the guy in the spin class who had a giant puddle that ran off to the adjacent bikes in under an hour.
an update…I ran 2 hrs this past Sunday, mid-afternoon…it was mid-80’s, low humidity. Drank 20 oz of fluid (NOT NEARLY ENOUGH) and still lost 7.5 lbs…so total fluid loss was about 8.75 lbs.
I bonked 3 miles from home…was suffering big-time.
I had 2 gels (GU’s) and InfinIT. I just didn’t have enough actual water…only took a 4 btl Fuel Belt, which after checking is 32oz of fluid, not 20 as I previously stated.
Still not enough. Next time, I either take another water bottle or plan a route with a water stop.
I run where I know I can get water to hydrate my gels. I sometimes carry an 8 oz hand bottle that I fill every 30-40 minutes som I can sip as I go. I hate carrying big bottles.
eGels are like Gatorade endurance in a gel, minus the water and WAY better tasting.
viva las vegas - i dropped 2.2 pounds (i’m 170) over the course of a 2-hour ride on which i consumed 2.25 liters of liquid. The air was dry but reasonably hot - call it 100 degrees.
that makes me, what, a “heavy but not ridiculous” sweater?
I sweat like a whore in church. World Class baby! I once lost 9 lbs on an hour twenty minute run. And drank a 1/2 liter of water immediately following the run and before weighing. But I am a fat ass too. I am sure that has alot to do with it.
In Houston in Aug. I can sweat 8 oz. just walking the dog around the block, but sweat less than 8 oz. for a hard 40 min run in January when its cold and dry (well, kind of…). I think the humidity info is just as important as the temperature.
I checked for the first time today. The temp outside is 59 and it was raining rather hard. I weighed myself with my work clothes on before and after. I lost 2.5lbs on the nose in just under 30 minutes. On a hot day that wouldn’t surprise me much, but basically cold and raining? my clothes were literally ring out soaked from the rain and i still managed to sweat 2.5lbs? is this an issue.
ran just under 5miles ~6:10 pace with shorts and a t-shirt.