Drat. Can anyone use a bathroom scale?

I’ve been wondering recently whether I should run my next marathon with a camelbak because I suspect I get dehydrated even though I try to drink from all the little cups of water they offer me on the course.

So Mike suggested that I weigh myself, run hardish for an hour, and weigh myself again (without drinking) to see how much water I lost from an hour’s running.

I didn’t have a bathroom scale, so I had to buy one. Then off I went to the Wilcox on Monday morning, scale in tow.

I ran one lap easily as a warmup, then got out my scale and weighed myself, and set out. I was to run at a 7 minute pace, which isn’t really hard for an hour, but isn’t easy either.

After a little more than an hour I was back at my scale. I weighed myself. I weighed exactly the same as I had an hour before. I moved the scale slightly and weighed myself again. Now I weighed 5lb more. I had tested the scale at home, and it seemed consistent, so I guess it doesn’t do well when it isn’t level.

This morning I went off to the gym to repeat the experiment, this time on an indoor treadmill and with a better scale (on a level surface). I weighed myself, got on the treadmill, and ran for an hour (dripping sweat by the end), and weighed myself again. I had lost 3¼lb.

Now it takes me about 3 hours to run a marathon, that’s about 10lb of water loss. That sounds like a lot (I can’t carry 10lb of water and run a reasonable race). I certainly haven’t drunk that much. And for a 50 mile race that takes about 9 hours that’s almost 30lb.

Of course my race won’t be in a 70° room, so I won’t sweat as much (probably), on the other hand I’ll lose more to transpiration (each breath loses water, unless you happen to be in air with 100% humidity and is at body temperature). And maybe today was a fluke. I should try again.

But… I have a bathroom scale I don’t need. Does anyone want it?

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6 Responses to “Drat. Can anyone use a bathroom scale?”

  1. Maggie Mason Says:

    I always lose way more on the treadmill indoors, than a moderate day outdoors. And CIM will be cool, no question about that, so you won’t lose as much. Don’t give away the scale. Put it in one place in your home, weigh yourself before and after your runs from home. Over time, you’ll get a realistic idea of how much water you lose.

  2. Maggie Mason Says:

    Well, weigh yourself before you jump on the bike, then!

    • georgeruns Says:

      The thought has crossed my mind. But the scale at the club is definitely more accurate. I have a better feeling for using a balance scale than a spring scale.

  3. Adger Says:

    Did you weigh your clothes? They may have picked up a noticeable amount of water.

    3 1/4 lbs. should be 3 1/4 pints right? Can that possibly be accurate?

    • georgeruns Says:

      I realized I should have weighed myself naked and toweled off beforehand to (to get rid of the layer of sweat that was on me too). But I don’t think that would have amounted to much. The scale (even the good one) isn’t accurate down to ounces.

      Yup. 3 1/4 pints, roughly 1.5 liters. Probably would be less in cooler temps. Need to do it again.

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