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  1. #1
    Senior Member kf5nd's Avatar
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    I went on a 32 mile roundtrip bike ride yesterday (a moderate distance for me, I do longer rides up to a Century). I rode out in the cool of the morning, helped teach a bike safety class to some schoolchildren, then headed back by 10:45 am when it was already hot (the high for the day was 95 F, with heat index near 100 F), getting home around noon.

    On the bike, I probably drank 1.0 liters of Gatorade in the early AM, drank about another 1.0 liters of blended plain water and Gatorade during the several hours of the bike safety event, also someone gave me about of a candy bar. On the ride back, I probably also drank about 1.5 liters of plain water, but I also had two energy gels spaced out over the entire ride back, which each have 230 mg Na 85 mg K (for comparison: one small 5.5 fl oz can of V-8 veg juice has 430 mg Na and 360 mg K). So, I followed good practices as far as hydration & nutrition are concerned.

    I felt fine during the ride (although hot), and immediately after the ride. At home, I felt like I wanted something salty (my skin tasted bitterly salty from so much sweating), so I had a two small, cold V-8 juices (so, 860 mg Na and 720 mg K all told).I had lunch, felt sleepy, and I had a headache. I took ibuprofen, and took a long nap. I drank water at lunch. I ate a normal dinner, had one small glass of wine, and drank several glasses of iced tea.

    By bedtime, I felt puffy in my face and hands. I stepped on the scale, and noticed that I was 7 pounds overweight from my usual weight. Most of this must have been fluid, right? I did not eat seven pounds of solid food. I am guessing that the headache results from cerebral edema, which is a disturbing thought, if correct. I did not encounter any altered mental state at any time, however.

    As I write this, 22 hours after the conclusion of the ride, I am still 4 pounds over my starting weight, presumably also fluid. Headache gone, but I feel definitely feel like just totally resting today.

    So why do I get this edema? Why the long (24 36 hr) recovery time? How do I prevent or mitigate it? Is this hyponatremia? But I ate lots of electrolytes!

    This is puzzling the heck out of me. Maybe I should just weigh myself before and after the ride, and resist the temptation to over-drink... but I feel thirstywhen it's hot and horrible here in the summer.

    That's like saying... don't breathe, you'll get too much oxygen.

    WTF !!!
    Last edited by kf5nd; 05-22-05 at 04:32 PM.

  2. #2
    sch
    sch is offline
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    Your sweat glands, this early in the hot season are not yet making low sodium sweat and even at their best a lot of sodium goes out in sweat. It takes a few weeks of heat exposure for the body to go into sodium preservation low sweat sodium mode.
    Even avid bicyclists don't expose enough to fully switch modes. The 3.5 liters of liquid you ingested on the ride + the other liquid later add up to more than 7# wgt. This is low sodium by definition (body fluids extracellular contain 3.6grams of sodium per liter, or 12.6 grams of sodium in the fluid volume you ingested) so you have an intake discrepancy of at least 10grams shy, plus all the salt you sweated out. So there was some dilutional hyponatremia there. How much urine did you make (most people empty their bladders at 250-400ml). Sounds like a combo of excessive water and sodium loss, not sweating a huge amount of fluid or urinating a lot and developing the blahs from this and tissue edema. As you exercise more in the heat your body should adjust but it does sound like there is some discrepancies here in the way your body handles heat stress and fluid loads. Some medications can do this. The recent spate of articles on hyponatremia and sudden death in marathoners is likely limited to a small group of people who didn't handle fluid loads well and diluted down. Most were slow runners out on the course for 4-5hrs, giving ample opportunity for large fluid intakes.
    You might want to back off on the fluid a bit and start doing pre/post ride weights and keeping track of your urine output for a while to see what the trend is.
    Steve

  3. #3
    2-Cyl, 1/2 HP @ 90 RPM slvoid's Avatar
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    Holy crap... I'm sorry, I thought you said "post ride enema" at first... whew.
    I dunno if you were overdoing it. But during the summer when it's 95 degrees out and I'm out on a 2 hour group ride at around 22-23mph, I pack 32 ounces of gatorade + 32 ounces of water and it just makes it.
    The same ride in 60 degree weather and I drink about 16 ounces of water. Your body should be able to regulate pretty well.

  4. #4
    Senior Member kf5nd's Avatar
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    Post-ride enema would do the same thing, overhydrate you!

    I think I'm going to have to take a scale to the rides... budget my fluids... my tongue is going to hate being denied, though. Maybe if I suck on some Jolly Rancher candies I won't get so parched... and take little tiny sips of water.

    This is an early heat wave. Was 96 today. Way too hot for May!

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