Sweat
I did a sweat test over the weekend while doing a 16 mile run (3.5 hours). Here are the results
Temps was 75 F at start and finished at 85 F. Humidity 60-80%.
Weight pre 269
Weight post 261
Dehydration 2.6%
Intake: 126 Oz fluid (36 oz/hr), 825 cal (236/hr), 770 mg Na (220/Hr), 388 mg K (110/Hr)
· 0-60 min: 24 oz Heed / Endurolytres Powder (210 cal/160 mg Na)
· 60-120 min: 24 oz Heed / Endurolytres Powder (210 cal/160 mg Na)
· 120-180 min: 4 oz concentrated perpetuem/endurolytes (270 cal, 300 mg Na); 48 oz water
· 180-210 min: 2 oz concentrated perpetuem/endurolytes (135 cal, 150 mg Na); 24 oz water
Overall I had no cramping, bloating or GI issues. I did urinate a moderate volume at 150 min, color was darker than normal. Pace did drop last 1-2 miles as I felt fatigued but I expect this caring so much weight. I have always had issue keeping up with loss as I am a heavy sweater.
1. So if I have things correct I should have drank 128 - 192 more oz of fluid or a total of 254 - 318 oz total(11-13 bottles) which is 73-91 oz per hr (3-4 bottles)? Is this correct? I do not think that I can carry that much fluid much less drink that while running? Am I calculating something incorrectly?
2. Calculated sodium intake; using 350-500 mg per 24 oz per Dr. Kitima B’s recommendation; should have been 3700-6625 mg (~1050 - 1900 mg/hr)? This also seems like a lot? Again am I miscalculating?
3. I know losing weight will help with the sweating and overheating and I’m working o that but any suggestions on ways to maintain hydration. I believe athletic performance is impacted at 2-3% dehydration and as you can see anything much longer than a Half Mary is a dehydrated me waiting to happen.
Comments
7 lbs x 16 oz/lb = 112 oz of fluid more that you needed to replace ALL of your fluid losses----which would be 32 oz EXTRA per hour on top of what you were already taking. That's 68 oz of fluid /hour. You're right, that's alot.
Most people will not ever replace ALL the fluid losses for long events simply because it's often not possible to absorb that much fluid and exercise at the same time unless you go really, really slow.
That being said, if you replaced your fluid losses so that you only lost 2.5 pounds (which would be less than 1% dehydration) that would be a total hourly fluid intake of 57 oz which is a bit more doable. I'm 130lbs and have taken 55 oz of fluid per hour running marathon to E pace with out gut shutdown.
As for sodium intake, the range of sodium in sweat is very large (300 to 1500 mg per liter). Seems like 220 mg/hour worked for you in that you had no muscle cramps or symptoms of hyponatremia (you weren't swollen, right?). In order for your intestines to absorb water, there needs to be sugar and sodium along with the water. If you are going to increase your hourly fluid intake to 57 oz then you should at least double your sodium intake with it (so 440mg/hour) in order to prevent hyponatremia.
As for taking 1000mg of sodium/hour---I've done that because I'm sweat alot of salt. I use cramping to titrate how much sodium I need. I do remember reading that the highest sodium sweat content per liter is 1500mg. As one becomes more acclimatized to heat, the body will conserve sodium and water therefore there will be lower fluid and sodium loss through sweat.
Hope that's helpful.
1. Any thought's on why unable in drink more during the run? Is it something I need to build up to?
2. Also was wondering in general.
a. Intake while exercising needs to be isotonic to speed absorption. How well does this work when taking in the concentrated multi-hours bottle the is hypertonic and
following with water that that is hypotonic?
b. Potassium and calcium are also involved in muscle contraction and re-polarization and both are lost in sweat. Any recommendations on overall needs for these minerals
during exercise?
Thanks again!!
1. 50+ oz of fluid is alot too drink while running. The higher the intensity/faster the pace the less blood flow to your GI system to process all that fluid. Your stomach will not empty as it should and feel sloshy. Also, if you are running in heat and have not acclimatized to that heat, with increased body temperature your body will shunt blood to your skin to cool itself (and decrease flow to the GI system).
During a race, you should hopefully have plenty of aid stations with ice and sponges with water to cool yourself. Also, you won't be carrying all your fluids/nutrition with you---so that will be less work you will be doing. Point is, you may not need the 50 oz of fluid during the run part of your race (if you properly hydrated during the bike) as your sweat rate may be lower because there are more resources to cool yourself and less weight to carry around compared to a training run.
Also, try sipping small amounts of fluid more frequently while running. I set my watch/Garmin alarm for every 9 minutes on my long runs in the heat. That may help your stomach feel less sloshy vs. drinking larger quantities less frequently.
2a. Yes, what you put in order stomach should be isotonic to promote better absorption. To achieve that with the concentrated bottles, you would have to drink enough water with each sip of concentrated fluid to make it isotonic. I've gone so far as to measure how much each "sip", "gulp", "swig" contains. If the concentrated solution is 2x the regular serving (normal concentration which is isotonic) then for every one "sip" you take of it you'll need to drink at least 2x that "sip" in water. Same goes if it's 3x, 4x, etc. You really have to be diligent about the water intake at first---but after a while it just becomes habit. If you want to simplify it, you could just remember to drink "alot" of water everytime you sip on the concentrated fluid (just make sure that "alot" is enough!)
2b. Potassium and magnesium are important for muscle contraction---especially the heart. Both electrolytes are contained mostly INSIDE your cells (vs. floating around in your plasma outside your cells like sodium). Unless you have a kidney problem there's really no benefit that's been shown to supplement with potassium and magnesium during exercise. That being said, you should make sure you are eating healthy foods that keep your potassium and magnesium levels normal. Foods with potassium: beans, carrot juice,dried apricots, avocados. Foods with magnesium: black beans, halibut, spinach, okra. Not a complete list, of course.
Hope that's helpful!
hi Kitima (and others) I am leaving for Tawain to do a 70.3, leave on Sunday get there on Monday and race is Saturday. I ALWAYS get very swollen and dehydrated on these super long flghts no matter how much fluid intake and then it takes about 2 days to return to normal (normal feet and ankles). I am a MASSIVE sweater, have never had it measured but literally soaking dripping wet even after an hour on indoor bike (with fan and adequate air) or treadmill. I drink two 18 ounce bottles an hour while indoor training and 3 large water bottles on a 45 mile bike outdoor. i am expecting very high humidity and high temps (80-s - 90s) during the 1/2 IM in Tawian am going to add electrolyte tabs and drink as much water as possible with nutition on bike , use sponges and ice and drink as much as i can on run but in Kona 70.3 I just couldn't keep up the fluids , i was not cramping, nothing "serious" but completely ran out of steam on the run, just smoldering hot. I have NO weight to loose, 99 pds right now and trying hard to keep weight on, Guess my biggest question is adequately dealing with dehydration from the flight and fatigue from time change and just plain being tired from traveling ,about 22 hours from point to point. Any extra thoughts on how to prepare better this time, also first time traveling international for a race this long (it took me 8 hours to do the 70.3 in Kona, had lots of knee injuries so the run sucked the time away) expect to do much better in Taiwan, but STILL I am out there ALL DAY if you really think about it. Thanks for any ideas
For those long transcontinental flights, it's really important to stay hydrated. The pressurized air in airplanes is very dry and not exactly the same atmospheric pressure as sea level. It makes for a very dehydrating environment. So make sure you are well-hydrated before you get on the plane by drinking plenty of non-caffeinated liquid so that the color of your urine is clear. When you get on the plane, no alcohol (tempting as it's free on those international flights) or caffeine. Keep drinking to keep your urine color clear or very light. When you get there, try to re-establish your circadian rhythm according to that time zone---that is, go to sleep when it's dark and stay awake when it's light out. Continue to hydrate well up until the very minute you start the race. Start adding some extra salt/sodium to your food 3-4 days out from your race. As you will be in Taiwan, there's plenty of sodium in Chinese food especially dim sum with lots of soy sauce, soup noodles, dumplings with more soy sauce, peking duck with hoisin sauce. Ah! I'm jealous of your dining opportunities!!
Here's the link to my article in the wiki about monitoring hydration status as well as sodium intake: http://members.endurancenation.us/Resources/Wiki/tabid/108/Default.aspx?topic=Monitoring+Hydration+Status
Thanks so much, all makes sense! Mostly your aritcle! But also the sleep patterns and caffeine in your response. I know better regarding the alcohol but love my diet cokes on airplanes and waiting in the lounge for hours.....so that will be hard but worth it!!!! Very helpful, I left my comments but the most important thing i learned (knew before but resisted believing it) was that it can't hurt (in fact would help_ to always add something to my "water bottle", eg. supplements of some sort. So last long race I just couldn't quence my thirst, now makes sense. Going to race this this time with lots of PLAIN water and hopefully have a much better outcome. Thanks again for taking the time for us little peeps!!