I think you’ve summarized the heavy-sweater situation perfectly, at least for me. I’ll add a comment and a question. For long rides / runs in humid weather, I’ve had success pre-loading with sodium. Extra salt at meals and salty foods. This helps retain extra water so you start the workout on the high side. It’s hard to say what my actual weight is in the summer, probably around 172 lbs. But I start workouts as high as 178 lbs and finish as low as 165. Lower than 165, and my power drops through the floor.
The question is: how did you dial in 1000 mg of sodium? I’ve been using 750, but really don’t know if that’s correct. Sweat rate is an easy calculation, sodium loss seems more elusive to quantify.
Interestingly, enough, I drank a ton of water on one of my long runs trying to replace my fluids, because in the previous week I did a sweat test and lost like 6 pounds on an 18 miler…and I drank 20oz/hr…so, I knew I had an issue. I was not educated that well on electrolyte loss, so the next week, I drank a ton more and I noticed my hands were swelled up. Talked to a nutritionist, and she said I was probably hyponatremic, and to add salt. So, we kept adding salt. As you suggested, she had me eat more salty foods (I have low blood pressure…so no issues there) and even gave me a salt loading protocol (I can share if you PM me - but its basically sipping on a NUUN + saltstick + table salt concentrated drink every 15’ for 2 hours the night before a long day or race). And then we upped my salt 800mg/hr to 1000 to 1200 for IMKY. After the race, I decided to get a sweat test (Levelen.com - no affiliation, but for $75 they will send out a test and you can return it and they will give you all your loss numbers), and found out my real sweat rate (yes, it can vary depending on temps/diet, etc., but at least you know what category you are in…they will recommend their products, but lots of good information and testimonials…they work with NFL and Hockey teams). I found out I seat 1800mg/hr+ of sodium and even more of CL. Just like fluids, they say you don’t have to replace all of it, but target 70-80%. They have a bunch of abstracts on their website that have more detail. Again, your mileage may vary, everyone is different. MOST of my training partners have no issues with drinking to thirst and occasional salt pills…I am NOT one of those people. I have tried it with a salty diet, I have tried to reduce salt, and all other crazy things nutritionists have suggested…and the only thing that keeps my performance on a hot day (80+ deg and/or 80% humidity and/or Dew points above 60) similar to a 50 deg day is drinking and supplementing with electrolytes.
I’m very interested in your loading protocol. Honestly, I haven’t tried anything quantitative to pre-load, just add a bunch of table salt to meals and enjoy some saltier foods (BBQ comes to mind.) Your method seems more efficient and reproducible. But, after numerous failures under hot / humid conditions (e.g., DNF in Cozumel 2011), I had a great race last year in Kona, and even negative split the run. But as you say, drinking to thirst with the occasional salt stick doesn’t even come close to sufficient.
Ironically, all of the training this summer in 65-70 F dewpoints is for IM Tahoe, where I’ll probably have to pee all race long if I consume more than 20 oz / hr of liquid. Unfortunately, I don’t have the luxury of training under race conditions.
