I have been trying to keep track of how much fluids I lose during workouts. Running I lose 2-3 pounds when it is hot or can’t refill the H2O bottle. On the bike, usually nothing unless it is really hot. However, on the swim I lose an incredible amount of weight. Today for a 1:06 swim (about 2.4 miles) at a reasonable HRT (avg 136) I lost 5 pounds. The water temp in the lake is about 70 and I wore a wet suit, but at 145, loosing that much weight is going to be a bear to recover on the bike during my up coming ironman!
Is this excessive or have I just “discovered” something everyone has known about? How do I replenish that much fluid on the bike? (If my calculations are correct, that is over 4 bike bottle of water.)
It’s probably not excessive if you consider you’re drinking while biking and running and not while swimming. How much would you lose while running for an hour with no water. I lose about 4-6 lbs an hour if I don’t drink in moderate weather. Try the swim without the wetsuit and see if there’s a difference.
You definitely sweat more than you probably realize when you swim. I’ve been told you sweat more swimming than you do for similar intensity/time running. I’m not sure if I believe that but I believe you sweat a lot, particularly in a wetsuit. Even still, your numbers have got to be off. If we lose 5lbs water/hour swimming at moderate intensity, all the swimmers doing hard 2.5 hour workouts without drinking water would be losing 12+ pounds of water and would end up in the ER or dead.
Also, annecdotally, I weigh myself just about every morning. Sometimes after a 2-hour swim workout, sometimes after a 2-hour run, sometimes after doing nothing. My weight never fluctuates more than a pound or two and I can promise you I’m not taking in 8lbs/day of water.
Weight fluctuation is interesting. I think some must fluctuate more than others. Most days I weigh 196, some days 203. After a 5 hour ride, consuming 5 liters on the ride, I weigh 188.
All the swimmers doing 2.5 hour workouts aren’t wearing wetsuits which is a huge difference. At a tri last year, a guy drowned in wetsuit and when they pulled him out his core temp was 107. The water was 78.
I have found that if I really load up on the salt and water during the 24 hours before a Tri, I can put on around 3 pounds. (Next time I’m gonna try 48 hours, to see if I can get it up another pound.) Also, if you salt your coffee, OJ, etc. on race day, you won’t have to urinate it out just before the race. Lastly, I drink a pedialyte singles (cherry or apple) just before the swim. (It is MADE for rapid absorption.)
This is interesting since I have never had a sense of how hot/cold I am during the swim. I doubt I have lost significant fluids at all during a swim. It really never gets warm enough here.
It is probably a good idea to follow the advice of remaining hydrated right up to the swim start. On really long swims I wondered if a camelbak would help- I mean long, military type swims where you are out there chugging along for two hours.