On Salt
I know the topic of salt intake has been beaten to death but I'm moving into the "worring about the details" phase of race prep and one thing that I've never really been able to properly address in connection with my first IM next month is salt intake. Generally speaking, I'm a heavy sweater but I wouldn't say I'm crusty when I'm done a long bike or ride. I can taste salt on my lips if I lick them, but my clothes aren't white or anything. And, other than foot cramps during swimming I've never experienced a cramp on the bike or running either in training or during a race (longest - 70.3). BUT, and here's the slight curveball, it very, very rarely gets about 72-75 degrees where I live & train but it's quite likely it will be in the 90's when I race. So I really have no idea how my body will react to an IM in temperatures that are 20 degrees higher than normal and other than a couple of days of acclimitization before the race, I'm not going to have an opportunity to find out. The Infinit forumula I will be using for the bike has 600mg of sodium and my run formula has 500mg (though I may opt for Ironman Perform and coke on the run - going to test that during next week's long run). Given that I'm going to be going into this somewhat blind, should I be taking salt pills along with me during the race on the bike and run to use in an emergency? Should I do my last few long rides and runs using salt tabs regardless of the ambient temperature on the assumption that I will probably need them on race day and need to make sure I can stomach them? Or just go with the Infinit and stop worrying about this stuff given my lack of cramping history? Thanks in advance.
Comments
Hey Tyler,
Ditto ...thanks for the question...I too am getting into the worrying about details phase for IMKY...I know it will be hot...and I have been measuring my sweat rate at 2lbs./hour...thats alot of fluid and I think salt intake will help....but so far I amy only taking in about 200mg/hour and plan on significantly bumping it this weekend and next week for my long ride and RR.....
My sweat rate at 80deg+ wth 50%+ humidity is often in the 65-75 ounces per hour (4-5 lbs/hr) so I have to make sure I take in sodium -- I use endurolytes powder/caps -- above and beyond what is in my Infinit for biking, or Perform for running. I have found that 2 caps per hour is usually good to preclude any cramping or bonking.
I thought that too and that's certainly not the case. Edema is the problem, which happened to me at IMTX. Coach P can vouch. He got to see my giant sausage fingers.
See below where they talk about blood flow to the kidneys. Insert hours of physical exertion as the underlying condition (instead of heart failure) and you get the picture.
Moral of the story: there can be consequences to taking in too much sodium. My Infinit bike mix probably had a similar amount of sodium as your's plus I also took about 10 Salt Sticks. I also took a Salt Stick every other aid station for about the first half of the run. Apparently, it was way too much for me. I stopped with the Salt Sticks and just drank water and some cola the rest of the day to dilute my apparent electrolyte imbalance and the swelling subsided.
How does salt intake affect edema?
The body's balance of salt is usually well-regulated. A normal person can consume small or large quantities of salt in the diet without concern for developing salt depletion or retention. The intake of salt is determined by dietary patterns and the removal of salt from the body is accomplished by the kidneys. The kidneys have a great capacity to control the amount of salt in the body by changing the amount of salt eliminated (excreted) in the urine. The amount of salt excreted by the kidneys is regulated by hormonal and physical factors that signal whether retention or removal of salt by the kidneys is necessary.
If the blood flow to the kidneys is decreased by an underlying condition such as heart failure, the kidneys react by retaining salt. This salt retention occurs because the kidneys perceive that the body needs more fluid to compensate for the decreased blood flow. If the patient has a kidney disease that impairs the function of the kidneys, the ability to excrete salt in the urine is limited. In both conditions, the amount of salt in the body increases, which causes the patient to retain water and develop edema.
I discussed bumping up my Infinit sodium to above the current 500 mg and Laurie (@Infinite) said she had me at the max for men. With my 2 lb/hr sweat rate & staying "even" with that on the bike, she didn't recommend supplementing to go higher.
Spoke with Laurie yesterday as I am slowly getting on the Infinit bandwagon. She claimed the gut can only process ~500 mg/hr and putting close to 1000mg/hr in leads to water staying in the gut longer trying to dilute the salt. Salt simply is a water transport mechanism and over doing salt (if Laurie is correct - plan to read more if I can find data) can lead to Edema (as Bob mentions) and also have a potentially negative impact by slowing down the gut.
All that said, I have been fine at 500-700 mg/hr thus far...
The only pro was I didn't have a any crusty salt deposits on me since I was apparently retaining all the sodium. ;-)
http://home.trainingpeaks.com/articles/nutrition/the-straight-dope-on-salt.aspx
@CoachP....so how do you know if you need it? What clues....cramping, swollen fingers, bonking, what?