Endurance athlete fueling, hydration, and electolyte

For all of you that are doing or want to do endurance type events and activities, it is very important to understand fueling, hydration, and electrolyte intake.   As some of you may have heard, some physical states that endurance exercise can induce can be potentially very dangerous.  I wanted to just briefly talk about a couple of things and then point you to a world of knowledge regarding these topics by linking to an endurance library that you will find very helpful.  The link is at the end of the post.  Most of the information in this post comes from Hammer Nutrition’ website.


First off, I wanted to talk about caloric intake.  When you are going to be out there doing your thing for a long long time it will be much more manageable if you take calories in.  Now you don’t have to take calories in up to a point, but the longer you go, the more important it is.  I take calories in from the start of my runs if they are longer than 13 miles.  It helps my mind and body to do so.  I can run much further without calories, but it is far More difficult to do it.  I burn around 700-800 calories per hour while running but the human body will only digest around 350 plus or minus some each hour.  You still end up in a deficit but you increase your endurance by doing this.

Dehydration is bad

It is important to take fluids in during your endurance activity.  As with food, you body can only take a certain amount of fluid in.  You will not be able to replace all the fluid you lose without putting yourself in danger of “water intoxication”.   Below  is a chart from this link to demonstrate the importance of hydration and its effect on endurance.

Symptoms by percent body weight water loss:

  • 0% — none, optimal performance, normal heat regulation
  • 1% — thirst stimulated, heat regulation during exercise altered, performance declines
  • 2% — further decrease in heat regulation, hinders performance, increased thirst
  • 3% — more of the same (worsening performance)
  • 4% — exercise performance cut by 20 – 30%
  • 5% — headache, irritability, “spaced-out” feeling, fatigue
  • 6% — weakness, severe loss of thermoregulation
  • 7% — collapse likely unless exercise stops
  • 10% — comatose
  • 11% — death likely


One of the most dangerous conditions that can happen to us is hyponatremia.  This is the state where the sodium levels in your body have been “watered” down by to much hydration without proper electrolyte replacement.  It is a common occurrence with marathoner who will take 6 hours or longer to finish their race.  This condition can be and has been fatal at the marathon levels. Here is a little blurb about this condition from hammer nutrition.

Tragic consequences

Hyponatremia usually results from drinking too much, especially when one drinks fluids such as plain water or a sports drink lacking the proper electrolyte profile. Training and fitness levels, weather conditions, and, undoubtedly, biological predisposition, also contribute to developing this form of hyponatremia known as “water intoxication.”

Sadly, we must note that this condition has lead, directly or in part, to the deaths of otherwise healthy runners in major American marathons. It is hard for us to comprehend the grief of the families they left behind. These athletes went out to run a marathon, to achieve a personal victory. Improper hydration took away their day of glory and also their lives. They collapsed and went into an irreversible condition involving uncontrollable brain edema, coma, and death. We report this to help prevent any future such tragedies. Over-hydration represents a very serious problem. Unlike dehydration, which will generally only result in painful cramping, possibly a DNF, or at the worst, IV treatment, over-hydration can incite a chain of ultimately fatal physiological consequences.

So you cannot replace all fluids lost but you can drink to much.  The reason for writing this post is because I used to be very scared of this condition and also of generally hurting myself doing these long runs. I want to share with you the most important resource I have found for learning about endurance activity and it’s necessary caloric and fluid replacement.

The complete endurance library

10 Responses to “Endurance athlete fueling, hydration, and electolyte”

  1. 1 whisfam4
    March 3, 2009 at 10:43 am

    Thanks for this post. I’m not there yet but this will be very helpful when I do get to endurance running. I have no clue about this stuff so I’m glad you posted it along with some links.

    • 2 run4change
      March 3, 2009 at 11:07 am

      Whis- Just keep the links on the back burner until you are ready. I promise you that if you read the info., and learn it, you will NOT be disappointed

  2. 3 Jen
    March 3, 2009 at 10:44 am

    Thanks for posting this Jason. I’m a biker and signed up for a 100-mile mountain bike race this summer. It will be my first endurance event 😉

    • 4 run4change
      March 3, 2009 at 11:08 am

      THat is awesome. Wow!!! 🙂 That is sooooo far. Great job. This information will work wonders for you. Just get yourself on an eating and drinking schedule for your long rides to work out a routine and then stick to it no matter what on race day

  3. 5 RobFitness
    March 3, 2009 at 2:19 pm

    I too appreciate you sharing all this information and knowledge. Plus thanks for that link as well. I know I don’t do long runs like you but still feel proper nutrition in any type of training is important and the information that you have shared will sure benefit me at some point in my training. Plus I do enjoy learning whatever I can to make me the best, fit and healthiest person I can be and this will help me achieve that goal as well.

    • 6 run4change
      March 3, 2009 at 2:39 pm

      No problem man. It is good info. regardless of how far, long, etc. you go. It is just good healthy info. based on science

  4. March 5, 2009 at 8:24 pm

    I’ve been MIA here for a bit :(. I miss your blog. I should add it to my blog roll so I don’t miss it next time :). Thanks for the link in this post. Congrats on keeping the chew out! You’ll make it. Is it at all easier after day 7? That’s when I’ve noticed kicking an old habit gets to be more routine for me. Those donuts in your latest post have me crying. I gave up donuts this week 😦 :(. I miss them already, but I’m sure when I hit day 7 I’ll be fine.

    • 8 run4change
      March 6, 2009 at 5:28 am

      For life- I am so glad so see you back. No problem on adding me to the blog roll if you want to. YOu are welcome for the links and I promise you that the info. that the links contain is supremely helpful. I used this info. to successfuly complete many ultras without dehydration or food or stomach issues.

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