Welcome to Jercol's Back to the Basics. This is where I will post useful information, tips, and gear reviews about what I learn about Outdoor Survival, Activities, and Disaster Preparation. My only goal is to be informative, realistic, and at least a little entertaining.

Sunday, February 10, 2013

The Metabolism of Endurance

When I was really into long distance trail running and hiking I spent a lot of time looking for the best options for food and drink (usually referred to in those circles as "fuel" and "hydration").  Some of those products were really cool, really effective, and a lot of those lessons I learned serve me well every time I head into the woods.  In this post I'm going to go over some of the basics, in the next post I'll talk about some of the specific food and drinks that have worked well for me.

Obviously, trail running is a much higher intensity than hiking, but a lot of the techniques can carry over.

When you are moving a lot, sweating a lot, you need to keep in mind fuel and hydration.  You need to intake calories, water, and electrolytes if you want to KEEP moving.  Too little fuel, food, and you run out of energy.  You have to maintain the proper electrolyte balance as well, you get too far either way and you lose your endurance, get sick, and it could eventually kill you.  Electrolytes are necessary to relay electrical impulses in the body, they include sodium, potassium (those are the two biggest), magnesium, and calcium.

Too much water (without enough electrolytes) and you can get hyponatremia, a condition that kills a couple long distance runners every year.  They run a long race, lose lots of electrolytes, then drink water trying to rehydrate.  By just drinking water they essentially dilute the levels of electrolytes in the blood, it throws off your body's balance.  Sports drinks are one way to intake electrolytes, but there are quite a few options (I'll go over them in my next post).  Hyponatremia outside of athletics is most commonly caused by kidney failure.  In other words, it's not the kind of thing you want to happen in the woods, in a survival situation, or during/after a race.  That's why you need to take in electrolytes.  Also, look at the drinks you are using, many common sports drinks only have sodium, potassium, and not necessarily in the ratios that are best (these are better than nothing but intended for short term activities, sporting events).  For extended activities you need to find a better option with Sodium to Potassium is about 3.5-1, calcium and magnesium levels should be lower and in a ratio about 2-1.  So, something with 180mg of Sodium, 50mg of Potassium, 10mg of calcium, and 5mg of magnesium should be about right for an hour of high level activity.  There are quite a few electrolyte pills available, a simple, easy solution when drinks are not as available.

Hypernatremia, or too much sodium, results in the same symptoms as dehydration; extreme thirst, lethargy, weakness, swelling, and at extreme levels seizures and coma (the same as drinking sea water).  Usually, it will start with swelling in the hands and feet.  When you get in tune with your body you will notice those symptoms and increase your water to electrolyte intake.

Ok, so those are the reasons that balance is important.  Now, how much overall fluid should you be taking in?  That depends on your personal physiology (some people sweat more than others, with more or less electrolytes lost), your fitness, the climate, and your current activity level.  Essentially, you need to do some testing and find how much you lose so you know how much you need to drink.  When I was running a race I would typically take in close to a liter of fluid an hour, that was trail running though; high activity level, extreme heat, lots of sweating.  For hiking I could probably make do with half that.

It's also better for your body to take in fluid frequently and in small amounts.  That helps maintain a steady balance rather than drinking a full liter once an hour and it's easier to absorb.  That's why hydration packs like the Camelbak or hand held bottles are so popular with long distance athletes, easy to take small, frequent sips.

Ok, now what about food or 'fuel'?  Again, that depends a lot on you and your activity level, but to maintain a high activity level for multiple hours you should probably try to take in at least 300 calories an hour.   Now, this is where it gets a little complicated... when your body is in high activity mode it's diverting blood away from your stomach and generally toward your legs (or skin for cooling), which means you won't be digesting food very well.  In fact, you are going to be digesting really poorly, absorbing calories very slowly and inefficiently, which means you need to bring along food which is easily digested or you will just get bloated, cramped, diarrhea, and not many calories.  Mostly you will need carbohydrates for energy, but you will also need fats (for long term energy), and protein (for energy and to maintain muscle endurance).  Easily digested foods are those like fruits, gels, liquids, and gummies.  For low intensity exercise, like easy walking and hiking, foods like trail mix have a pretty good mix of carbs, fats, and protein. Just like the water, you want to eat small amounts frequently, it's easier on the stomach and will help maintain a better overall balance of energy level.

I know, it all sounds complicated, but once you do a little experimenting with what products and balance work for you the benefits are drastic.  You can go longer, feel better, and recover faster.

Next post, I'll show you some of the cool products I've found that work well for me.

No comments:

Post a Comment