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Sunday, March 1, 2015

When Is The Best Time To Eat In An Endurance Event?

I believe this article will help most with people of whom are just getting started with their adventure in endurance sports.  I've not ever discussed nutrition in my blog and there's a reason for this.  The intake of nutrients during an endurance event is different for each individual person.  Nutrition is very customized.  A person will go through a period of trial and error with several different types of energy gels and bars before settling on one or two that work best for them.  So what I'm going to do in this post is give you the basic breakdown of the different types of nutrients or fuel that is used during a endurance event.

Fuel intake during endurance events seemed to become of strong interest in the early 80's.  The default fuel intake during this time were bananas.  Why bananas?  Bananas contained essential electrolytes and the right type of sugar that could be quickly converted to the appropriate type of fuel for the muscles without disrupting the gastrointestinal (GI) system during high physical output.  This was great!  The problem however was that the energy the banana supplied was short lived.  In addition, carrying enough bananas with you during a long event wasn't practical.  So what was needed was a compact lightweight fuel that would provide a person with enough energy for a sustained period of time and a fuel that didn't disrupt the GI system.  Another consideration for the right type of fuel is one that wouldn't pull too much blood from the working muscles to the stomach in order to breakdown and digest the fuel.  So what did the researchers come up with?  Here's the answer:

"Monosaccharides and Disaccharides" along with other nutrients such as electrolytes, anti-oxidants, amino acids or proteins, caffeine, vitamins, and flavoring.  Each energy company has their own secret recipe.  Because of the varying ingredients from one gel to the next is the reason why a person may have to go through a trial and error of which gel is the best one.  One gel may have too high of a concentrate of one or another sugar or caffeine for a particular person's digestive system.  Using a gel or bar that doesn't get along with your digestive system can cause cramping, diarrhea, and the inability to absorb any type of nutrient because of the current digestive system upset.

Monosaccharide and disaccharide?  What the heck are these?  No worries.  They are just fancy names for sugars that we consume in our everyday foods.  Let's start with a monosaccharide.

Monosaccharide (one sugar by itself):  This would be the same thing as glucose or dextrose.  This is a single molecule sugar.  Single molecule sugars breakdown in to useable energy very quickly and is very easy on  the GI system.  Glucose is the sugar that our muscles and brain use as energy.  This sugar is the most easily digested sugar and is most readily available.  

Disaccharide (two sugars bonded together):  Fructose is a disaccharide.  A disaccharide is a two molecule sugar and therefore slower to break down into useable energy.  Fructose is a sugar that is found in fruits and vegetables.

Maltodextrin:  This is the most common sugar found in energy gels.  Maltodextrin is a more complex sugar because it is made up of more than one or two molecules.  Maltodextrin breaks down in an optimum manner to provide you with the right flow of fuel or energy to the bloodstream without disrupting the GI system.  

Sucrose:  This too is a disaccharide.  This molecule is made up of one glucose molecule and one fructose molecule.

There are other sugars used in energy gels and bars but the above listed are the most common.  You notice how I just breezed over the names and definitions.  To say more about them would be getting into the chemistry of each and this can become complicated.  Here's an example of the chemistry and considerations when creating an energy gel:
  • If you noticed, sucrose is a disaccharide (glucose + fructose).
  • Glucose by itself is a monosaccharide.  Same as fructose.    
  • Maltodextrin is varying lengths of glucose chains, i.e. glucose + glucose + glucose... up to ten or more molecules combined together.  When many sugar molecules are bonded together then the sugar becomes a polysaccharide.  These too are used in energy gels and bars for sustained energy release.  The more bonds in a sugar chain that need to be broken down, then the slower the release of energy into your system.
  • But in any gel or bar, the main ingredients will be a combination of sucrose, glucose, fructose, and maltodextrin.
Energy gel and energy bar manufacturers go through a tremendous amount of combinations of these sugars as well as vitamins, amino acids, electrolytes, etc. so as to get the energy gel or bar just right.

What Does "Just Right" Mean?

Just right means that the gel will absorb at just the right rate and release just the right amount of energy to keep the GI system working just right.  The sugars listed above are simple and not complex sugars that break down in the stomach and are either absorbed via the stomach or as they just enter the small intestine.  If the gel or bar contained a more complex sugar then it would take longer to be absorbed, require more blood to be pulled from the working muscles, and could cause an upset stomach as well as muscle cramping.

So, When is the best time to ingest the energy gel or bar?

This really is the question now isn't it?  Now that the gel has been properly formulated, when is the best time to consume the gel?  Most manufacturers give a general guideline of when and how to consume the gel.  The general guideline is 15 minutes prior to your activity and then 45 minutes to one hour after you've begun your exercise and then every 45 minutes until you've completed your exercise.  Remember, this is a general guideline.  This absolutely does not work across the board for everyone.  Each person burns through calories and fuel at a different rate as they exercise.  However, this is the link as to when it's best to consume a bar or gel.  

Exercise exertion plays a big factor in the timing of when to consume an energy gel.  Your fitness level also plays a role in when to consume an energy gel.  Generally, the more trained and conditioned you are, then you have greater lee way of when to consume a gel and how much you need to or are able to consume.

Fitness level aside, physical exertion or the intensity of the exertion is the factor on when to consume energy fuel.  The intensity of work being done will determine how well and how quickly the energy will be absorbed and then used by your body.  This is one of those factors that fall into the trial and error category.  To get straight to the point, it's best to consume energy gels/bars when you are not exercising or racing at a high intensity.  If you've ever watched professional cycling, the feed zones are usually placed along the course in which the cyclists are not cycling at their highest intensity.  There is a reason for this.  When exercising at a high intensity, blood and oxygen are diverted into the working muscles.  When you consume an energy gel, blood is called away from the working muscles to the stomach in order to digest the gel or bar.  The amount of blood that is diverted is also relative to how much of the gel or bar is consumed and how dense the nutrients are in the fuel.  If too much energy fuel is consumed at one time this can cause GI distress and even muscle cramping.  This is one reason why energy gels come in small packets.  Gels are meant to be taken in smaller amounts so that GI distress does not occur.  

There are several reasons why energy gels and bars are designed the way they are.  And I'm not talking about the shape or size of the energy fuel.  I'm talking about the chemistry of the energy fuel.  Here are the most important reasons.  They are designed:

  • To be digested with minimal blood being diverted from the working muscles to the stomach
  • To be absorbed by your digestive system as easily as possible and as quickly as possible
  • To not create a blood sugar spike and then low.  This is where the "chemistry" of energy gels really come into play.  Energy gels need to release energy into the blood stream in a even and fluid manner.  If too much sugar and electrolytes are released to quickly, then the possibility of GI distress becomes a risk.
  • To release the right amount of energy over a designated period of time.  This is where monosaccharides, disaccharides, and polysaccharides come into play.  The longer the sugar chain is, then the longer it takes to digest.  However, the long chain sugars will provide energy over a longer period of time.  A good example of a longer releasing energy fuel would be a Power Bar or Cliff Bar.
In summary, an energy gel or bar is best taken when not exercising or racing at your highest intensity.  It's also best to consume several ounces of water with the gel or bar to aide in proper digestion.  Energy bars and gels are created for specific purposes so read the labels and make sure you are consuming the proper gel or bar for the specific activity that you are performing and at what intensity.  Personally, I don't feel I've done this article justice.  There is a lot to consider when fueling up during high intensity activity.  As previously stated, it takes a period of trial and error to get the right energy fuel that works best for you.  Some gels are much more concentrated than others.  Some contain high amounts of caffeine and others high amounts of electrolytes.  Often, more than just one specific gel is consumed so that all bases are covered during training or competition.  

As usual, if you have any questions, thoughts or concerns, please feel free to contact me.  In the mean time, Bon Appetite!

Brad Senska, PT, DPT, BS, ASTYM.

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