Articles Written by Rehan Jalali

Nutrition Articles

The Quest For Energy: What You Need to Know Before Going on Your Next Run or Bike Ride

Anyone who has gone on a long run or intense bike ride knows how important it is to keep energy levels steady.  Maintaining sustained energy levels prevent "bonking", as one popular company puts it.   There are many sports drinks, carbohydrate gels, and dietary supplements out there claiming to increase energy levels.   But which products work best? When should these products be taken? Is there clinical research to support their use? How about gels vs. sports drinks? And what about hydration (good 'ole water) and electrolyte balance? What the heck is electrolyte balance?  By investigating the science of exercise feeding, we can answer these and other questions relating to this fascinating topic.

Before we dive into the details of products on the market designed to improve energy and aerobic performance, let's look at some basic fact about carbohydrate and energy metabolism. Carbohydrates, specifically glucose, are an important energy source for many human tissues including skeletal muscle. It would not be practical or efficient for your body to store significant amounts of glucose in solution. Therefore, carbohydrate reserves are stored in the form of the branch chained polysaccharide (a cool scientific term describing the chemical structure) called glycogen.  Two-thirds of glycogen is stored in muscle tissue and one-third is stored in the liver.  The muscle glycogen is what is important in providing energy to endurance athletes and fitness enthusiasts.  So we'll leave the liver glycogen alone for now.  Glycogen can be converted into glucose to provide energy to working muscles.  This process can be circumvented and glycogen can be spared if a carbohydrate containing solution is ingested during exercise.  Another important point to remember is that for every gram of glycogen stored in the muscle tissue, there are three grams of water stored with it. This is important for hydration.

There have been many studies conducted showing the positive benefits of feeding during exercise.  This is mainly in liquid form as liquids are better absorbed than solid foods especially when exercise is being performed.  Solid foods are not recommended during aerobic exercise as they may cause dehydration due to the digestive process plus since they are not absorbed into the blood stream as fast, they can't provide the quick burst of glucose like sports drinks.  By the way, feeding during aerobic exercise comes into play and can be beneficial when exercise is longer than 30 minutes.  Exercise less than thirty minutes may not be impacted as much by the use of sports drinks or other workout aids during exercise.  Consuming 12-16 oz of water is one of the best things to take during exercise less than 30 minutes. Some research suggests that a 3% decrease in body water causes a 12% loss of strength.  The moral of the story here is, DRINK PLENTY OF WATER BEFORE, DURING, AND AFTER EXERCISE. So those of you "aerobic renegades" out there who like to go on those 1-2 hour runs or bike rides, listen up. 

So which sports drink are best? According to a study published in the Sports Medicine journal March 2000, Coombes and his colleagues concluded that "there is little evidence that any one sports drink is superior to any of the other beverages on the market."  Some important things to look for in a sports drink according to another study published in the same journal March 1998 are osmolality (250 to 370 mOsm/kg), carbohydrate concentration (5 to 7%), and carbohydrate type (multiple transportable carbohydrates). Osmolality measures the concentration of particles in solution. Osmolality increases with dehydration and decreases with overhydration.  There are many types of carbohydrates found in sports drinks and gels including maltodextrin, glucose, dextrose (which is basically glucose), sucrose (which is glucose +fructose), fructose, glucose polymers, and high fructose corn syrup (which is dextrose).  The type of carbohydrate found in a sports drink is important to its performance enhancing benefits. It is important to get high glycemic carbohydrates (carbohydrates that raise blood sugar levels quickly and provide a fast burst of energy like dextrose or glucose).  It is also important to get low glycemic carbohydrates (carbohydrates that are absorbed slower like fructose) to provide sustained energy.  The combination of these is important to look for in a sports drink or gel.  Maltodextrin is very interesting in that it is called a glucose polymer and a complex carbohydrate but it has a high glycemic index and impacts blood sugar levels very quickly.  This type of carbohydrate is great to take after a long run or bike ride to help replenish energy stores.  In fact, sports drinks in general should not only be taken during exercise but also within 20 minutes after exercise to enhance the recovery process.  Another important thing that sports drinks provide are electrolytes.  It is important to maintain a proper electrolyte balance (the proper balance of minerals in the body) to prevent muscle cramping, dehydration, PH imbalance, and other "unwanted" effects. 

Look for a sports drink that has potassium, sodium, and magnesium in it.  Magnesium and potassium are especially important, especially in helping to prevent cramping.  In fact, anyone that runs or cycles regularly should be taking in between 500-750 mg magnesium (in the citrate or chelated form) daily to help prevent cramping and enhance energy levels.

Sports gels have also become popular on the market and some good ones include PowerGel by Powerbar, GU by Sports Street Marketing, and Clif Shot by Clif Bar.  All of these gels not only contain carbohydrates but also contain caffeine which can be a potent athletic performance aid (so much so that higher levels are banned by the International Olympic Committee).  However, caffeine is also a diuretic which can cause dehydration so it is important to drink at least 16 oz. of water with each pack of gel.  GU contains maltodextrin and fructose as it's primary sources of carbohydrates.  It also contains ginseng which can have some performance benefit, anti-oxidants to help boost immune function, and leucine and valine which are amino acids of the "branched chain" variety that can have some possible benefit to exercising individuals.  PowerGel also contains maltodextrin, fructose, and dextrose.  But it also contains glycerine (or glycerol). Glycrerol (glycerine) is a trihydric alcohol found as the backbone of triglycerides in the body.  It has a very low glycemic index so it does not impact blood sugar levels greatly.  Interestingly enough there are ergogenic (performance enhancing) benefits associated with ingesting glycerol such as increasing the amount of water retained in the body and enhancing hydration.  Powergel has ginseng and anti-oxidants in it as well.  The Clif Shot has brown rice syrup as it's main source of carbohydrates and contains magnesium and potassium.

There is a relatively new dietary supplement out called RIBOSE that has some great potential as a pre, during, and post exercise energy booster.  More to come on this unique ingredient in future columns. 

For now, before going on a long run or bike ride (or performing other long term exercise), get your water bottle ready, sports drink or gel set, and intensity ready to go!

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