PROPER FUELING DURING ENDURANCE EVENTS

By Steve Born

Endurance and ultra endurance athletes require all three forms of fuel the body can use as energy. A major factor for optimal performance is using the proper fuel in the proper amounts. This is the goal of this article and, like everything regarding athletic performance, it requires practice in training to derive maximal benefits come race day.

As we all know, carbs are king when it comes to fueling the body in all forms of endurance exercise. However, carbohydrates can enhance performance or hinder it, depending on what type is used and how much is used. Misinformed athletes continue to misuse simple sugars, or use too much complex carbohydrates prior to exercise, during exercise, and after exercise.

Sugar is defined as a monosaccharide or a disaccharide. The shorter the chain length a carbohydrate is, the higher it raises the solution osmolality (the solution concentration of particles carrying an electric charge) in the stomach. Simple sugar must be mixed in weak 6-8% solutions or they will sit undigested in the stomach and not pass the gastric lining, possibly creating sour stomach, cramps, or flatulence. Maltodextrin is a multiple of sugars hooked together, allowing from 18% to 24% solution immediately in transit to the liver where it is turned back to the energy cycle as muscle glycogen. The Amylose-Amylopectin content of maltodextrin or potato starch are very similar in their chemistry to human stored glycogen. Therefore the "Gold-Standard" carbohydrate source for energy drinks, bars, or gels originates from longer-chain carbohydrates (Maltodextrins) because more caloric volume crosses gastric lining with less distress to the competing athlete. Sports drinks or gels containing simple sugars need to be extremely diluted to match body fluid osmolality. This weak of a concentration will more than likely not allow enough calories (most are up to 100 calories at a 6-8% solution) to be available to working muscles on an hourly basis.

What the above means is that complex carbohydrates are superior to simple sugars in that they allow more volume of calories to get into the bloodstream from the GI tract than anything containing simple sugars does. The biggest problem is that once only a minimum (it doesn't take much) of the short chain sugars are present in the blood channels, a "Sugar/Insulin Spike" occurs followed by traumatic blood-sugar below-fasting depression or "Bonk". Because complex carbohydrates may enter at a relatively high 15-20% solution, the typical crashing "Bonk" is not typically as low as the simple sugar "Crash". There are several studies that show that glucose (a simple sugar) causes a greater drop in blood sugar levels (even BELOW fasting baseline levels!) than complex carbohydrates. Simply put, simple sugars are a very inefficient fuel source. Trying to use simple sugars to fuel your exercise is kind of like trying to heat your home burning newspapers in the stove. They*re hot but very short-lived. If you want to keep warm you’d have to constantly add more and more newspapers to the fire - highly inefficient! This is why neither HAMMER GEL nor SUSTAINED ENERGY contains any simple sugars.

The other question people always seem to ask is in regards to the glycemic index (GI) of various carbohydrates. Prior to exercise this is critical unless the pre-workout meal is completed three hours prior to exercise, thus allowing insulin levels to return to baseline. After exercise begins glycemic index impact on insulin release is moderated DURING exercise and is inhibited because sympathetic nervous system hormones are generated in a low depleting blood sugar environment. In other words, the body has a highly effective way of regulating insulin during exercise. Processed simple sugars are usually in the 95-110 GI range, while processed complex carbohydrates are generally in the 110-130 GI-range. During exercise Glycemic Index is not a factor unless one consumes more than the liver can return to the energy cycle (again about 280 carbohydrate calories per hour maximum). I believe that anyone who is concerned with the GI makeup of a carbohydrate source more than the saccharide profile is making a big mistake.

So now you know what kind of carbohydrates to use, the next step is how much? While permitting for a greater allowance for the larger athlete, a maximum of 280 carbohydrate calories an hour is the most the liver can return to the energy cycle. Yes, you may be using up 400-500 calories or more an hour but your body cannot replace those in equal amounts on an hourly basis. The body can only process a given amount of calories an hour and to force additional food down, in the hopes of "topping off" or "getting ahead of" calorie needs, will usually backfire. Instead of having more calories available for fuel, they will sit in your stomach causing, at the very least, bloating, at the most, nausea and vomiting. Few things will slow you down faster or cause you to have to stop than taking in too many calories than your body can handle. Even the leanest of athletes has several thousand calories available in the form of stored fatty acids, most carrying nearly 100,000 calories of energy from their stores of fatty acids. Body fat stores are the fuels of choice, providing 60-65% of your energy needs, when exercise goes beyond two hours in length. A very important part of our performance is determined by our ability to utilize stored fatty acids as energy, which is why we can continue to exercise on so seemingly few ingested calories during exercise. One of the benefits of training is an increase in utilizing these stores more efficiently and, as mentioned, the body will rely more on these stored fatty acids to provide fuel during prolonged exercise.

The chart listed below will give you a general idea, based on body weight, the maximal amount of carbohydrates you can consume and efficiently process on an hourly basis. To make things easy we’ve listed the amount of servings of HAMMER GEL and/or SUSTAINED ENERGY you can experiment with in training based on those numbers. But as a general rule of thumb during exercise, keep carbohydrate consumption at or below 280 calories (70 grams) per hour.

SUGGESTED MAXIMUM CARBOHYDRATE [CHO] GRAMS PER HOUR
HG=HAMMER GEL, SE=SUSTAINED ENERGY

WEIGHT----MAX CHO g./HOUR-----[k/cal]-----HG[servings]-----SE[scoops]
110-----------48---------------[192]----------2----------------2.0
121-----------53---------------[212]----------2----------------2.17
132-----------58---------------[232]----------2.3--------------2.38
143-----------62---------------[248]----------2.5--------------2.54
154-----------67---------------[268]----------2.75-------------2.75
165-----------72---------------[288]----------3.0--------------3.0
176-----------77---------------[308]----------3.0--------------3.16
187-----------82---------------[328]----------3.25-------------3.36
198-----------86---------------[344]----------3.50-------------3.53

Once exercise goes beyond 90 minutes it will be necessary to incorporate protein into the fuel mix. After about 90 minutes of exercise, our bodies begin utilizing protein as a partial fuel source for energy demands. After the first 70-90 minutes of exercise, and until you stop exercising, about 12.5%-15% of the calories you burn will come from protein. Technically, this process is called gluconeogenesis. This process is unavoidable and if you don’t provide protein in your fuel, your body will literally scavenge it from your muscles. It’s something called catabolism, also known as "protein cannibalization", and it will cause premature muscular fatigue while you exercise (due to excess ammonia production) as well as more post workout soreness, in addition to compromising your immune system in the long run.

The preferred protein for use during exercise is soy as it has less chance of degrading into ammonia compared to whey protein (with its high glutamine content). While glutamine is a vital amino acid for recovery, it tends to degrade into ammonia rather quickly making it an unwise choice to ingest prior to and during exercise. Soy has a superior Branch Chain Amino Acid (BCAA) profile compared to other proteins. BCAA will aid in the replenishing of glutamine within the body (without the excess ammonia production experienced from supplemental glutamine) in addition to providing nitrogen for the production of alanine. Alanine is an amino acid that is converted to glucose in the liver. More glucose means more fuel. As exercise duration increases it will be necessary to add protein to the fuel mix along with your carbohydrate intake to satisfy the 5-15% of the body’s energy requirements (and to help preserve lean muscle tissue).

*Steve Born is the senior technical advisor for E-CAPS/HAMMER NUTRITION . He is a three-time Race Across America official finisher, the 1994 Furnace Creek Champion, the 1999 Furnace Creek Runner Up, the first and only Double Furnace Creek 508 finisher (in 2002), and has two Ultra Cycling National Records to his credit. For more info, click Hammer Nutrition and/or E-CAPS.