One of the most interesting attributes, I find, regarding cyclists, triathletes, and runners is that they spend thousands of dollars and countless hours in perfecting and fine-tuning their technique in hopes of capitalizing on the advantage come race day. While it is rather obvious that technology and training are quite important to compete, especially, in the upper echelons of endurance sport, what is not so obvious, and this is said out of shear personal observation, is the level of attention and degree of detail that is paid to nutrition while performing.
While the following cliché is quite overplayed, it is still undeniably true: Imagine owning a Farrari 599, putting regular unleaded in the tank, then being disappointed when the car fails to perform. How could you then fault the car for being too heavy, too wide, or simply not as high-performance as you had originally been told? You would first give the car the highest grade of fuel possible and then make your determinations regarding its abilities. Why then, do we as athletes fail to provide our bodies the most scientifically proven fuels and then fault it when it fails to impress us or has an adverse reaction? The truth is this: Many athletes, even professionals, have little understanding of what is necessary, nutritionally, in order to keep the body running at maximum.
The answer? Simplicity. If you’ve every heard of “Occam’s Razor”, you know it is a proverb that asserts that the most simplistic answer is probably the most correct. So to arrive at the simplest solution one must understand a little about the body and what it requires while performing at race intensities before a nutritional strategy can be implemented. First of all, the single most important molecule in the human body is carbohydrate (CHO). It is the sole source of energy for the brain, powers red blood cells, and packs one hell of a punch as a high performance fuel for muscular contraction. It should come as no surprise then that athletes need copious amounts of carbohydrate when participating in their respective sports. The only question is this: How do you get it and in what forms? Unfortunately, the endurance market is awash with multitudes of different CHO replacement products asserting more of a positive effect on the body than their competitors. However, there are only so many ways to bundle the exact same substance and sell it with ridiculous claims for enhanced performance. So, here’s a guide for making your selection before I give you my recommendation… I know it’s a bit like putting the milk and bread at the back of a grocery store, but trust me, it’ll be worth your time to read what comes next instead of skipping directly to the epilogue.
First of all, when you scan the nutrition panel of any CHO replacement product you’ll notice right away that “sugars” or “glucose” is always a sub-heading underneath the main heading “Total Carbohydrates”. This causes mass confusion in the endurance population so pay particular attention to this next part: If you subtract “glucose” or “sugars” (depending on the way it’s labeled) from total carbohydrates, you’ll have the total amount of maltodextrin or glucose polymers in the product and NOT the amount of glucose itself. Maltodextrin, a common ingredient in CHO replacement products, is a one type of glucose polymer, which is basically a chain of glucose molecules (poly = many) biochemically bonded to each other. The reason nutritional companies use maltodextrin and other glucose polymers is because 1) maltodextrin does not participate in the osmotic balance (amount of small particles dissolved in a solution) in the stomach 2) it has the ability to be broken down slowly (you may have heard the term “slow-release carbs”), and 3) it has a relatively long shelf life with few necessary preservatives. However, because of its chain-like form, maltodextrin is biochemically inert as an energy producer. In other words, it has to be broken down into individual glucose molecules before it can participate in the formation of useful energy. Because this process takes considerable time and occurs only under the right conditions, maltodextrin will sometimes languish in the digestive tract while being biochemically whittled down into much smaller more manageable components. Due to the polarity of maltodextrin, it attracts vast amounts of water to gather around it, which can quickly precipitate bloating, severe gastrointestinal distress, even diarrhea and/or vomiting. So why use maltodextrin? Because, in products that are single-use such as those found in tear-off foil packages, where quite a large amount of carbohydrate must be injected into the stomach at once, maltodextrin is actually a good choice. If the dose were straight glucose, the exact same situation would occur (bloating, GI distress, nausea, etc.), due to the fact that glucose would increase the osmolarity of the stomach and force it to retain water. To circumvent this issue, maltodextrin is used because, at low exercise intensities (~70%VO2max) when there is plenty of blood flow to digestive tract, it can alone satisfy the need for CHO to keep the brain and muscles working at a suitable rate with minimal disturbance to the delicate balance of the stomach.
While exercising at or above 75%VO2max, the need for carbohydrate can be met by a modest amount (~40g/hr) of CHO. But as intensities begin to rise, the muscles, brain, and internal organs require more CHO (~60g/hr) in order to continue functioning under an increased energy demand. Unfortunately due to a shunting of blood away from the digestive tract at these intensities (~80% VO2max), precious little exogenous CHO (CHO coming from foods and drinks) actually makes it into circulation. This problem is compounded when maltodextrin is used as the primary CHO source. Due to its bulky nature and digestive complexity, it actually forces the muscles to become more dependent on finite stores of muscle glycogen, which, when empty, spell a catastrophic and immediate decline in performance.
So, how does one safeguard themselves from glycogen depletion and the potential side effects of reduced rates of gastric emptying when using maltodextrin in concert with high intensity exercise? It’s quite simple, really. Don’t use maltodextrin. Use glucose instead.
The use of glucose-based products will have a variety of advantages at high intensities. First of all, glucose can more easily perfuse through the walls of the small intestine, enter directly into the vascular stream, and doesn’t it require any cellular remodeling (as does maltodextrin) before it is absorbed. The only catch with glucose intake during high intensity exercise is this- it is an ABSOLUTEnecessity that it be taken in very small doses. Where most energy gels can be taken on a more sporadic basis (and in larger volumes due to the stability of maltodextrin), glucose should be ingested in very small amounts via more frequent feedings. Ingesting glucose in small amounts will insure that the delicate balance of fluid osmolarity inside the stomach is preserved so as to prevent any gastrointenstinal distress. It is here that most athletes make gross miscalculations in supplementing glucose over maltodextrin. Athletes commonly assume that the glucose supplementation can occur on the same frequency and in the same dosage as maltodextrin based products, which can commonly result in severe gastrointestinal distress due to the inherent properties of glucose itself. If glucose was administered in smaller doses and on a much more frequent basis, these problems would almost certainly be non-existent.
So, what sources of glucose-based products are most advantageous? There are several with purported benefits, like electrolytes, B-vitamins, and stimulants all designed to give you an advantage over their competitors. However, according to basic structure and consistency, they are all second to one source that is literally the most perfect form of glucose supplementation currently available to endurance athletes. Honey. Honey is a form of CHO storage that is not only composed of glucose, but also of fructose (fruit sugar and the sweetest naturally occurring CHO in existence). Not only can your body use glucose to create energy, but it can also use fructose via a secondary transport enzyme in the small intestine. In strictly glucose containing supplements, glucose absorption in the small intestine can only occur at the rate of 1g glucose/min. With the additional influx of fructose at the rate of 0.25-0.5g/min, your total carbohydrate intake can be increased by nearly 50% when using fructose and glucose-containing supplements such as honey.
The effectiveness of honey is, of course, dependent upon how it’s used. If small doses are taken every 10mins (small sips instead of large doses every 30mins as is the case with maltodextrin-based products), honey has a higher propensity to elevate blood-glucose levels, increase neurological output from the brain (increasing contraction strength and velocity), and will decrease the dependence upon internal carbohydrate stores. These effects are most notable at high intensities where digestive rates are slowed due to a shunting of blood away from the GI tract and to the working muscles. The best way we have found to supplement honey is through the use of the common gel flask containing a mixture of honey and water. The water acts to decrease the natural viscosity of honey and allows the user to more easily track the volumes of each dose. One tablespoon of honey contains 17g of carbohydrates which means that a gel flask with 5-6 tablespoons of honey will meet the CHO needs of athletes exercising at 80% VO2max for approximately 2hrs.
The issue of CHO supplementation is complex but will become much less confusing if you remember a few key points. Maltodextrin is relatively stability inside the stomach, will not influence stomach osmolarity, and can be taken in large doses. Thus, it is a perfect low-intensity exogenous CHO source. As exercise intensities increase and the body becomes limited in its digestive capabilities, the combination of simple glucose and fructose based supplements are perfect high-intensity solutions. As long as the delivery method of each one of these CHO replacement strategies is understood and respected, maltodextrin and glucose/fructose-based supplements can actually be used as perfect complements to each other as intensities constantly ebb and flow during a race. Due to the perfect combination of fructose and glucose, honey provides simplicity, a low economic impact, and the ability to meticulously control the rate of CHO intake when it matters most. Above all, honey’s ability to elevate blood glucose levels allows the brain to continue performing without the threat of malnutrition. All of these factors combined work to enhance the efficiency of “the” complex biochemical matrix that allows you to continue performing at your peak.