What Science Says about Nutrition for Long Distance Gravel Events

As we rapidly approach the big weekend of the Unbound Gravel, amidst an array of other long distance gravel events, there are a few important components to putting together a successful ride. Arguably the two most important factors that a person has the ability to change and control is the training component and then a strategy for nutrition. Of these two areas to focus on, your nutritional strategy will largely influence the effectiveness of your training regimen. Given the interdependence of training and nutrition, the training itself should incorporate nutrition not just as an side note, but rather a priority. Given the importance of having an optimal nutritional strategy, this article will outline a basic strategy on how you to approach a long distance gravel race. The last few weeks out from the event, you have the opportunity to fine tune everything, including your nutrition. Before getting into amounts and timings of this and that you’ll need some base knowledge in physiology.
In a 200 mile gravel race, a person will burn a significant amount of energy of which the primary fuel source is the stored form of carbohydrate -muscle glycogen. The Second highest contributor in terms of energy contribution is fatty acids which is also coming mostly from on-board stores. Although there is merit to training the body to burn fat as a fuel source for an individual seeking to lose weight, training and racing demand a completely different set of rules.  An attempt to try to reduce body fat or weight within the last few weeks will only be detrimental and the clear purpose of the last month of training should be on building up your glycogen storage for your all day journey. Building up our glycogen stores will require adequate consumption of carbohydrates on a daily basis, especially post exhaustive training ride where your glycogen synthesis rates are the highest.
At intensities of 55-60% of VO2 max., muscle glycogen may be oxidized as much as 80-85%.[1] From the elite racer standpoint, 55% of VO2 max is on the lower end of the spectrum. Regardless of skill level upwards of 85% of the entire energy contribution could be expected to from muscle glycogen. So if most of our energy comes from muscle glycogen, why is it so crucial to eat? The answer is that your body is constantly trying to defend blood glucose to make sure the brain has what it needs to survive. The brain can ONLY use carbohydrate as a fuel source. Your other organs also need to function and benefit from feedings during such a grueling ride. Additionally, a major need is to spare your muscles and the branched chained amino acid (BCAA) pool from being broken down to fuel the demands of the race. Especially at a race pace, our glycogen stores are drastically reduced after only 4 hours as the approximate contribution of stored glycogen dips down to only 8%.  Staying relatively consistent is the contribution of blood glucose starting at 27 % and ending at 34% after 4 hours. The big difference maker here is that the fatty acid contribution goes from 40% in the first 30 minutes to over 60% after hour 4.[2] This fact shows strong support for not only a continued need for carbohydrate supplementation but also amino acid supplementation.
In a review of literature, prominent researcher in the field of exercise nutrition Asker Jeukendrup explored the topic of carbohydrate oxidation rates.[3]  In his own research among others reviewed, a single simple sugar is only absorbable up to 60g/hr, however when multiple carbohydrate sources are introduced (glucose and fructose in particular) the oxidation rates may be improved up to 105g/hr. In terms of providing the body with energy over the course of an entire day of riding, this is a very large difference. Although this research shows that two simple sugar sources are better than one, many of his studies used subjects cycling at 55% of VO2 Max. Knowing that multiple simple sugars are more readily oxidized than a single source, what about in comparison to complex carbohydrates? Essentially a complex carbohydrate is a chain of three or more simple sugars linked together. Although complex carbohydrates are found in whole grains, pastas, oatmeals, etc., complex carbohydrates found in whole plant foods are also high in vitamins and minerals. However, it’s not so much the amounts that we take in but rather the concentration of solute:solvent ratio. We all have done it or know someone who has: drank too much simple sugar energy drink before or during a ride, had too many energy gels, or just ate the wrong thing in general that caused us gastrointestinal distress. That’s because the concentration wasn’t right and our body responded to tell us so. Steve Born of Hammer Nutrition contends that the optimal absorption rate of simple sugars is 6-8% for efficient digestion to reach optimal osmolality (280-303 mOsm).[4] As this is not near enough KCals per/ hour at 80 -100, complex carbohydrates provide a 15-18 % concentration to reach the same osmolality and provide more than twice the amount of KCals oxidized and therefore utilized by the body. In addition, mixing simple sugars to complex carbohydrates whether in solution or through food creates a much higher concentration than we are able to digest leading to suboptimal oxidation as well as digestive discomfort. In terms of amounts and a sport specific application, Dr. Iñigo San Millán provides some insight regarding his strategy from working with Tour de France teams in addition to laboratory testing. He contends that as the standard for carbohydrate consumption is anywhere from 30-60g/ hr for competition but that may fall drastically short of what the needs are for an endurance or ultra-endurance competitor.[5]] Per his work with Grand Tour riders, he contends that 80-100g/ hr should prove to be more beneficial. All of this in basic terms, it will be highly beneficial to an athlete seeking to perform all day at somewhat higher intensities (>60% VO2 Max) to use solely complex carbohydrates as a fuel source as they are actually just as easily utilized given the concentration fits optimal digestion. Avoiding sucrose, glucose, fructose, and other simple sugars in your food and drink on race day may prove to be the most beneficial as far as carbohydrates are concerned.
Beyond Carbohydrates, A sufficient amount of amino acids should also be incorporated. A common recommendation is an 8:1 carb: amino acid ratio for a drink mix. With whatever drink you mix you go with make sure that it contains the three branch chained amino acids: leucine, isoleucine and valine. For the most part, any quality energy drink will have this in it and at the appropriate concentrations. Alongside adequate protein, your drink mix needs to have the right electrolyte balance of sodium and potassium especially, but also calcium and magnesium among a few others. This balance could be the difference between hypo and hypernatremia,  of which both may lead to a decrement in performance. Per recommendations from researchers in the field, other professionals in the field and experiences from riders that we have worked with, the following recommendations may be made regarding nutrition on training days as well as race day.
RACE DAY
~250 Calorie drink mix of carbs/ protein/electrolytes (usually two scoops depending on product) in a 25 oz water bottle (approximately one of these bottles every hour). Knowing that 1 g of carbohydrate = 4 KCal, a single or double serving of a drink mix will have roughly 50-60g of carbohydrate which equates to 200-240 KCals. If your drink mix doesn't have Amino acids, find an amino acid supplement and match the concentration to the 8:1 or just add the typically recommended 4-5g of BCAA’s per serving.  1 bottle per hour is a good recommendation, however it isn’t feasible to limit your intake to just bottles with energy drink as you’ll want to eat whole foods as well. Below are few recommended fruits to consider when planning your feedings.

• Strawberries- High in potassium, and a good source of vitamin C, folate, Manganese, and dietary fiber
• Blueberries- Good source of Dietary fiber and manganese.
• Almonds- vitamin E and magnesium
• Avocado- a well balanced food containing protein/ fat/ carbohydrates, and a good source of sodium, potassium, magnesium

Any of the contents  listed above, may be added to either a cold smoothie or a homemade energy bar containing oats, ground flax seed, brown rice, etc. Among seasoned racers, foods like peanut butter and jelly, and ham and cheese sandwiches also seems to be popular. With whatever you eat in terms of solids, try to limit or eliminate the simple sugar content of that food. Homemade energy bars are a great way to monitor the actual contents of your food source and are apt to be easier to digest than processed foods as well. When you stop at the sag stops you should know exactly what you’ll be grabbing in terms of food and drink and this should all be planned out in your last month of training. As maintaining proper hydration is also a concern, An individual may need to account for water loss and therefore should also consider additional needs for hydration with the appropriate concentration of electrolytes. It is important to note that what works for one person, may not work for another. In looking at what the combination of researchers and professionals in the field have done, this is a basic strategy that should work for anyone hoping to complete 200 miles of cycling in one day.
In addition to this basic strategy, there are a few supplements that have shown to be beneficial in peer reviewed research as well as practical application. Although this list is not conclusive, a good starting point is offered by looking into these supplements to use both pre/ during/ and post training and racing.

• Quality protein source with Branch Chain Amino Acids. As mentioned previously, these three amino acids are crucial rate limiting structures in protein synthesis. Not only are the inclusion of BCAA’s important but many endurance athletes, especially those high volume athletes, struggle to maintain a positive nitrogen balance. Amino acids play an important role in regulating the BCAA (branched chain amino acid) to tryptophan ratio in our blood. When our amino acid pool becomes depleted through exhaustive exercise, we increase this ratio, which induces the onset of neurological fatigue. Supplementing with amino acids has shown to reduce the onset of fatigue. This is a prime example of how the quality, not necessarily the quantity, of our intake directly affects performance.
• Beet juice or dietary nitrates. Although the research on this suggests that there is much less benefit if any at higher intensities, it’s also hard to gather statistically significant data across short time spans. Even still, There are measured significant benefits of supplementing with dietary nitrates at intensities below 70% of VO2 Max. For more info, see review article here.[6]
• Magnesium-Supplement or natural forms. Research on this shows confounding results that favor no effect, yet there are numerous dosages and distances that were observed with widely varying effects. It is known however, that Mg is responsible for over 300 enzymatic reactions in the body and that it has been used with success as a treatment for chronic fatigue among athletes and the general population. For this reason, it may be worth adding in especially as training volumes and/or intensities reach peak levels.

Although there are certainly a wide range of supplements that have led to performance increases in sport, the supplements listed above are a good start. Supplements may be useful, but try to focus on eating clean and making sure you eat enough especially in the last few weeks leading up On the whole, don’t shy away from calories trying to bring your weight down. As discussed you’ll want to keep you calories at a normal range and make sure that glycogen replenishment happens very soon after your workout as within 30 minutes post exercise is when replenishment rates are the highest.
With one week to go until the big race day, this is when you want to focus on glycogen loading. If you wait until the day before the race to have that big pasta dinner, you’ve already missed your window and could be spending the early hours of the race morning in disposal mode. As there are a couple different strategies that have led to the same result when it comes to glycogen loading, the last seven days leading up to the event should have a three day block where a high carbohydrate and normal protein and fat amounts are adequate to load the body with as much glycogen as it will be able to store per individual. However a three day loading window should not include the night before the race. Eating a caloric heavy meal within a 12 hours would likely not add much more muscle glycogen and you want to start to go into race mode rather than relaxation  mode.
The morning of your epic journey one should be prepared on all fronts, and nutrition is no exception. In summary, you’ll want to make sure that with all of the training you do, that you aren’t diminishing your returns by creating unnecessary errors on the nutrition/hydration side of things. Understanding that various challenges may be presenting due to the unpredictable nature of the race, it should be understood that these are guidelines and the practical application may be harder to apply than is presented. Regardless, having an in-depth understanding of caloric needs and the caloric demands as well as physiological limitations in terms of nutrition, should serve you well.
Check out some of our other articles on Gravel Riding and Racing. 

Grant Harrison grew up competing in a variety of sports including college football, competitive soccer and hockey. Since then things have switched all things cycling- in multiple disciplines to boot. His extensive Master’s education in Human Performance gives him a solid background in all things athlete-related. He’s focused on the delicate balance between pyschological skills, coaching, nutrition, and athlete performance. In addition to coaching services, he also offers one-on-one nutrition consultations. Learn more about Grant.

References:

1. Kjaer M, Kiens B, Hargreaves M, Richter EA. Influence of active muscle mass on glucose homeostasis during exercise in humans. 71(2):552-7. 1991
2. Misner W. Carbohydrates 101, http://www.hammernutrition.com/knowledge/carbohydrates-101.294.html
3. Jeukendrup, Asker E. (2008), Carbohydrate feeding during exercise, European Journal of Sport Science, 8:2, 77-86, DOI: 10.1080/17461390801918971
4. Born, S. (2016) https://www.hammernutrition.com/knowledge/simple-sugars-and-complex-carbohydrates-an-incompatible-combination.17539.html?sect=blog-section
5. San Millán, I. (2013) The Importance of Carbohydrates and Glycogen for Athletes
6. Harrison, G. (2014) Nutritional Considerations To Performance: Beet Juice And Nitrate Supplementation.https://sourcee.wpengine.com/nutritional-considerations-to-performance-beet-juice-and-nitrate-supplementation/