The Carb Revolution In Endurance Sport Training

If you have talked about marathon training or even googled anything related to running lately, more than likely “big brother” has started to flood your news feed with articles and nutrition products. It can be a bit overwhelming to decipher what is beneficial and what is merely propaganda marketing with an attempt to get you to purchase the next supplement guaranteed to make you stronger, faster, and suffer less during your marathon training.

Long gone are the days where carbo loading involved devouring platefuls of pasta piled high the night before the big race, or attempting to swallow thick, tough Powerbars (those of us who started running in the 80’s and early 90’s probably remember those bland chocolate or peanut butter flavored chewy bars). The philosophy has changed from counting calories and determining how much you should take to fuel a workout based on energy expenditure and weight. Today’s focus is all about carbohydrate fueling.

Many brands attempt to overwhelm runners by differentiating their products using terms like “hydrogel technology” or “cluster dextrin” to make their product appear to be a better or more complex and a specified formula for a goal or activity. While certain products may have more advanced, state-of-the-art technology in their creation, the reality is, athletes should find what works best for them.

This brings me to the next question: Why do we need carbs during longer, more intense exercise sessions? In general, your body begins a cardiovascular exercise session utilizing stored glycogen. Glycogen is stored in muscles and the liver. It is waiting to be utilized and burned during activity. This is one of the reasons people start increasing their carbohydrate intake, or carb loading, leading up to a big event to top off their glycogen stores. We use stored glycogen, which is converted into glucose early on during high-intensity aerobic exercise. However, just like gasoline sitting in the tank of a car, once it is depleted, the car stops moving forward unless its tank is refueled. That is where taking in carbohydrates during harder effort activities lasting longer than 60-90 minutes becomes important so performance isn’t compromised. How much and what type of carbohydrate-rich, digestible fuel is up to the individual.

I encourage athletes to follow the K.I.S.S. strategy for fueling. (K.I.S.S. = Keep It Simple Smartypants!) What you take in is important, but getting the right amount of carbohydrates in and delivering them in a way that works for your body to ingest and process is way more important for you to be properly fueled for success. This can be in the form of gels, gummies, carb and electrolyte-rich liquids, bars, or even easily digestible, simple carbohydrate-rich foods such as bananas, rice patties, or potatoes.

General guidelines for fueling before, during, and after longer, intense exercise sessions or races:

1. 2-3 hours before a race or long training session: eat a carb-rich, but not heavily dense meal. Stay away from protein or dairy products that sit in the stomach and take longer to process for usable energy (protein doesn’t break down into usable fuel for 7-8 hours and dairy digests in 3-4 hours. If blood is being pumped to the stomach to aid in digestion rather than the muscles, your body may begin to suffer GI distress and cramping) Good pre-event foods include oatmeal, rice, bagels, or toast. Even a quick energy bar, graham crackers, pretzels, or fig bars taken within an hour of running will top off glycogen stores and prepare the body to take on the workout you are about to put it through.
2. Fuel early and often during the race or long, hard training session. While you might not feel hungry or depleted yet, if you are running longer than 60 minutes, start with 30 grams of carbohydrates every 30-45 minutes. This will keep energy stores even and constantly feed your muscles with usable fuel. Like the analogy of the car, if you start running low on gas, your car will start sputtering, slowing down and eventually the gas will run out… if you have ever been stranded on the side of the road with no gas, you know how hard it is to get the car moving again after hiking to fill up a portable gas storage can. Don’t let this happen to your body or the dreaded “bonk”, which is almost impossible to dig out from, will occur.
3. Train your body to take in and process carbs. The general rule of thumb is to take in 60-90 grams of carbohydrates per hour of exercise. This equates to 2 gels (30g carbs each), chews (pay attention to how many chews in a packet equal one serving), a mix of gel and carb/electrolyte drink (Note: gels don’t dissolve when taken with drink mixes. They often require water to help with the digestion and absorption in your stomach. Maurten, which will be available on course for the Chicago marathon, is a “hydrogel” and technically can be taken without needing water to help wash it down and process), or high carb drink mix which works well for people who have a hard time swallowing a gel or solid substance during intense exercise. Many elite runners and cyclists have been practicing taking in up to 90+ carbs/hour and the results are showing performance benefits, however, it takes time to train the gut to effectively process such a high volume of carbohydrates so if you want to take in more carbs, practice leading up to a race to see what type and how much your stomach can handle.
4. When you cross the finish line or complete the long, hard workout you once thought you would never be able to do, celebrate… but before you grab that finish line beer, it’s important to take in a 60-120g “healthy” carbohydrate/protein mix 30-60 minutes after finishing… then go for a beer. For women specifically, research has determined that restoring muscle glycogen with a carb/protein combination food or beverage is imperative within the first 30 minutes of completion of the activity to maximize glycogen recovery and help repair muscle. Examples of good recovery foods: are protein smoothies, greek yogurt with fruit, peanut butter and banana, or chocolate milk.

(Note: I am an endurance athlete coach, not a registered sports dietitian so if you have specific challenges or restrictions, please consult a dietitian to help you plan your nutritional needs while training and racing.)