An amazing thing to watch is a fighter jet being refueled in midflight. The fighter pilots ease their way to the tail of the fuel tanker and with the precision of threading a needle, one by one they guide their war machines to sync with the fuel nozzle and take on fuel, all while moving at several hundred miles an hour. In order to keep flying, these machines not only need fuel, they need the right kind of fuel. You as a runner are no different!
Like jet fighters, you burn fuel as you run and when the fuel runs out, you have to stop. There are two types of fuel our bodies utilize, glucose or sugar and fat. We store about 2,000 calories of glucose and several thousand calories of fat. Even the leanest runners have several thousand calories of fat to be burned as fuel.
Glucose is mostly utilized for high intensity workouts where fat can fuel longer, slower runs. Have you ever gone out and run really hard and fast and ran out of energy sooner than you do on your long runs? That’s because you burned through your “sugar” stores and hit the wall. You burned all your matches so to speak and your body did not convert to fat for a fuel source.
When you run longer and slower distances your body senses the activity and turns to fat for its fuel sources. Since everyone has ample calories from fat, burning fat is optimal for distance runners. A steady, controlled pace is the key to ignite the fat stores.
As you increase your distance and speed, your body becomes more efficient at burning fat at higher levels of output. According to Competitor.com, one of the most important determinants of success in distance running and endurance events is how efficiently your body can use fat as a fuel source as opposed to carbohydrates. The more readily you can burn fat while running at distance race pace, the longer your glycogen stores will last–providing crucial energy for that last 10K.
Most research has shown that you can run about 2 hours at marathon intensity before you run out of glycogen. For mere humans, this is going to leave you far short of your goal. Midrace fueling is limited by how quickly your digestive system can deliver the glycogen to your bloodstream and, under the duress of distance racing; the stomach is not very efficient.
It is critical that you find ways to optimize the amount of fat you burn while running at race. One of the most obvious places to look for these improvements is in the long run. Some research has shown that individuals that exercised BEFORE eating breakfast (fasting state) had much higher levels of glycogen stores than those that ate before they exercised. In effect what you are doing is further depleting your glycogen stores so your body becomes more efficient at utilizing fat for fuel. A word of caution is in order. Long term training and running long distances on low glycogen stores will hamper performance and slow recovery. You want to utilize this practice judiciously to train your body to be more efficient.
As a general rule if you run under 75 minutes you only need to drink water. It’s when you run over 75 minutes you need to consider fueling options, in particular when you are competing in an event as you are likely pushing yourself harder than when you train. For me, I can run most training runs of 20+ miles only consuming water but it took me two years to reach this point. I run my short runs in a fasting state as I usually run at 4:30 in the morning. For my long runs, I do eat before heading out but more on that in a minute.
Conversely, when I am racing distances over a half marathon, I start to ingest quick-digesting carbs like PowerBar or Honey Stinger Gels and chews, sports drinks like Gatorade or Powerade or soft energy bars like Honey Stinger Waffles or Clifbars every four miles. My new favorite is min Pay Day bars. Since I am a profuse sweater, I like the salt and the protein from the nuts along with the sweet. The end goal is you want to be able to push yourself while ingesting enough carbohydrates to avoid the dreaded “Bonk”. The “Bonk” is when your body runs out of carbs and you find it difficult to continue running.
So how much fuel do you need when running? According to Nancy Clark, M.S., R.D. (in an article written by Sarah Bowen Shea for Runnersworld.com) you should ingest 100 to 250 calories (or 25 to 60 grams of carbs) per hour, after the first hour of running. That's the equivalent of one to 2 1/2 sports gels or 16 to 40 ounces of sports drink per hour.
A runner's exact calorie needs vary from person to person. As Clark puts it, "A Hummer needs more gas than a Mini Cooper." Smaller runners will need fewer calories than larger runners. How fit you are also plays a role in determining how many calories you need during long runs. The less fit you are, the more calories you need as you will burn them more quickly. This means you will need more calories mid-run to keep your tank full and avoiding the “Bonk”. Running at a quick pace, high intensity or in extreme heat or cold also uses glycogen at a faster rate just as a jet fighter going at Mach 4 burns more fuel than when its cruising at a lower speed.
Here are some tips to consider when looking at fuel options when running over 75 minutes:
- · Have a proper pre- run meal. Look for light and easily to digest items that will easily be turned into sugar for fuel. A few of my favorites include plain oatmeal, bananas, almond milk and homemade peanut butter on graham crackers.
- · Have plenty of water to drink when consuming race fuel. Many gels are thick and sticky and not having water to could result in an unpleasant experience.
- · Be sure experiment with your fuel of choice prior to a race or long run. Everyone reacts differently to foods, especially sweet foods during exercise. Better to find out what works and what doesn’t on a training run.
- · Find out what liquid carbohydrates are used in your races and practice with them in training.
- · Most carbohydrates fuels for exercising are VERY, VERY sweet. For very hot races where you will perspire a lot, consider some salty foods as well. This will cut the sweetness and the salt will also help prevent cramping.
- · Many sports fuels are very sweet and if you are on a low sugar diet, you may want to look for alternate forms of fuel that still provide simple carbs like graham crackers or try and make your own recipes.
Here is to being fit for a lifetime!
Chris is a Certified Personal Trainer, exercise and endurance enthusiast. He competes yearly in numerous running races, marathons, ultra marathons, triathlons and other endurance events.