How to Avoid Bonking in a Marathon

Most runners are familiar with the tired legs, extreme fatigue, and overall discouragement experienced when we "hit the wall" during long, strenuous outings. You can be on track for a personal record one moment, and then in the next, you suddenly feel like you just can't go on. This happens to many long-distance athletes, and having a better understanding of what "bonking" is and how it happens can actually help you fend it off.

"Bonking" is the common phrase used by endurance athletes to refer to that horrible moment where extreme fatigue and discouragement hit. It usually comes about quite suddenly and can be devastating for performance.

The main reason we bonk is because our muscles have run out of easily accessible fuel. In our bodies, energy is stored in two ways: as carbohydrates and as fat. The carbohydrate form of energy is held in our muscles and liver as glycogen which can easily be used as fuel for running. Energy derived from fat is harder to utilize, as it requires a slower metabolism to become accessible for our muscles to use.

Our bodies have about 1800 to 2000 calories stored as easily accessible glycogen in our muscles and liver. Since most runners burn around 100 calories per mile, many of us run out of glycogen stores at around the 18 to 20 mile mark.

Despite this, our bodies still have quite a bit of usable energy available; it's just stored as fat. Unfortunately, fat metabolism is a much slower process than burning carbohydrates, and our bodies may struggle to keep the same pace while using this process to fuel running. Our legs start feeling weak, our mental state declines, and our pace slows. We have "hit the wall."

1. Train your body to metabolize fats better – You can train your body to more quickly and efficiently metabolize fat by practicing running longer distances. Doing at least four to six long-distance runs before a marathon can boost the speed at which your body converts fat to glycogen and increase your capacity to store glycogen in your muscles. This means that you will have more fuel available longer into your run.

2. Increase your fitness – This one seems obvious, but here's how it works. Increased fitness means that you will burn fewer calories per mile depending on the strenuousness of the run. Increased fitness will also help your body metabolize fats longer into the run before switching to a higher percentage of carbohydrates for fuel. With more easily accessible energy stores available, you can help to stave off the "wall."

3. Fuel your body properly BEFORE a race – As bonking is related to energy stores, it is important to ensure proper nutrition just before a race. Many runners are familiar with the concept of carb loading prior to a race, but this does not necessarily mean that you need to eat five bowls of pasta the night before. It only means that the carbohydrate stores in your muscles should be completely replenished before a race, regardless of your diet.

4. Fuel your body properly DURING a race – It is also important to make sure that you are getting easily digestible forms of energy during the race. This is where things like gels, blocks, and jelly beans come in. Start consuming calories early and often to ensure that your energy stores don't become depleted as you run.

5. Keep your body hydrated – Though not directly related to energy depletion, it is essential to drink plenty of water and electrolytes during your race. This will aid in metabolism and prevent fatigue due to dehydration. Proper hydration will also protect your body from having to use glycogen stores to avoid overheating.

6. Focus on form – As the fatigue sets in, your form may want to fall apart. Your legs will start to feel like dead weight, and you'll feel like you just can't keep going. The is the time to focus on your body position. Better form will lead to better running efficiency and faster times.

7. Disassociate – To help get through "the wall," it is good to disassociate from the fatigue. Think of something else to take your mind off of the exhaustion: sing, fantasize, observe the world around you, chat with other runners. Keep your focus off your watch or the mileage, and those last miles will fly by.

8. Mind over matter – Your body may be capable of completing a marathon, but as your energy stores become depleted, your brain will want to conserve energy and will send you signals to stop running. The biggest issue with overcoming "the wall" has to do with willpower. The last 5K of a marathon can the most difficult, even for elite runners. Fight through the fatigue and be proud of seeing what your body can do as you cross that finish line.