Run-Specific Fuel Needs (2 of 14)
It’s easy enough to understand that running requires energy. Energy is generated by your body by burning fuel. How should you fuel your body? How is this different for running than for other sports? We’ll address that and some of the special considerations of the topic:
What are your Run-Specific Fuel Needs? Why; how much; what; and when? As I mentioned before the human body is an amazing machine chugging along on complex chemical reactions. Keeping balance in those reactions is the key to fueling your runs. Say it with me – balance.
- Why do we need to fuel? The body generates running by elastically loading the muscles into a contracted position, like compressing and stretching springs. This is achieved by signaling each cell to forcefully shorten itself – when the whole group shortens at the same time, the muscle contracts. This shortening requires ATP (adenosine triphosphate), a chemical produced inside the body by “burning” glycogen. Glycogen is the sugar your body uses to function.
Typically glycogen is made though extraction of glucose from food and another series of chemical reactions. Fructose and sucrose can also be used to create glycogen, and each is absorbed by the body at a different rate. Finally, stored proteins and fats can be torn apart by the body to convert into glycogen, but this process is inefficient (the energy comes less quickly).
- How much fuel is required? The American Council on Exercise says running will burn approximately 100 calories per mile. Running faster requires more energy, but you cover the mile in a shorter time. Conversely running slower requires less energy, but takes longer. These factors basically cancel out and we estimate 100 calories per mile. If you eat properly with a balanced diet you can expect your muscles to contain enough glycogen to power approximately 5 miles of running before you have to “borrow” sugars from the liver and brain. After that you need to think about keeping a constant blood sugar level.
- Running is different from other sports because of the intense whole-body nature of the activity. Good running requires nearly every major muscle group in the body to be active. If you’re not using them all, you’re probably deficient in your running form and therefore prone to injury. But that’s a different topic.
In cycling, for example, the upper half of the body is relatively relaxed during a ride. The opposite is true for swimming, relatively speaking. Running requires full-body participation and therefore burns more calories. The legs can’t borrow sugars from the arms, or vice versa. Additionally, the forces your muscles have to produce are greater than in other sports, so your energy requirement is much higher. So running is a great way to burn calories! But you have to burn the right ones at the right rate to avoid the “wall.”
- The Wall is when you’re metabolism rate exceeds the available rate of release of sugar into the bloodstream. If you body doesn’t have enough sugar left it will start burning fat and proteins, but if those slow burning molecules aren’t broken down fast enough to match the rate at which you burn up the sugars from your bloodstream, your blood sugar drops. When it does, the muscles don’t have enough sugar to make ATP and you start to feel VERY tired.
To avoid this, specifically in runs longer than 1 hour, you want to consider supplementing with a sugar-based fuel. This will help slow down the drop in your blood sugar and therefore help the body keep up with the demands as it’s breaking down fats and proteins. You do not want to eat so much as to stop fat burning. This is important! If running requires 100 calories per mile, you want 20 to 30 of those to come from food (after 1 hour) and the other 70 - 80 to come from fat and protein burning. So this equates to 1 gel per 5 miles if you can tolerate gel.
- Gels vary greatly in their contents and ratios of salts and sugars. Get in a habit of reading the labels. Which one is the best? If you take gels, the PowerGel from PowerBar Nutrition is the most balanced option for runners. It provides 100 calories of balanced (say it again, balanced) glucose, fructose, and sucrose to help level out your blood sugar. Because the three sugars are absorbed in different parts of the body, energy from the gel is distributed over a longer period of time and reduces the peaks and valleys people often experience from other gels. It also provides a more balanced palate of electrolytes but again, different topic to be covered in a future blog. Taking a PowerGel after your first hour of running, and every 35 – 45 minutes thereafter, will keep you running strong.
- If you don’t eat gels you have a variety of vegan options. Sweet potatoes and beets are nutrient rich foods with excellent ratios of sugars and electrolytes for runners. These vegetables can be pounded into a convenient fueling option for longer runs. If you sweat a lot you may need more electrolytes so add Morton’s Light Salt (50% sodium, 50% potassium) to your potato/beet mix.
The old standards – bananas – are the world’s most popular runner-friendly fruit for good reason. They contain an 11% daily recommended value of potassium and a large dose of glucose and fructose for conversion to glycogen. The come with a healthy dose of fat too, if you’re running ultra distances. Other options are papaya, peaches, grapes, and plums if you want fructose-rich foods without a lot of fiber which may set heavy on your stomach during the run. To supplement your fruit fuels, consider black beans to provide long-chain carbohydrates as well as protein, and chia for vitamins and minerals. Combining these foods will keep you running strong.
- Diversify! On the run, I recommend having PowerGels in your pocket because they’re light on the stomach. It can be hard to eat a lot of fruit, nuts, or beans during the run so alternating whole food mashes with gels as you go can provide welcomed relief to your guts while providing the needed power to your muscles.
Never experiment on race day. Practice with a variety of fueling strategies in your weekly training runs to learn what works best for you. Also, I can’t cover all the endless combinations of foods available but this should provide you a framework to start educating yourself about what’s out there. Pasta isn’t everything, and it’s rarely enough! I'll talk more about gels specifically, and especially on the wide topic of whole-food diets and meals in their own blogs later.
Next topic: Knowing the “Signs,” what’s working for you and what’s not.