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Fuel Your Body |  |
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See the Index for more topics, information, hints and tips.
See more topics on Nutrition.
I am not a nutrition professional, this is based on my experimenting on myself and what I have learned from others. I have no affiliation with any of the products mentioned here.
The human body is amazing! It runs on almost anything you put into it. Just take a look at the various diets or life styles like vegan and people who live mainly on alcohol.
The reports of what nutrition works for different individuals is all over the map. It almost seems that nutrition may be unique to each individual. This may stem from the ability of the human body to adapt to almost any situation. Some people can run taking in gels, others cheeseburgers or pretzels and marshmallows, and still others nothing at all. You will have to experiment on yourself to see what works best for you.
There are basically two sources of energy that your body uses - glycogen and fat.
Glycogen comes from carbohydrates. Glycogen is sugars stored in the muscles and liver. Carbohydrates give you higher energy levels, but wider swings in blood sugar as you consume them. You have a fairly limited supply of glycogen - only enough to last for an hour or so. The body easily converts it to energy. Burning glycogen creates lactic acid. You burn more glycogen when you run anaerobically, that is, fast or hard.
Fat is stored throughout the body as we all know. A pound of fat has 3,500 calories. If you burn 100 calories to run a mile then you could run further than a marathon on a single pound of fat. And almost everyone has a pound of fat. Fat is more difficult and takes more time to turn into energy that the body can use than glycogen. But it doesn't produce as many bad waste products and we have a lot more of it. It takes a little glycogen to burn fat. You burn fat when you run aerobically - slow and easy.
Your body can only digest maybe 300 calories per hour. So if you are burning 100 calories to run each mile, then you HAVE to be utilizing some fat as your energy source. People running marathon and longer distances rely almost entirely on fat as their fuel source. They do need to consume some carbohydrates to replenish the glycogen that they are using or they will Hit the Wall.
Long, slow, and easy runs are designed to teach your body to burn fat for energy. Having a source of quick energy just before does not help this and will have a negative effect on your performance that day and in the long run because in these cases your body has to derive most of its energy from fat. Your body cannot process, nor will it let you process (digestive issues, vomiting …) enough calories to get through a long event.
Your brain uses glycogen for its energy. So as you exhaust your glycogen stores through anaerobic activity (running too fast or hard) or you don’t replace them over an endurance event (remember that your body uses some glycogen to burn fat) you won’t think as clearly. You may feel confused, get lost, making bad decisions ... In many ultra-marathons they allow another person to run with you as a pacer. One of the main reasons for this is to help think for you to solve problems that come up and keep you safe.
Your body has only so much glycogen. If you use it up early in a race to power up a hill, then you won’t have it later to help you through the miles.
The slower you run and the longer the duration of the race the better your body can digest real foods.
During your weekly easy long run you may not need to take in any or only a little nutrition. If you stay in your aerobic zone your body will happily burn fat with a little glycogen. But in a race you are working harder and will be using your glycogen much faster. That’s why it’s important to consume carbohydrates during a race – to help replenish your glycogen.
For shorter races like 5K and 10K, your body will be happy to burn glycogens.
The problem is that we don't train our bodies to burn fat. Most training runs are shorter and slower. If your body is not used to this switch of fuels, you may “hit the wall” or bonk. Your legs will feel heavy, you'll feel really slow, you may not think you can go any further, and you may not think clearly as your body struggles to transition from burning glycogen to fat.
But it's best to get your body used to this transition during training. There are a couple of ways that you can do this. First, practice it by not taking any nutrition before or during some of your longer training runs midway through your training schedule. This is easiest to do by not having breakfast so you are basically starting off with an empty tank. Another way to train your metabolism is about two thirds into your long easy run start doing strides (surges) or simply speed up to your race pace. This will force your body to conserve glycogen and start burning fat.
If you notice that you are dragging or scuffing your feet, it may mean that you are low on glycogen and need to eat something quickly. It could also mean that you are dehydrated (see Hydration) or your electrolytes are out of balance (see Electrolytes).
It takes a minimum of about 30 minutes for your body to digest most foods, even simple sugars. It is important to eat before your body asks for food. If you wait until you are hungry then you really risk running out of energy, Hitting the Wall or Bonking.
Don't forget the importance of Hydration and Electrolytes in making your body function to the best of its ability.
Once I had about 16 ounces of fruit juice an hour before an easy workout. I typically have a glass of Gatorade™ before I run so I wasn't anticipating any problems. I started running and everything was fine for the first 30 minutes. Then I started to feel real tired, my legs were heavy, I was having trouble keeping my slow/easy pace, and I was thinking that I wouldn’t be able to complete my 60 minute run. But I continued to run for about ten minutes.
Then I remembered that I'd heard that if you do a Strides/Surges that it could get you out of a struggle.
So I did a couple strides and soon my body got back into a comfortable state. I was running easy at the same pace as before and finished the workout without any problems.
I believe that what was going on is that in the first part of my workout, my body was burning the sugar I had just given it. But when it ran out of sugar it took a while for my body to switch over to using fat.
