Nutrition to Go - Guide to Energy Bars

by Sally Young

There once was a simple world with no energy bars; a world where runners nimbly sprinted through a KFC and pocketed a few honey packets.

Our world has changed. It’s raining thick with energy bars, compressed meal replacements, packed food supplements and anvil-hard protein bars.

Just as there are many types of nutrition bars, there are many types of runners. We are a group made up of recreational runners, competitive runners and runners who just like to make up the crowd. Some of us can claim prize money on our IRS 1040—most of us will never have to worry about that. But one thing that we all have in common is our quest for good health. We are committed to a healthy lifestyle, and nutrition is a considerable piece of that picture.

The plethora of nutrition bars will only continue to grow. "For $50,000 or $100,000, you can be in the bar business," Brian Maxwell, president and CEO of PowerBar, Inc., told Food Processing magazine. In other words, anybody can fit their heads under the money spigot of snack foods and drink mightily from the $40 billion industry. Given the ever-increasing number of choices, we need the knowledge that will enable us to choose the products that best fit our lifestyle and how we run.

Turbo Charging

How well you run today will depend, in part, on what you ate after your last run. A runner’s body is a model of efficiency, storing energy inside the muscles that are going to use them. This energy, derived from carbohydrates, is known as glycogen. Muscles that are conditioned to run will naturally store increasing amounts of glycogen. Thus, high-octane legs come from repeated training and a diet rich in carbohydrates.

Muscle glycogen, depleted after running, is ready to be replenished as soon as the muscles are at rest. Eating carbohydrates within two hours restores glycogen the quickest, but the window of opportunity remains open for days. Complex carbohydrates work best to replenish muscle glycogen, possibly because they cause a steady release of insulin which is necessary to escort glucose across cell membranes.

Although most cells can store minute amounts of glycogen, the liver is the warehouse. The primary function of this supply is to maintain healthy blood sugar levels. This is important for distance runners, as maximum liver stores of glycogen will stave off the dreaded "bonk." The synthesis and degradation of glycogen are processes that go on continuously, and the liver uses dietary carbohydrates as they become available. That is why "eating on the run," literally, can help endurance athletes.

Reading the Label

Runners who want to take advantage of the convenience of energy bars should look for products made with a mix of dried fruits, whole grains and a soluble form of fiber. Total carbohydrates should be at least 40 grams.

Most energy bars include a very high quality protein, and 7-10 grams is sufficient to repair any micro injuries and build stronger muscles. Look for whey protein, made from milk and cheese, or soy protein if dairy products are a problem. Both sources provide "complete proteins," meaning all eight essential amino acids are present. Your body can make the nonessential amino acids, so don’t be duped into spending money on something like branched chain amino acids that you already have.

Short and Middle Distance Runs

Sprinters may benefit from foods high in sugar taken a few minutes before they leave the gate. Blood glucose is the main source of energy for sprints of 2-3 minutes. A marshmallow-krispie treat can provide high sugar, low fat and the nutrients of a fortified breakfast cereal.

Individual differences in metabolism allow this to work for some. However, a few runners will react with rebound hypoglycemia. Their blood sugar will spike, only to be met with a flood of insulin, which quickly sweeps the glucose out of the blood and into the cells. The result is a sudden drop in blood sugar, a shaky feeling, and a brain that has gone off-line.

Longer runs up to a 10K distance don’t require any dietary attention beyond hydration, unless a meal, especially breakfast, has been skipped. A meal substitute that is rich in complex carbohydrates, eaten as close to the run as is comfortable, will slowly release sugar into the blood, keeping blood sugar in a healthy, normal range. Blood sugar levels can be expected to peak after 30 minutes, long enough for a refreshing run.

Long Distance and Endurance Runs

Athletes who exert themselves for long periods of time, such as during marathons and adventure runs, should start refueling after 60 to 90 minutes. Glycogen stores become depleted after about two hours, and small bites of an energy bar starting before this occurs will provide a continuous supply of calories. Uncoated bars that won’t melt into goo are more convenient, as are ingredients such as honey and fructose that resist freezing into teeth-shattering shockers.

The best choice of energy bars for long endurance runs will come with trial and error because we are all different in many respects—but there are some significant considerations.

All three energy-containing nutrients—carbohydrates, fat and protein—can be converted to glucose when needed. The appeal of carbohydrates is that it gives a "clean burn." The end-products of glucose combustion are heat, water and carbon dioxide.

Fat metabolism produces ketones. The body can adapt to using some ketones for energy, but there’s a risk of dangerously lowering the blood pH and a mental feeling that all critical thinking is sliding off your brain.

High protein during an endurance run should be avoided. One of the metabolites of protein is urea. This is a toxic waste product that the kidneys will flush out. Urine formation requires water, however, and fluids are already at a premium for the long distance runner. Energy bars that follow the diet of Dr. Atkins or "The Zone" will be higher in fats and protein, and lower in carbohydrates. Plan to take these only on your next Iditarod, where snowmelt is plentiful.

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