Energy is required by all cells of the body to conduct any life process. The foods you eat provide the source of this energy, primarily from carbohydrates and fats. Adequate consumption of these nutrients is necessary so the body does not resort to breaking down protein for fuel. The more intensely you exercise, the greater will be your calorie burn. Whether carbohydrates are the primary source depends upon your exercise intensity and the energy state of your muscles.
Energy Sources
Your body relies primarily on fat and carbohydrates to provide energy. The breakdown of these nutrients releases chemicals the body then uses to produce ATP (adenosine triphosphate), which is the energy currency of the body. The body uses sugars circulating in the bloodstream for energy. It also breaks down stored sugars in the skeletal muscles and liver when blood glucose levels drop.
What Is a Carbohydrate?
Carbohydrates are organic compounds found in sugars, starches and plant foods. They can be either simple or complex depending on their chemical structure. Simple carbohydrates include foods like fruits and sugary foods the body can easily break down to produce energy for exercise. Complex carbohydrates include starches like corn and potatoes as well as whole grains. Because of their complicated chemical structure, it takes more time for the body to break them down.
Carbohydrates and Exercise
How the body uses carbohydrates during exercise varies with the intensity. The overriding factor driving energy production is energy efficiency. The body has adapted though thousands of years of evolution to maximize energy use. During light to moderate exercise, the body relies primarily on carbohydrates and fat for energy. It uses carbohydrates in the bloodstream, but this source quickly becomes depleted. The release of hormones then triggers the body to break down stored sugars called glycogen. During intense exercise, the body relies on glycogen to meet its primary energy needs.
Carb-Loading Diet
You can work with your body's physiology to encourage it to use carbohydrates in the form of glycogen by following a carb-loading diet before an athletic event -- about a week before, recommends MayoClinic.com. Basically, you deplete the reserves in your muscles prior to the event, followed by a period of high carbohydrate intake a few days before the event. This builds up glycogen in your muscles, giving you an extra boost of energy to improve your performance. While not for everyone, a carb-loading diet is one way to maximize performance through diet.
References
- KidsHealth.org: Figuring Out Fat and Calories, 4-4-9
- "Principles of Anatomy and Physiology"; G. Tortora et al.; 2005
- Centers for Disease Control and Prevention: Carbohydrates
- Recreational Equipment; How to Choose a Heart Rate Monitor; Derek Klobucher; July 2010
- Polar USA: Exercise Zones
- MayoClinic.com: Carbohydrate-Loading Diet
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