Your body needs fuel to create energy for daily activities, as well as for exercise, stamina and endurance. The body's fuel comes from carbohydrates, fats and proteins. The carbohydrate glucose is your metabolism's major source of energy, and comes from the foods you consume. Your body utilizes glucose during daily activities and in your exercise workout.
Glucose and Metabolism
Metabolism determines the speed at which your body uses energy for activity or exercise. Your metabolism may be slow or fast, depending on your age, physical fitness level and lifestyle. Your body gets its energy from glucose, a simple sugar created by the body from foods that contain carbohydrates, fats and proteins. The body stores glucose from carbohydrates the form of glycogen.
During a workout, your body converts the glycogen, stored in your muscles and ready for use, into glucose. This glucose circulates in your bloodstream, transporting energy and fuel to cells, tissues and muscles. Your blood glucose levels are determined by the level of sugar in your blood when you take a blood sugar reading.
Blood Sugar Levels
Exercise may quickly deplete your blood glucose levels. After 20 to 40 minutes of exercise, your body has used up its stores of available glucose, according to fitness expert and Burn Fitness Founder Tom Williams. The speed at which your body uses its glucose also depends on the intensity of your workout and your physical condition. At this point, the liver begins to convert its own stored reserves of glycogen into glucose energy. If you exercise long enough, your body will look for and rely on fast-acting carbohydrates from foods like orange juice or raisins for energy.
Diabetics
If you've been diagnosed with diabetes, carefully monitor your blood sugar levels before, during and after exercise. Diabetes reduces or eliminates the effect of insulin production in your body. Your body needs insulin, a hormone, to piggyback glucose into your body's blood, tissues and cells. Exercise can have an immediate impact on a diabetic's blood glucose levels. However, by eating a high carbohydrate snack about 20 minutes before exercising and checking your blood glucose levels after exercising for 30 minutes, you will eventually be able to gauge how your body reacts to different forms and intensities of exercises.
Symptoms of High or Low Blood Sugar
High or low levels of blood sugar create a number of symptoms. For example, low levels of blood glucose further depleted by exercise can cause weakness, trembling, nausea and lightheadedness. Hyperglycemia, or high blood glucose levels, can cause increased thirst and frequent urges to urinate. If you experience any of these symptoms during exercise, slow down. If you're a diabetic, monitor your glucose levels. If you have not been diagnosed with diabetes, discuss the symptoms with your doctor.
Testing Blood Glucose
You can test your blood glucose levels using a blood glucose monitor before you exercise or engage in physical activity. Blood glucose levels under 100 mg per deciliter indicate that you may need to eat a carbohydrate snack before you exercise. If you're a diabetic, your health care provider can explain how different types of sports and exercise routines alter your blood sugar levels.
References
- John Hopkins: Diabetes on exercise, glucose levels, diabetes: John Hopkins Special Reports; Feb. 7, 2006
- National Diabetes Information Clearninghouse: Hypoglycemia
- American Diabetes Association: Hyperglycemia
- Burn Fitness: Tom Williams Offers Advice in Fitness Magazine; July 2007
- Key Vive: Not All Exercise Is Created Equal. The Secret to Burning Fat & Lowering Diabetes Risk; Tom Williams
- Diabetes Self Management: Fast-Acting Carbohydrate; May 22, 2006
