Nutrients Burned First During Exercise

To maximize your workout regimen, it is important to understand what food your body is burning for fuel. This will allow you to set up your workouts in a manner that will support high energy levels and optimize nutrient burning. Learning the difference between aerobic and anaerobic exercises and when to perform each will shed light on how to organize your workouts.

  1. Digestion

    • When you bite into a bagel, the enzymes in your mouth attack the carbohydrates to break them down into simple sugars. You then swallow the ball of food, or bolus, and it is propelled down your esophagus, into your stomach and through your intestines by involuntary muscle contraction and relaxation. This is called peristalsis. By the end of the cycle, the carbs have been completely broken down into glucose. Glucose then travels into the blood, is stored as glycogen in the muscles or is broken down for energy.

    Energy Source During Aerobic Exercise

    • Glycogen is the primary source of energy during moderate-intensity aerobic exercise. During aerobic exercise, muscle oxygen demand is in equilibrium with oxygen delivery or supply. As you start to jog or walk, your body enters a process called glycolysis, which breaks down glycogen into glucose, yielding ATP or cellular energy. Although the duration and type of activity will determine the type of food metabolized for energy, in general after 30 minutes of sustained exercise, the body runs out of stored glycogen. When it does, it turns to fatty acids.

    Energy Source During Anaerobic Exercise

    • Anaerobic exercise, like weight training and sprinting, requires high bursts of energy for a short time. During anaerobic exercise, oxygen demand is greater than oxygen delivery. Similar to aerobic exercise, anaerobic exercise uses stored glycogen as its primary energy source. However, since the supply and demand of oxygen are not balanced, lactic acid is produced, which causes muscle fatigue by lowering the pH inside muscles cells. At a lower pH, glycolysis cannot occur, which means your muscles are out of energy. Although lactic acid is transported out of muscle cells passively, the process is not fast enough to prevent muscle exhaustion.

    Maximizing Your Workout

    • To maximize your workout, start with anaerobic exercises such as weight training, then transition into aerobic or cardio exercises such as jogging or using an elliptical machine. This will ensure that the energy needed for your aerobic or weight training session is available for you to use as energy. After 30 minutes of aerobic training, most of your stored glycogen will be used. When you proceed to your aerobic or cardio exercise, your body will shift from burning glucose to burning fat. By following this format, you will optimize the use of stored carbohydrates and increase the burning of fat during exercise.