What do aerobic and anaerobic mean?
Aerobic means with oxygen. Aerobic exercises are low-to-moderate in intensity and are sustainable for long periods of time. Walking, jogging, biking, and swimming are all aerobic exercises.
Anaerobic means without oxygen. Anaerobic exercises are activities that require quick bursts of power at high intensities. Sprinting and weightlifting are anaerobic exercises.
During aerobic conditions, the muscle cells have adequate fuel and oxygen, and they can contract repeatedly without fatigue. During anaerobic conditions, muscle cells must rely on other reactions that do not require oxygen. This anaerobic metabolism in the cells produces waste molecules that can impair muscle contractions. This results in fatigue.
Fatigue causes you to experience added discomfort and weakening muscles. Eventually you will need to lower your intensity level and allow your body to remove the waste molecules.
What is the metabolic threshold?
We rely on aerobic metabolism to handle most of our body's energy needs. As we begin exercising, the increased energy requirements cause us to increase our breathing rate. If we increase our exercise intensity slowly, the muscles can maintain aerobic metabolism, and we don't experience symptoms of fatigue.
As exercise intensity increases, the need for energy eventually exceeds what can be supplied by aerobic metabolism. Our muscles simply need more reactions to support the demand for energy. Therefore, anaerobic metabolism increases. We refer to this change in metabolism as the metabolic threshold.
Keep in mind that we never switch from total aerobic to total anaerobic metabolism. Instead, the proportion of anaerobic metabolism increases the more intensely we exercise.
How do I find my metabolic threshold?
Fortunately, we do not need sophisticated equipment to detect when we transition from aerobic to anaerobic exercise. As we approach and pass our metabolic threshold, we start to breathe harder and exercise simply becomes uncomfortable. You can use a heart rate monitor to record the heart rate at which you sense these symptoms of over-exertion.
How do I use aerobic and anaerobic exercise in my workouts?
It depends on your goals. Most of us are not elite athletes. We simply exercise to feel good and lose weight. Aerobic exercise enables us to exercise for long periods of time, which allows us to burn more calories. It also tends to be less stressful to our muscles, joints, and heart, which may be important for individuals with arthritis, heart disease, or high blood pressure. However, some anaerobic exercise training is necessary to more rapidly improve your fitness and performance.
The best option for improved fitness is to include aerobic and anaerobic exercises in your workout routine. The American College of Sports Medicine recommends that adults get at least 150 minutes of aerobic exercise, and perform strength training (anaerobic) two times per week. You can also add anaerobic exercise to your aerobic workouts by incorporating short sprints into your run or adding plyometric training (sometimes called jump training).