Expert explains anaerobic, aerobic exercise
Q: I keep hearing two terms in the spa: aerobic and anaerobic exercises. What type of exercise is aerobic and what are examples of anaerobic? A: Aerobic exercise is any type of sustained, rhythmic movement of low to moderate intensity that uses large muscles and is continued for more than 15 minutes. Examples include walking, running, biking, or swimming. Anaerobic exercises typically refers to stop-and-start exercises such as weight lifting.
“Aerobic exercise basically pumps up the heart and cardiovascular system, allowing for greater volumes of blood to be circulated through the body. Anaerobic exercise tones the muscles which are the factories that determine the basal metabolic rate, the rate at which we burn calories,” says Connie Harnum, assistant professor of physical education at Susquehanna University in Selinsgrove, Pa.
If you’re trying to “get in shape” then you need both types of exercise. Aerobic exercises are good for the heart, lungs, and fat burning. Anaerobic exercises strengthen bones, muscles and speed metabolism by improving the ratio of muscle to fat.
“In order to burn fat one must engage in anaerobic type exercises. However, aerobic exercise facilitates the exchange of oxygen and wastes in the muscle cells,” says Harnum.
Jerry Green, director of the Fitness Center at Rider University in Lawrenceville, N.J., notes that anaerobic exercise is something that only lasts for 30 seconds to three minutes, and at that stage, the body is using carbohydrates.
“After three minutes, the body needs oxygen and uses oxygen to balance off your glycogen storage. With aerobic exercise at 20-30 minute levels, the glycogen is depleted, and the body then burns your fat storage for energy. That means aerobic exercise is better at burning fat than anaerobic exercise,” says Green.
Green details the three energy systems that are utilized during anaerobic and aerobic exercise this way:
– At high intensities, the phosphogen system is used. In this phase, ATP and creatine phosphate are the main sources of energy.
“Depending on the intensity, they can last between 10 to 20 seconds,” says Green. “Examples of activities that can utilize this system are 100 and 200-meters sprints, a play in football, Olympic weight training.”
– As the phosphogen system is depleted, the next energy system – the anaerobic glycolysis system begins and can last from 30 seconds to three minutes – depending on the intensity of the activity. “This system relies on glycogen, which is stored in the muscles and liver. Glycogen is derived from eating carbohydrates.
“Examples of activities that can utilize this system are longer sprints, weight training, some plays in a basketball or volleyball game,” he says.
After about three minutes, there is a build up of lactic acid – then the aerobic metabolic system takes over. In this system, oxygen is needed to utilize the balance of glycogen stores.
“After about 20 to 30 minutes, glycogen can be depleted. Then, fat is the main source of the body’s fuel,” says Green.
Examples of activities in this system are jogging, biking, aerobics classes at moderate to moderate-high intensities lasting 20 minutes or longer.
(Send your questions to Steve Infanti, A Fit Life columnist, at Wheeling Jesuit University, sinfanti@nttc.edu.)