Cheat Sheet: Aerobic vs. Anaerobic
Article by: Jonathan S. via www.livestrong.com
The human body relies on oxygen to perform physical exercise. Aerobic exercise is the form that uses oxygen on a steady basis and results in improved cardiovascular fitness. Anaerobic exercise uses less oxygen, relatively quickly, to build muscular strength and endurance.
THE AEROBIC PROCESS
Aerobic exercise is a metabolic process occurring when a given quantity of energy (about 5 calories), is used for each liter of oxygen consumed. This energy is released when oxygen chemically causes muscles to utilize glycogen (stored sugars). In this context “sugar” refers to the sugar derived from healthy complex carbohydrates such as whole-wheat pasta, as well as that from simple sugars such as table sugar. The body’s uptake of oxygen increases during the first minutes of exercise to “steady-state.” At steady-state, the body’s oxygen requirements conform to the demands of the tissues. When exercise stops, the oxygen uptake gradually returns to its resting level.
THE ANAEROBIC PROCESS
Anaerobic exercises use very little oxygen during the performance of sports such as weightlifting. The body eventually replenishes its sugar supply to the muscle by the conversion of most built-up muscular lactic acid (about 85 percent) to glycogen. Anaerobic metabolic processes are utilized when workloads increase in severity. When exercise begins, there is a discrepancy between energy demand and the energy provided by aerobic processes. Anaerobic energy allows the exercise process to begin.
Aerobic fitness is often determined by a scientific measure called “maximal oxygen uptake.” This can be assessed by a physician using advanced metabolic equipment yet is unnecessary for the recreational athlete. Tests below the maximal level are sometimes utilized to extrapolate a maximum value. A simple and useful test of aerobic fitness is to jog or run on a local high school track while timing the number of minutes it takes to run one mile without exhaustion. A beginner can expect to take eight to 12 minutes to run one mile, while serious running devotees can expect to run one mile in about five to seven minutes.
Aerobic sports have been ranked for fitness by Per-Olof Astrand, M.D., a world authority on exercise physiology. (Anaerobic sports have not been categorized because they consist primarily of weightlifting and bodybuilding, both of which have similar effects.) The highest maximal oxygen uptake readings occur in the following sports: cross-country skiing, long-distance running and orienteering (hiking/climbing). Other high-ranking aerobic sports include skating, bicycling and swimming.
Assessing the ability to lift a given weight is performed in essentially the same scientific manner as for aerobic processes. A more reasonable approach is to ask an assistant to spot you (so you don’t hurt yourself by dropping a barbell) while executing a simple military barbell press or bench press. By experimenting with a few different weights, the weight that can be held steadily for three to six seconds provides a good estimate of overall maximal anaerobic fitness.
Aerobic and anaerobic exercises carry the risk of overexertion. Athletes often push themselves too hard in order to achieve fitness goals. If you feel dizzy, faint or heart palpitations, seek medical attention immediately. In the case of aerobic exercises, it is always important to be well hydrated before starting to exercise, rather than to drink water only when thirst sets in.