Aerobic exercise is performed when the exercise is continuous and prolonged for more than three minutes. Aerobic exercise requires oxygen to be supplied to the muscles to keep them contracting. Aerobic activities include walking or jogging, cycling, swimming, aerobics, circuit weight training and sports, such as soccer, squash and tennis, where there are repeated bursts of high intensity activity over the course of a game.
Regular aerobic exercise improves the functional capacity of the heart, lungs and blood vessels to deliver oxygen to our body and increases our aerobic fitness. This can be measured as the VO2max (also known as aerobic capacity, endurance exercise potential). It is assessed by measuring an individual’s oxygen consumption as the exercise intensity is progressively increased each minute, until physical exhaustion is achieved. The test may be performed on a treadmill, bike or rowing machine (often referred to an ergometer). The oxygen consumption is calculated by measuring the volume and composition of expired air, with the maximum value achieved near the end of the test, being the VO2max.
Although aerobic fitness is strongly associated with improved health and wellbeing, it must not be viewed in isolation. In general, most forms of aerobic training does not increase muscle strength or bone mass, which buffer the impacts of aging.
Although aerobic fitness relies on continuous activities, additional improvements can be achieved in active individuals, by alternating short bursts of near-maximal exertion with intervals of lower intensity activity. This form of training is known as ‘interval training’. This may involve short periods of jogging as part of a basic walking program and progress to including multiple sprints of 100 – 200m with alternate periods of walking or jogging.
Swimmers may include a couple of faster laps followed by slower laps. The higher-intensity phase should be sufficiently long and strenuous enough that you are out of breath. Recovery periods should be only long enough to result in a partial recovery before the next exercise interval begins. The total of burst-recovery repeats should initially total some 15-20 minutes and be preceded by 10-15 mins of warming up and concluded by 10-15 mins of cooling down and stretching.
Interval training is generally more strenuous than continuous aerobic training, and generally requires increased levels of motivation. It can be included in your basic aerobic exercise program on 1-2 occasions/week. It should only be completed by healthy individuals and those with no history of muscle or joint injury. If interval running forms part of a program, then it is best to run on a soft surface to reduce the stress on muscle and joints (to avoid the risk of developing a chronic injury).
Anaerobic exercise means undertaking short bursts of intense exertion performed at close to, or above 100% effort, like fast running or lifting heavy weights. Because the energy required for this kind of activity is at or above the maximal ability to supply oxygen to fuel the muscles (i.e. above the VO2 max), anaerobic exercise must use stored energy in the muscles. However, this store is limited and maximal exertion cannot be sustained for more than 2-3 minutes. While anaerobic exercise will burn more energy in a period of time, when compared to aerobic exercise, the body will be unable to sustain this level of exercise for more than a few minutes without a period of recovery.