What Does A VO2 Max Test Measure?

A VO2 max test measures a person's maximal volume of oxygen consumption. VO2 max may also be referred to as maximal oxygen uptake, maximal aerobic capacity, or peak oxygen uptake.

The test offers a valid and reliable way to measure a person's cardiorespiratory fitness level (heart and lung fitness), and the efficiency of their muscles. Prolonged physical activity is aerobic in nature, which means that it requires oxygen in order for it to be sustained. The oxygen must be effectively pumped to the working muscles via the circulatory system.

Essentially, a VO2 max test will measure a person's ability to process oxygen at a given intensity.

Why A VO2 Max Test May Be Required

When a person's VO2 max is known, it can be measured against the physical requirements for a particular job role. Physically demanding job roles may require a VO2 max test to be completed during the pre-employment period. This is because a certain base level of fitness may be needed to carry out the job role safely and effectively.

A low VO2 max result can be indicative that the person will tire more quickly during activities that require a specific base level of cardiorespiratory fitness. Therefore, the results from a VO2 max test could be used to determine a person's suitability for a physically demanding job role.

A VO2 max test may also be used as one indicator of a person's overall health status. As well, it can be used by athletes and fitness enthusiasts to measure changes in cardiovascular fitness over time.

Types Of VO2 Max Tests

There are a number of fitness testing options that have been developed in order to estimate VO2 max. To obtain an accurate measurement however, a test will need to be carried out in a laboratory. A test that accurately measures VO2 max requires a face mask to be worn. This allows the amount of air that is breathed in and out to be accurately measured, and the concentration of gas in that air is also measured.

An employer must consider whether an accurate measure of VO2 max is appropriate and necessary, or whether a submaximal aerobic capacity test that estimates VO2 max would be a better choice.

A couple of points to consider:

• Lab test results will be more accurate but will cost more and take more time to carry out than submaximal aerobic capacity tests
• Lab tests require the person to exercise to their maximal ability. Therefore, they are generally not suitable for those with medical concerns, injuries or a low level of fitness

Submaximal Testing Options To Estimate VO2 Max

There are several fitness tests that can offer an estimated value for VO2 max. These are often more suitable for the general population than a lab test. It should be noted, however, that many of these options also require a high level of physical exertion.

Submaximal testing options include the following:

• The 12-minute run (known as the Cooper test), a test in which the person being tested runs as far as they can in 12 minutes
• The Rockport walking test, a timed 1-mile walk where VO2 max is estimated based on the time to complete the walk, as well as age, gender, body weight, and heart rate at the end of the mile
• The beep test (multi-stage fitness test), in which shuttle runs are completed over a 20-meter distance. The person being tested must reach the 20m mark before the next "beep," and the time between the beeps gets progressively shorter throughout the test

Maximal Lab Testing To Accurately Measure VO2 Max

Depending on the testing facilities, VO2 max testing in a lab will normally be completed on a treadmill or cycle ergometer. If both options are available, the most relevant mode should be chosen, based on the person and their usual activities or sports.

The basic procedure for the test is as follows:

• Pre-screening for health risks and informed consent is carried out.
• Relevant personal details for the test, such as age, gender, and body weight are recorded.
• Testing procedures are explained and the person who will be tested carries out an appropriate warm-up. If a cycle ergometer is used, the handlebars and seat will be adjusted to an appropriate height.
• The person gets into position on the treadmill or cycle ergometer, ready to begin the test.
• A face mask is worn, which is attached to a machine that measures oxygen consumption and carbon dioxide production.
• The test commences at a moderate intensity level based on perceived level of exertion. The initial workload is an important consideration because the goal is for the person being tested to reach their maximum exercise capacity within about 10 minutes
• The intensity of the test is increased every minute. On a treadmill, this involves increasing the incline. On a cycle, the resistance level (load) is increased each minute.
• The test finishes when the person reaches their maximum effort and can no longer continue. VO2 max is calculated from the volumes of inspired and expired air, and the oxygen and carbon dioxide concentrations.

Throughout a VO2 max test, rate of perceived exertion (RPE), and heart rate values may also be measured and recorded at regular intervals.

The Results From A VO2 Max Test

Your VO2 max results are affected by how much blood your heart can pump, your red blood cell count, and how adapted (well-trained) you are for the activity at hand. The exact formula used to calculate or estimate VO2 max will depend on which test has been used.

VO2 max is most commonly expressed as a relative rate. This means that it is adjusted for a person's body mass and is measured in milliliters per kilogram per minute (ml/kg/min).

A normal VO2 max result falls between 30 and 60 ml/kg/min. Elite aerobic endurance athletes (e.g. long-distance runners or cyclists) usually have a VO2 max of around 90 ml/kg/min. A physically demanding job role may have a baseline requirement for VO2 max that the individual must meet.

A consistent and progressive approach to aerobic fitness can help improve VO2 max test results over time. Aerobic fitness activities include running, cycling, swimming, walking, and most team sports.