Define Direct measurement of individual's Work Capacity?

Direct measurement of VO₂ max is determined by having the subject perform exercise at increased loads, for 12 to 15 minutes. A stationary bicycle or a treadmill is used The test starts with a moderate work load which is maintained for a few minutes The load is increased gradually every few minutes until reaching the maximum level that the subject can tolerate. This is done by increasing the cycling resistance or the speed and grade of the treadmill. The oxygen uptake measured at the maximal load is the subject's VO₂max. The higher the VO₂ max, the more work one can perform; thus, the better the level of aerobic fitness. These tests are expensive, and are beyond the reach and capability of most people.