INTRODUCTION

In many communities and occupations, human muscle is still the main source of power for the performance of physical work. The power output is determined by the quantity of muscle and the effectiveness with which it is used; this in turn is influenced by the adequacy of nutrition, the extent of any disease and the levels of physical training and skill. A high absolute power output is of benefit to the community in question, a high output relative to the quantity of muscle is evidence for optimal efficiency in the individuals concerned. Power output for work of a few minutes' duration is reflected by the maximal oxygen uptake (aerobic capacity). In physiological terms it is a measure of the combined function of all components of the oxygen transport chain from respired air to muscle mitochondria. In ergonomic terms it is the maximal power output in the circumstances of the test which may be on one or more of a treadmill, cycle ergo meter or step. These forms of exercise utilise the main muscle mass of the body but in different ways and so the result which is obtained varies with the type of ergometer. It is also influenced by environmental factors including ambient temperature, but in the laboratory this can usually be controlled.

MAXIMAL OXYGEN UPTAKE IN POPULATION STUDIES

The procedure, for measuring maximal oxygen uptake entails the subject exercising at progressively increasing intensity up to the maximum. In objective terms this is the point at which oxygen uptake reaches a plateau and does not increase with a further increment in external work.