In general athletes and armies are special cases and concern a minority. The fitness, exercise patterns and skills achieved are for a particular time, place and purpose.

It is the "exercise of everyday" which is of greater interest to the epidemiologist and health worker; it is the exercise pattern of ordinary people and given the sedentary lifestyle and eating patterns of the western societies the sort of change necessary to provide improvement in health, life, fitness and slimness for the many.

The epidemiologist in population medicine is particularly concerned to make a small shift in the median of a population towards a better health index.

The question is what level of exercise should be recommended to most people,most of the time that they will enjoy, readily accept and integrate into their existing lifestyles?