The reason for emphasising the study of the complete system is the strong interaction between most individual items. For example, it is no use selecting a chair of sufficiently low height adjustment to allow small people to rest their feet on the floor if the work surface is of a fixed height which is too high for the resulting seated height. In fact, for work at fixed surfaces, the benefits of seat height adjustment are largely lost, as shown in Figure 1. For such cases, the purchase of footrests becomes essential, whereas footrests are not needed.
