Hence, the highest level of efficiency is possible only by converting as much as possible of the mechanical effort into a useful form with little or none of it being dissipated in holding or supporting things. The greater the proportion of mechanical energy to go into state for, the lower the efficiency. This is particularly true when work is carried out with a bent back.
In every kind of heavy work it is important to aim at maximal physiological efficiency, not only to use energy economically but to minimise stresses upon the operator. For this reason work physiologists have made a great many attempts to measure the physiological efficiency of various kinds of working methods and the use of different tools and other equipment. Their results make it possible to formulate guidelines for the layout of work and the design of equipment, which are of particular importance where strenuous work is concerned.
Some examples are given in Table 6.3.