In all human work, the body is involved, and knowing how it functions is highly important in understanding the possibilities and limitations of how people do work. The interesting amalgam of psychology, industrial engineering, and work physiology, that throughout Europe is called ergonomics, recognizes this. So it is important in any systematic study of working life to give full consideration to the physical and physiological condition of the human body. This must include not only such human engineering phenomena as fitting the man and the machine, but also what kind of limits are set in terms of time and space and all the other physical factors that affect effective performance.
There is a very large part of physiology -- indeed, most of what is found in texts and journals of physiology -- that is of no direct relevance to the topics discussed in this volume. Some physiological topics, like the relation of nutrition to human performance or the physiology of various athletic or sporting events, are of only tangential interest. But some are directly relevant, such as what physical factors in the environment affect the functioning of the body and thus affect work performance; what sorts of physiological changes precede, accompany, or follow upon certain forms of human performance; and the relations of psychological functions to physiological functions.
The study of healthy individuals as their behavior is affected by the environment comprises an important part of psychology as well as of the social and biological sciences. It is also the focus of environmental physiology, which is a discipline a bit broader than that of work physiology.