Biomechanics

Biomechanics (bio=life + machine) is the application of the principles of mechanics and physics to measure the forces exerted by and upon living forms.   Human Factors is principally concerned with occupational biomechanics which is the application of these principles to the measurement of forces exerted by and upon the human body during the performance of work.  These measurements are used to determine physical work performance tolerances with the goal of maximizing work performance while protecting worker occupational health and safety.

The application of the principles of mechanics and lever systems to the human body requires the use of anthropometric data, critical data being the distance/length of body levers (bones) between joints.

Male subject lifting an object (above)

Female subject lifting the same object (adapted from Tichauer, E. R., The Biomechanical Basis of Ergonomics: Anatomy Applied to the Design of Work Stations, New York: John Wiley & Sons, 1978)

Human variability in physical size (static anthropometry) and physical strength (dynamic anthropometry) is also important in biomechanics with respect to the worker population in terms of gender, age, and ethnicity.  Above is an example of biomechanical calculations of the forces acting upon the lumbosacral joint during a lifting task.  Note, the forces differ between males and females because of gender dependent differences in body segment proportions. That is, the majority of females have shorter legs and longer torsos than males (Tichauer, 1978, op.cit).