Assessment of human muscle strength for engineering purposes: a review of the basics.

Contracting skeletal muscles pull on body segments to withstand or overcome internal and external opposing forces. Various methods and techniques can be employed for measuring muscular exertions. Information on strength that can be applied to objects such as hand tools or handling loads is of great importance for ergonomic design. This paper establishes a systematic context regarding: (1) the contractile muscle actions and their associated metabolic and circulatory processes, which are often the limiting factors for exertion; (2) the internal biomechanical effects of muscle contraction in terms of the application of muscle force to body links and the internal transmission of the generated torque through the body to the point of external exertion; (3) the various kinds of muscular efforts, ranging from strictly bounded statics (isometrics) to freely executed dynamics; and (4) the ensuing possibilities to measure human muscular capabilities for the application of this information to ergonomic design of tasks and equipment.