Naturally preferred directions for the exertion of maximal manual forces

Abstract

Because the strength of a standing person varies with the direction of exertion, a component of a manual force whose resultant deviates from a required direction may exceed the magnitude of the directed force. Naïve subjects instinctively deviated their directions of exertion in order to maximize their attempts to lift, push or pull. The deviations observed were close to those predicted as necessary in order to achieve the maximum advantage of using a component of exertion (MACE). The quantitative definition of MACE is put forward as a basis forjudging the efficiency of a static exertion.