Volitional Postures during Maximal Push/Pull Exertions in the Sagittal Plane

A set of push/pull experiments was performed by six men and women of varying anthropometry who were asked to exert maximal one-handed and two-handed push and pull forces on a load cell set at three different heights (67, 109, and 152 cm). They were each permitted to experiment with their postures to determine that which they sensed would permit the largest push or pull force, though no direct feedback was given as to their actual performance. Once they achieved what they believed to be their optimal posture, sagittal-plane photographs were taken. The angles of major body joints were then recorded along with the isometric force produced. It is shown that foot placement, handle height, and body postures affect push and pull force capability in a manner that is reasonably logical, using biomechanical concepts. It is proposed that future biomechanical models of push an pull strengths and workplace layouts must be carefully assessed with reference to the postural variations reported.