Force means the muscular effort a task needs, and forceful exertions overload muscles, tendons, joints and discs and are linked to most disorders. Repetitive force is applied repeatedly over time (stacking pallets, bricklaying, repeatedly pressing components, preparing surgical equipment). Sustained force is applied continually (pushing a trolley, holding a power tool trigger, supporting a sheet while fixing it, long carries). High force appears where a worker finds the task very demanding, needs help or needs a stronger person or two people, such as lifting heavy objects, loads that cannot be held close, pushing or pulling objects hard to start or stop, uneven or jerky forces, sudden forces and restraining people or animals, and includes high hand and finger force from pinch grips, tight squeeze tools and two-handed tools. Sudden force comes from jerky or unexpected movements, such as nail gun recoil, throwing or catching, unstable loads that shift, frightened animals and patients who suddenly resist.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.