An Objective Measure for Postural Comfort

Biomechanics determines the physical range in which humans can move their bodies. Human factors research delineates a subspace in which humans can operate without experiencing musculoskeletal strain, fatigue or discomfort. We claim that there is an even tighter space which we call the comfort zone. It is defined as the range of postures adopted voluntarily – despite the availability of other postures. We introduce a measurable, objective foundation for comfort, which was previously assumed equivalent to the absence of discomfort, a subjective quantity. Interfaces designed outside a user’s comfort zone can prompt the adoption of alternative use patterns, which are often less favorable because they trade off the unnoticeable potential of injury for comfort. Designing interfaces within the limits of comfort zones can avert these risks.