Determination of Preferred Lumbar Support Handle Type and Location

The objective of this paper was to determine an acceptable position of a manual lumbar support handle and the type of handle best suited for the location. Ten male and ten female subjects evaluated three different handles (knob, lever, and ratchet) in three different seat locations (side of backrest, side of seat cushion, and front corner of seat cushion). The subjects operated each handle in each location for ten seconds. Electromyography (EMG) was used to measure the amount of muscle activity as a percent Maximum Voluntary Contraction (%MVC) required to actuate the handles. The muscles measured were the biceps, triceps, posterior deltoid, forearm flexors, and forearm extensors on the left arm. Subjective questionnaires were distributed to collect data on amount of effort, shoulder and hand/wrist comfort, type of handle preferred, and preferred handle location. The results found the ideal location was the side of the seat cushion and the ratchet actuator was preferred in each location.