The three primary ergonomic risk factors that cause MSDs are awkward posture, high force, and high or long frequency. Combination of postures, forces and frequencies increase the chance of developing an MSD.
Posture – In neutral posture, the joints can absorb force more easily that in others. Awkward and extreme postures increase susceptibility to injury, as they may stress joint components and reduce or block blood flow.
Force – Gripping, pinching, pushing, pulling, and lifting objects place additional force on the body’s joints. Increasing these forces requires additional muscle exertion, and places greater loads on joints and connective tissues which can cause fatigue and may contribute to MSD when there is inadequate time for rest and recovery.
Frequency – Higher frequency of awkward postures and/or forces increases the potential for damage to a joint.