Physical risk factors for neck pain.

To identify physical risk factors for neck pain, a systematic review of the literature was carried out. Based on methodological quality and study design, 4 levels of evidence were defined to establish the strength of evidence for the relationship between risk factors and neck pain. Altogether, 22 cross-sectional studies, 2 prospective cohort studies, and 1 case-referent study were eligible for determining the level of evidence. The results showed some evidence for a positive relationship between neck pain and the duration of sitting and twisting or bending of the trunk. A sensitivity analysis was carried out excluding 3 items of the quality list, the importance of which seemed doubtful. On the basis of this sensitivity analysis, it was concluded that there is some evidence for a positive relationship between neck pain and the following work-related risk factors: neck flexion, arm force, arm posture, duration of sitting, twisting or bending of the trunk, hand-arm vibration, and workplace design.