Cranio-cervical flexor muscle impairment at maximal, moderate, and low loads is a feature of neck pain

Impairment of the cranio-cervical flexor (CCF) muscles is a feature of painful cervical spine disorders. The aim of this study was to investigate if CCF muscle impairment is present over a range of contraction intensities (maximal, moderate, low) in neck pain sufferers compared to individuals with no history of neck pain. Isometric CCF muscle strength (isometric maximal voluntary contraction (MVC)), and endurance at moderate (50% of MVC), and low (20% of MVC) loads was compared in 46 participants with neck pain (Neck Disability Index (NDI): mean+/-SD; 22.8+/-5.2) and 47 control participants (NDI: 2.6+/-2.6). Compared to the control group, the neck pain group had a significant deficit (15.9%, P=0.037) in their MVC peak torque recordings, as well as a significantly reduced capacity to sustain isometric CCF muscle contractions to task failure at 20% of MVC (35% deficit, P=0.03) and 50% of MVC (27% deficit, P=0.002). Neck pain participants also demonstrated poorer accuracy in maintaining their MVC(20) contraction at the nominated isometric CCF torque amplitude (P=0.02), compared to control participants. It would appear that impairment in isometric CCF muscle performance exists over a range of contraction intensities in neck pain sufferers, which may benefit from specific therapeutic intervention.