Reliability of an assessment of deep neck flexor muscle endurance test: A cross-sectional study

Background: Deep neck flexor (DNF) muscles assist in stabilising the cervical spine during gross neck movements. Patients with neck pain often exhibit reduced deep neck flexor muscle endurance. Aims: This study's primary purpose was to determine the inter-rater and intra-rater reliability of measurements obtained using a simple clinical test of DNF muscle endurance in a healthy Indian population. The secondary purpose was to determine and compare the average hold time for deep neck flexor muscle endurance in healthy male and female participants, to add to the body of knowledge around deep neck flexor muscle endurance testing. Methods: In this cross-sectional study, 60 participants (30 male, 30 female) were evaluated using a deep neck flexor endurance test, which involved them lifting their head while maintaining their craniocervical region in a flexed position. Deep neck flexor endurance was measured by two physiotherapists. Each tester measured the DNF hold time of each participant twice, and there was a 5-minute rest between trials. Results: Inter-rater reliability was moderate to good (ICC = 0.69-0.88) and intra-rater reliability was good to excellent (ICC = 0.82-0.93). Neck flexor endurance time was significantly greater in males (mean = 63.73 seconds; SD = 20.27 seconds) than females (mean = 38.43 seconds, SD = 11.71 seconds, (F = 72.89, P<0.001). Conclusion: The results suggest that healthy males have greater deep neck flexor endurance than females. This is the first normative data available that reports on deep neck flexor endurance in healthy Indian adults.