Isometric endurance testing of cervical flexor and extensor muscles in subjects with neck pain.

ABSTRACT Background and Objectives Several tests can evaluate the isometric endurance of the cervical flexor (NFME) and extensor (NEE) muscles. This study aims to investigate the relationship between neck flexors endurance and extensor endurance and among cervical muscle endurance, disability, pain amount and pain stage in subjects complaining of non-specific neck pain (NP). Materials and Methods Thirty subjects (18 women, 12 men, mean age=43.9 SD 12.78) with NP filled out the 100 mm Visual Analogue Scale (VAS) and the Neck Pain and Disability Scale - Italian version (NPDS-I). They also completed the timed endurance tests for the cervical muscles. Results The mean endurance was 246.7 SD 150 seconds for the NEE test, and 44.9 SD 25.3 seconds for the NMFE test. A significant correlation emerged between the results of these tests (r=0.52, p=0.003). A positive relationship was also found between VAS and NPDS-I (r=0.549, p=0.002). The endurance rates were similar for acute/subacute and chronic subjects, whereas females demonstrated significantly lower values compared to males in NFME test. Discussion Our study showed significantly higher endurance of neck extensor muscles compared to flexor ones and significant relationship between pain and disability and between NFME and NEE tests. Nevertheless, we did not demonstrate any relevant relationship between each of the endurance tests, pain and disability. The results of these tests did not significantly differ between acute/subacute and chronic subjects, despite chronic subjects appeared more disabled. The different endurance between males and females can be interpreted on the light of physiological characteristics related to genetic factors. Comparison between this study and other similar ones demonstrated some variability of endurance during the NMFE or NEE tests between different samples. Conclusions These findings suggest that neck flexors and extensors endurance are related and cervical endurance is not significantly altered with the duration of symptoms in subjects with NP. REFERENCES 1. Edmondston SJ, Björnsdóttir G, Pálsson T, Solgard H, Ussing K, Allison G. Endurance and fatigue characteristics of the neck flexor and extensor muscles during isometric tests in patients with postural neck pain. Manual Therapy 2011; 16: 332-8. 2. Grimmer K. Measuring the endurance capacity of the cervical short flexor muscle group. Australian Journal of Physiotherapy 1994; 40: 251–4. 3. Harris KD, Heer DM, Roy TC, Santos DM, Whitman JM, Wainner RS. Reliability of a measurement of neck flexor muscle endurance. Physical Therapy 2005; 12:1349-5. 4. O’Leary S, Falla D, Elliott JM, Jull G. Muscle dysfunction in cervical spine pain: implications for assessment and management. The Journal of Orthopaedic and Sports Physical Therapy 2009; 39: 324-33. 5. Olson L, Millar A, Dunker J, Hicks J, Glanz D. Reliability of a clinical test for deep cervical flexor endurance. Journal of Manipulative and Physiological Therapeutics 2006; 29: 134-8.