NORMS: Below are a few studies that found different results with the DNF endurance test. Based on the data published, males with and without neck pain tend to have longer neck flexor endurance than females.
Asymptomatic Men (mean = 63.73 seconds), asymptomatic woman (38.43 seconds), mean age 23-26 y.o. - (Painkra et al. 2014)
Asymptomatic Men (mean = 25 seconds), asymptomatic woman (20 seconds) - (Olson et al. 2016)
Asymptomatic group (mean = 39 seconds), group with neck pain (mean - 24 seconds) - (Harris et al, 2005)
PREHAB GOAL = 45-60s
REFERENCES:
1. Painkra JP, Kumar S, Anwer S, Kumar R, Nezamuddin M, Equebal A. Reliability of an assessment of deep neck flexor muscle endurance test: A cross-sectional study. International Journal of Therapy and Rehabilitation. 2014 May;21(5):227-31.
2. Parazza S, Vanti C, O’Reilly C, Villafañe JH, Moreno JM, De Miguel EE. The relationship between cervical flexor endurance, cervical extensor endurance, VAS, and disability in subjects with neck pain. Chiropractic & manual therapies. 2014 Dec;22(1):10.
3. Olson LE, Millar AL, Dunker J, Hicks J, Glanz D (2006) Reliability of a clinical test for deep cervical flexor endurance. J Manipulative Physiol Ther 29: 134–8
4. Harris KD, Heer DM, Roy TC, Santos DM, Whitman JM, Wainner RS (2005) Reliability of a measurement of neck flexor muscle endurance. Phys Ther 85(12): 1349–55
5. https://www.physio-pedia.com/Muscle_Performance_in_Neck_Pain