A new method of isometric dynamometry for the craniocervical flexor muscles.

BACKGROUND AND PURPOSE A new method of dynamometry has been developed to measure the performance of the craniocervical (CC) flexor muscles by recording the torque that these muscles exert on the cranium around the CC junction. This report describes the method, the specifications of the instrument, and the preliminary reliability data. SUBJECTS AND METHODS For the reliability study, 20 subjects (12 subjects with a history of neck pain, 8 subjects without a history of neck pain) performed, on 2 occasions, maximal voluntary isometric contraction (MVIC) tests of CC flexion in 3 positions within the range of CC flexion and submaximal sustained tests (20% and 50% of MVIC) in the middle range of CC flexion (craniocervical neutral position). Reliability coefficients were calculated to establish the test-retest reliability of the measurements. RESULTS The method demonstrated good reliability over 2 sessions in the measurement of MVIC (intraclass correlation coefficient [ICC]=.79-.93, SEM=0.6-1.4 N x m) and in the measurement of steadiness (standard deviation of torque amplitude) of a sustained contraction at 20% of MVIC (ICC=.74-.80, SEM=0.01 N x m), but not at 50% of MVIC (ICC=.07-.76, SEM=0.04-0.13 N x m). DISCUSSION AND CONCLUSION The new dynamometry method appears to have potential clinical application in the measurement of craniocervical flexor muscle performance.