Maximal isometric muscle strength of the cervical spine in healthy volunteers.

OBJECTIVE: To describe the maximal isometric neck muscle strength in healthy Chinese volunteers, in six different directions, as measured by a Multi Cervical Rehabilitation Unit. DESIGN: A standardized cross-sectional observational study. SETTING: A university rehabilitation unit. SUBJECTS: Ninety-one healthy volunteers aged 20-84. METHODS: During the measurement the subject was instructed to do three consecutive steady contractions as hard as possible, with a 10-second rest in between each contraction and a 2-minute rest between different directions. The peak isometric strength for each of the six directions (flexion, extension, lateral flexions, protraction and retraction) was calculated. RESULTS: No significant difference was found in muscle strength between different age groups. Isometric muscle strength in the direction of right lateral flexion was significantly greater than that to the left in men (p = 0.030), but no difference was found in women (p = 0.297). Isometric strength in all directions in men was 1.2-1.7 times that in women (all p < 0.028). Correlations between physical measurements (height and weight) and strength values were all insignificant in both genders. CONCLUSION: Men have approximately 20-70% greater isometric neck muscle strength than women. Both men and women can maintain high levels of cervical muscle strength in six different directions up to their seventh decade. There is no significant correlation between physical measurements and isometric neck muscle strength.