Neck Strength Evaluated With Fixed and Portable Dynamometers in Asymptomatic Individuals: Correlation, Concurrent...

Area of Science:

• Biomechanics
• Musculoskeletal assessment
• Rehabilitation engineering

Background:

• Accurate measurement of cervical isometric force is crucial for assessing neck strength and guiding rehabilitation.
• Both fixed and portable dynamometers are used, but their comparability in measuring cervical isometric force is not well-established.

Purpose of the Study:

• To evaluate the correlation, concurrent validity, and agreement between fixed and portable dynamometers for isometric cervical force measurements in asymptomatic individuals.

Main Methods:

• Fifty asymptomatic individuals performed maximal isometric cervical contractions (flexion, extension, lateral flexion) using both fixed and portable dynamometers.
• Spearman's correlation coefficient and intraclass correlation coefficient (ICC) were used to assess correlation and validity.
• Bland-Altman analysis was employed to evaluate agreement between the two devices.

Main Results:

• A moderate to high correlation (r_s = 0.68-0.82) and moderate to good concurrent validity (ICC = 0.67-0.80) were found between the dynamometers for all movements.
• However, significant mean differences and broad limits of agreement were observed, indicating a lack of measurement equivalence.
• Errors ranged from 61% to 77% of the mean force measured by the fixed dynamometer.

Conclusions:

• While fixed and portable dynamometers show good correlation and validity for cervical isometric force, they do not provide interchangeable measurements.
• Due to significant discrepancies, it is recommended to consistently use the same type of dynamometer for serial reassessments of neck strength.