Inter- and intra-rater reliability and construct validity of a hand-held dynamometer for assessing muscle strength in patients with chronic neck pain

• Grant number: 25/07248-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2025
• End date: June 30, 2026
• Field of knowledge: Health Sciences - Physiotherapy and Occupational Therapy
• Principal Investigator: Luiz Fernando Approbato Selistre
• Grantee: Giovanna Silva Nunes
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Chronic neck pain is considered the third most common cause of disability worldwide among musculoskeletal conditions. Among its repercussions, there is ample evidence that these individuals have weakness of the cervical muscles. Muscle strength tests are important in clinical practice for its measurement, and hand-held dynamometry has proven to be an accessible alternative for measuring isometric muscle strength. Despite this, its reliability and validity have not yet been tested specifically in the population with chronic neck pain and with an adequate sample size, considering the recommendations of COSMIN (Consensus-based Standards for the selection of health Measurement Instruments), or that have included all four cervical muscle strength tests (flexion, extension, and right and left lateral flexion). Objective: (1) To investigate the inter- and intra-rater reliability, standard error of measurement (SEM), and minimum detectable change (MDD) of the strength test with the hand-held dynamometer in patients with chronic neck pain; (2) To evaluate the construct validity of the strength test with the hand-held dynamometer in patients with chronic neck pain. Methods: Eighty participants aged 18 years or older who present with chronic and nonspecific neck pain will be recruited. The isometric cervical muscle strength tests will be performed by two evaluators with a 10-minute interval between them and will repeat the procedure 5 to 7 days after the first visit. The intra-rater (ICC3, 1) and inter-rater (ICC2,1) reliability analysis will be performed using the intraclass correlation coefficient (ICC) test.. The standard error of measurement (SEM) and the smallest detectable change (SDC) will be calculated. Construct validity will be assessed using the predefined hypothesis test and the Pearson or Spearman correlation coefficient will be used depending on the normality of the data. The test will be considered valid if at least 75% of the hypotheses are confirmed.