The reliability and validity of a designed setup for the assessment of static back extensor force and endurance in older women with and without hyperkyphosis

ABSTRACT

Objective: The purpose of this study was to investigate the intra-rater reliability and validity of a designed load cell setup for the measurement of back extensor muscle force and endurance. Participants: The study sample included 19 older women with hyperkyphosis, mean age 67.0 ± 5.0 years, and 14 older women without hyperkyphosis, mean age 63.0 ± 6.0 years. Methods: Maximum back extensor force and endurance were measured in a sitting position with a designed load cell setup. Tests were performed by the same examiner on two separate days within a 72-hour interval. The intra-rater reliability of the measurements was analyzed using intraclass correlation coefficient (ICC), standard errors of measurement (SEM), and minimal detectable change (MDC). The validity of the setup was determined using Pearson correlation analysis and independent t-test. Results: Using our designed load cell, the values of ICC indicated very high reliability of force measurement (hyperkyphosis group: 0.96, normal group: 0.97) and high reliability of endurance measurement (hyperkyphosis group: 0.82, normal group: 0.89). For all tests, the values of SEM and MDC were low in both groups. A significant correlation between two documented forces (load cell force and target force) and significant differences in the muscle force and endurance among the two groups were found. Conclusion: The measurements of static back muscle force and endurance are reliable and valid with our designed setup in older women with and without hyperkyphosis.

KEYWORDS:

• Spine
• back extensor
• maximal static force
• endurance
• hyperkyphosis
• women
• reliability
• validity

Acknowledgments

This study is related to the project NO 1395/66075 from Student Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran. We also appreciate the “Student Research Committee” and “Research & Technology Chancellor” in Shahid Beheshti University of Medical Sciences for their financial support of this study. Authors thank Motahare Ababaf Behbahani (MSC student) for assisting with measurements and data collections..

Declaration of interest

The authors report no declarations of interest.

Additional information

Funding

This work was supported by the National Institute on Aging (NIA) (grant number: R01 AG041921); and theNational Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) (grant number: NIH P50 AR063043)