Test-retest reliability of a load cell setup, Ito, and timed loaded standing tests for measuring muscle strength and endurance in older adults with and without hyperkyphosis

Abstract

Background The association of back muscle weakness with greater thoracic kyphosis has been widely documented. Reliable and easy-to-use techniques are needed to monitor changes in muscle function over time and assess the effectiveness of therapeutic interventions. Therefore, the present study aimed to evaluate the test-retest reliability of a designed load-cell setup and two clinical tests, namely Ito and Timed loaded standing (TLS) tests for measuring back muscle function (i.e., strength and endurance) in older adults with and without hyperkyphosis. Method Fifty-three older people (28 with thoracic hyperkyphosis and 25 normal age-matched controls) completed the present test-retest reliability study. A two-way random model of the Intraclass Correlation Coefficient (ICC2,3) was used to estimate relative reliability. Absolute reliability was assessed by calculating Standard Error of the Measurements (SEM) and Minimal Detectable Change (MDC). Results The findings showed excellent test-retest reliability in all performed tests for this population (ICC = 0.95–0.99). In addition, the MDC values for measuring endurance time via load cell, Ito, and TLS tests in the hyperkyphosis group, were 16.5, 28.2, and 35.1 s, respectively. These values ranged from 36 to 39 s for the control group. Conclusion The present study suggests high test-retest reliability of the designed load-cell setup, Ito, and TLS for assessing back extensor muscle strength and endurance in older adults with and or without hyperkyphosis. Keywords: HyperkyphosisPsychometric propertiesBack extensor musclesMaximum extensor force