Reliability of hand-held dynamometer in measuring gluteus medius isometric muscle strength in healthy population

Objectives: To determine the inter-rater and intra-rater reliability of the hand-held dynamometer in measuring isometric gluteus medius muscle strength in asymptomatic healthy population. Methods: It was a cross sectional study conducted at the department of physiotherapy, Sindh Institute of Physical Medicine and Rehabilitation from March 2021 to April 2021. Thirty healthy subjects aged 18 to 25 years of both sexes and no previous or current complaints of hip or knee pain were included through nonprobability purposive sampling technique. The strength of the unilateral isometric gluteus medius muscle was measured using a hand-held dynamometer by two raters at the same day and a week later. Pearson Correlation coefficient was calculated to see the relationship of muscle strength measured by each rater within and between day's sessions. Intra-class correlation was calculated with 95% confidence interval and Standard error of measurements using reliability analysis. Results: In the present study there were thirty participants studied by two raters, the mean age of participants was 21.53 (SD=+/- 1.40) years, the mean BMI was 24.05 (SD=+/- 1.12) kg/m(2) and 70% participants were female and 30% were males. This study showed the mean muscle measurement of participants within days was 12.92 (SD=+/- 0.94), with intra-class correlation ICC (2,2) 0.94 and SEM 0.12 and mean muscle measurement of patients between days was 12.99 (SD=+/- 0.91), with intra-class correlation ICC (2,2) 0.90 and SEM 0.12. Conclusion: Hand-held dynamometer has shown excellent inter-rater and intra-rater reliability in measuring isometric strength of Gluteus Medius muscle among healthy population. It is convenient to be used in clinical settings and can be a useful outcome tool to assess strength in interventional studies.