Inter- and intra-rater reliability of a technique for assessing the length of the Latissimus Dorsi muscle

Abstract

Introduction The length of a muscle has been described as one of the factors contributing to the ideal movement at a joint. A decrease in the length of a muscle results in a decrease in the range of motion at the joint in direct relation to the function of that specific muscle. M Latissimus Dorsi is a muscle which undergoes length changes (loss of extensibility) and this muscle has a functional role in many aspects of sport and rehabilitation. The loss of extensibility may result in a decreased range of motion at the glenohumeral joint leading to dysfunction. Evidence-based practise requires the use of objective, valid and reliable tests for measuring the length of a muscle. No scientific evidence of reliability for any documented technique testing the length of m Latissimus Dorsi (LD) was found. Aim The aim of this study was to assess the inter-rater and intra-rater reliability of a technique adapted by Commerford and Mottram (2012) for assessing the length of LD. Study design The design of the study is a within-participant test-retest non-experimental quantitative study for reliability purposes Method Fifty-six volunteering students recruited from the Physiotherapy Department of the University of Pretoria were the participants in this study. Four qualified physiotherapists with varying numbers of years of clinical experience independently performed the test for assessing the length of LD. The test was performed twice by each physiotherapist on every participant and two measurement sessions were done. A pilot study was also done. Data Analysis and conclusion A sample of 56 participants provided an intraclass correlation coefficient (ICC) of less than 0.9 and this is regarded as poor reliability. The agreement between each rater and the differences in the two levels of experience of raters were also assessed. The ICC was used to determine the inter-rater and intra-rater reliability of the LD length test. A 0.05 level of significance was employed. The ICC between the experienced raters was found to be 0.48 with a novice rater ICC of 0.48 as well. The ICC between all the raters was 0.33. This constitutes poor reliability. The poor reliability of the technique testing the length of LD was identified and addressed in order for adequate usage thereof, in research and in practice. Recommendations of a new technique to test the length of LD was provided by the researcher. A suggestion was made regarding a manner of testing its reliability.