Intrarater repeatability of manual testing of first muscle movement resistance

Abstract

First resistance in passive muscle lengthening is very important in both diagnosis and treatment in many muscle disorders. Many therapeutic methods use this muscle length as a point of reference. All of them assume that a therapist is able to feel this moment during manual muscle testing in precise and repeatable way. In this paper assumption regarding repeatability of such test is verified. The study included 34 tests conducted on 17 participants, both men and women, aged 35.6 (±8.5). Every test consisted of three trials on passive ankle dorsiflexion, performed by a single, skilled therapist. Joint angle and estimated length of triceps surae muscle was recorded in realtime measurement using ZEBRIS system and set of four active ultrasound markers. Results of that test shows that standard deviation and range of results between minimal and maximal in each trial for both ankle joint and muscle length were below 1 degree and millimeter respectively. Standard error of this measurement for joint and muscle length were below 0.5 degree and millimeter, respectively. This lead to conclusion that manual testing of first resistance in manual muscle lengthening performed by skilled therapist has a very good repeatability.