Myrotonometer intra- and interrater reliabilities

Objectives: To assess the intra- and interrater reliabilities of the Myotonometer(R), a hand-held, computerized, electronic device that quantifies muscle stiffness (tone/compliance). Design: Reliability study. Setting: Research laboratory. Participants: Thirty-five healthy, nondisabled adults (age range, 22-42y). Interventions: Not applicable. Main Outcome Measures: Two raters used the Myotonometer to evaluate subjects' lateral gastrocnemius and biceps brachii muscles. Muscles were measured in a relaxed state and during a voluntary isometric contraction. Coefficients were calculated for each muscle and each condition (relaxed, contracted). Results were analyzed by using Design II intraclass correlation coefficients. Results: Reliability coefficients were highest when the instrument exerted moderate to strong forces against the muscle (range, 0.50-2.00kg; intrarater reliability R range,.84-.99; interrater reliability R range, .75-.96). Conclusions: Myotonometer measurements had high to very high intra- and interrater reliabilities for measurements of the lateral gastrocnemius and biceps brachii muscles. (C) 2003 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.