Myotonometer intra- and interrater reliabilities

Objectives: To assess the intra- and interrater reliabilities of the Myotonometer®, 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. © 2003 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.