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, 22-42 y).

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, 0.50-2.00 kg; 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.