The feasibility of measuring joint angular velocity with a gyro-sensor

Objectives: To determine the reliability of an assessment of joint angular velocity using a gyro-sensor and to examine the relationship between ankle angular velocity and physical functions. Design: Cross-sectional. Setting: Kinesiology laboratory. Participants: Twenty healthy young adults (mean age, 22.5y) and 113 community-dwelling older adults (mean age, 75. 1 y). Interventions: Not applicable. Main Outcome Measures: Maximal ankle joint velocity was measured using a gyro-sensor during heel-rising and jumping with knee extended. The intraclass correlation coefficient (ICC) was used to determine the intertester and intratester reliability. The Pearson correlation coefficient was used to examine the relationships between maximal ankle joint velocity and isometric muscle strength and isokinetic muscle power in young adults and also to examine the relationships between maximal ankle joint velocity and functional performance measurements such as walking time in older adults. Results: High reliability was found for intertester (ICC=.96) and intratester reliability (ICC=.96). The data from the gyro-sensor highly correlated with muscle strength (r range, .62-.68; P<.01) and muscle power (r range, .45-.79; P range, .01 -.05). In older subjects, mobility functions significantly correlated with the angular velocity of ankle plantarflexion. Conclusions: Measurement of ankle angular velocity using a gyro-sensor is both reliable and feasible, with the results representing a significant correlation to muscle power and performance measurements.