Reliability and validity of electrogoniometry measurement of lower extremity dance movement

Goals. Exposure risk factors (repetitive motions, high forces and velocities, awkward postures) have been identified for work-related musculoskeletal disorders (WMSD) of the neck, upper extremity, and back. However, little research has been conducted to identify lower extremity WMSD risk factors. Dancers represent an occupational group with a high incidence of lower extremity WMSD. This investigation establishes the accuracy, reliability, and concurrent validity of electrogoniometers(s) for measuring occupational lower extremity exposure among dancers.; Method. This project employed two separate experiments. Investigation I determined the accuracy of electrogoniometry measurement compared to a digital protractor. Correction equations were determined to diminish measurement error. Investigation II compared electrogoniometry to a criterion measure, motion analysis, in 10 dance movements in a sample of 17 dancers. Intraclass correlation coefficients (ICC) and standard error of measurement (SEM) were calculated for hip, knee, and ankle angular displacements. Correction equations were applied to the data to ascertain whether SEM and ICC results improved.; Results. In Investigation I, correlations of the electrogoniometers to the digital protractor were very high (r ≥ 0.998, SEM ≤ 3.65°). Application of a 6th order polynomial equation resulted in improved 'fit' (r ≥ 0.999, SEM ≤ 2.55°). In Investigation II, instrument and intra-rater reliability correlations were very high (r ≥ 0.946 and r ≥ 0.947, SEM ≤5.93° and ≤5.42°). The electrogoniometers demonstrated acceptable concurrent validity correlations (r ≥ 0.799) to motion analysis with one exception (grand battement arabesque hip r ≥ 0.616). This exception may be due to sensor crosstalk. SEM for all sensors were ≤ 9.73°. The correction equations did not consistently improve the SEM and ICC results.; Implication. Compared to other types of motion measurement, this error is acceptable for workplace studies of dancers. Peak amplitudes revealed that common dance angular displacements exceed those typically found in activities of daily living, substantiating that dance functional movements require work at joint motion extremes. Validating this instrumentation facilitates future studies to characterize dance exposure and identify risk factors that contribute to lower extremity WMSD.