Activities of daily living in healthy persons: Reliability of registrations with 9-DOF sensors.

Abstract

INTRODUCTION: Patients with neurological diseases such as stroke or cerebral palsy often encounter arm-hand problems during daily life. Assessment is important to determine the progress of arm-hand performance in patients during rehabilitation, and to ascertain the effectiveness of therapies. Many instruments are available to assess capacity or perceived performance, but instruments assessing actual performance are scarce. Inertial sensors can be used to assess actual performance. Before these sensors can be used, the reproducibility of execution of activities of daily living, measured with these sensors, should be determined. PURPOSE: Aim has been to assess the reproducibility of activities of daily living performed by healthy individuals, as measured with multiple 9-DOF sensors. METHODS: Thirty-three healthy individuals (mean age: 58.2 ± 5.0) participated. Four 9-DOF sensors, each containing a tri-axial accelerometer, gyroscope and magnetometer were attached to the dominant arm-hand and chest of the participant: on the dorsal hand, on the dorsal wrist, on the humerus and on the sternum. Data were registered during the execution of 5 repetitions of 2 tasks, i.e. ‘drinking from a cup’ and ‘eating with knife and fork’. Tasks were first performed without instructions, and subsequently with instructions on how to perform the task. Signals were filtered with a 2nd order zero-time lag low-pass Butterworth filter (cut off frequency of 2.5 Hz). Intra class correlation coefficients (ICC) for the composed sensors and signal types were determined as a measure for reproducibility, both within and between subjects. RESULTS: Table 1 displays the mean ICC for all conditions. Both within-subject and between-subject reproducibility were high to very high for both tasks. Reproducibility was higher for the condition with instructions compared to without instructions. Reproducibility of the drinking task was higher compared to the eating task. CONCLUSIONS: Larger variability in the execution of the tasks without instructions explains the lower reproducibility compared to tasks with instructions. Within subjects, variability was lower compared to between subjects. The instrument as used in the current setting can be used to assess skilled arm-hand use in healthy individuals. Future research will focus on the investigation of the reproducibility of activities of daily living performed by patients.