Otago Exercises Monitoring for Older Adults by a Single IMU and Hierarchical Machine Learning Models

TL;DR

This study develops a hierarchical machine learning system using a single waist-mounted IMU to accurately monitor older adults performing Otago Exercises, achieving high recognition scores for activity detection both in lab and home settings.

Contribution

The paper introduces a novel hierarchical deep learning approach for unobtrusive monitoring of Otago Exercises with a single IMU, improving activity recognition accuracy in real-world scenarios.

Findings

OEP recognition with over 0.95 f1-score in stage 1.

Four activities recognized with over 0.8 f1-score in home setting.

Potential for monitoring exercise compliance and detailed activity analysis.

Abstract

Otago Exercise Program (OEP) is a rehabilitation program for older adults to improve frailty, sarcopenia, and balance. Accurate monitoring of patient involvement in OEP is challenging, as self-reports (diaries) are often unreliable. With the development of wearable sensors, Human Activity Recognition (HAR) systems using wearable sensors have revolutionized healthcare. However, their usage for OEP still shows limited performance. The objective of this study is to build an unobtrusive and accurate system to monitor OEP for older adults. Data was collected from older adults wearing a single waist-mounted Inertial Measurement Unit (IMU). Two datasets were collected, one in a laboratory setting, and one at the homes of the patients. A hierarchical system is proposed with two stages: 1) using a deep learning model to recognize whether the patients are performing OEP or activities of daily life (ADLs) using a 10-minute sliding window; 2) based on stage 1, using a 6-second sliding window to recognize the OEP sub-classes performed. The results showed that in stage 1, OEP could be recognized with window-wise f1-scores over 0.95 and Intersection-over-Union (IoU) f1-scores over 0.85 for both datasets. In stage 2, for the home scenario, four activities could be recognized with f1-scores over 0.8: ankle plantarflexors, abdominal muscles, knee bends, and sit-to-stand. The results showed the potential of monitoring the compliance of OEP using a single IMU in daily life. Also, some OEP sub-classes are possible to be recognized for further analysis.