Synthetic Data Guided Feature Selection for Robust Activity Recognition in Older Adults

TL;DR

This study develops a robust activity recognition system for older adults using synthetic data to improve generalization and accuracy in detecting daily activities during rehabilitation.

Contribution

It introduces a synthetic data guided feature selection method that enhances activity recognition robustness specifically for older adults in clinical rehabilitation settings.

Findings

Achieved high F1-scores for activity detection, e.g., 0.896 for walking and 0.927 for standing.

Synthetic data improved model generalization across different participants.

Significantly enhanced detection of postural transfers, a critical activity in clinical monitoring.

Abstract

Physical activity during hip fracture rehabilitation is essential for mitigating long-term functional decline in geriatric patients. However, it is rarely quantified in clinical practice. Existing continuous monitoring systems with commercially available wearable activity trackers are typically developed in middle-aged adults and therefore perform unreliably in older adults with slower and more variable gait patterns. This study aimed to develop a robust human activity recognition (HAR) system to improve continuous physical activity recognition in the context of hip fracture rehabilitation. 24 healthy older adults aged over 80 years were included to perform activities of daily living (walking, standing, sitting, lying down, and postural transfers) under simulated free-living conditions for 75 minutes while wearing two accelerometers positioned on the lower back and anterior upper thigh. Model robustness was evaluated using leave-one-subject-out cross-validation. The synthetic data demonstrated potential to improve generalization across participants. The resulting feature intervention model (FIM), aided by synthetic data guidance, achieved reliable activity recognition with mean F1-scores of 0.896 for walking, 0.927 for standing, 0.997 for sitting, 0.937 for lying down, and 0.816 for postural transfers. Compared with a control condition model without synthetic data, the FIM significantly improved the postural transfer detection, i.e., an activity class of high clinical relevance that is often overlooked in existing HAR literature. In conclusion, these preliminary results demonstrate the feasibility of robust activity recognition in older adults. Further validation in hip fracture patient populations is required to assess the clinical utility of the proposed monitoring system.