University of Oulu

Farrahi, V., Niemelä, M., Kangas, M., Korpelainen, R., Jämsä, T. (2019) Calibration and validation of accelerometer-based activity monitors: A systematic review of machine-learning approaches. Gait and Posture, 68, 285-299. doi:10.1016/j.gaitpost.2018.12.003

Calibration and validation of accelerometer-based activity monitors : a systematic review of machine-learning approaches

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Author: Farrahi, Vahid1; Niemelä, Maisa1,2,3; Kangas, Maarit1,3;
Organizations: 1Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
2Infotech, University of Oulu, Oulu, Finland
3Medical Research Center, Oulu University Hospital and University of Oulu, Oulu, Finland
4Center for Life Course Health Research, University of Oulu, Oulu, Finland
5Oulu Deaconess Institute, Department of Sports and Exercise Medicine, Finland
6Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.4 MB)
Persistent link:
Language: English
Published: Elsevier, 2019
Publish Date: 2019-04-09


Background: Objective measures using accelerometer-based activity monitors have been extensively used in physical activity (PA) and sedentary behavior (SB) research. To measure PA and SB precisely, the field is shifting towards machine learning-based (ML) approaches for calibration and validation of accelerometer-based activity monitors. Nevertheless, various parameters regarding the use and development of ML-based models, including data type (raw acceleration data versus activity counts), sampling frequency, window size, input features, ML technique, accelerometer placement, and free-living settings, affect the predictive ability of ML-based models. The effects of these parameters on ML-based models have remained elusive, and will be systematically reviewed here. The open challenges were identified and recommendations are made for future studies and directions.

Method: We conducted a systematic search of PubMed and Scopus databases to identify studies published before July 2017 that used ML-based techniques for calibration and validation of accelerometer-based activity monitors. Additional articles were manually identified from references in the identified articles. Results: A total of 62 studies were eligible to be included in the review, comprising 48 studies that calibrated and validated ML-based models for predicting the type and intensity of activities, and 22 studies for predicting activity energy expenditure.

Conclusions: It appears that various ML-based techniques together with raw acceleration data sampled at 20–30 Hz provide the opportunity of predicting the type and intensity of activities, as well as activity energy expenditure with comparable overall predictive accuracies regardless of accelerometer placement. However, the high predictive accuracy of laboratory-calibrated models is not reproducible in free-living settings, due to transitive and unseen activities together with differences in acceleration signals.

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Series: Gait & posture
ISSN: 0966-6362
ISSN-E: 1879-2219
ISSN-L: 0966-6362
Volume: 68
Pages: 285 - 299
DOI: 10.1016/j.gaitpost.2018.12.003
Type of Publication: A2 Review article in a scientific journal
Field of Science: 3141 Health care science
217 Medical engineering
Funding: This work has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 713645, the Ministry of Education and Culture in Finland [grant numbers OKM/86/626/2014, OKM/43/626/2015, OKM/17/626/2016], Infotech Oulu, Finland, and Northern Ostrobothnia Hospital District.
EU Grant Number: (713645) BioMEP - Biomedical Engineering and Medical Physics
Copyright information: © 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (