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Measuring physical activity in obese populations using accelerometry

Gerrard-Longworth, SP 2015, Measuring physical activity in obese populations using accelerometry , PhD thesis, University of Salford.

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The thesis is concerned with objectively measuring human physical activity through accelerometry, and compares the effectiveness of algorithms between obese and non-obese groups. The thesis comprises three studies: Classification of Aerobic and Gym-based Exercises from Accelerometer Output. This study investigated whether accurate classification could be achieved from hip- or ankle-mounted accelerometers for a programme of aerobic exercises and free-living activities. It also examined whether accuracy was affected by obesity, and whether a single classifier could be applied across BMI groups. The study achieved high classification accuracies (85% for hip and 94% for ankle) for both obese and normal BMI groups using the same approach across groups. Walking Speed Estimation Using Accelerometry. This study aimed to develop a speed estimation model that was applicable across BMI groups, and which utilised a hip-mounted accelerometer. To achieve this, multiple accelerometer signal features were evaluated for use in a linear speed estimation model, and performance was compared between obese and normal BMI groups. The speed estimation algorithm achieved overall RMSE of 0.08ms-1 for a mixed BMI group, which is comparable with previous research using homogeneous groups. Prediction of Energy Expenditure from Accelerometer Output. This study aimed to identify physiological and anthropometric parameters for use in an improved energy expenditure estimation model. Model performance was tested on a mixed BMI group. The energy expenditure prediction model incorporating subject attributes showed around 20% improvement over the standard model. This research found that current approaches to activity classification using accelerometry are equally applicable to obese groups and normal BMI groups. Walking speed prediction was shown to be possible from a hip-mounted accelerometer for both obese and normal BMI groups. Energy expenditure estimation is improved by including subject-specific parameters in the prediction model. Accelerometry is, therefore, a suitable tool for measuring different aspects of physical activity for obese and mixed BMI groups.

Item Type: Thesis (PhD)
Contributors: Preece, SJ (Supervisor)
Schools: Schools > School of Health Sciences
Funders: SSHOES (part funded)
Depositing User: SP Gerrard-Longworth
Date Deposited: 27 Jul 2015 15:01
Last Modified: 05 Apr 2016 18:21

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