Development of the CUELA Activity Measurement System for the measurement of physical activity

Status:

completed 12/2010

Aims:

Labour-saving devices and the widespread use of computers have led to a great many workplaces being associated with low levels of physical activity. Since physical inactivity and static body postures are accompanied by serious health risks, many companies are taking measures to promote physical activity. In order for physical activity at the workplace to be quantified and for the efficacy of measures taken at the workplace to be evaluated, the CUELA Activity System was developed for long-term analysis of movement behaviour.

Activities/Methods:

The CUELA Activity System was developed by modification of the original CUELA measurement system. Miniaturized movement sensors which record the physical activity were fabricated for this purpose. An adapter box was required through which the sensors can be connected to a standard CUELA data logger for recording of the movement data. In order to permit reactionless measurements over the long term, an arrangement had to be developed by which the sensors could be worn under normal clothing, comfortably, and without slipping. The existing analysis software was also adapted and developed further.

Results:

The CUELA Activity System uses a total of seven sensor units to measure the test subject's movement behaviour. Each unit comprises acceleration and gyroscopic sensors. The sensors are attached by means of elastic and breathable strips to the back, both legs and the dominant arm under the subject's normal clothing.
Body angles are first determined from the acceleration and gyroscope data, and serve as the basis for the data analysis. The software uses pattern recognition algorithms to detect body postures and tasks (such as sitting, standing, lying, kneeling, squatting, walking at different speeds, ascending and descending stairs) automatically. The energy expenditure is estimated from the nature of the activity, the intensity of movement and the personal data recorded beforehand (sex, age, body-mass index (BMI), heart rate at rest, activity level reported by the subject). Statistics are also generated automatically on the nature, intensity, duration and frequency of physical activity and body postures. Development and validation of the associated model for determining the energy expenditure was the subject of IFA Project 4167, "Calibration and validation of energy expenditure measurement by means of the CUELA Activity Measurement System".
The CUELA Activity System has already been used in a pilot study, for analysis of the effectiveness of measures intended to promote physical activity at workplaces associated with a low level of movement (see IFA Project 4180, "Intervention in physical inactivity").

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