Challenges and Opportunities for Harmonizing Research Methodology: Raw Accelerometry.

Objectives: Raw accelerometry is increasingly being used in physical activity research, but diversity in sensor design, attachment and signal processing challenges the comparability of research results. Therefore, efforts are needed to harmonize the methodology. In this article we reflect on how increased methodological harmonization may be achieved.

Associations between multiple accelerometry-assessed physical activity parameters and selected health outcomes in elderly people--results from the KORA-age study.

Introduction: Accelerometry is an important method for extending our knowledge about intensity, duration, frequency and patterns of physical activity needed to promote health. This study has used accelerometry to detect associations between intensity levels and related activity patterns with multimorbidity and disability. Moreover, the proportion of people meeting the physical activity recommendations for older people was assessed.

Exploring patterns of accelerometry-assessed physical activity in elderly people.

Background: Elderly people obtain significant health benefits from physical activity (PA), but the role of activity patterns has scarcely been researched. The present study aims to describe the patterns of PA among different intensities of activity in elderly people. We assess how patterns differ between more and less active groups ('rare', 'average', and 'frequent'), and explore whether and how various PA parameters are associated with functional exercise capacity (FEC).

Recommendations for collecting and processing accelerometry data in elderly people.

Due to the large variety of methods for collecting and analyzing accelerometer data to assess physical activity, it is difficult to compare results from different studies. Therefore, this work aims to provide recommendations for the collection and processing of such data in older people, focusing on the assessment of wearing time and intensity levels.

Does the low power mode of the actigraph GT3X+ accelerometer influence the device output in sleep research in healthy subjects?

We measured lower limb activity by means two, above each ankle vertically aligned GT3X+ accelerometers in 4 healthy adults during a single night. Triaxial raw data vector magnitude units (VMU) were recorded at 100 Hz, in order to compare two different modes of operation (i.e.

Where to wear accelerometers to measure physical activity in people?

13 volunteers walked on a treadmill at 6 different speeds while wearing different accelerometers on different body positions, a spirometry unit and heart rate devices. The goal of this experiment was to find which position on a person's body and which of the sensors is best to measure physical activity (PA) in people by means of an accelerometer.

Detecting periodic limb movements with off-the-shelf accelerometers: a feasibility study.

Periodic limb movements are short movements of the legs that can lead to low sleep quality in the general population. Currently, the gold standard to measure periodic limb movements for diagnostic purposes is polysomnography. This is an expensive technique that requires specially fitted laboratories and specialized personnel.

Physical activity in German adolescents measured by accelerometry and activity diary: introducing a comprehensive approach for data management and preliminary results.

Introduction: Surveillance of physical activity (PA) is increasingly based on accelerometry. However, data management guidelines are lacking. We propose an approach for combining accelerometry and diary based PA information for assessment of PA in adolescents and provide an example of this approach using data from German adolescents.

Separating movement and gravity components in an acceleration signal and implications for the assessment of human daily physical activity.

Introduction: Human body acceleration is often used as an indicator of daily physical activity in epidemiological research. Raw acceleration signals contain three basic components: movement, gravity, and noise. Separation of these becomes increasingly difficult during rotational movements.

Decline in gait performance detected by an electronic walkway system in 907 older adults of the population-based KORA-Age study.

Background: Gait changes at older ages are a strong predictor of a decline in lower extremity functions. However, large population-based studies assessing gait parameters in various gait tasks are lacking.

Objective: We investigated the relationship of age, the use of mobility aids and being fitted with an endoprosthesis with selected gait parameters, assessed in different walking tasks.

Comparison of recording positions of physical activity in patients with severe COPD undergoing LTOT.

Background: Accelerometry is increasingly used to assess physical activity (PA) in patients with chronic obstructive pulmonary disease (COPD). It is not known how the relationship of PA to clinical results depends on the position of the PA sensor.

Methods: We assessed the effect of monitor position by measuring lower extremity (ankle), upper extremity (wrist) and total body movement (hip) in 52 patients with severe COPD (mean [± SD] age, 62 ± 10 years; FEV(1), 38 ± 12% predicted) undergoing long-term oxygen therapy with and without walkers during a pulmonary rehabilitation (PR) program.

Scale-space methods for live processing of sensor data.

A temporal scale-space is a vector space spanned by time and a scale parameter, and by constructing the scale-space correctly a causal structure can be imposed on the scale-space. This enables early warning of significant changes in sensor data at an early time, and on any scale. We describe a feasibility study on how to use these ideas for live surveillance of monitoring processes such that important features can be visualized and users warned about changes an early stage.

Using a robotic arm to assess the variability of motion sensors.

For the assessment of physical activity, motion sensors have become increasingly important. To assure a high accuracy of the generated sensor data, the measurement error of these devices needs to be determined. Sensor variability has been assessed with various types of mechanical shakers.

Extracting gait parameters from raw electronic walkway data.

Spatiotemporal gait parameters are very important for the detection of gait impairments and associated conditions. Current methods to measure such parameters, e.g.