title: Associations between sensor-based physical activity behaviour features and health-related parameters.
abstract: OBJECTIVE
  Wearable actimetry devices are used increasingly in cohort and cross-sectional studies to assess physical activity (PA) behaviour objectively. Thus far, the medical relevance of distinct PA groups, as identified by using new methods of sensor data analysis, remains unclear. The objective of this research paper is to evaluate whether such PA groups differ in commonly accepted health risk parameters.
  
  
  METHODS
  PA sensor data and corresponding outcome data of the NHANES 2005-06 study were obtained. Data pre-processing included elimination of potential outliers, data splitting and the computation of PA parameters, including a novel regularity measure. PA groups were identified using the x-Means clustering algorithm, and groups were evaluated for differences in CRP, BMI and HDL.
  
  
  RESULTS
  Data sets of 7334 NHANES participants were analysed, and four distinct PA groups were identified. Statistically significant group differences were found for CRP and BMI (p<0.001), but not for HDL (p=0.67).
  
  
  CONCLUSIONS
  PA groups derived from objective accelerometer mass data differ in exemplary health-related outcome parameters. The novel PA regularity measure is of particular interest and may become part of future PA assessments, especially when regarding low-intensity, short-lived PA events. Further research in pattern recognition methods and analytic algorithms for PA data from current multi-sensing devices is necessary.
authors.affiliation: Hanover Medical School, Peter L. Reichertz Institute for Medical Informatics, Carl-Neuberg-Str. 1, Hanover 30625, Germany. Electronic address: Michael.Marschollek@plri.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Marschollek
mesh_terms: D061725:Accelerometry; D000328:Adult; D000465:Algorithms; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism; D008076:Cholesterol, HDL / Q000097:blood; D016000:Cluster Analysis; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D015438:Health Behavior; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D009043:Motor Activity; D009749:Nutrition Surveys
chemical_list: D008076:Cholesterol, HDL; D002097:C-Reactive Protein
keywords: Accelerometry; Cohort studies; Pattern recognition; Physical activity