Cross-validation of waist-worn GENEA accelerometer cut-points.
OBJECTIVE
The purpose of this study was to determine the classification accuracy of the waist gravity estimator of normal everyday activity (GENEA) cut-points developed by Esliger et al. for predicting intensity categories across a range of lifestyle activities.


METHODS
Each participant performed one of two routines, consisting of seven lifestyle activities (home/office, ambulatory, and sport). The GENEA was worn on the right waist, and oxygen uptake was continuously measured using the Oxycon mobile. A one-way chi-squared test was used to determine the classification accuracy of the GENEA cut-points. Cross-tabulation tables provided information on under- and overestimations, and sensitivity and specificity analyses of the waist cut-points were also performed.


RESULTS
Spearman rank order correlation for the GENEA gravity-subtracted signal vector magnitude and Oxycon mobile MET values was 0.73. For all activities combined, the GENEA accurately predicted intensity classification 55.3% of the time, and it increased to 58.3% when stationary cycling was removed from the analysis. The sensitivity of the cut-points for the four intensity categories ranged from 0.244 to 0.958, and the specificity ranged from 0.576 to 0.943.


CONCLUSIONS
In this cross-validation study, the proposed GENEA cut-points had a low overall accuracy rate for classifying intensity (55.3%) when engaging in 14 different lifestyle activities.
1Department of Kinesiology, Recreation, and Sport Studies, University of Tennessee, Knoxville, TN; 2Department of Kinesiology, University of Massachusetts, Amherst, MA; and 3Department of Health Sciences, Northeastern University, Boston, MA.
Whitney A
WA
Welch
David R
DR
Bassett
Patty S
PS
Freedson
Dinesh
D
John
Jeremy A
JA
Steeves
Scott A
SA
Conger
Tyrone G
TG
Ceaser
Cheryl A
CA
Howe
Jeffer E
JE
Sasaki
D061725:Accelerometry / Q000295:instrumentation* / Q000379:methods; D000203:Activities of Daily Living; D000328:Adult; D001490:Basketball / Q000502:physiology; D001642:Bicycling / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D010101:Oxygen Consumption; D005082:Physical Exertion; D011237:Predictive Value of Tests; D013177:Sports / Q000502:physiology*; D013715:Tennis / Q000502:physiology; D016138:Walking / Q000502:physiology; D014953:Wrist