Document Detail


Biomechanical examination of the 'plateau phenomenon' in ActiGraph vertical activity counts.
MedLine Citation:
PMID:  22260902     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
This paper determines if the leveling off ('plateau/inverted-U' phenomenon) of vertical ActiGraph activity counts during running at higher speeds is attributable to the monitor's signal filtering and acceleration detection characteristics. Ten endurance-trained male participants (mean (SD) age = 28.2 (4.7) years) walked at 3, 5 and 7 km h(-1), and ran at 8, 10, 12, 14, 16, 18 and 20 km h(-1) on a force treadmill while wearing an ActiGraph GT3X monitor at the waist. Triaxial accelerations of the body's center of mass (CoM) and frequency content of these accelerations were computed from the force treadmill data. GT3X vertical activity counts demonstrated the expected 'plateau/inverted-U' phenomenon. In contrast, vertical CoM accelerations increased with increasing speed (1.32 ± 0.26 g at 10 km h(-1) and 1.68 ± 0.24 g at 20 km h(-1)). The dominant frequency in the CoM acceleration signals increased with running speed (14.8 ± 3.2 Hz at 10 km h(-1) and 24.8 ± 3.2 Hz at 20 km h(-1)) and lay beyond the ActiGraph band-pass filter (0.25 to 2.5 Hz) limits. In conclusion, CoM acceleration magnitudes during walking and running lie within the ActiGraph monitor's dynamic acceleration detecting capability. Acceleration signals of higher frequencies that are eliminated by the ActiGraph band-pass filter may be necessary to distinguish among exercise intensity at higher running speeds.
Authors:
Dinesh John; Ross Miller; Sarah Kozey-Keadle; Graham Caldwell; Patty Freedson
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-20
Journal Detail:
Title:  Physiological measurement     Volume:  33     ISSN:  1361-6579     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-20     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9306921     Medline TA:  Physiol Meas     Country:  -    
Other Details:
Languages:  ENG     Pagination:  219-230     Citation Subset:  -    
Affiliation:
Department of Kinesiology, University of Massachusetts, 30 Eastman Lane, Amherst, MA 01003, USA.
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