The effect of epoch and cut-point on the assessment of physical activity levels in Kenyan school children

RC Internal medicine

Budd, Hannah ; Pitsiladis, Yannis

University:University of Glasgow

Department:Institute of Neuroscience and Psychology

关键词: Accelerometry, Kenya, MVPA, objective assessment;   

Others  :  http://theses.gla.ac.uk/1244/1/2009BuddMSc.pdf

来源: University of Glasgow

【 摘 要 】

The aim of this study was to investigate the effect of using different accelerometer cut-points and epoch on reports of sedentary behavior and physical activity (PA) levels in a group of Kenyan school children. The PA levels of 26 children from the Nandi region of Kenya aged 4-16 years, was assessed for 3 consecutive days using uniaxial accelerometry combined with a PA diary. No significant differences were found in counts per minute (CPM) (753±214, 753±212, 724±220, 723±229, 721±220, 733±212 CPM; P>0.05) or total monitoring time (689±109, 693±110, 693±108, 693±109, 695±108, 693±110 min; P=1.00) across all six epochs.Time spent engaging in sedentary behavior was not effected by epoch or cut-point (Sirard cut-point, 590±87, 592±87, 594±88, 596±89, 598±90, 598±94 min; Reilly cut-point, 573±86, 567±87, 554±85, 554±88, 550±86, 547± 89min; P>0.05), while the amount of light (Sirard cut-point, 38±11, 43±12, 76±22, 79±23, 81±24, 81±23 min; Puyau, 70±20, 87±27, 104±35, 111±38, 120±34, 123±42 min; Pate, 596±87, 595±87, 595±87, 597±88, 601±90, 604±94 min; P<0.05) and moderate-to-vigorous physical activity (MVPA) (Sirard, 73±25, 71±26, 37±23, 35±24, 32±24, 28±24; Puyau, 59±22, 52±23, 45±24, 41±25, 38±26, 36±28; Pate, 108±29, 107±40, 110±31, 109±32, 106±33, 102±34 min; P<0.05) were influenced by choice of cut-points and epoch. Shorter epochs, such as 1 and 5 s, resulted in significantly less reported minutes of light PA (Sirard, 1 s 38±11 and 5 s 43±12 min vs. 76±22, 79±23, 81±24 and 81±23 min; Puyau, 1 s 70±20 and 5 s 87±27 vs. 104±35, 111±38, 120±43 and 123±42 min; P<0.05) and significantly more minutes of moderate and vigorous activity (Sirard 1 s 73±25 and 5 s 71±26 vs. 37±23, 35±24, 32±24 and 28±24 min; Puyau 1 s 59±22 vs. 60 s 36±28 min P<0.05). Lower cut-points led to significantly more minutes of light, moderate and vigorous PA compared to higher cut-points (see above; P<0.05). In conclusion, choice of cut-points and epoch significantly influences PA classification, where it may be more appropriate to use smaller epochs when assessing PA levels of active children. Additionally, one should be wary when comparing PA calculated using different cut-point values.