Variability in measuring physical activity in children with cerebral palsy

Mitchell, Louise E., Ziviani, Jenny and Boyd, Roslyn N. (2015) Variability in measuring physical activity in children with cerebral palsy. Medicine and Science in Sports and Exercise, 47 1: 194-200. doi:10.1249/MSS.0000000000000374

Author Mitchell, Louise E.
Ziviani, Jenny
Boyd, Roslyn N.
Title Variability in measuring physical activity in children with cerebral palsy
Journal name Medicine and Science in Sports and Exercise   Check publisher's open access policy
ISSN 0195-9131
Publication date 2015-01
Year available 2014
Sub-type Article (original research)
DOI 10.1249/MSS.0000000000000374
Open Access Status
Volume 47
Issue 1
Start page 194
End page 200
Total pages 7
Place of publication Philadelphia PA, United States
Publisher Lippincott Williams & Wilkins
Collection year 2015
Language eng
Formatted abstract
Introduction: This study aimed to establish the variability in the measurement of habitual physical activity using the ActiGraph® GT3X+ accelerometer in children with cerebral palsy (CP).

Method: Repeated measures: Independently ambulant children with unilateral CP (n = 30; age, 11 yr 3 months (2 yr 4 months)) completed standardized tasks over two consecutive days, wearing an ActiGraph® GT3X+ accelerometer and HR monitor. Testing protocol comprised 5 min of seated rest (REST), walking at light, moderate, and vigorous pace, and rapid stepping on/off a step. Agreement was calculated between days using intraclass correlation coefficients (ICC) (two-factor mixed agreement model). Minimum detectable difference was calculated (minimum detectable difference = [SD[square root]1 - ICC] × 1.96[square root]2). Performance variability: Participants (n = 102) wore an ActiGraph® GT3X+ accelerometer for 4 d in the community. Activity counts were converted into activity intensity using uniaxial-derived cut points to classify the time spent in moderate-to-vigorous physical activity (MVPA). Between-day intraclass reliability coefficients (R) and Spearman–Brown prophecy formula ([ICCdesired/(1 - ICCdesired)][(1 - ICCestimated)]/ICCestimated]) were calculated.

Results: Agreement between repeated measures was strong for light physical activity and MVPA (ICC, 0.80). For MVPA, the minimum detectable difference was 1412 counts per minute. In the community, 345 d (87%) were recorded. Three days of monitoring produced acceptable variability estimates of MVPA (R = 0.63–0.73). Spearman–Brown prophecy analysis estimated that 3 d would achieve a reliability coefficient of 0.7 and 11 d would achieve 0.9.

Conclusions: Measurement of habitual physical activity using the ActiGraph® GT3X+ accelerometer is reliable under controlled walking and stepping conditions as well as in a community environment in independently ambulant children and adolescents with CP.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online ahead of print April 2014

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Health and Rehabilitation Sciences Publications
School of Medicine Publications
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