June 5, 2010Open Access
View Full PaperAccuracy and validity of a combined heart rate and motion sensor for the measurement of free-living physical activity energy expenditure in adults in Cameroon
Key Result
A combined heart rate and motion sensor validly estimated physical activity energy expenditure compared to doubly-labelled water, showing a non-significant mean bias of -5.4 kJ/kg/day (P=0.3).
Study Design
Type
Observational (n=33)
Multicenter
Yes
Structured PICO
Does a combined heart rate and motion sensor accurately estimate physical activity energy expenditure compared to doubly-labelled water in free-living adults?
P
Population
33 free-living rural and urban adults in Cameroon
I
Intervention
Combined heart rate and motion sensor (recording HR and uni-axial acceleration) with individual HR vs PAEE calibration via step test
C
Comparator
Doubly-labelled water (DLW) over 7 consecutive days
O
Outcome
Validity and accuracy of physical activity energy expenditure (PAEE) prediction (expressed as mean bias and root mean square error)surrogate
A combined heart rate and motion sensor is a valid method for estimating free-living physical activity energy expenditure at the group level in sub-Saharan African adults.
Main Result
p-value: p=0.3
Abstract
BACKGROUND: The increasing burden of non-communicable diseases in sub-Saharan Africa (SSA) warrants rigorous studies of contributing lifestyle factors. Combined heart rate (HR) and movement monitoring make it possible to objectively measure physical activity in free-living individuals. We examined the validity of a combined HR and motion sensor in estimating physical activity energy expenditure (PAEE) in free-living adults in rural and urban Cameroon compared with doubly-labelled water (DLW) as criterion. METHODS: PAEE was measured in 33 free-living rural and urban dwellers by DLW over 7 consecutive days. Simultaneously, the combined sensor recorded HR and uni-axial acceleration. Individual HR vs PAEE calibration was done by a step test. Branched equation modelling was used to estimate PAEE from HR and acceleration. Validity and accuracy of prediction were expressed as mean bias and root mean square error (RMSE). Agreement was analysed using Bland and Altman limits of agreement (LOA). RESULTS: There was no significant mean bias between PAEE estimated from the combined sensor or measured by DLW mean bias (standard error): -5.4 (5.1) kJ/kg/day; P = 0.3; RMSE = 29.3 kJ/kg/day. The bias doubled for group compared with individual calibration of HR -9.1 (5.0) kJ/kg/day, P = 0.08. PAEE prediction was more accurate in urban compared with rural volunteers. The 95% LOAs between predicted and measured PAEE were ∼50-60 kJ/kg/day above or below perfect agreement. CONCLUSIONS: Combined HR and movement sensing is a valid method for estimating free-living PAEE on group level in adults in SSA.