VALIDITY OF HEART-RATE, PEDOMETRY, AND ACCELEROMETRY FOR PREDICTING THE ENERGY-COST OF CHILDRENS ACTIVITIES

Heart rate telemetry is frequently used to estimate daily activity in children and to validate other methods. This study compared the accura cy of heart rate monitoring, pedometry, triaxial accelerometry, and un iaxial accelerometry for estimating oxygen consumption during typical children's activities. Thirty Welsh children (mean age 9.2 +/- 0.8 yr) walked (4 and 6 km/h) and ran (8 and 10 km/h) on a treadmill, played catch, played hopscotch, and sat and crayoned. Heart rate, body accele rations in three axes, pedometry counts, and oxygen uptake were measur ed continuously during each 4-min activity. Oxygen uptake was expresse d as a ratio of body mass raised to the power of 0.75 [scaled oxygen u ptake (s(V) over dot O-2)]. All measures correlated significantly (P < 0.001) with s(V) over dot O-2. A multiple-regression equation that in cluded triaxial accelerometry counts and heart rate predicted s(V) ove r dot O-2 better than any measure alone (R-2 = 0.85, standard error of the estimate = 9.7 ml.kg(-0.75).min(-1)). The best of the single meas ures was triaxial accelerometry (R-2 = 0.83, standard error of the est imate = 10.3 ml.kg(-0.75).min(-1)). It is concluded that a triaxial ac celerometer provides the best assessment of activity. Pedometry offers potential for large population studies.