VALIDITY OF THE COMPUTER-SCIENCE AND APPLICATIONS, INC (CSA) ACTIVITYMONITOR

The validity of the Computer Science and Applications, Inc. (CSA) acce lerometer in assessing physical activity was assessed during treadmill walking and running at three different grades. Energy expenditure (EE ) served as the criterion measure. CSA data were compared to data coll ected with the Caltrac accelerometer. Both accelerometers were sensiti ve to changes in treadmill speed, but neither discriminated changes in treadmill grade. Caltrac and CSA activity counts were significantly a nd similarly correlated with EE (r = 0.66-0.82), relative VO2 (r = 0.7 7-0.89), heart rate (r = 0.66-0.80), treadmill speed (r = 0.82-0.92), and with each other (r = 0.77-0.82). CSA data were used to develop mod els to predict EE (kcal . min(-1)). Cross-validation resulted in a mea n difference between actual and predicted EE of 0.02 kcal . min(-1) (S EE = 0.85 kcal . min(-1)). The range of individual differences in the validation group was large for both the CSA model (-2.86 to +3.86 kcal . min(-1)) and Caltrac (-4.17 to +2.04 kcal . min(-1)). It is conclud ed that the CSA and Caltrac accelerometers have similar validity and t hat either instrument can be used to estimate EE of groups.