Approaches to estimating physical activity in the community: calorimetric validation of actometers and heart rate monitoring

The relationship between actometer measurements, heart rate monitoring and energy expenditure during exercise and resting periods was assessed in a whole-body indirect calorimeter on 12 young male volunteers. Equations derived from these studies were applied to actometer measurements taken during a further 7 d recording in free-living conditions to predict daily energy expenditure over 1 week on an individual basis. Actometers proved to be a satisfactory means of estimating energy expenditure and heart rate monitoring improved the estimates in a few selected subjects. Indirect measures of energy expenditure could be developed by this approach but individual calibration is essential