Estimating energy expenditure by heart-rate monitoring without individual calibration
Heart rate monitoring has been shown to be a valid method for measuring free-living energy expenditure at the group level, but its use in large-scale studies is limited by the need for an individual calibration of the relationship between heart rate and energy expenditure. Purpose: To determine whether energy expenditure can be estimated from heart rate monitoring without individual calibration in epidemiological studies. Methods: Our previously validated heart rate monitoring method relies on measuring individual calibration parameters obtained from resting energy expenditure and the regression line between energy expenditure and heart rate during exercise. We developed prediction equations for these parameters using easily measured variables in a population-based study of 789 individuals. The predictive ability of these parameters was tested in a separate population-based sample (N = 97). Results: Physical activity level (PAL = total energy expenditure/basal metabolic rate) using the four estimated parameters was correlated with PAL using the measured parameters (r = 0.82, P < 0.01). Comparison of measured and estimated PAL showed that 97.9% of the scores were placed in the same or adjacent quartile. Conclusion: A combination of simple measurements and heart rate monitoring produces estimates of energy expenditure that are highly correlated with those obtained using full individual calibration. This simplification of the heart rate monitoring method could extend its use in ranking individuals in epidemiological studies.