Heart rate as a predictor of energy expenditure in people with spinal cord injury

This study evaluated the accuracy of heart rate calibrated from a maximum exercise test for predicting energy expenditure during five activities of daily living (ADL) in participants with spinal cord injury (SCI). Thirteen individuals with SCI underwent maximum exercise testing, followed by portable heart rate and metabolic testing during five ADL. A regression equation was developed from heart rate and oxygen uptake responses during the maximum exercise test for each subject. Based on this individualized equation, heart rate measured during the ADL was used to estimate energy expenditure for each participant. Predicted energy expenditure from heart rate was compared with that measured by indirect calorimetry with the use of oxygen uptake. Heart rate derived from the individualized regression equations explained 55% of the variance in measured energy expenditure, compared with only 8.3% from heart rate alone. However, calibrated heart rate consistently overestimated the actual kilocalories used; on average, the estimated energy expenditure was roughly 25% higher than that measured by oxygen uptake. Heart rate can be used as a gross estimate of energy expenditure during higher-intensity ADL in people with SCI when individual calibration of heart rate from maximum exercise testing is used.