A NOVEL ENERGY EXPENDITURE EQUATION FOR INTERMITTENT ACTIVITY, BASED ON HEART RATE (HR), RECOVERY HR AND MOTION COUNTS

Abstract

On the basis of the linear relationship between heart rate (HR) and oxygen consumption (VO2), it is possible to predict activity energy expenditure (EE) from HR, alone or in combination with accelerometry. To our knowledge, the impact of intermittent activity, and HR from previous workload or recovery periods, has not yet been studied in the estimation of EE. PURPOSE: This study was designed i) to characterise relative contributions of current and preceding HR and motion counts in the prediction of activity EE; and ii) to model these and other determinants using linear regression analysis. METHODS: 75 subjects (52 men, 23 women, 35 ± 9 yrs, BMI, 23.7 ± 2.5 kg/m2) were tested. On visit 1, body composition and maximum VO2 (using multi-stage treadmill test) were measured. On visit 2, subjects completed 12 four-minute workloads, separated by 4 one-minute rest periods. HR, triaxial motion counts and VO2 were continously monitored. RESULTS: The following parameters contributed significantly to the estimation of EE during intermittent activity: age, gender, VO2 max max HR, HR, motion counts (P < 0.0001), and preceding HR (P < 0.02). The final regression equation yielded an adjusted R2 of 0.84, with a standard error of the estimate of 6.4 kJ/min. Preceding HR contributed > than 3% to total variance, and attenuated the slope of the relationship between HR and EE. CONCLUSION: HR and motion counts may be used to successfully predict EE during intermittent activity. Including maximal HR data and HR during the preceding workload or recovery periods may provide additional accuracy for EE prediction. Supported by Winning Wellness BODYiQ