Free-living energy expenditure of adult men assessed by continuous heart-rate monitoring and doubly-labelled water

Abstract

Free-living energy expenditure was estimated by doubly-labelled water (DLW) and continuous heart-rate (HR) monitoring over nine consecutive days in nine healthy men with sedentary occupations but different levels of leisure-time physical activity. Individual calibrations of the HRenergy expenditure (EE) relationship were obtained for each subject using 30 min average values of HR and EE obtained during 24 h whole-body calorimetry with a defined exercise protocol, and additional data points for individual leisure activities measured with an Oxylog portable O2 consumption meter. The HR data were processed to remove spurious values and insert missing data before the calculation of EE from second-order polynomial equations relating EE to HR. After data processing, the HR-derived EE for this group of subjects was on average 0.8 (SEM 0.6) MJ/d, or 6.0 (SEM 4.2) 'YO higher than that estimated by DLW. The diary-respirometer method, used over the same 9 d, gave values which were 1.9 (SEM 0.7) MJ/d, or -12.1 (SEM 4.0) 'YO lower than the DLW method. The results suggest that HR monitoring can provide a better estimate of 24 h EE of groups than the diary-respirometer method, but show that both methods can introduce errors of 20 'YO or more in individuals.Energy expenditure: Doubly-labelled water: Heart-rate monitoringThe possibility that heart-rate (HR) monitoring may provide an alternative to whole-body calorimetry or doubly-labelled water (DLW) as a measure of 24 h energy expenditure (EE) is an attractive one due to the low cost of the HR monitors and the acceptability of HR monitoring for a wide range of subjects. The development of monitors which store minuteby-minute HR data for periods of 24 h or more has renewed interest in the method as it is now possible to estimate EE on a minute-by-minute basis rather than deriving a single value based on a mean daily HR. However, initial hopes that the relationship between HR and EE could be established for groups of subjects have not been realized, and the need for individual calibration of HR-EE relationships has been clearly established (Bradfield et al. 1970;Kalkwarf et al. 1989;Li et al. 1993). This requirement increased the complexity of the method, although the cost remains much less than that of DLW. Investigators differ in the mathematical model used to predict EE from HR, although it is generally agreed that an approach which takes account of the difference in the gradient of the relationship between HR and EE at low-and high-intensity activity is needed.

Total daily energy expenditure and pattern of physical activity measured by minute-by-minute heart rate monitoring in 14–15 year old Swedish adolescents

“…HR was recorded on an average of 1 min intervals from the ®rst waking hour until removal close to (Davidson et al, 1997).…”

Validation of energy intake estimated from a food frequency questionnaire: a doubly labelled water study

“…Although there is no reason to believe that there would be any significant bias in the DLW-derived group mean energy expenditure (Haggarty et al, 1994a, b), the technique is not perfect. Some of the within-individual disagreement when comparing the two methodologies can be ascribed to the expected variability in DLW derived energy expenditure (Davidson et al, 1997).…”

Energy balance and obesity: a UK perspective on the gluttonyv.sloth debate

“…In contrast, the women who were also lean (BMI 20·2 kg/m 2 ), walked half the distance of the men (5·8 km/d), with lower PAL (1·78; range 1·44-2·53). Also studies of lean UK subjects with high levels of leisure physical activity have been shown to have PAL values that are consistent with their activity (74) . For this group of healthy lean men (BMI 21·6 (SD 1·5) kg/m 2 , age 38 (SD 9) years), with sedentary jobs but most of whom (seven out of nine) reported active leisure activities, the active men exhibited high PAL (mean 2·12; range 1·79-2·41) and for competitive runners in training, mean PAL was 2·2 (range 2·02-2·41).…”

“…2 (51) , of the studies showing study mean PAL values $2·0 (n 15; six women and nine men), three were from low or moderate developed societies, seven were overweight or obese, all were aged less than 65 years and most studies were very small (median n 8). However, as indicated above, PAL values in excess of 2·0 were recorded in DLW studies of lean adult subjects in which either sedentary jobs were accompanied by high leisure activities (74) , or who exhibited high activity lifestyles (African (71) or South American farmers (72) ) or African hunter -gatherer men (73) for whom walking long distances was recorded. Thus a population PAL for the UK in 1955 considerably higher than currently assumed values is certainly possible.…”