Heart rate monitoring as a field method for estimating energy expenditure as evaluated by the doubly labeled water method

A systematic literature review of reviews on techniques for physical activity measurement in adults: a DEDIPAC study

The links between increased participation in Physical Activity (PA) and improvements in health are well established. As this body of evidence has grown, so too has the search for measures of PA with high levels of methodological effectiveness (i.e. validity, reliability and responsiveness to change). The aim of this “review of reviews” was to provide a comprehensive overview of the methodological effectiveness of currently employed measures of PA, to aid researchers in their selection of an appropriate tool. A total of 63 review articles were included in this review, and the original articles cited by these reviews were included in order to extract detailed information on methodological effectiveness.

Self-report measures of PA have been most frequently examined for methodological effectiveness, with highly variable findings identified across a broad range of behaviours. The evidence-base for the methodological effectiveness of objective monitors, particularly accelerometers/activity monitors, is increasing, with lower levels of variability observed for validity and reliability when compared to subjective measures. Unfortunately, responsiveness to change across all measures and behaviours remains under-researched, with limited information available.

Other criteria beyond methodological effectiveness often influence tool selection, including cost and feasibility. However, researchers must be aware of the methodological effectiveness of any measure selected for use when examining PA. Although no “perfect” tool for the examination of PA in adults exists, it is suggested that researchers aim to incorporate appropriate objective measures, specific to the behaviours of interests, when examining PA in free-living environments.

Estimation of Free-Living Energy Expenditure by Heart Rate and Movement Sensing: A Doubly-Labelled Water Study

Background

Accurate assessment of energy expenditure (EE) is important for the study of energy balance and metabolic disorders. Combined heart rate (HR) and acceleration (ACC) sensing may increase precision of physical activity EE (PAEE) which is the most variable component of total EE (TEE).

Objective

To evaluate estimates of EE using ACC and HR data with or without individual calibration against doubly-labelled water (DLW) estimates of EE.

Design

23 women and 23 men (22–55 yrs, 48–104 kg, 8–46%body fat) underwent 45-min resting EE (REE) measurement and completed a 20-min treadmill test, an 8-min step test, and a 3-min walk test for individual calibration. ACC and HR were monitored and TEE measured over 14 days using DLW. Diet-induced thermogenesis (DIT) was calculated from food-frequency questionnaire. PAEE (TEE ÷ REE ÷ DIT) and TEE were compared to estimates from ACC and HR using bias, root mean square error (RMSE), and correlation statistics.

Results

Mean(SD) measured PAEE and TEE were 66(25) kJ·day^-1·kg^-1, and 12(2.6) MJ·day^-1, respectively. Estimated PAEE from ACC was 54(15) kJ·day^-1·kg^-1 (p<0.001), with RMSE 24 kJ·day^-1·kg^-1 and correlation r = 0.52. PAEE estimated from HR and ACC+HR with treadmill calibration were 67(42) and 69(25) kJ·day^-1·kg^-1 (bias non-significant), with RMSE 34 and 20 kJ·day^-1·kg^-1 and correlations r = 0.58 and r = 0.67, respectively. Similar results were obtained with step-calibrated and walk-calibrated models, whereas non-calibrated models were less precise (RMSE: 37 and 24 kJ·day^-1·kg^-1, r = 0.40 and r = 0.55). TEE models also had high validity, with biases <5%, and correlations r = 0.71 (ACC), r = 0.66–0.76 (HR), and r = 0.76–0.83 (ACC+HR).

Conclusions

Both accelerometry and heart rate may be used to estimate EE in adult European men and women, with improved precision if combined and if heart rate is individually calibrated.

An evaluation of the IDEEA™ activity monitor for estimating energy expenditure

Objective estimates of activity patterns and energy expenditure (EE) are important for the measurement of energy balance. The Intelligent Device for Energy Expenditure and Activity (IDEEA) can estimate EE from the thirty-five postures and activities it can identify and record. The present study evaluated the IDEEA system's estimation of EE using whole-body indirect calorimetry over 24 h, and in free-living subjects using doubly-labelled water (DLW) over 14 d. EE was calculated from the IDEEA data using calibration values for RMR and EE while sitting and standing, both as estimated by the IDEEA system (IDEEA(est)) and measured by indirect calorimetry (IDEEA(meas)). Subjects were seven females and seven males, mean age 38·1 and 39·7 years, mean BMI 25·2 and 26·2 kg/m2, respectively. The IDEEA(est) method produced a similar estimate of EE to the calorimeter (10·8 and 10·8 MJ, NS), while the IDEEA(meas) method underestimated EE (9·9 MJ, P < 0·001). After removing data from static cycling, which the IDEEA was unable to identify as an activity, both the IDEEA(est) and IDEEA(meas) methods overestimated EE compared to the calorimeter (9·9 MJ, P < 0·001; 9·1 MJ, P < 0·05 and 8·6 MJ, respectively). Similarly, the IDEEA system overestimated EE compared to DLW over 14 d; 12·7 MJ/d (P < 0·01), 11·5 MJ/d (P < 0·01) and 9·5 MJ/d for the IDEEA(est), IDEEA(meas) and DLW, respectively. The IDEEA system overestimated EE both in the controlled laboratory and free-living environments. Using measured EE values for RMR, sitting and standing reduced, but did not eliminate, the error in estimated EE.

Physical activity in an indigenous Ecuadorian forager-horticulturalist population as measured using accelerometry

OBJECTIVE

Minimal information on physical activity is available for non-Western populations undergoing the transition to a market economy. This is unfortunate given the importance of these data for understanding health issues such as the global obesity epidemic. We consider the utility of using accelerometry technology to examine activity patterns and energy use regulation among indigenous Shuar, an Ecuadorian forager-horticulturalist population undergoing economic and lifestyle change. We investigate sex differences in Shuar activity patterns and the effects of reproductive status on activity. Finally, we discuss the potential of accelerometry use in human biology research.

METHODS

Physical activity levels were measured using Actical accelerometers in 49 indigenous Shuar adults (23 males, 26 females) from a rural Ecuadorian community. Female participants were in various reproductive states including pregnant, lactating, and nonpregnant/nonlactating.

RESULTS

Activity counts (AC), activity energy expenditure (AEE), and physical activity levels (PAL) were significantly higher (P < 0.05) in males than females. Significant differences in energy expenditure were found among pregnant or lactating females and males with pregnant or lactating partners (P < 0.001). Males with pregnant or lactating partners also had significantly higher activity levels than did other men (P < 0.01).

CONCLUSIONS

Shuar activity levels are relatively low compared to other non-Western populations. Despite increasing market integration, pregnant and lactating females seem to be adopting a strategy noted in other subsistence populations where male participation in subsistence activities increases to compensate for their partners' elevated reproductive costs. Despite certain limitations, use of accelerometry in human biology research shows promise.

Estimation of total daily energy expenditure and its components by monitoring the heart rate of Japanese endurance athletes

The estimation of total daily energy expenditure (TEE) or the energy needs of athletes is important for maintaining a proper energy balance during training. This study was conducted to measure the TEE of Japanese middle- and long-distance runners using a heart-rate monitoring method (the HR method), and to ascertain the impact of three key energy expenditure (EE) components occurring within the day: sleep, exercise (training) and inactivity (other daily habitual activities). Additionally, energy balance was evaluated by comparing TEE with energy intake (EI). The mean TEE of six male athletes aged 19-21 y was 4,514+/-739 kcal/d and their mean EI was 3,784+/-91 kcal/d during the training period of 11 d. This negative energy balance led to a significant decline in body weight (p<0.01), indicating that proper care should be taken to balance energy during training. The mean daily EEs during sleep, inactivity, and exercise were 536+/-46 (12.0% of TEE), 1,722+/-145 (38.7%), and 2,255+/-658 (49.3%) kcal/d, respectively. There was a significant correlation between TEE and exercise EE (p<0.01) in the athletes. The TEE of the endurance athletes was higher than expected and significantly affected by exercise EE, indicating that the TEE of athletes, in general, must be carefully evaluated before incorporating nutritional support for them.

Measurement of energy expenditure

Measurement of energy expenditure in humans is required to assess metabolic needs, fuel utilisation, and the relative thermic effect of different food, drink, drug and emotional components. Indirect and direct calorimetric and non-calorimetric methods for measuring energy expenditure are reviewed, and their relative value for measurement in the laboratory and field settings is assessed. Where high accuracy is required and sufficient resources are available, an open-circuit indirect calorimeter can be used. Open-circuit indirect calorimeters can employ a mask, hood, canopy or room/chamber for collection of expired air. For short-term measurements, mask, hood or canopy systems suffice. Chamber-based systems are more accurate for the long-term measurement of specified activity patterns but behaviour constraints mean they do not reflect real life. Where resources are limited and/or optimum precision can be sacrificed, flexible total collection systems and non-calorimetric methods are potentially useful if the limitations of these methods are appreciated. The use of the stable isotope technique, doubly labelled water, enables total daily energy expenditure to be measured accurately in free-living subjects. The factorial method for combining activity logs and data on the energy costs of activities can also provide detailed information on free-living subjects.

Regression-based prediction of net energy expenditure in children performing activities at high altitude

We developed a simple, non-invasive, and affordable method for estimating net energy expenditure (EE) in children performing activities at high altitude. A regression-based method predicts net oxygen consumption (VO(2)) from net heart rate (HR) along with several covariates. The method is atypical in that, the "net" measures are taken as the difference between exercise and resting VO(2) (DeltaVO(2)) and the difference between exercise and resting HR (DeltaHR); DeltaVO(2) partially corrects for resting metabolic rate and for posture, and DeltaHR controls for inter-individual variation in physiology and for posture. Twenty children between 8 and 13 years of age, born and raised in La Paz, Bolivia (altitude 3,600m), made up the reference sample. Anthropometric measures were taken, and VO(2) was assessed while the children performed graded exercise tests on a cycle ergometer. A repeated-measures prediction equation was developed, and maximum likelihood estimates of parameters were found from 75 observations on 20 children. The final model included the variables DeltaHR, DeltaHR(2), weight, and sex. The effectiveness of the method was established using leave-one-out cross-validation, yielding a prediction error rate of 0.126 for a mean DeltaVO(2) of 0.693 (SD 0.315). The correlation between the predicted and measured DeltaVO(2) was r = 0.917, suggesting that a useful prediction equation can be produced using paired VO(2) and HR measurements on a relatively small reference sample. The resulting prediction equation can be used for estimating EE from HR in free-living children performing habitual activities in the Bolivian Andes.

Measuring human energy expenditure: what have we learned from the flex-heart rate method?

The measurement of daily energy expenditure is an important aspect of research on human health and nutrition. Over the last 30 years, G.B. Spurr has been a leader in developing and implementing methods for more effectively assessing energy expenditure and physical activity in traditional and modernizing populations. One of his most notable contributions has been the development of the "Flex Heart Rate" (flex-HR) method. Since its inception in the late 1980s, the flex-HR method has become a standard tool for measuring daily energy expenditure in free-living human populations. This article reviews the initial development and validation of the flex-HR technique, and examines recent refinements of the method and its application to research in biomedicine and human population biology. The review and analyses highlight how the flex-HR technique has improved on earlier methods of assessing energy expenditure and greatly advanced our understanding of variability in human energy requirements.

Physical activity levels are low in free-living adults with chronic paraplegia

OBJECTIVES

To compare physical activity levels (PALs) of free-living adults with chronic paraplegia with World Health Organization recommendations and to compare energy expenditure between persons with complete vs. incomplete paraplegia.

RESEARCH METHODS AND PROCEDURES

Twenty-seven euthyroid adults (17 men and 10 women) with paraplegia (12.5 +/- 9.5 years since onset; 17 with complete lesions and 10 with incomplete lesions) participated in this cross-sectional study. Resting metabolic rate was measured by indirect calorimetry and total daily energy expenditure (TDEE) by heart rate monitoring. PAL was calculated as TDEE/resting metabolic rate. Total body water was measured by deuterium dilution and fat-free mass (FFM) and fat mass (FM) by calculation (FFM = total body water/0.732; FM = weight - FFM). Obesity was defined using the following percentage FM cutoffs: men 18 to 40 years >22% and 41 to 60 years >25%; and women 18 to 40 years >35% and 41 to 60 years >38%.

RESULTS

Nineteen subjects (70.4%; 13 men and six women) were obese. Fifteen subjects (56%) engaged in structured physical activity 1.46 +/- 0.85 times during the observation period for a mean of 49.4 +/- 31.0 minutes per session. Despite this, mean PAL of the group was 1.56 +/- 0.34, indicative of limited physical activity. TDEE was 24.6% lower in subjects with complete paraplegia (2072 +/- 505 vs. 2582 +/- 852 kcal/d, p = 0.0372).

DISCUSSION

PAL of the group was low, indicating that persons with paraplegia need to engage in increased frequency, intensity, and/or duration of structured physical activity to achieve a PAL >/=1.75 and, thereby, to offset sedentary activities of daily living.