Evaluation of methods for measuring daily physical activity in terms of energy expenditure]

Various methods exist for measuring daily physical activity and daily energy expenditure and daily pedometer readings are most commonly used for the amount of physical activity. In this study, three methods for measuring energy expenditure-24-hr heart rate method (HR), time study method, and caloric expenditure accumulator (CC)-, and the feasibility of a pedometer for the assessment of energy expenditure were examined under laboratory conditions and during normal daily life. Daily physical activity was measured by four methods (HR, Time study, CC, Pedometer) in a field study of 14 young, healthy and sedentary women, and compared. Laboratory validation of the three methods with measurement of oxygen uptake was performed with 5 young men and 1 woman walking and running at different speeds and grades on a treadmill. In addition validation tests of whether pedometer readings reflect differences in energy expenditure due to speed and grade and whether pedometer counts steps exactly were also conducted. The 24-hr energy expenditure derived from CC was significantly lower than that derived from HR and Time study, due to lower estimation of energy expenditure from activities compared to other methods. In the laboratory study, the energy expenditure measured at 5% grade was low by CC and differences in energy expenditure for changes in grade could not be differentiated. Time study revealed a significant relationship between CC and HR in field study. These results suggest that CC tends to underestimate the 24-hr energy expenditure from activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tracmor system for measuring walking energy expenditure

OBJECTIVE: Walking is an important mode of exercise and is likely to represent a major component of nonexercise activity thermogenesis. The question arises, how best to quantify walking-energy expenditure (EE) in free-living individuals. The triaxial accelerometer for movement registration (Tracmor) is a valid measure of body displacement and so we wanted to evaluate this tool for quantifying walking-EE. HYPOTHESIS: In this study, we test the hypothesis that walking-EE, measured in a Room Calorimeter, can be predicted from Tracmor output using a regression equation derived from a brief Tracmor/treadmill/Metabolic Cart protocol. DESIGN: First, 11 healthy subjects completed a 40-min procedure whereby they wore a Tracmor unit and walked on a treadmill at 0, 1, 2 and 3 mph while EE was measured using a Metabolic Cart. This allowed a regression equation to be defined for each subject to convert Tracmor output to EE. Each subject then entered a Room Calorimeter wearing the Tracmor Unit and walked at two self-selected velocities ('slow', 'fast') while EE was measured. 'Tracmor/regression equation' predictions of walking-EE were compared with Room Calorimeter measurements of walking-EE for the two velocities. RESULTS: The 'Tracmor/regression equation' prediction of EE for walking slowly was 6.36+/-1.67 kJ/min, and for walking fast it was 11.0+/-2.60 kJ/min. Room Calorimeter measurements were 6.43+/-1.85 and 10.9+/-3.03 kJ/min, respectively. The intraclass correlation coefficient for slow-paced walking was 0.93 (P<0.001), and for fast-paced walking it was 0.82 (P<0.005). CONCLUSIONS: When combined with laboratory measures of EE, the Tracmor accelerometer provides useful data on walking-EE and is applicable to free-living individuals.     

A simple method of measuring total daily energy expenditure and physical activity level from the heart rate in adult men

OBJECTIVE: To evaluate a simple method that uses only a heart rate monitor to predict total energy expenditure (TEE) and physical activity level (PAL) from 24 h heart rate (HR) measurements. DESIGN: The simple method involved the determination of the physical activity ratio (PAR) from corresponding heart rate ratios (HRR) (ratio of observed to resting HR), from an individualized calibration curve relating activities with known PAR to the HRR. Several curve fits were evaluated for this curve. The PAL was calculated from minute to minute PAR. The TEE was computed as the product of the PAL and the predicted basal metabolic rate (BMR). The accuracy of the simple method was assessed by within-subject comparisons of the simple method versus the oxygen consumption - HR method and a time and motion study. SETTING: Bangalore City, India. Subjects: In all, 17 healthy male subjects between 18 and 44 years were recruited for the study. Interventions: None. RESULTS: The simple method correlated well with both the reference methods when using a calibration curve that involved the fitting of two straight lines at low and high PAR activities, respectively, to the PAR and HRR data. The mean error in TEE, as a product of BMR and PAL, was about 1%, but with limits of agreement between the methods that were about 20% of the TEE. However, the low mean error could have been due to a canceling of errors in the determination of BMR and PAL. CONCLUSIONS: The simple method is a relatively cheap, useful technique for evaluating TEE and PAL in resource-poor situations. It may particularly be of use in epidemiological investigations where population estimates of TEE and PAL are required.     

Sedentary daily expenditure: a base for estimating individual energy requirements

As a base for estimating individual energy requirements, we propose using the energy expenditure of a sedentary day with regular meals and sleep at night. Ninety-five 24-h measurements of sedentary daily expenditure (SDE) by direct calorimetry on 37 men and women were analyzed, showing that fat-free mass combined with body mass index correlated highly with SDE (r2 = 0.92) with an SE of 5%. Weight and fat mass were better predictors for women and excellent predictors for men. We found that weight and height accurately predicted fat mass if suitable exponents were used in the expression wt/htx. Testing predictive equations with our own and other sets of data showed good agreement between estimated and observed SDEs. As a base for estimating individual energy requirements. SDE is more precise than basal metabolic rate and it can be predicted with useful accuracy from simple measures of weight and height.     

Total daily energy expenditure and activity level in anorexia nervosa.

Clinical reports consistently comment on high physical activity for anorexia nervosa patients but provide few quantitative measurements. To assess activity, total daily energy expenditure (TDEE) by doubly labeled water, basal metabolic rate (BMR), and thermic effect of meals (TEM) were measured in six female outpatients with anorexia nervosa (67% of ideal body weight) and age-, sex-, and height-matched to six control subjects. Anorexia nervosa patients expended more energy as physical activity than did control subjects [0.084 +/- 0.012 vs 0.044 +/- 0.008 MJ/kg body wt, respectively (20.1 +/- 3.0 vs 10.5 +/- 1.9 kcal/kg body wt, respectively), P less than 0.04], although they had a lower BMR [4.17 +/- 0.37 vs 5.52 +/- 0.15 MJ/d, respectively (997 +/- 89 vs 1319 +/- 37 kcal/d, respectively), P less than 0.01]. TDEE and TEM were similar in both groups. There was a reduction in serum triiodothyronine (T3; 1.20 +/- 0.15 vs 2.04 +/- 0.13 nmol/L, respectively; P less than 0.003) and a slight reduction in serum thyroxine (T4); reverse T3, thyrotropin, free T4, serum cortisol, and adrenocorticotropin values were normal. BMR correlated with total body weight and fat-free mass. These results provide quantitative evidence for increased physical activity in anorexia nervosa despite profound underweight and hypometabolism.     

Comparison of two systems of measuring energy expenditure

BACKGROUND: Health care professionals typically use resting metabolic rate (RMR) via indirect calorimetry to determine a person's energy expenditure. Traditional indirect calorimetry measurements involve an expensive, cumbersome piece of equipment that requires careful calibration. The recent development of a handheld indirect calorimeter makes it easier to measure RMR. The purpose of this study was to compare simultaneous measurements of RMR with handheld and traditional indirect calorimeters. METHODS: Healthy, free-living subjects (n = 50) age 18 years and older were tested simultaneously with both indirect calorimeters. All subjects breathed through the handheld device using a mouthpiece while wearing noseclips to prevent leaks. The handheld indirect calorimetry device was placed inside a canopy. The exhaled gas from the handheld was positioned directly over the inlet to the port delivering gases to the traditional device's mixing chamber. The canopy facilitated the simultaneous collection of all expired gases into the traditional device. During the measurement, oxygen consumption and RMR were continuously recorded on a personal computer. RESULTS: Mean oxygen consumption and RMR did not significantly differ between the two devices, with a mean difference of 0.58 +/- 15.33 mL/min (p = .790) and 4.66 +/- 113.39 kcal/day (p = .773) and an absolute difference of 12.3 +/- 8.99 mL/min and 86.58 +/- 72.32 kcal/day, respectively. Correlation coefficients for oxygen consumption and RMR were 0.945 and 0.941, respectively. CONCLUSIONS: No significant difference was found between the measurements of indirect calorimetry with the MedGem (HealtheTech, Golden, CO) device compared with the DeltaTrac device (Datex-Ohmeda, Madison, WI). These findings suggest that the handheld indirect calorimeter may provide an accurate measure of oxygen consumption and RMR measurements for spontaneously breathing subjects.     

Impacts of vigorous and non-vigorous activity on daily energy expenditure

Activity intensity is a potential determinant of activity-induced energy expenditure. Tri-axial accelerometery is the most objective measurement technique for the assessment of activity intensity, in combination with doubly-labelled water for the measurement of energy expenditure under free-living conditions. Data on the effects of subject characteristics, including body size and age, and exercise training on the relationship between activity intensity and daily energy expenditure are reviewed. Average daily metabolic rate and non-basal energy expenditure are positively related to body size. The duration and intensity of physical activities do not need to be equivalent to the energy spent on activity. Obese subjects spend more energy on physical activity but can perform fewer activities, especially high-intensity (weight-bearing) activities, because of their higher body weight. Physical activity generally declines gradually from about 60 years of age onwards. Most subjects > 80 years have an activity level well below the level defined for sedentary middle-aged adults. Spending relatively more time on low-intensity activities has a negative effect on the mean physical activity level. To obtain a higher physical activity level does not necessarily imply high-intensity activities. In an average subject 25% of the activity-induced energy expenditure may be attributed to high-intensity activities. Exercise training, as a form of high-intensity activity, affects the physical activity level more in younger subjects than in elderly subjects.     

Relation between energy expenditure and body composition in man: specific energy expenditure in vivo of fat and fat-free tissue

The relationship between energy expenditure and body composition, in terms of fat and fat-free masses, has previously been described by a variety of predictive regression equations with parameters devoid of physiological content. We present here results obtained by calculating the specific energy expenditure, ie, the energy expenditure per unit of mass, of fat and fat-free tissue on the basis of measurements of the total energy expenditure (EE), the masses of fat (FM), and fat-free (FFM) tissue using the following simple model: EE = k1.FM + k2.FFM where k1 and k2 are the specific energy expenditures of fat and fat-free tissue, respectively. The results of observations on 104 women at rest yielded values for k1 and k2 of 0.31 and 1.35 watts/kg of fat and fat-free mass, respectively, with standard errors of estimate of 0.074 and 0.052 watts/kg, respectively. Analysis of several series of measurements, from other sources and on smaller samples of subjects, yielded similar values at rest but with larger standard errors of estimate. Data from subjects performing varying amounts of work in 24-h measurements showed, as expected, larger values for both tissues. The results explain to a very large extent the well-established relation between resting metabolic rate and body weight, ie, a linear relation with a non-zero intercept. The results also offer a clear-cut explanation for the well known difference in energy expenditure between men and women with the same body weight.     

The influence of nutrient administration on energy expenditure in man

Recent data on the thermic effect of nutrients are presented. When given intravenously (i.v.), glucose (+ insulin) induces an increase of energy expenditure (EE) of 7% of energy infused, whereas lipid (Intralipid) infusion stimulates EE by 3% of energy infused. The stimulation of EE due to amino acid infusion in depleted patients is 30-40% of the energy infused as amino acids. Glucose induced thermogenesis includes an 'obligatory thermogenesis' which accounts for the energy cost of storing the nutrient and a 'facultative thermogenesis' which is mainly due to a stimulation of sympathetic activity; the latter is suppressed by propranolol infusion. Comparison of nutrient induced thermogenesis during continuous administration of nutrients between the enteral and parenteral routes reveal similar responses. This shows that the energy costs of digestion and absorption of nutrients is low in comparison with the cost of nutrient storage. However, when given by the enteral route, the net efficiency of energy utilisation is also dependent on the co-efficient of nutrients absorption. Oral administration of nutrients (bolus) induces a larger thermogenic response than continuous enteral administration, due to a larger nutrient storage for the former. It is therefore advisable to allow for the thermic effect of nutrients when assessing the efficiency of energy utilisation in patients.     

Total daily energy expenditure in wasted chronic obstructive pulmonary disease patients

OBJECTIVES: To investigate total daily energy expenditure in chronic obstructive pulmonary disease (COPD) patients during a rehabilitation programme. DESIGN: Observational study involving a case and a control group. SUBJECTS: Ten COPD patients (six with body mass index (BMI) <18.5 kg/m(2) and four with BMI >18.5 kg/m(2)) were evaluated for their energy expenditure profile. Four additional healthy age-matched volunteers were also included for methodology evaluation. INTERVENTIONS: Measurements of total daily energy expenditure (TEE), resting energy expenditure (REE) and diet-induced thermogenesis (DIT) and energy intake were undertaken by indirect calorimetry and bicarbonate-urea methods and dietary records. RESULTS: REE in COPD patients was not significantly different from that predicted by the Harris-Benedict equation. Before the exercise day the mean TEE was 1508 kcal/day and physical activity level (PAL as calculated by TEE/REE) was 1.52. On the exercise day the TEE increased to 1568 kcal/day and PAL was 1.60, but neither of these changes were significant. The energy cost of increased physical activity during rehabilitation exercise was estimated to be 191 kcal/day. No significant change was found in DIT between the two patient groups. However, overall energy balances were found to be negative (-363 kcal/day). CONCLUSION: The rehabilitation programme did not cause a significant energy demand in COPD patients. TEE in COPD patients was not greater than in free-living healthy subjects. Patients, who were underweight, did not have a higher TEE than patients with normal weight. This suggested that malnutrition in COPD patients was not due to an increased energy expenditure. On the other hand, a significant negative energy balance due to insufficient energy intake was found in seven out of 10 patients.     

Increasing dietary palmitic acid decreases fat oxidation and daily energy expenditure

BACKGROUND: Oleic acid (OA) is oxidized more rapidly than is palmitic acid (PA). OBJECTIVE: We hypothesized that changing the dietary intakes of PA and OA would affect fatty acid oxidation and energy expenditure. DESIGN: A double-masked trial was conducted in 43 healthy young adults, who, after a 28-d, baseline, solid-food diet (41% of energy as fat, 8.4% as PA, and 13.1% as OA), were randomly assigned to one of two 28-d formula diets: high PA (40% of energy as fat, 16.8% as PA, and 16.4% as OA; n = 21) or high OA (40% of energy as fat, 1.7% as PA, and 31.4% as OA; n = 22). Differences in the change from baseline were evaluated by analysis of covariance. RESULTS: In the fed state, the respiratory quotient was lower (P = 0.01) with the high OA (0.86 +/- 0.01) than with the high-PA (0.89 +/- 0.01) diet, and the rate of fat oxidation was higher (P = 0.03) with the high-OA (0.0008 +/- 0.0001) than with the high-PA (0.0005 +/- 0.0001 mg . kg fat-free mass(-1) . min(-1)) diet. Resting energy expenditure in the fed and fasting states was not significantly different between groups. Change in daily energy expenditure in the high-OA group (9 +/- 60 kcal/d) was significantly different from that in the high-PA group (-214 +/- 69 kcal/d; P = 0.02 or 0.04 when expressed per fat-free mass). CONCLUSIONS: Increases in dietary PA decrease fat oxidation and daily energy expenditure, whereas decreases in PA and increases in OA had the opposite effect. Increases in dietary PA may increase the risk of obesity and insulin resistance.     

Validation of doubly labeled water for measuring energy expenditure during parenteral nutrition

The doubly labeled water method was compared with intake-balance for measuring energy expenditure in five patients receiving total parenteral nutrition (TPN). Because parenteral solutions were isotopically different from local water, patients had to be placed on TPN at least 10 days before the metabolic period. Approximately 0.1 g 2H2O and 0.25 g H2(18)O per kg total body water were given orally. We collected saliva before, 3 h, and 4 h after the dose for measurement of total body water and urine before, 1 day, and 14 days after the dose for measurement of isotope eliminations. On day 14, total body weight was remeasured and change in body energy stores was calculated, assuming constant hydration. Intake was assessed from weights of TPN fluids plus dietary record for any oral intake. Energy expenditure from doubly labeled water (+/- SD) averaged 3 +/- 6% greater than intake-balance. Doubly labeled water method is a noninvasive, nonrestrictive method for measuring energy expenditure in patients receiving TPN.