Biomedical subjects

K R Westerterp

Publications and source records attributed to K R Westerterp.

158 records · Page 9Linked to original sources

PubMed1991

Methods to assess physical activity with special reference to motion sensors and accelerometers.

Motion sensors may be applied for the assessment of physical activity. This paper reviews the evolution of these instruments from the mechanical pedometer to the electronic accelerometer. We conclude that for accurate assessment of physical activity under free living conditions the recently introduced accelerometer looks most promising, although little information was available regarding the reliability of these instruments. Subsequently, reliability of an accelerometer with a three-directional sensor was examined. Intrainstrument variation in a bench test was less than 8% during four measurements over a week. Interinstrument variation during treadmill experiments while subjects wore two accelerometers at the same time was on average 22% and was not improved after adjustment for differences found in the bench test. Reproducibility in the treadmill experiment was approximately 76, 85, and 95% at 3, 5, and 7 km/h, respectively. Bench testing revealed that the sensitivity of a piezoelectric element is prone to shifts, probably due to mechanical, electromagnetic, and/or temperature shock, which may be encountered during outdoor application. However, the relevance of the bench test in this study may be questioned, as results did not correspond with the findings in subjects. This needs further investigation.

Adult↗

PubMed1991

Comparison of short term indirect calorimetry and doubly labeled water method for the assessment of energy expenditure in preterm infants.

The accuracy of 8-hour indirect calorimetry (IDC) as an estimate of energy expenditure was investigated in 8 healthy preterm infants (birth weight 1,270 +/- 193 g, gestational age 32 +/- 3 weeks, mean +/- SD) in comparison with an analysis over 5 days using the doubly-labeled water (2H2(18)O) method (DLW). The infants that were fed continuously by nasogastric drip with 120 kcal/kg/day of special infant formula were measured twice under thermoneutral conditions in a closed system indirect calorimeter during 8 h with a 4-day interval; simultaneously isotope decay was measured by isotope ratio mass spectrometry in urine samples collected daily during 5 days from 6 h after an oral dose of 2H2(18)O on the first day of IDC, all during the 4th postnatal week. The mean differences between carbon dioxide production rate (rCO2) measured either by single 8-hour IDC or by duplicate 8-hour IDC and the 5-day DLW method, using the two-point analysis or the multipoint analysis were not significantly different from zero. The rCO2 calculated from the DLW method using the two-point analysis differed -1.4 +/- 1.7% from that measured by the multipoint analysis. The mean differences between the metabolic rate estimated from 8 h of IDC and from the 5-day DLW method based on a measured RQ of 0.90 was -6.7 +/- 6.2% and based on the RQ of the feeding -4.5 +/- 6.0%. These differences were not significantly different from zero. We conclude that IDC over 8 h and two-point DLW measurement over 5 days, both methods that can be applied with relative ease in practice, offer an adequate average estimate of energy expenditure in continuously fed preterm infants under thermoneutral conditions.

Calorimetry, Indirect↗

PubMed1991

Influence of the feeding frequency on nutrient utilization in man: consequences for energy metabolism.

A study was conducted to investigate whether there is a diurnal pattern of nutrient utilization in man and how this is affected by meal frequency to explain possible consequences of meal frequency for body weight regulation. When the daily energy intake is consumed in a small number of large meals, there is an increased chance to become overweight, possibly by an elevated lipogenesis (fat synthesis and accumulation) or storage of energy after the meal. Thirteen subjects, two males and eleven females, were fed to energy balance in two meals per day (gorging pattern) and seven meals per day (nibbling pattern) over 2-day intervals. On the second day on each feeding regimen, the diurnal pattern of nutrient utilization was calculated from simultaneous measurements of oxygen consumption, carbon dioxide production and urinary nitrogen excretion over 3 h intervals in a respiration chamber. A gorging pattern of energy intake resulted in a stronger diurnal periodicity of nutrient utilization, compared to a nibbling pattern. However, there were no consequences for the total 24 h energy expenditure (24 h EE) of the two feeding patterns (5.57 +/- 0.16 kJ/min for the gorging pattern; 5.44 +/- 0.18 kJ/min for the nibbling pattern). Concerning the periodicity of nutrient utilization, protein oxidation during the day did not change between the two feeding patterns. In the gorging pattern, carbohydrate oxidation was significantly elevated during the interval following the first meal (ie from 1200 h to 1500 h, P less than 0.01) and the second meal (ie from 1800 h to 2100 h, P less than 0.05). The decreased rate of carbohydrate oxidation observed during the fasting period (from rising in the morning until the first meal at 1200 h), was compensated by an increased fat oxidation from 0900 to 1200 h to cover energy needs. In the nibbling pattern, carbohydrate and fat oxidation remained relatively constant during the active hours of the day.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1991

Determinants of weight loss after vertical banded gastroplasty.

Weight loss after gastric partition is highly variable even when the operation itself has been successful. We studied changes in body composition in relation to energy expenditure before and one year after surgery in one woman and five men, age 20-38 years, and BMI 42-62 kg/m2. Observations were performed shortly before, and 6, 12, 27 and 54 weeks after surgery. Body composition was measured with hydrostatic weighing and isotope dilution, and energy expenditure over 24 h (24EE) and during complete rest (sleeping metabolic rate (SMR)) with a respiration chamber and in five of the six subjects under daily living conditions over two-week intervals with doubly labeled water (average daily metabolic rate (ADMR). Weight loss and fat loss over the full observation period until 54 weeks after surgery was 54 +/- 8 and 43 +/- 9 kg (mean +/- s.e.m.), respectively. There was a more than three-fold difference in fat loss between the subject losing most, i.e. 70 kg, and the subject losing least, i.e. 20 kg. Fat loss was not related to initial fat mass in this group of six subjects but there was a significant negative relation with the loss of protein mass. There was a strong negative relation between fat loss and activity level of the subjects expressed as the quotient ADMR/SMR. These results show the contrary from what would be expected. Reduction of fat mass after successful gastric partition is highest in those subjects having the lowest physical activity level (before and) after surgery; these subjects lose less fat-free mass.

Adult↗

PubMed1991

Physical activity and sleeping metabolic rate.

In the present investigation we determined metabolic rate during sleep (SMR) as a function of physical activity (PA) in normal daily life. Subjects were nine females and six males, with an average age of 30 yr (range 19-48) and an average Quetelet Index of 32 (range 14-62). The level of SMR was expressed as an index; SMI = SMR/BMR, where SMR was measured in a respiration chamber while subjects were asleep and basal metabolic rate (BMR) was calculated with the equation from Harris and Benedict. Physical activity, calculated from average daily metabolic rate (ADMR) and BMR, was expressed as an index: PAI = ADMR/BMR, where ADMR was measured with doubly labeled water and BMR was calculated as indicated above. Individual values of SMI were 0.8-1.2. SMI was positively correlated with PAI (r = 0.85, P less than 0.001). Subjects with either a high or a low Quetelet Index were concentrated in the lower range of PAI compared with normal-weight subjects. In conclusion, subjects with an extremely low or high body weight generally show a lower than expected SMR associated with a low physical activity.

Adult↗

PubMed1990

The shape of the cumulative food intake curve in humans, during basic and manipulated meals.

The shape of the cumulative food intake curve of normal weight and obese women was studied during solid food lunches, artificially prolonged meals, and energetically enriched meals eaten in a laboratory setting. Subjects (86 normal weight, 50 obese) displayed consistent eating behaviour over 3-6 repeated meals, with marked differences between individuals. Aspects of eating behaviour were reflected in decelerated and nondecelerated (or linear) cumulative intake curves depending on changes or no changes in eating rate during the course of a meal, respectively. A change in eating rate was generally related to decrease in bite size, with bite rate remaining constant, from the third temporal quarter of the meal onwards, resulting in a decelerated cumulative intake curve. The nondecelerated (linear) cumulative intake curve does not show this change in eating rate: in the first three temporal quarters bite size and bite rate were constant, whereas in the fourth temporal quarter bite size decreased slightly, compensated by a small increase in bite rate. Intraindividual ranges for meal parameters such as chewing time per bite, bite interval and initial eating rate indicated consistency of individual eating behaviour. In manipulation experiments with a subset of 21 subjects in which meals were artificially prolonged by an interval of 8 min, the cumulative intake curves did not differ significantly from the original cumulative intake curves in 10 nondecelerated (linear) eaters, but showed a change towards nondecelerated curves in 8 out of 11 decelerated eaters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Estimation of body composition by bioelectrical impedance in cancer patients.

Measurement of body composition is important in the assessment of nutritional status in cancer patients. The purpose of this study was to validate the bioelectrical impedance (BI) method for body composition estimation in 33 elderly cancer patients (mean age 66 +/- 9 years) using the deuterium dilution technique (2H2O) as the reference method. Height2/Resistance (H2/R) correlated significantly with total body water (TBW) computed from 2H2O (r = 0.89, P less than 0.001; s.e.e. = 2.4 l). The prediction equation for TBW improved significantly (P less than 0.001) by addition of H2/R to the predictor variables weight, height, age and sex. We conclude that BI is a useful measure for the assessment of body composition in cancer patients.

Aged↗

PubMed1989

Study on food intake and energy expenditure during extreme sustained exercise: the Tour de France.

Food intake and energy expenditure (EE) were studied in five cyclists during the 22-day race of the Tour de France. The course is about 4000 km including 30 mountain passages (up to 2700 m altitude) and can be considered as one of the most strenuous endurance endeavors. Nutritional intake was calculated from daily food records. EE was estimated from sleeping time and the low activity period. EE during cycling was predicted based on detailed information. Mean energy intake (EI) was 24.7 MJ with a highest mean daily EI of 32.4 MJ. Mean EE was 25.4 MJ with a highest mean daily EE of 32.7 MJ. Relative contribution of protein, CHO, and fat was 15, 62, and 23 En% resp. 49% of EI was taken during the race resulting in a CHO intake of 94 g.h-1 representing 69 en%. It is questioned whether this amount of CHO is optimal in relation to CHO oxidation and performance. About 30% from CHO intake came from CHO-rich liquids. High EI resulted in high Ca and Fe intake. For vitamins, especially B1, this relation was not found. Vitamin B1 nutrient density dropped to 0.25 mg/4.2 MJ during the race caused by a large intake of refined CHO-rich food items. However, vitamin supplementation was high. Daily water intake was 6.71 with extremes up to 11.81. Therefore, the strategy of intake of large quantities of CHO-rich liquids seems to be the appropriate answer to maintain energy and fluid balance under these extreme conditions.

Bicycling↗

PubMed1989

Comparison of energy expenditure by the doubly labeled water technique with energy intake, heart rate, and activity recording in man.

Average daily energy expenditure determined by the doubly labeled water technique (dlwEE) was compared in six subjects (aged 20-30 y) over 2 wk under usual living conditions; average food energy intake and energy expenditure estimated from individual diary records of physical activity. In addition, energy expenditure was estimated from 24-h heart rate recordings carried out on two randomly chosen days of the 2-wk period. The group means of the dlwEE were 1.94 +/- 0.24 (means +/- SD) times larger than resting metabolic rate (= 1.94 met) and nearly identical to the average daily energy intake (1.93 +/- 0.23 met). Energy expenditure estimated from the diaries of activity and from the 24-h heart rate recording varied between 1.67 and 2.24 met depending on the calculation procedure. The dlwEE (1.94 +/- 0.24 met) is much higher than that recently determined for sedentary people (1.25 met) and thus explains that young students may achieve body weight balance with a relatively high daily food energy intake.

Adult↗

PubMed1989

Assessment of energy expenditure by recording heart rate and body acceleration.

The feasibility of a portable accelerometer equipped with a three-directional sensor for the assessment of physical activity and the consequences for energy expenditure was examined under laboratory conditions and during normal daily life. Heart rate monitoring was also conducted to allow comparison of both techniques. In the laboratory study 16 healthy subjects performed a number of specified exercises within a range of activity levels that may be expected in normal life. Accelerometer output was compared with energy expenditure measured by continuous respirometry. A linear relationship was found between accelerometer output and energy expenditure for the pooled data. The standard error of estimate is 79.1 J.min-1.kg-1. In the field study four subjects were observed during a week under free living conditions. Energy expenditure was calculated from food intake registered over the whole period. Energy expenditure calculated from accelerometer output and heart rate exceeded the energy intake figures by 30% and 33%, respectively. Possible explanations for this discrepancy are discussed. Despite this discrepancy, accelerometer output appeared to correlate highly with energy intake (r = 0.99, P less than 0.025), which suggests accurate performance of the accelerometer under free living conditions. The heart rate method gave much poorer results in estimating individual energy expenditure.

Acceleration↗

PubMed1988

Obesity, restrained eating and the cumulative intake curve.

The cumulative intake curves of 50 obese and 86 normal weight women during test meals were related to body mass index, age and the three factors of Stunkard & Messick's questionnaire (Journal of Psychosomatic Research, 29, 71-83), cognitive restraint, disinhibition and perceived hunger. Eating behaviour was monitored by a concealed camera and rate of intake via an electronic balance built into the table under the plate. The eating behaviour of each subject was very consistent over a series of three or six lunches of the same solid food consumed solitarily in a constant environment, with marked differences between subjects. Differences in body mass index over the whole sample were not related to the shape of the cumulative intake curve during test meals. In multiple regression analysis, the normal-weight subjects who scored high on disinhibition of restraint in response to emotions and external influences showed a more nearly constant rate of intake. In a separate multiple regression, the overweight subjects with the same characteristic showed a decelerating rate of intake. Susceptibility to hunger had no discernible relationship to the shape of the cumulative intake curve in either normal or overweight subjects. We conclude that the shape of the cumulative intake curve can be attributed more to cognitive than to biological factors.

Adult↗

PubMed1988

Comparison of doubly labeled water with respirometry at low- and high-activity levels.

In previous studies the doubly labeled water method for measuring energy expenditure in free-living humans has been validated against respirometry under sedentary conditions. In the present investigation, energy expenditure is measured simultaneously with doubly labeled water and respirometry at low- and high-activity levels. Over 6 days, five subjects were measured doing mainly sedentary activities like desk work; their average daily metabolic rate was 1.40 +/- 0.09 (SD) times sleeping metabolic rate. Four subjects were measured twice over 3.5 days, including 2 days with heavy bicycle ergometer work, resulting in an average daily metabolic rate of 2.61 +/- 0.25 (SD) times sleeping metabolic rate. At the low-activity level, energy expenditures from the doubly labeled water method were on the average 1.4 +/- 3.9% (SD) larger than those from respirometry. At the high-activity level, the doubly labeled water method yielded values that were 1.0 +/- 7.0% (SD) lower than those from respirometry. Results demonstrate the utility of the doubly labeled water method for the determination of energy expenditure in the range of activity levels in daily life.

Adult↗

PubMed1986

Use of the doubly labeled water technique in humans during heavy sustained exercise.

We measured energy expenditure with the doubly labeled water technique during heavy sustained exercise in the Tour de France, a bicycle race lasting more than 3 wk. Four subjects were observed for consecutive intervals of 7, 8, and 7 days. Each interval started with an oral isotope dose to reach an excess isotope level of 200 ppm 18O and 130 ppm 2H. The biological half-lives of the isotopes were between 2.25 and 3.80 days. Energy expenditure was compared with simultaneous measurements of energy intake, and body mass and body composition did not change significantly. The doubly labeled water technique gave higher values for energy expenditure than the food record technique. The discrepancy showed a systematic increment from the first to the third interval, being 12.9 +/- 7.9, 21.4 +/- 9.8, and 35.3 +/- 4.4% of the energy expenditure calculated from dietary intake, respectively. Possible explanations for the discrepancy are discussed. The subjects reached an average daily metabolic rate of 3.4-3.9 or 4.3-5.3 times basal metabolic rate based on the food record technique and the doubly labeled water technique, respectively. Thus, when measured with the same technique, the energetic ceiling for performance in humans is comparable with that of animals like birds.

Deuterium↗

PubMedDate not supplied

Estimating historical changes in physical activity levels.

OBJECTIVE: To compare activity levels between a simulated "historical" lifestyle and a "modern" lifestyle to try to validate earlier estimates of secular changes in activity. DESIGN: Triaxial accelerometers (TRACMORs) were used to measure activity levels in a "historical" group of seven male actors who were paid to live like early Australian settlers at a theme park north of Sydney (eg, minimising the use of modern technology) for a week. Results were compared with those from a group of seven "modern" sedentary office workers. RESULTS: Activity levels were up to 2.3 times greater in the historical group than the modern group. Calculations based on body weight and energy expenditure suggest the difference is the equivalent of walking up to 16 km per day more in the past than today. CONCLUSIONS: These findings accord with two previous estimates of changes in daily activity levels over time and suggest that recent public health guidelines for increasing physical activity may be inadequate.

Adult↗