Biomedical subjects

K R Westerterp

Publications and source records attributed to K R Westerterp.

At least 37 records · Page 2Linked to original sources

PubMed2001

Total energy expenditure in stable patients with cystic fibrosis.

BACKGROUND AND AIMS: Undernutrition is a common problem in patients with cystic fibrosis and is associated with a poor prognosis. The two aims of this study were to assess and compare the two main field techniques in the measurement of total energy expenditure and, secondly, to assess total energy expenditure in stable patients and compare with healthy controls. METHODS: Resting energy expenditure was measured using indirect calorimetry and total energy expenditure was measured using 24-h heart rate (HR) methodology and doubly isotopically labelled water. RESULTS: Seventeen patients, mean age 23 years and FEV(1)52% predicted and thirteen controls were recruited. Resting energy expenditure was higher in patients 0.24 (0.03) MJ/kg Fat-Free Mass (FFM) compared to controls 0.22 (0.02) MJ/kg FFM, P=0.02. Twenty-four hour heart rate underestimated total energy expenditure, 9.49 (1.85) MJ/day in patients compared to 11.69 (2.79) MJ/day using doubly labelled water. There was no difference in total energy expenditure in patients and controls using both methods, 11.69 (2.79) MJ/day compared to 11.38 (2.71) MJ/day using doubly isotopically labelled water. CONCLUSIONS: In clinically stable young adult patients with moderately severe respiratory disease total energy expenditure is comparable to that an a control population despite in increase in resting energy expenditure and both 24-h HR and doubly isotopically labelled water are suitable for use in patients with cystic fibrosis.

Adult↗

PubMed2001

Comparison of two questionnaires with a tri-axial accelerometer to assess physical activity patterns.

Two physical activity questionnaires were evaluated against cardiorespiratory fitness (VO2 peak), and a tri-axial accelerometer for movement registration (Tracmor) in 166 men, aged 40 years, within the framework of the Leuven Longitudinal Study on Lifestyle, Fitness, and Health. Tracmor data were obtained during four successive days. Besides the work index, the sport index, and the total activity index from the Baecke questionnaire, the subjective activity score, calculated energy expenditure during work, work index, and the total activity index from the Tecumseh Community questionnaire showed significant correlation coefficients with the mean Tracmor output (r = 0.26-0.47, p < 0.01). The questionnaire submeasures and the Tracmor output as generated in the same physical activity dimension showed the same relationships (r = 0.22-0.50, p < 0.01). Multiple stepwise regression and stepwise discriminant analyses showed the Baecke questionnaire as the best indicator of the subject's physical activity level. Extra information about the physical activity level was given by two Tecumseh submeasures, e.g. energy expenditure during work and sleeping time. The results indicated that the Baecke questionnaire is superior in large-scale studies because of simplicity. However, the Tecumseh questionnaire can give detailed information about physical activity patterns and energy expenditure.

Activities of Daily Living↗

PubMed2001

Body composition in Prader-Willi syndrome compared with nonsyndromal obesity: Relationship to physical activity and growth hormone function.

OBJECTIVE: To study the relationship of fat mass, extracellular-to-intracellular-water ratio, and bone mineral density with growth hormone function and physical activity in Prader-Willi syndrome. STUDY DESIGN: There were 17 patients with PWS (10 women, ages 7.5-19.8 years) and 17 obese control patients, matched for gender and bone age. FM and extracellular-to-intracellular-water ratio were measured by bromide-deuterium dilution, BMD by dual-energy x-ray absorptiometry, GH function by fasted serum insulin-like growth factor-I concentration, and physical activity by doubly-labeled water in combination with basal metabolic rate by a ventilated hood. RESULTS: The PWS group had a similar fat mass, but a lower fat-free mass, whereas the extracellular-to-intracellular-water ratio was higher compared with the control group (0.87 +/- 0.07 l/l and 0.80 +/- 0.06 l/l, respectively [P <.01]). Fat mass was inversely related with PA in the PWS group, whereas IGF-I was positively correlated with FFM, ICW, and BMD of the limbs. BMD tended to be lower in patients with PWS. CONCLUSIONS: In children and adolescents with PWS, adiposity is associated with a reduced fat-free mass and extracellular-to-intracellular-water ratio is increased. Both findings are related to GH function and physical activity. BMD, especially in the limbs, tends to be reduced in patients with PWS and is related to GH function.

Adolescent↗

PubMed2001

Repeated measurement of habitual food intake increases under-reporting and induces selective under-reporting.

The aim of the current study was to measure differences in reporting behaviour between a first occasion of 7 d food recording and a second occasion of 7 d food recording 12 weeks later, in a group of elderly men (n 17) and women (n 17). Half the group followed an exercise intervention. The mean age was 61 (sd 5) years and mean BMI was 26.2 (sd 3.8) kg/m2. Reported energy intake was compared with energy expenditure as calculated from measured BMR and physical activity assessed with a tri-axial accelerometer for movement registration. Total under-reporting was divided into undereating and under-recording. Undereating was calculated from the change in body mass over the recording week and the under-recording was measured using the water balance technique. In the first period, the total under-reporting was 21 % and increased to 27% in the second period In the first period there was no indication for subjects eating less during the recording week, however, in the second period subjects lost body mass during the food recording indicating undereating. The amount of under-recording was calculated at 21% in the first period and 18% in the second period of recording (P 0.28). During the second period subjects selectively under-reported their fat intake and over-reported their protein intake. In conclusion, repeated assessment of food intake caused a higher quantitative and a qualitative under-reporting of food intake. The effect of interventions (dietary or otherwise) on habitual food intake might be confounded by changes in food-reporting behaviour.

Case-Control Studies↗

PubMed2001

Antioxidant supplementation and exercise-induced oxidative stress in the 60-year-old as measured by antipyrine hydroxylates.

The effects of 12 weeks of antioxidant supplementation on exercise-induced oxidative stress were investigated in older adults (60 (SE 1) years; BMI 26 (SE 1) kg/m(2)). Subjects were randomly divided in two groups: supplementation (n 11) with 100 mg dl-alpha-tocopheryl acetate, 200 mg ascorbic acid, and 2 mg beta-carotene, and placebo (n 9). Before and after the 12 week supplementation period, subjects cycled for 45 min at submaximal intensity (50 % maximal workload capacity). Antipyrine was used as marker for oxidative stress. Antipyrine reacts quickly with hydroxyl radicals to form para- and ortho-hydroxyantipyrine. The latter metabolite is not formed in man through the mono-oxygenase pathway of cytochrome P450. Daily supplementation significantly increased plasma concentrations of alpha-tocopherol and beta-carotene in the supplemented group (Delta 14.4 (SE 3.2) and 0.4 (se 0.1) micromol/l; P<0.001 and P<0.01). No significant differences, within and between groups, were observed in the exercise-induced increase in the ratios para- and ortho-hydroxyantipyrine to antipyrine. In addition, supplementation did not affect the exercise-induced increase in thiobarbituric acid reactive substances in plasma. In conclusion, in 60-year-old subjects antioxidant supplementation had no effect on the exercise-induced increase in oxidative stress as measured by free radical products of antipyrine.

Antioxidants↗

PubMed2001

Exercise training and oxidative stress in the elderly as measured by antipyrine hydroxylation products.

Effects of 12 wk exercise training on oxidative stress were examined in elderly humans. We measured oxidative stress during a 45 min cycling test by using antipyrine hydroxylation products. Antipyrine breakdown is independent of blood flow to the liver, which is important during exercise. Furthermore, antipyrine reacts quickly with hydroxyl radicals to form para- and ortho-hydroxyantipyrine. Ortho-hydroxyantipyrine is not formed in man through the mono-oxygenase pathway of cytochrome P450. Twenty subjects (9 women; 60 +/- 3 y) participated in the training program. Thirteen subjects (5 women; 64 +/- 7 y) served as inactive controls. Subjects trained, twice a week for 1 h, at a fitness center. After 12 wk, maximal oxygen uptake (p < .005) and workload capacity (p < .001) were only significantly elevated in the training group. After 12 wk, both groups observed no change in the ratios of antipyrine hydroxylates, para- and ortho-hydroxyantipyrine, to native antipyrine. Furthermore, no differences were observed within or between groups in the exercise-induced increase in the plasma level of thiobarbituric acid reactive species. In conclusion, 12-wk training had no effect on exercise-induced oxidative stress in elderly humans as measured by free radical reaction products of antipyrine. Despite the fact that training in elderly humans improves functional capacity, it appears not to compromise antioxidant defense mechanisms.

Aging↗

PubMed2001

Use of a triaxial accelerometer to validate reported food intakes.

BACKGROUND: An easy and cheap method for validating reported energy intake (EI) is needed. OBJECTIVE: Reported EI was compared with calculated energy expenditure (EE(calc)) and with energy expenditure measured by the doubly labeled water method (EE(DLW)). DESIGN: EE was calculated on the basis of basal metabolic rate (BMR) measured with the ventilated-hood technique and physical activity (PA) measured with a triaxial accelerometer (EE(VH+PA)) and on the basis of BMR estimated by using World Health Organization equations and PA (EE(WHO+PA)): EE(calc) = -1.259 + 1.55 x BMR + 0.076 x counts/min (r(2) = 0.90, P = 0.0001). Subjects [n = 12 men and 12 women aged 60 +/- 3 y; body mass index (in kg/m(2)): 26 +/- 4] reported their food intakes for 7 d and EE(DLW), EE(VH+PA), and EE(WHO+PA) were assessed over the same 7 d. RESULTS: Reported EI (9.0 +/- 2.1 MJ/d) was lower (P: < 0.0001) than were EE(DLW) (11.3 +/- 2.3 MJ/d), EE(VH+PA) (10.8 +/- 1.7 MJ/d), and EE(WHO+PA) (10.8 +/- 1.8 MJ/d). Underreporting was 19.4 +/- 14.0%, 16.7 +/- 13.6%, and 16.4 +/- 15.5% on the basis of EE(DLW), EE(VH+PA), and EE(WHO+PA), respectively. The difference of 2.7 +/- 8.0% between EE(DLW) and EE(VH+PA) was not related to the average of both percentages and was not significantly different from zero. The percentage of underreporting calculated with EE(WHO+PA) was not significantly different from that calculated with EE(DLW). CONCLUSIONS: The use of a combination of BMR (measured or estimated) and PA is a good method for validating reported EI. There was no significant difference between the percentage of underreporting calculated with EE(VH+PA), EE(WHO+PA), or EE(DLW).

Aged↗

PubMed2001

Physical activity and parameters of aging: a physiological perspective.

Increasing age is associated with a decline in fat-free mass. The question is whether age-related changes in body composition can be delayed by an active life style. This analysis includes data where physical activity was assessed with doubly labeled water and body composition with hydrodensitometry or isotope dilution. Subjects were 136 women and 180 men over 20 years, who were tested in Maastricht University between 1983 and 1998. Increasing age was associated with lower activity levels and lower fat-free mass. After controlling for age there was no longer any association between physical activity and fat-free mass. A few exercise intervention studies showed that elderly subjects compensate for exercise training by a decline in spontaneous physical activity, in contrast to younger subjects. Although no effect of habitual activity level on changes in body composition are observed, training has a positive effect on muscle function. Elderly subjects with relatively high levels of physical activity are not different from those with low activity levels, as far as fat-free mass and fat mass are concerned. However, training might delay the age-induced impairment of personal mobility associated with a reduction in physical activity.

Adipose Tissue↗

PubMed2001

Validation of the Tracmor triaxial accelerometer system for walking.

PURPOSE: Walking is likely to contribute substantially to nonexercise activity thermogenesis. The Tracmor triaxial accelerometer system (Maastricht, The Netherlands) is the most widely validated system for detecting body movement in free-living subjects. The aim of this study was to validate the Tracmor triaxial accelerometer system for estimating the energy expenditure of walking. METHODS: Experiments were conducted in healthy subjects. First, baseline variability for Tracmor output was determined for subjects standing still. Second, Tracmor output was compared for walking on a treadmill and on level ground. Third, both Tracmor output and energy expenditure were compared for walking on a treadmill and walking on level ground. Finally, the effect of gradient on Tracmor output and energy expenditure was compared for subjects walking on a treadmill. RESULTS: The data demonstrated excellent reproducibility for comparing Tracmor output for standing (CV < 2%). There were excellent log-linear relationships between velocity and Tracmor output walking on a treadmill (r = 0.998) and on level ground (r = 0.999). Tracmor output and the energy expenditure of walking were inseparable for the two modalities of walking. However, the variance in response was such that to reliably derive the relationship between Tracmor output and energy expenditure, separate regression equations are needed for each subject. Finally, the Tracmor accelerometer did not detect the increased energy expenditure of walking that occurs as gradient increases. CONCLUSION: The Tracmor triaxial accelerometer provides reproducible and reliable data on the body motion associated with walking regardless of whether a subject walks on a treadmill or level ground. Tracmor units can be used to predict the energetic cost of walking provided that separate regression equations are derived for each subject to convert Tracmor output to energy expenditure.

Adult↗

PubMed2001

Energy metabolism in relation to body composition and gender in adolescents.

OBJECTIVE: To study the effect of body composition on average daily metabolic rate (ADMR) and basal metabolic rate (BMR) in adolescence, and to examine current BMR prediction equations. STUDY: Dutch adolescents were pooled with previously reported American and British subjects (n = 90 overall). BMR and ADMR were analysed by multiple regression. RESULTS: Fat-free mass, BMR, and ADMR were higher in the obese than in the non-obese group (mean (SD): 53.2 (10.7) kg, 8.35 (1.57) MJ/d, and 13.64 (2.78) MJ/d, compared with 41.0 (8.1) kg, 6.42 (0.94) MJ/d, and 11.16 (2.21) MJ/d, respectively). BMR remained higher when adjusted for fat-free mass, age, and sex. ADMR adjusted for BMR was similar in the two groups. WHO equations overestimated BMR in obese boys and underestimated BMR in non-obese boys. CONCLUSIONS: BMR, but not activity, is increased in obese adolescents and in male adolescents. The WHO BMR equations for adults are recommended for obese adolescents.

Adolescent↗

PubMed2001

Measurement of the components of nonexercise activity thermogenesis.

Nonexercise activity thermogenesis (NEAT) accounts for the vast majority of nonresting metabolic rate and changes in NEAT-predicted susceptibility to fat gain with overfeeding. Measuring physical activity and its components in free-living humans has been a long-standing challenge. In this study, we combine information about lightweight sensors that capture data on body position and motion with laboratory measures of energy expenditure to calculate nonfidgeting NEAT. This measurement of nonfidgeting NEAT was compared with total NEAT measured in a room calorimeter in 11 healthy subjects. The measurement of nonfidgeting NEAT accounted for 85 +/- 9% of total NEAT measured in the room calorimeter. The intraclass correlation coefficient for the two methods was 0.86 (95% confidence interval 0.56, 0.96; P < 0.05). This suggests that 86% of the variance is attributable to between-subject variance and 14% to between-method disagreement. These instruments are applicable to free-living subjects; they are stand-alone, are lightweight, and allow normal daily activities. This novel technology has potential application for not only assessing NEAT but also tracking physical activity in free-living humans.

Adult↗

PubMed2001

Energy and water balance at high altitude.

Many studies have shown that subjects lose significant amounts of body mass, fat mass as well as fat-free mass, during a climb to and/or a stay at high altitude. Altitude-induced weight loss is mainly caused by malnutrition due to hypoxia-related satiety, independent of acute mountain sickness.

Altitude↗

PubMed2001

Limits to sustainable human metabolic rate.

There is a limit to the performance of an organism set by energy intake and energy mobilization. Here, the focus is on humans with unlimited access to food and for whom physical activity can be limited by energy mobilization. The physical activity level (PAL) in the general population, calculated as doubly-labelled-water-assessed average daily metabolic rate as a multiple of basal metabolic rate, has an upper limit of 2.2-2.5. The upper limit of sustainable metabolic rate is approximately twice as high in endurance athletes, mainly because of long-term exercise training with simultaneous consumption of carbohydrate-rich food during exercise. Endurance athletes have an increased fat-free mass and can maintain energy balance at a PAL value of 4.0-5.0. High altitude limits exercise performance as a result of combined effects on nutrient supply and the capacity to process nutrients. Thus, trained subjects climbing Mount Everest reached PAL values of 2.0-2.7, well below the observed upper limit at sea level.

Altitude↗

PubMed2000

Operation Everest III: energy and water balance.

We hypothesized that hypoxia decreases energy intake and increases total energy requirement and, additionally, that decreased barometric pressure increases total water requirement. Energy and water balance was studied over 31 days in a hypobaric chamber at 452-253 Torr (corresponding to 4,500-8,848 m altitude), after 7 days acclimatization at 4,350 m. Subjects were eight men, age 27+/-4 years (mean+/-SD), body mass index 22.9+/-1.5 kg/m2. Food and water intake was measured with weighed dietary records, energy expenditure and water loss with labelled water. Insensible water loss was calculated as total water loss minus urinary and faecal water loss. Energy intake at normoxia was 13.6+/-1.8 MJ/d. Energy intake decreased from 10.4+/-2.1 to 8.3+/-1.9 MJ/d (P<0.001) and energy expenditure from 13.3+/-1.6 to 12.1+/-1.8 MJ/d (P<0.001) over the first and second 15-day intervals of progressive hypoxia. Absolute insensible water loss did not change (1.67+/-0.26 and 1.66+/-0.37 l/d), however, adjusted for energy expenditure it increased with ambient pressure reduction (P<0.05). In conclusion, hypoxia induced a negative energy balance, mainly by a reduction of energy intake. Overall insensible water loss was unchanged because the increase in respiratory evaporative water loss was counterbalanced by a decrease in metabolic rate that probably limited the hypoxia-induced increase in ventilation.

Acclimatization↗

PubMed2000

The role of high-fat diets and physical activity in the regulation of body weight.

The prevalence of obesity is increasing in westernized societies. In the USA the age-adjusted prevalence of BMI > 30 kg/m2 increased between 1960 and 1994 from 13% to 23% for people over 20 years of age. This increase in the prevalence of obesity has been attributed to an increased fat intake and a decreased physical activity. However, the role of the impact of the level of dietary fat intake on human obesity has been challenged. High-fat diets, due to their high energy density, stimulate voluntary energy intake. An increased fat intake does not stimulate its own oxidation but the fat is stored in the human body. When diet composition is isoenergetically switched from low to high fat, fat oxidation only slowly increases, resulting in positive fat balances on the short term. Together with a diminished fat oxidation capacity in pre-obese subjects, high-fat diets can therefore be considered to be fattening. Another environmental factor which could explain the increasing prevalence of obesity is a decrease in physical activity. The percentage of body fat is negatively associated with physical activity and exercise has pronounced effects on energy expenditure and substrate oxidation. High-intensity exercise, due to a lowering of glycogen stores, can lead to a rapid increase in fat oxidation, which could compensate for the consumption of high-fat diets in westernized societies. Although the consumption of high-fat diets and low physical activity will easily lead to the development of obesity, there is still considerable inter-individual variability in body composition in individuals on similar diets. This can be attributed to the genetic background, and some candidate genes have been discovered recently. Both leptin and uncoupling protein have been suggested to play a role in the prevention of diet-induced obesity. Indeed, leptin levels are increased on a high-fat diet but this effect can be attributed to the increased fat mass observed on the high-fat diet. No effect of a high-fat diet per se on leptin levels is observed. Uncoupling proteins are increased by high-fat diets in rats but no data are available in human subjects yet. In conclusion, the increased intake of dietary fat and a decreasing physical activity level are the most important environmental factors explaining the increased prevalence of obesity in westernized societies.

Animals↗

PubMed2000

Postabsorptive respiratory quotient and food quotient-an analysis in lean and obese men and women.

OBJECTIVE: Macronutrient intake is difficult to measure under free-living conditions, because of errors in the reporting of food intake. The aim of the current study was to assess whether postabsorptive respiratory quotient (RQ) is indicative for the food quotient (FQ), with other factors, such as body composition and energy balance, taken into account. SUBJECTS: Thirty lean subjects (age 31+/-9 y, body mass index (BMI) 22.0+/-2.1 kg/m2) and 20 obese subjects (age 48+/-12 y, BMI 33.3+/-4.4 kg/m2) participated in the study. DESIGN: Body mass changes were determined over a 7 day period before the measurement of postabsorptive RQ and in this period subjects reported their total food intake in a dietary record. A subgroup of 12 lean subjects was supplied with their total food intake in this period (twice with different diets). Food quotients were calculated from the valid food records (<10% underrecording and undereating). Body composition was estimated using the three-compartment model of Siri. RESULTS: Postabsorptive RQ was not related to FQ (n=31, r=-0.24, P=0.2) and no difference was observed between the two diet periods (n=12 paired t-test, P=0.9). Postabsorptive RQ was related to the change in body mass (r=0.57, P=0.0001), but not to BMI, fat mass or fat-free mass. CONCLUSIONS: In the present study, the energy balance over the days prior to the measurement was the most important factor influencing postabsorptive RQ. Postabsorptive RQ was not a reliable indicator for habitual FQ even when corrected for energy balance and body composition.

Absorption↗

PubMed2000

Validation of a dietary record routine in geriatric patients using doubly labelled water.

OBJECTIVE: To validate a 7-day estimated dietary record routine with standardized portion sizes and household measuring in a clinical setting with the doubly labelled water (DLW) method as the reference method. DESIGN: Energy expenditure was measured with deuterium ((2)H) and oxygen-18 ((18)O), and water loss was estimated by 2H dilution as part of the DLW measurements. Energy and water intake was measured with a 7 day dietary record. SETTING: Five nursing home wards in Sweden. SUBJECTS: Thirty-one geriatric patients with a mean age of 86 y. Inclusion criteria were stable body weight, defined as a maximum change of +/-4% during the last 4 months of +/-2% during the last 2 months and without any acute illness. RESULTS: The mean daily energy intake was 7.2 MJ (1727 kcal) and the mean daily energy expenditure was 6.7 MJ (1595 kcal). The mean daily water intake was 1787 ml and mean daily water loss assessed by labelled water was 1774 ml. Using the dietary record routine, the staff overestimated the patients' energy intake by 8% and water intake from food and beverages by <1% compared to DLW. CONCLUSION: The 7 day dietary record routine based on standardized portion sizes and household measuring seems to be a valid method for assessing the intake of energy and fluids by geriatric patients.

Aged↗

PubMed2000

Activity related energy expenditure in children and adolescents with Prader-Willi syndrome.

OBJECTIVE: To measure activity related energy expenditure in Prader-Willi syndrome (PWS) corrected for body size. SUBJECTS: 17 PWS subjects (10 females, seven males, age 7.5-19.8 y) and 17 obese controls, matched for gender and bone age. MEAUREMENTS: Basal metabolic rate (BMR) was measured by ventilated hood and average daily metabolic rate (ADMR) was measured with doubly labelled water. Activity induced energy expenditure (AEE) was calculated as 0.9ADMR -BMR. Activity related energy expenditure was corrected for body size using the following measures: AEE per kg body weight (AEE/kg), ADMR/BMR (PAL), and the residual of the regression of ADMR on BMR (rADMR). Group differences were analyzed by analysis of covariance adjusting for bone age, fat mass (FM) and gender. RESULTS: ADMR, AEE and PAL were lower (P < 0.01) in the PWS group compared with the control group (7.14 +/- 1.72, 1.07 +/- 0.69 and 1.33 +/- 0.15 MJ/day compared with 9.94 +/- 2.64, 2.56 +/- 1.03 and 1.55 +/- 0.12 MJ/day respectively). The variance of AEE/kg and PAL was significantly explained by gender and PWS, while AEE was additionally explained by FM. The variance of rADMR was explained by PWS and not by FM or gender. CONCLUSION: Activity related energy expenditure is decreased in PWS compared with controls adjusted for bone age, FM and gender.

Adolescent↗