96 research outputs found
Physical activity in confined conditions as an indicator of free-living physical activity
No full textPhysical activity in confined conditions as an indicator of free-living physical activity. Westerterp KR, Kester AD. Department of Human Biology, Maastricht University, Maastricht, The Netherlands. [email protected] OBJECTIVE: The main determinants of daily energy expenditure are body size and physical activity. Activity energy expenditure is the most variable component of total energy expenditure. It was assessed whether the physical activity level in confined conditions is an indicator of free-living physical activity. RESEARCH METHODS AND PROCEDURES: Activity energy expenditure was measured over 1 day in a confined environment of a respiration chamber (floor space, 7.0 m(2)), where activities were restricted to low-intensity activities of daily living, and over 2 weeks in a free-living environment using doubly labeled water. Subjects were 16 women and 29 men (age, 31 +/- 10 years; BMI, 24.2 +/- 2.7 kg/m(2)). RESULTS: The free-living activity level of the subjects, as a multiple of resting energy expenditure, was 1.76 +/- 0.13. Activity energy expenditure in the chamber was 47 +/- 13% of the value in daily life, and the two values were correlated (r = 0.50, p < 0.001; partial correlation corrected for age, gender, and BMI: 0.40, p < 0.01). The chamber value explained 25% of the total variance in free-living activity energy expenditure. DISCUSSION: The activity level of a subject under sedentary conditions is an indicator of activity energy expenditure in daily life, showing the importance of nonexercise activity for daily energy expenditure
Seasonal variation in sleeping metabolic rate, thyroid activity, and leptin
No full textSeasonal variation in sleeping metabolic rate, thyroid activity, and leptin. Plasqui G, Kester AD, Westerterp KR. Dept. of Human Biology, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands. [email protected] We investigated seasonal variation in sleeping metabolic rate (SMR) and the possible relation to body composition, thyroid activity, and leptin. Twenty-five healthy volunteers were examined four times during the year: in spring (April, May), summer (July, August), autumn (October, November), and winter (January, February). Body composition was determined using a three-compartment model based on underwater weighing and the deuterium dilution method. SMR was measured during an overnight stay in a respiration chamber. A blood sample was taken for the analysis of free and total thyroxine, TSH, and leptin. SMR showed a significant seasonal variation (P < 0.01) with a maximum in winter (4.54 kJ/min) and a minimum in summer (4.34 kJ/min). The amplitude was 0.10 +/- 0.02 kJ/min, and the phase was November 5th. Season explained 17% of the intraindividual variation in SMR. The circannual rhythm in SMR could not be explained by changes in body composition, thyroid activity, or leptin. Interindividual variation in SMR was explained by fat-free mass (P < 0.001) and leptin (P < 0.001)
Validation of a computerized metabolic measurement system (Oxycon-Pro) during low and high intensity exercise.
No full textInt J Sports Med 2001 May;22(4):291-4 Related Articles, Books, LinkOut Validation of a computerized metabolic measurement system (Oxycon-Pro) during low and high intensity exercise. Rietjens GJ, Kuipers H, Kester AD, Keizer HA. Department of Movement Sciences, Maastricht University, The Netherlands. [email protected] The aim of the study was to validate a new, fast metabolic measurement system (the Oxycon-Pro) during low and high exercise intensities against the Douglas bag method. For this purpose twelve highly trained subjects performed an incremental cycle ergometer test. In the third minute of each exercise step simultaneous measurements of the Douglas bag and the Oxycon-Pro were performed. No significant differences between the Oxycon-Pro and the Douglas bag measurements for minute ventilation (VE), oxygen uptake (VO2) and carbon dioxide expiration (VCO2) were found. Bland and Altman analysis of validity demonstrated minimal bias and low standard deviations. In conclusion, the results show that the Oxycon-Pro is a valid apparatus for determination of minute ventilation (VE), oxygen uptake (VO2) and carbon dioxide expiration (VCO2) during low as well as during maximal exercise intensities. Unlike with the Douglas bag method, this fast metabolic measurement system can be used for accurate and quick determination of ventilatory variables during exercise
A new validated endurance performance test.
No full textA new validated endurance performance test. Jeukendrup A, Saris WH, Brouns F, Kester AD. Department of Human Biology, University of Limburg, Maastricht, NETHERLANDS. The extensive use of performance tests in diet intervention studies mirrors the importance of such a measurement. Although many different endurance performance tests have been used in the past, the majority of these different protocols has never been validated. In this study reproducibility of three different endurance performance tests was evaluated. Thirty well-trained subjects were matched on age, weight, and Wmax and divided into three subgroups. Each group of subjects performed one of three exercise protocols: protocol (A) consisted of cycling at 75% Wmax until exhaustion. In (B) subjects received a preload of 45 min 70% Wmax and then performed as much work as possible in 15 min. (C) consisted of a time trial, in which subjects had to complete a preset amount of work as fast as possible. Each subject performed one of the trials six times. Coefficient of variation (CV) was calculated for each protocol. CV(A) was 26.6%, CV(B) 3.49%, and CV(C) 3.35%. It was concluded that reproducibility of a test at 75% Wmax until exhaustion is poor and these tests are not reliable. Time trial protocols may result in better performance evaluation
Effect of the dietary fat type on arterial thrombosis tendency: systematic studies with a rat model.
No full textDepartment of Human Biology, Maastricht University, Netherlands. [email protected] To study the influence of dietary fatty acids on arterial thrombosis tendency 65 groups of male rats were fed diets containing 50% of their digestible energy as fat from 32 different oils and fats. After 8 weeks their arterial thrombosis tendency was assessed by measuring the obstruction time (OT) of a loop-shaped polythene cannula inserted into the abdominal aorta. Using multiple regression analysis log10 OT was modelled as a function of the relative amounts of the various dietary fatty acids and their combinations. The best fit (R2 = 0.79) was obtained for the sums of all monoenoic and (n-6) and (n-3) polyenoic fatty acids, which appeared antithrombotic. The fit for the sum of all saturated fatty acids, which had a prothrombotic effect, was almost as good (R2 = 0.76). The ratio between dietary polyunsaturated and saturated fatty acids (P:S ratio) appeared a strong predictor of arterial thrombosis tendency (R2 = 0.77). Marine oils did not have a more powerful antithrombotic effect than could be expected on the basis of their P:S ratios. Using stepwise regression analysis myristic acid, 14:0, was shown to be the strongest prothrombotic fatty acid whereas linoleic acid, 18:2(n-6), was the strongest antithrombotic fatty acid. Since the number of marine oils was very limited the effects of the 'fish fatty acids' eicosapentaenoic acid, 20:5(n-3) and docosahexaenoic acid, 22:6(n-3), on arterial thrombus formation could not be tested reliably. The same appeared true for gamma-linolenic acid, 18:3(n-6), and stearidonic acid, 18:4(n-3), present in a few vegetable oils only
Use of a triaxial accelerometer to validate reported food intakes
No full text: Am J Clin Nutr 2001 Mar;73(3):549-53 Related Articles, Books, LinkOut Use of a triaxial accelerometer to validate reported food intakes. Goris AH, Meijer EP, Kester A, Westerterp KR. Departments of Human Biology and Methodology and Statistics, Maastricht University, Maastricht, Netherlands. [email protected] 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)
Long-chain polyunsaturated fatty acids at birth and cognitive function at 7 y of age
No full textLong-chain polyunsaturated fatty acids at birth and cognitive function at 7 y of age. Bakker EC, Ghys AJ, Kester AD, Vles JS, Dubas JS, Blanco CE, Hornstra G. Department of Human Biology, Universiteit Maastricht, The Netherlands. [email protected] OBJECTIVE: During the central nervous system (CNS) growth spurt, rapid accretion of long chain polyunsaturated fatty acids (LCPUFA) takes place. This particularly concerns docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6), which are thought to play important roles in CNS development and function. The aim of this study was to investigate the relationship between cognitive performance at 7 y of age and LCPUFA levels in umbilical venous plasma phospholipids, representing the prenatal fatty acid availability, and in plasma phospholipids sampled at 7 y. DESIGN: As part of a follow-up study, the cognitive performance of 306 children, born at term, was assessed at 7 y of age with the Kaufman Assessment Battery for Children. Backward stepwise regression analysis was used to study the relationship between the outcomes and LCPUFA status. Social class, maternal intelligence and parenting skills were included as covariables, among others. RESULTS: Results show no significant association with either DHA or AA at birth and the cognitive performance at 7 y of age. The LCPUFA levels at 7 y were not associated with these outcomes either. Consistent with the literature, significant relationships were found between cognitive outcome measures and maternal education, maternal intelligence and the child's birthweight. CONCLUSIONS: In conclusion, our results do not provide evidence for a positive association between cognitive performance at 7 y and LCPUFA status at birth or at 7 y of ag
Essential fatty acid composition of plasma phospholipids and birth weight: a study in term neonates.
No full text: Am J Clin Nutr 2001 Apr;73(4):797-806 Related Articles, Books, LinkOut Comment in: Am J Clin Nutr. 2001 Apr;73(4):671-2. Essential fatty acid composition of plasma phospholipids and birth weight: a study in term neonates. Rump P, Mensink RP, Kester AD, Hornstra G. Department of Human Biology and the Nutrition and Toxicology Research Institute Maastricht, Maastricht University, Maastricht, Netherlands. [email protected] BACKGROUND: Essential fatty acids (EFAs) in umbilical cord blood samples are associated with attained birth weight in premature infants and low-birth-weight neonates. OBJECTIVE: The objective was to investigate relations between the EFA composition of cord and maternal plasma phospholipids and birth weight in term neonates. DESIGN: This was a cross-sectional study in 627 singletons born at term. The plasma phospholipid EFA composition of the mothers was determined by gas-liquid chromatography at study entry (< or = 16 wk gestation), at delivery, and in cord plasma at birth. Birth weights were normalized to SD scores. RESULTS: In cord plasma, the dihomo-gamma-linolenic acid concentration was positively related to weight SD scores. Both arachidonic acid (AA) and docosahexaenoic acid (DHA) were negatively related to weight SD scores. EFA-status indicators showed similar negative associations, whereas eicosatrienoic acid concentrations were positively related to neonatal size. In maternal plasma, proportions of n-3 long-chain polyenes (LCPs) and n-6 LCPs decreased during pregnancy. Larger decreases in AA, DHA, n-3 LCP, and n-6 LCP fractions were observed in mothers of heavier babies. Higher concentrations of LCPs in maternal plasma were, however, not related to a larger infant size at birth. CONCLUSIONS: A lower biochemical EFA status in umbilical cord plasma and a larger decrease in maternal plasma LCP concentrations are associated with a higher weight-for-gestational-age at birth in term neonates. Our findings do not support a growth-stimulating effect of AA or DHA; however, they do suggest that maternal-to-fetal transfer of EFAs might be a limiting factor in determining neonatal EFA status
The inner strength of the designer: the role of intuition in the design proces
No full textThe aim of this research is to clarify the role of intuition in the design process. For this purpose, nineteen in depth interviews with designers were recorded and analysed. Through these interviews, it has been revealed that both rational as well as intuitive aspects play a part in the design process. This research shows a way of designing in which the development of the designer, the development of the designers intuition and the design process, all combines together. Conditions for a similar design methodology is the designers readiness to learn to consciously manage his inuition, through which he learns more about himself and his way of designing. Not only is he then capable of using his intuition in a more conscious manner, but also able to more consciously call on his rational cognition. In this way, a symbiosis can be created between the supposed conflicts in the design process, and the designer can develop a non-dualistic method of design.Industrial Design Engineerin
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