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Biomedical subjects

Klaas R Westerterp

Publications and source records attributed to Klaas R Westerterp.

At least 37 records · Page 2Linked to original sources
PubMed2004

Seasonal variation in total energy expenditure and physical activity in Dutch young adults.

OBJECTIVE: The impact of season on energy expenditure and physical activity is not well quantified. This study focused on summer-winter differences in total energy expenditure (TEE) and physical activity. RESEARCH METHODS AND PROCEDURES: Twenty-five healthy Dutch young adults, living in an urban environment, were measured in the summer season and the winter season. TEE was measured using doubly labeled water, and sleeping metabolic rate (SMR) was measured during an overnight stay in a respiration chamber. Subsequently, the physical activity level (PAL = TEE/SMR) and activity-related energy expenditure [(0.9 x TEE) - SMR] were calculated. Maximal mechanical power (Wmax) was determined with an incremental test on a cycle ergometer. Body composition was measured with hydrostatic weighing and deuterium dilution using Siri's three-compartment model. RESULTS: There was no difference in TEE between seasons. PAL was higher in summer than in winter (1.87 +/- 0.22 vs. 1.76 +/- 0.18; p < 0.001), and the difference was higher for men than for women (0.20 +/- 0.14 vs. 0.05 +/- 0.16; p = 0.04). The difference in PAL between seasons was dependent on the initial activity level. There was a strong linear relation (R2 = 0.48) between PAL and physical fitness (Wmax/fat-free mass), but Wmax/fat-free mass did not change between seasons in response to the lower PAL in winter. DISCUSSION: The extent of the changes in PAL is of physiological significance, and seasonality in physical activity should be taken into account when studying physical activity patterns or relationships between physical activity and health.

Adult↗
PubMed2004

Alcohol energy intake and habitual physical activity in older adults.

Alcohol forms a significant component of many diets and it supplements rather than displaces daily energy intake. Surprisingly, alcohol intake does not systematically increase body weight. The present study assessed whether a higher level of habitual physical activity in the daily environment is associated with a higher alcohol intake. Alcohol intake as part of total food intake was measured with a 7 d dietary record while at the same time physical activity was monitored with a tri-axial accelerometer for movement registration. Subjects were twenty women and twenty-four men, aged 61+/-5 years, of BMI 27.1+/-4.6 kg/m(2). Between subjects, there was a positive association between the level of habitual physical activity and alcohol intake (r 0.41; P<0.01). The subjects with higher alcohol intake had a higher activity level. On days with and days without alcohol consumption there was no difference in physical activity within subjects. In conclusion, it was shown that subjects with higher alcohol consumption are habitually more active. This may explain the lack of increasing body weight through additional energy intake from alcohol.

Alcohol Drinking↗
PubMed2004

Physical activity and human energy expenditure.

PURPOSE OF REVIEW: This is a review on the measurement of physical activity under daily life conditions. The focus is on the doubly labelled water method and accelerometry. Doubly labelled water is a gold standard and the reference for the validation of field methods to assess physical activity. Accelerometry is the most objective and precise technique to assess activity patterns in terms of frequency, duration and intensity. Applications of the two techniques are illustrated with the limits of physical activity and energy expenditure and with activity intensity as a determinant of the physical activity level. RECENT FINDINGS: The upper limit of the physical activity index (total energy expenditure as a multiple of basal metabolic rate) of 2.5, as derived from cross-sectional data, is confirmed by training intervention studies. Exercise training, in which total energy expenditure was measured before and at the end of the training programme, showed no increase in physical activity index when training was combined with an energy restricted diet and in elderly subjects. In children, the distribution of time spent at activities with low and high intensity determines the physical activity index while in adults moderate-intensity activities are the main determinant. SUMMARY: In adults, within the normal physical activity index range, the distribution of time spent at activities with low and moderate intensity determines the physical activity level. High-intensity activity does not have much impact on daily energy expenditure. High-intensity activity is not required to increase the activity energy expenditure.

Adult↗
PubMed2004

Comparative response of EPO and soluble transferrin receptor at high altitude.

PURPOSE: Soluble transferrin receptor (sTfR) classically raises with increased erythropoiesis, along with the rise in erythropoietin (EPO). However, the specific effect of altitude-induced erythropoiesis on sTfR remains poorly documented. This study investigated the response of sTfR during high-altitude exposure in human and verified that sTfR was related to EPO response in this case. METHODS: EPO, sTfR, red cell volume (RCV), ferritin, and iron intake were measured during: 1) experiment A (N = 8, 31 d at 5000-8848 m), at sea level (SL), and at the simulated altitude of 5000, 6000, 7000, and 8000 m; and 2) during experiment B (N = 10, 7 d at 4350 m), at SL, after 3, 5, and 7 d at 4350 m and 1-2 d after return to SL (RSL). RESULTS: In experiment A, progressive decompression from SL to 8000 m induced a large parallel rise in EPO (33.8-fold) and sTfR (5.9-fold), whereas ferritin was dramatically decreased and iron intake reduced. RCV was increased after 31 d of decompression. In experiment B, EPO peaked at day 3 at 4350 m, then declined later at altitude and returned to baseline values at RSL, whereas sTfR progressively rose at altitude (+86%) and remained elevated during RSL (+64%). Ferritin progressively declined at 4350 m, whereas iron intake was unchanged. RCV was not enhanced after exposure to 4350 m. CONCLUSION: In summary, sTfR mirrors EPO response for a given level of altitude hypoxia but differs from EPO response during transitory phases, such as early acclimatization or reoxygenation. Analysis of sTfR may therefore account for altitude-related erythropoiesis, at a time when EPO is blunted.

Altitude↗
PubMed2003

Physical activity level measured by doubly labeled water and accelerometry in children.

The present study investigated the use of a tri-axial accelerometer, Tracmor2, for the measurement of physical activity in children. Eleven children [age 6.9 (2.2) years, body mass 19.5 (5.3) kg and height 112.3 (14.4) cm] were studied. Total daily energy expenditure (TDEE) was measured using the doubly labeled water method over a 2-week period. In addition, basal metabolic rate (BMR) was determined by the ventilated hood system. Physical activity level (PAL) was defined as TDEE/BMR. Tracmor2 was worn during the same 2-week period throughout waking hours after which average counts per day were calculated. The average counts per day were shown to be highly correlated to PAL values measured by doubly labeled water: PAL = 1.156 x 10(-5) x Tracmor2 average counts day(-1) + 0.978 (r=0.79, P<0.01). In conclusion, Tracmor2 is a valid instrument to measure physical activity in children under free-living conditions.

Basal Metabolism↗
PubMed2003

Physical activity in confined conditions as an indicator of free-living physical activity.

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.

Activities of Daily Living↗
PubMed2003

Energy balance in depleted ambulatory patients with chronic obstructive pulmonary disease: the effect of physical activity and oral nutritional supplementation.

Patients with chronic obstructive pulmonary disease (COPD) often suffer from weight loss. The aim of the present study was to gain insight into the energy balance of depleted ambulatory COPD patients, in relation to their habitual level of physical activity and consumption of oral nutritional supplements. Clinically stable and weight-stable patients (n 20; BMI 19.8+/- SD 2.0 kg/m2) were studied 1 and 3 months after rehabilitation or recovery in the clinic and were at random assigned to a control or intervention group with regard to nutritional supplementation. Energy intake was measured with a 7 d food record. Energy expenditure was estimated from a simultaneous 7 d assessment of physical activity with a tri-axial accelerometer for movement registration in combination with measured BMR. Body mass was measured at several time points. The body mass remained stable in both groups after 1 or 3 months and mean energy balances were comparable for both groups. The mean body-mass change between month 1 and 3 was negatively related to the mean physical activity level (r -0.49; P=0.03). Weight change over the 3 months was negatively associated with the physical activity level. These results suggest that knowledge about the individual physical activity level is necessary for the estimation of the energy need of the COPD patient.

Body Mass Index↗
PubMed2003

Intra-individual variation of basal metabolic rate and the influence of daily habitual physical activity before testing.

The present study determined the intra-individual variation of BMR measurements, using a standard out-patient protocol, with the subjects transporting themselves to the laboratory for the BMR measurements after spending the night at home. The effect of a non-fasting state and variation in daily habitual physical activity the day before testing was evaluated. Eight male and eleven female subjects participated in three BMR measurements with 2-week intervals. Physical activity was estimated with a tri-axial accelerometer for movement registration, during the 3 d before each BMR measurement. There were no significant differences in estimated BMR (ANOVA repeated measures, P=0.88) and in physical activity (ANOVA repeated measures, P=0.21). Mean within-subject CV in BMR was found to be 3.3 (SD 2.1) %, ranging from 0.4 to 7.2 %. Differences between BMR measurements could not be explained by differences in physical activity the day before; however the mean within-subject CV in BMR changed from 5.7 to 5.2 % after correcting for within-machine variability and from 5.2 to 3.3 % after excluding five measurements because of non-compliance to the protocol including fasting. In conclusion, BMR values measured with a standard out-patient protocol are sufficiently reproducible for most practical purposes despite the within-subject variability in physical activity the day before the measurement. For this purpose, however, non-fasting subjects must be excluded and a regular function check of the ventilated-hood system is recommendable.

Adult↗
PubMed2003

Habitual meal frequency in relation to resting and activity-induced energy expenditure in human subjects: the role of fat-free mass.

Habitual meal frequency was assessed as a possible function of components of energy expenditure (EE) in human subjects. Fifty-six subjects participated (four categories differing in body composition): ten older women (fat-free mass (FFM) 42.0 (sd 6.3) kg, aged 59 (sd 2) years, BMI 27.5 (sd 6.9) kg/m(2)), fifteen younger women (FFM 45.5 (sd 5.2) kg, aged 34 (sd 10) years, BMI 21.9 (sd 2.3) kg/m(2)), twelve older men (FFM 56.8 (sd 5.9) kg, aged 62 (sd 4) years, BMI 25.7 (sd 3.3) kg/m(2)) and nineteen younger men (FFM 63.9 (sd 7.5) kg, aged 23.1 (sd 3.9) years, BMI 22.9 (sd 1.8) kg/m(2)). Measurements consisted of habitual meal frequency by validated food-intake diaries, physical activity by tri-axial accelerometers and resting EE by a ventilated hood system. Habitual meal frequency was expressed as a function of resting EE (including resting EE as a function of FFM), and of activity-induced EE, using regression analysis. FFM differed according to gender and age categories (P<0.01). Physical activity level was higher in the younger men than in the other categories (P<0.05). No relationship of meal frequency with the variables assessed was observed in subjects with a low FFM (the women). In the subjects with a medium FFM (the older men), meal frequency was positively related to resting EE (r(2) 0.4, P<0.05), but not to the residuals of resting EE as a function of FFM, and inversely related to activity-induced EE (r(2) 0.3, P<0.05). Resting EE explained 40 % of the variation in meal frequency; adding activity-induced EE increased this to 60 %. In the subjects with a high FFM (the younger men), meal frequency was inversely related to resting EE (r(2) 0.8, P<0.0001) and to the residuals of resting EE as a function of FFM (P=0.03), and positively related to activity-induced EE (r(2) 0.6, P<0.0001). Resting EE explained 85 % of the variation in meal frequency; adding activity-induced EE increased this to 89 %. Habitual meal frequency was a function of components of EE, namely resting EE and activity-induced EE, only in subjects with a medium to high FFM (men). FFM-related differences in these relationships suggest a role of physical activity.

Adult↗
PubMed2003

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.

Adult↗
PubMed2003

Using a correction factor to correct for overreporting in a food-frequency questionnaire does not improve biomarker-assessed validity of estimates for fruit and vegetable consumption.

To correct for overreporting of fruit and vegetable (FV) consumption in a food-frequency questionnaire, summary questions about consumption of main FV groups are often used to calculate correction factors. This study compared the ability to rank people according to their FV intake of those summary questions and the sum of questions on individual FV items within categories, and of corrected or uncorrected estimates of specific sorts of FV. Healthy middle-age women (n = 161) completed a food-frequency questionnaire about FV consumption during the previous month and gave a single fasting blood sample. Correction factors were calculated as the reported frequency on a summary question divided by the summed frequencies of all items in a category. Plasma carotenoids and vitamin C served as biomarkers of FV consumption. Significant correlations between FV consumption and biomarkers were observed (e.g., Spearman's correlation coefficient r with total carotenoids/vitamin C: 0.32/0.34 for vegetables, 0.30/0.25 for fruits). Summary estimates of cooked, raw and total vegetable consumption correlated higher with biomarkers than sum estimates. For fruits no differences in correlations between sum and summary estimates were observed. Applying a correction factor on the consumption of carrots and total cabbage resulted in lower correlations with relevant biomarkers. For broccoli/cauliflower, Brussels sprouts and citrus fruits, correlations with biomarkers did not change after correction. We conclude that summary questions may suffice to rank individuals according to their intake of main FV categories, and that correction for overreporting of individual FV items is probably not advisable when ranking individuals according to intake of these items.

Adult↗
PubMed2003

Seasonal variation in sleeping metabolic rate, thyroid activity, and leptin.

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).

Adult↗
PubMed2003

Short-term effects of growth hormone on body composition as a predictor of growth.

The objective of this study was to investigate whether short-term changes in metabolism, as a result of GH therapy, could be used to predict its growth effect after 1 yr. Twenty-eight children (8.7 +/- 2.8 yr) were selected, based on anthropometric criteria characterizing GH-deficient patients. In addition, 21 healthy, age- and sex-matched controls (8.9 +/- 3.1 yr) were included. Total body water (TBW) and height were measured before and at 6 wk and 1 yr after the start of treatment. After 1 yr of treatment, patients were divided into good and poor responders, based on a change in height of at least 0.7 SD. Because individuals of different heights were compared, changes in TBW after 6 wk were corrected for height(2), in accordance with the body mass index. Eighty percent of the children who showed a good response to GH therapy had a change in TBW divided by height(2) exceeding the 2 SD reference line of the controls. In contrast, poor responders did not differ from controls. Maximum GH concentrations found during endocrine tests were not significantly different between good and poor responders. Changes in body composition data, after 6 wk, proved valuable in identifying good responders to GH therapy.

Body Composition↗
PubMed2002

Exercise-induced oxidative stress in older adults as a function of habitual activity level.

OBJECTIVES: It has been suggested that regular physical activity might maintain and promote the antioxidant defense capacity against oxidative stress. Therefore, we assessed exercise-induced oxidative stress in relation to habitual physical activity level (PAL) in older adults. DESIGN: The study included a 2-week observation period for the measurement of average daily metabolic rate (ADMR) and PAL. Exercise-induced oxidative stress was measured during a 45-minute cycling test at submaximal intensity. SETTING: A university medical research center. PARTICIPANTS: Twenty-six subjects volunteered for the study (n = 26; mean age +/- standard deviation 60 +/- 1; body mass index 27 +/- 1 kg/m2). MEASUREMENTS: PAL was determined as ADMR combined with a measurement of basal metabolic rate (BMR): PAL = ADMR/BMR. ADMR was measured over 2 weeks with the doubly labeled water method, preceded by a BMR measurement with a ventilated hood. Antipyrine oxidation was used as marker for oxidative stress in vivo. Reaction of antipyrine with hydroxyl radicals results in the formation of para-hydroxyantipyrine (p-APOH) and ortho-hydroxyantipyrine (o-APOH), where o-APOH is not formed through alternative oxygenetic pathways. RESULTS: PAL was inversely related to the exercise-induced increase in the ratio of o-APOH to native antipyrine (r = 0.49, P = .010). The relationship between PAL and exercise-induced increase in the ratio of p-APOH (r = 0.30, P = .140) or thiobarbituric acid reactive species (r = 0.31, P = .130) did not reach the level of significance. CONCLUSION: Physically active older adults have a reduced exercise-induced oxidative stress than older adults with a lower level of physical activity. It seems that regular physical activity improves the antioxidant defense capacity.

Aged↗
PubMed2002

Validity of reported energy expenditure and energy and protein intakes in Swedish adolescent vegans and omnivores.

BACKGROUND: It is difficult to obtain accurate reports of dietary intake; therefore, reported dietary intakes must be validated. Researchers need low-cost methods of estimating energy expenditure to validate reports of energy intake in groups with different lifestyles and eating habits. OBJECTIVE: We sought to validate the reported energy expenditure and energy and protein intakes of Swedish adolescent vegans and omnivores. DESIGN: We compared 16 vegans (7 females and 9 males; mean age: 17.4 +/- 0.8 y) with 16 omnivores matched for sex, age, and height. Energy expenditure as reported in a physical activity interview and energy and protein intakes as reported by diet history were validated by using the doubly labeled water method and by measuring urinary nitrogen excretion. RESULTS: The validity of reported energy expenditure and energy and protein intakes was not significantly different between vegans and omnivores. The physical activity interview had a bias toward underestimating energy expenditure by 1.4 +/- 2.6 MJ/d (95% CI: 2.4, 0.5 MJ/d). The diet-history interview had a bias toward underestimating energy intake by 1.9 +/- 2.7 MJ/d (95% CI: 2.9, 1.0 MJ/d) but showed good agreement with the validation method for nitrogen (protein) intake (underestimate of 0.40 +/- 1.90 g N/d; 95% CI: 1.10, 0.29 g N/d). CONCLUSIONS: The physical activity and diet-history interviews underestimated energy expenditure and energy intake, respectively. Energy intake and expenditure were underestimated to the same extent, and the degree of underestimation was not significantly different between vegans and omnivores. Valid protein intakes were obtained with the diet-history method for both vegans and omnivores.

4-Aminobenzoic Acid↗
PubMed2002

Validity of the assessment of dietary intake: problems of misreporting.

PURPOSE OF REVIEW: This is a review of recent studies on the analysis of misreporting of food intake and on the consequences of misreporting for the interpretation of dietary surveys. Bias in the assessment of dietary intake was analysed from studies comparing reported intake with doubly labelled water assessed energy expenditure. RECENT FINDINGS: There is not yet a method for the accurate determination of dietary intake. Physical and psychological characteristics of study participants play an important role in the observed reporting bias. The degree of misreporting might increase with repeated dietary assessment in the same subjects, confounding the results of intervention studies. SUMMARY: Campaigns aimed at changing food intake might not be as successful as concluded from the results of national food consumption measurements. Subjects might be reporting according to expected instead of real intake. In a clinical setting, the increased awareness of the nursing staff has been observed to result in overreporting of intake.

Bias↗