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Biomedical subjects

W van Mechelen

Publications and source records attributed to W van Mechelen.

At least 37 records · Page 2Linked to original sources
PubMed2003

Computerization of a dietary history interview in a running cohort; evaluation within the Amsterdam Growth and Health Longitudinal Study.

OBJECTIVE: In nutritional research, a growing interest in the use of computer-assisted cross-check dietary history interview methods exists in order to improve cost-effectiveness. The introduction of such a method in an ongoing longitudinal study was evaluated with special emphasis on the effect on interviewer bias. DESIGN: A study for the interviewer bias within and the agreement between a previously used paper-based face-to-face cross-check dietary history interview method and a newly developed interviewer-administered computer-assisted version of this interview method. SUBJECTS: The interviewer bias of 436 face-to-face interviews is compared with that of 352 computer-assisted interviews. A subset of 82 subjects underwent a face-to-face interview at the mean age of 27 and 32 y and a computer-assisted interview at their mean age of 36 y. Energy, three macronutrients (protein, fat and carbohydrate), two micronutrients (calcium and iron) and alcohol intakes obtained by these three measurements are compared to analyse the agreement between the two interview methods. RESULTS: ANOVA showed no interviewer bias for all seven analysed nutrients within the data from the computer-assisted interview, while for the face-to-face interview method, several nutrients varied significantly among the interviewers. Five different measures, used to analyse the agreement (differences, Pearson's correlation, ICC, square weighted kappa and Bland-Altman plots), showed no relevant differences between the two cross-check dietary history interview methods. CONCLUSIONS: It is concluded that the computer-assisted interview caused a reduction of interviewer bias and is of similar quality to the face-to-face interview method. Computerization of a paper-based interview can be implemented in a running cohort if a change in method is unavoidable.

Adult↗
PubMed2003

Short term effect of feedback on fitness and health measurements on self reported appraisal of the stage of change.

BACKGROUND: An individual's current status of physical activity and nutrition and readiness to change can be determined using PACE assessment forms. Practitioners have suggested that feedback on the fitness and health components can produce a change in a subject's awareness of their behaviour and thereby lead to a beneficial change in stage of behaviour change. OBJECTIVE: To evaluate the short term effect of personalised feedback on fitness and health status on self reported appraisal of the stage of change. METHODS: A total of 299 civil servants were randomised to an intervention or a reference group. After having been tested for fitness and health, the intervention group received immediate feedback on their test results, whereas the reference group did not. PACE assessment forms were completed twice: before testing and after testing (reference group), or after testing and feedback (intervention group). The time interval between was one hour. The influence of feedback was determined using a x(2) test and analysis of variance. RESULTS: On the basis of the x(2) test, no significant effect of feedback was found on the stage of change of physical activity, nor on the stage of change with regard to nutrition. Analysis of variance results showed no significant effect on the raw PACE score as to physical activity, intake of fruit and vegetables and dietary fat. However, a significant effect was observed on the PACE score of "calorie intake and weight management". Subjects in the intervention group significantly more often regressed on their PACE score on this topic than the reference subjects. CONCLUSIONS: Feedback at baseline on measurements of an intervention study can influence PACE scores and can be considered as a small but relevant start of the intervention itself.

Adaptation, Psychological↗
PubMed2003

Occupational health guidelines for the management of low back pain: an international comparison.

BACKGROUND: The enormous socioeconomic burden of low back pain emphasises the need for effective management of this problem, especially in an occupational context. To address this, occupational guidelines have been issued in various countries. AIMS: To compare available international guidelines dealing with the management of low back pain in an occupational health care setting. METHODS: The guidelines were compared regarding generally accepted quality criteria using the AGREE instrument, and also summarised regarding the guideline committee, the presentation, the target group, and assessment and management recommendations (that is, advice, return to work strategy, and treatment). RESULTS: and CONCLUSIONS: The results show that the quality criteria were variously met by the guidelines. Common flaws concerned the absence of proper external reviewing in the development process, lack of attention to organisational barriers and cost implications, and lack of information on the extent to which editors and developers were independent. There was general agreement on numerous issues fundamental to occupational health management of back pain. The assessment recommendations consisted of diagnostic triage, screening for "red flags" and neurological problems, and the identification of potential psychosocial and workplace barriers for recovery. The guidelines also agreed on advice that low back pain is a self limiting condition and, importantly, that remaining at work or an early (gradual) return to work, if necessary with modified duties, should be encouraged and supported.

Disability Evaluation↗
PubMed2002

Effects of health information in youth and young adulthood on risk factors for chronic diseases--20-year study results from the Amsterdam Growth and Health Longitudinal Study.

In the Amsterdam Growth and Health Longitudinal Study (AGAHLS) biological risk factors for chronic diseases were measured on eight separate occasions over a period of 20 years in a group of apparently healthy males and females (n = 164). Data were first collected from participants at 13 years of age. At each of the eight measurements, a medical checkup was performed and participants were given information about their current health status based on their personal biological risk factor profile (cholesterol, blood pressure, body composition, and physical fitness). A comparable group (n = 113) was measured on two occasions only: at age 13 and again at age 33. It was hypothesized that the group with eight measurements would present a more favorable 20-year development of the risk factors than the group with only two measurements. In the present article the six additional measurements with personal feedback of one's health status were perceived as an "intervention," even though the AGAHLS never intended to improve the lifestyle or health of its subjects. The intervention appeared to have had a positive effect on body fat distribution and, in men, on systolic blood pressure. However, it was expected that these significant results were not true effects of the intervention, but that they were type-I errors. For the other variables, total cholesterol, high-density lipoprotein cholesterol, and the ratio between these two, for the sum of four skinfolds, diastolic blood pressure, neuromotor fitness, and for maximal oxygen uptake, the 20-year development did not differ between the two groups. Thus, the effects of a 20-year health measurement and information intervention begun in youth on biologic risk factors for chronic diseases were limited. The absence of clear significant findings may be due to the low contrast between the two groups, as only six intervention measurements were conducted over a period of 20 years. Another reason may be that the young and relatively healthy population under study here was not amenable to changing their fitness and health.

Adolescent↗
PubMed2002

Validation of a physical activity questionnaire to measure the effect of mechanical strain on bone mass.

Most of the questionnaires available to estimate the daily physical activity levels of humans are based on measuring the intensity of these activities as multiples of resting metabolic rate (METs). Metabolic intensity of physical activities is the most important component for evaluating effects on cardiopulmonary fitness. However, animal studies have indicated that for effects on bone mass the intensity in terms of energy expenditure (metabolic component) of physical activities is less important than the intensity of mechanical strain in terms of the forces by the skeletal muscles and/or the ground reaction forces. The physical activity questionnaire (PAQ) used in the Amsterdam Growth and Health Longitudinal Study (AGAHLS) was applied to investigate the long-term effects of habitual physical activity patterns during youth on health and fitness in later adulthood. The PAQ estimates both the metabolic components of physical activities (METPA) and the mechanical components of physical activities (MECHPA). Longitudinal measurements of METPA and MECHPA were made in a young population of males and females ranging in age from 13 to 32 years. This enabled evaluation of the differential effects of physical activities during adolescence (13-16 years), young adulthood (21-28 years), and the total period of 15 years (age 13-28 years) on bone mineral density (BMD) of the lumbar spine, as measured by dual-energy X-ray absorptiometry (DXA) in males (n = 139) and females (n = 163) at a mean age of 32 years. The PAQ used in the AGAHLS during adolescence (13-16 years) and young adulthood (21-28 years) has the ability to measure the physical activity patterns of both genders, which are important for the development of bone mass at the adult age. MECHPA is more important than METPA. The highest coefficient of 0.33 (p < 0.01) was between MECHPA measured over the total period of 15 years (13-28 years) and lumbar BMD at age 32 years. Only during adolescence (12-16 years) was METPA more important with regard to lumbar BMD at age 32 years, with a beta of 0.21 (p < 0.01). The relative validity of the PAQ was established by comparing PAQ scores during four annual measurements in 200 boys and girls with two other objective measures of physical activity: movement counters (pedometers) and heart rate monitoring. These showed significant (p < 0.01) correlations in both genders, varying between 0.16 and 0.20. The small variation indicates, however, that all three instruments measure different aspects of physical activity. The results from the PAQ, with respect to MECHPA, validated in humans the results from animal studies in which bone adaptation during skeletal growth and development continuously adjust skeletal mass and architecture to changing mechanical stimuli caused by physical activity.

Absorptiometry, Photon↗
PubMed2002

The relationship between physical fitness and physical activity during adolescence and cardiovascular disease risk factors at adult age. The Amsterdam Growth and Health Longitudinal Study.

The purpose of this study was to analyse the relationship between physical activity and physical fitness during adolescence (between 13 and 16 years of age) and cardiovascular disease (CVD) risk factors at adult age (32 years). The following CVD risk factors were considered: lipoprotein levels (total serum cholesterol (TC), high density lipoprotein cholesterol (HDL), the TC:HDL ratio, systolic and diastolic blood pressure, and indicators for body fatness and body fat distribution (sum of four skinfolds, waist to hip ratio, waist circumference). The data were derived from the Amsterdam Growth and Health Longitudinal Study, an observational longitudinal study in which eight repeated measurements were carried out over a period of 20 years. Physical fitness (measured by maximal oxygen uptake per kg bodyweight and by maximal slope reached on a treadmill test) during adolescence was related to a healthy CVD risk profile at the age of 32 years (i. e. inversely to the sum of four skinfolds, waist circumference and to total serum cholesterol). Physical activity during adolescence was not related to a healthy CVD risk profile at the age of 32 years.

Adolescent↗
PubMed2002

High physical work load and low job satisfaction increase the risk of sickness absence due to low back pain: results of a prospective cohort study.

OBJECTIVE: To determine whether physical and psychosocial load at work influence sickness absence due to low back pain. METHODS: The research was a part of the study on musculoskeletal disorders, absenteeism, stress, and health (SMASH), a 3 year prospective cohort study on risk factors for musculoskeletal disorders. Workers from 21 companies located throughout The Netherlands participated in the part of this study on sickness absence due to low back pain. The study population consisted of 732 workers with no sickness absences of 3 days or longer due to low back pain in the 3 months before the baseline survey and complete data on the reasons for absences during the follow up period. The mean (range) period of follow up in this group was 37 (7-44) months. Physical load at work was assessed by analyses of video recordings. Baseline information on psychosocial work characteristics was obtained by a questionnaire. Data on sickness absence were collected from company records. The main outcome measure was the rate of sickness absences of 3 days or longer due to low back pain during the follow up period. RESULTS: After adjustment of the work related physical and psychosocial factors for each other and for other potential determinants, significant rate ratios ranging from 2.0 to 3.2 were found for trunk flexion, trunk rotation, lifting, and low job satisfaction. A dose-response relation was found for trunk flexion, but not for trunk rotation or lifting. Non-significant rate ratios of about 1.4 were found for low supervisor support and low coworker support. Quantitative job demands, conflicting demands, decision authority, and skill discretion showed no relation with sickness absence due to low back pain. CONCLUSIONS: Flexion and rotation of the trunk, lifting, and low job satisfaction are risk factors for sickness absence due to low back pain. Some indications of a relation between low social support, either from supervisors or coworkers, and sickness absence due to low back pain are also present.

Absenteeism↗
PubMed2002

Comparison of two different approaches for the analysis of data from a prospective cohort study: an application to work related risk factors for low back pain.

AIMS: To compare the results of a traditional approach using standard regression for the analysis of data from a prospective cohort study with the results of generalised estimating equations (GEE) analysis. METHODS: The research was part of a three year prospective cohort study on work related risk factors for low back pain. The study population consisted of a cohort of 1192 workers with no low back pain at baseline. Information on work related physical and psychosocial factors and the occurrence of low back pain was obtained by means of questionnaires at baseline and at the three annual follow up measurements. In a traditional standard logistic regression model, physical and psychosocial risk factors at baseline were related to the cumulative incidence of low back pain during the three year follow up period. In a GEE logistic model, repeated measurements of the physical and psychosocial risk factors were related to low back pain reported at one measurement point later. RESULTS: The traditional standard regression model showed a significant effect of flexion and/or rotation of the upper part of the body (OR = 1.8; 95% CI: 1.2 to 3.0), but not of moving heavy loads (OR = 1.4; 95% CI: 0.7 to 3.1). The GEE model showed a significant effect of both flexion and/or rotation of the upper part of the body (OR = 2.2; 95% CI: 1.5 to 3.3) and moving heavy loads (OR = 1.5; 95% CI: 1.0 to 2.4). No significant associations with low back pain were found for the psychosocial work characteristics with either method, but the GEE model showed weaker odds ratios for these variables than the traditional standard regression model. CONCLUSIONS: Results show that there are differences between the two analytical approaches in both the magnitude and the precision of the observed odds ratios.

Follow-Up Studies↗
PubMed2001

High quantitative job demands and low coworker support as risk factors for neck pain: results of a prospective cohort study.

STUDY DESIGN: A 3-year prospective cohort study among 1334 workers was conducted. OBJECTIVE: To determine whether the work-related psychosocial factors of quantitative job demands, conflicting job demands, skill discretion, decision authority, supervisor support, coworker support, and job security are risk factors for neck pain. SUMMARY OF BACKGROUND DATA: Among the various risk factors for neck pain, work-related psychosocial factors play a major role. Previous studies on risk factors for neck pain often had a cross-sectional design, and did not take both physical and psychosocial factors into account. METHODS: At baseline, data on work-related psychosocial factors were collected by means of a questionnaire. During the 3-year follow-up period, data on the occurrence of neck pain were collected by means of postal questionnaires. Individuals without neck pain at baseline were selected for the analyses. Cox regression analysis was applied to examine the relation between the work-related psychosocial factors and the cumulative incidence of neck pain. Adjustments were made for various physical factors and individual characteristics. RESULTS: The analysis included 977 patients. Altogether, 141 workers (14.4%) reported that they had experienced neck pain at least once during the 3-year follow-up period. The relation of neck pain to high quantitative job demands (relative risk [RR], 2.14; 95% confidence interval [CI], 1.28-3.58) and low coworker support (RR, 2.43; 95% CI, 1.11-5.29) was statistically significant. An increased risk was found for low decision authority in relation to neck pain (RR, 1.60; 95% CI, 0.74-3.45), but this relation was not statistically significant. CONCLUSIONS: High quantitative job demands and low coworker support are independent risk factors for neck pain. There are indications that another risk factor for neck pain is low decision authority.

Adult↗
PubMed2001

ATP utilization for calcium uptake and force production in different types of human skeletal muscle fibres.

The contractile properties and ATPase activity of skinned human skeletal muscle fibres from vastus lateralis were examined. Fibre types were resolved from single fibre segments by SDS-polyacrylamide gel electrophoresis. ATPase activity was determined by enzymatic coupling of ATP resynthesis to the oxidation of NADH. The partitioning of ATPase activity into (a) calcium-activated activity due to actomyosin (AM) interaction, (b) calcium-activated activity of the sarcoplasmic reticular (SR) calcium pump, and (c) basal (calcium independent) activity was investigated by comparing ATP utilization before and after exposure of the preparations for 30 min to a solution containing 0.5 % Triton X-100, which effectively abolished the SR ATPase activity. Partitioning of ATPase activity was also determined by measuring ATP utilization and force at different concentrations of butanedione monoxime (BDM), which inhibits AM interaction. The results obtained with Triton X-100 and BDM were similar. At saturating Ca2+ concentrations and 20 degrees C, the AM, SR and basal ATPase activities per litre cell volume (+/- S.E.M.) amounted to 46 +/- 4, 51 +/- 4 and 19 +/- 2 muM s-1 in type I fibres (n = 21), 139 +/- 14, 69 +/- 8 and 30 +/- 3 muM s-1 in type IIA fibres (n = 25), 137 +/- 22, 175 +/- 28 and 26 +/- 8 muM s-1 in type IIA/B fibres (n = 4) and 108 +/- 13, 169 +/- 42 and 32 +/- 8 muM s-1 in type IIB fibres (n = 2). These results indicate that ATP utilization for SR Ca2+ pumping in fast fibres is considerably larger than in slow fibres. The SR ATPase activity in human muscle represents a considerable fraction of the total (AM + SR + basal) ATPase activity.

Adenosine Triphosphatases↗
PubMed2001

Psychosocial risk factors for neck pain: a systematic review.

BACKGROUND: Neck pain, which is assumed to be a multifactorial disease, is a major problem in modern society. METHODS: To identify the most important psychosocial risk factors for neck pain, a systematic review of the literature was carried out. The methodological quality of all studies in the review was assessed. Four levels of evidence were defined to assess the strength of evidence for potential risk factors for neck pain (strong, moderate, some or inconclusive evidence). RESULTS: Some evidence was found for a positive relationship between neck pain and high quantitative job demands, low social (coworker) support, low job control, high and low skill discretion and low job satisfaction. Inconclusive evidence was found for high job strain, low supervisor support, conflicts at work, low job security, and limited rest break opportunities. CONCLUSIONS: The procedure of the assessment of the methodological quality and the rating system applied to distinguish between high- and low-score studies, had a considerable influence on the level of evidence, indicating that changes in this procedure may have a major impact on the overall conclusions of this review.

Humans↗
PubMed2001

A 15-year physical activity pattern is positively related to aerobic fitness in young males and females (13-27 years).

The purpose of this paper is to test the hypothesis that daily physical activity over a period of 15 years has been beneficial to aerobic fitness in young male and female participants (13-27 years) in the Amsterdam Growth and Health Longitudinal Study. Only subjects with the maximal data of six sets of measurements were included (83 male and 98 female participants). Daily physical activity was assessed using a standardized interview on activity and expressed as a weighted activity score. Aerobic fitness was assessed using a maximal running test on a treadmill and measuring the maximal oxygen uptake (VO2max) and the maximal slope of the track (Smax). To assess the longitudinal relationship between daily physical activity and aerobic fitness a real longitudinal analysis was carried out with generalized estimating equations, adjusting for differences in initial aerobic fitness at age 13, and for other lifestyle (dietary intake, smoking and alcohol consumption) and biological parameters (biological age, body fat, blood pressure and concentration of serum cholesterol). A significant relationship (P < 0.01) was observed between daily physical activity and both VO2max and Smax. It can be concluded that the development of aerobic fitness between the age of 13 and 27 years is independently and positively related to daily physical activity in this group of male and female participants in the study. The functional implications, however, are small: a relatively high increase in the weighted physical activity score of 30% over a period of 15 years results in a 2%-5% increase in aerobic fitness.

Adolescent↗
PubMed2001

Phosphocreatine and ATP content in human single muscle fibres before and after maximum dynamic exercise.

The recovery of high-energy phosphate levels in single human skeletal muscle fibres following short-term maximal (all-out) exercise was investigated. Three male volunteers exercised maximally for 25 s on an isokinetic cycling ergometer. Muscle biopsy samples from the vastus lateralis were collected at rest, immediately post-exercise and at 1.5 min of recovery. The subjects also performed a second exercise bout 1.5 min after the first, on a separate occasion. Single muscle fibres were dissected, characterized and assigned to one of four groups according to their myosin heavy chain (MyHC) isoform content; namely, type I, IIA, IIAx and IIXa (the latter two groups containing either less or more than 50% IIX MyHC). Fibres were analysed for adenosine 5'-triphosphate (ATP), inosine-5'-monophosphate (IMP), phosphocreatine (PCr) and creatine (Cr) levels. Type I fibres had a lower Cr content than type II fibres (P<0.01). Within type II fibres resting [PCr] increased with increasing MyHC IIX isoform content (r=0.59, P<0.01). Post-exercise [PCr] was very low in all fibre groups (P<0.01 versus rest) while great reductions in ATP were also observed (P<0.01 versus rest), especially in the type II fibre groups. [PCr] at 1.5 min of recovery was still lower compared to rest for all fibre groups (P<0.01) especially in the IIAx and IIXa fibres.

Adenosine Triphosphate↗
PubMed2001

Effects of health measurements and health information in youth and young adulthood in dietary intake--20-y study results from the Amsterdam Growth and Health Longitudinal Study.

BACKGROUND: The Amsterdam Growth and Health Longitudinal Study (AGAHLS) is a 20 y observational study concerning biological, psychological and lifestyle risk factors for cardiovascular disease and osteoporosis. In the AGAHLS two cohorts can be distinguished: the so-called Multi-Measurement Group (MMG), which received eight repeated measurements, and a Bi-Measurement Group (BMG), which received two measurements, one at the beginning and one at the end of the 20 y period. OBJECTIVE: In health-related longitudinal research, the outcomes of the study may be influenced by the measurements themselves and the health information provided. It was hypothesized that the repeated measurements and the health information given to the MMG would result in a more healthy dietary intake in comparison to the BMG. DESIGN: The MMG consisted of 164 subjects and the BMG consisted of 90 subjects. At the start of the study, subjects were teenagers of 13-y-old. The hypothesis was tested with use of regression analysis, analysing group differences in mean individual change scores. RESULTS: Only the MMG showed a significantly larger decrease in the intake of mono- and disaccharides compared to the BMG. CONCLUSIONS: The effect of the repeated measurements and the health information provided on dietary intake was relatively small, since it was only one out of the 14 nutrients that differed between the MMG and the BMG.

Adolescent↗
PubMed2001

Metabolism changes in single human fibres during brief maximal exercise.

Changes in high-energy phosphate levels in single human skeletal muscle fibres after 10 s of maximal (all-out) dynamic exercise were investigated. Muscle biopsies from vastus lateralis of two volunteers were collected at rest and immediately post exercise. Single muscle fibres were dissected from dry muscle and were assigned into one of four groups according to their myosin heavy chain (MyHC) isoform content: that is type I, IIA, IIAx and IIXa (the latter two groups containing either less or more than 50% IIX MyHC). Fragments of characterised fibres were analysed by HPLC for ATP, inosine-monophosphate (IMP), phosphocreatine (PCr) and creatine levels. After 10 s of exercise, PCr content ([PCr]) declined by approximately 46, 53, 62 and 59 % in type I, IIA, IIAx and IIXa fibres, respectively (P < 0.01 from rest). [ATP] declined only in type II fibres, especially in IIAx and IIXa fibres in which [IMP] reached mean values of 16 +/- 1 and 18 +/- 4 mmol (kg dry mass)(-1), respectively. While [PCr] was reduced in all fibre types during the brief maximal dynamic exercise, it was apparent that type II fibres expressing the IIX myosin heavy chain isoform were under a greatest metabolic stress as indicated by the reductions in [ATP].

Adenosine Triphosphate↗
PubMed2001

Are neck flexion, neck rotation, and sitting at work risk factors for neck pain? Results of a prospective cohort study.

OBJECTIVE: To study the relation between neck pain and work related neck flexion, neck rotation, and sitting. METHODS: A prospective cohort study was performed with a follow up of 3 years among 1334 workers from 34 companies. Work related physical load was assessed by analysing objectively measured exposure data (video recordings) of neck flexion, neck rotation, and sitting posture. Neck pain was assessed by a questionnaire. Adjustments were made for various physical factors that were related or not related to work, psychosocial factors, and individual characteristics. RESULTS: A significant positive relation was found between the percentage of the working time in a sitting position and neck pain, implying an increased risk of neck pain for workers who were sitting for more than 95% of the working time (crude relative risk (RR) 2.01, 95% confidence interval (95% CI) 1.04 to 3.88; adjusted RR 2.34, 95% CI 1.05 to 5.21). A trend for a positive relation between neck flexion and neck pain was found, suggesting an increased risk of neck pain for people working with the neck at a minimum of 20 degrees of flexion for more than 70% of the working time (crude RR 2.01, 95% CI 0.98 to 4.11; adjusted RR 1.63, 95% CI 0.70 to 3.82). No clear relation was found between neck rotation and neck pain. CONCLUSION: Sitting at work for more than 95% of the working time seems to be a risk factor for neck pain and there is a trend for a positive relation between neck flexion and neck pain. No clear relation was found between neck rotation and neck pain.

Cohort Studies↗