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Biomedical subjects

W van Mechelen

Publications and source records attributed to W van Mechelen.

At least 73 records · Page 4Linked to original sources
PubMed1998

Behavioral variables and development of a central pattern of body fat from adolescence into adulthood in normal-weight whites: the Amsterdam Growth and Health Study.

Associations were investigated between the amount of physical activity, energy and macronutrient intake, smoking behavior, alcohol intake, and a central pattern of body fat (subscapular skinfold thickness and waist circumference) measured six times between the mean ages of 13 and 27 y in a healthy white population. Subjects (84 males, 98 females) were participants in the longitudinal Amsterdam Growth and Health Study. In longitudinal analyses, alcohol intake was positively associated with the subscapular skinfold thickness (beta = 0.09, 95% CI: 0.01, 0.16) in males. In females, the subscapular skinfold thickness was negatively associated with physical activity (beta = -0.10. 95% CI: -0.15, -0.05) and, unexpectedly, energy intake (beta = -0.25, 95% CI: -0.31,-0.19), whereas a positive association was found with carbohydrate intake (beta = 0.09. 95% CI: 0.02, 0.16). In both sexes, the mean value of behavioral variables, obtained from the mean value in adolescence and the values obtained at 21 and 27 y of age was not significantly associated with the subscapular skinfold thickness or waist circumference at the mean age of 27 y, except for a small positive association between physical activity and the subscapular skinfold thickness in males (R2 = 2.3%).

Adipose Tissue↗
PubMed1998

Tracking of lung function parameters and the longitudinal relationship with lifestyle.

The purpose of this study was to analyse tracking (i.e. relative stability over time/predictability of future values by early measurements) of lung function parameters and their longitudinal relationship with lifestyle (smoking, alcohol consumption, daily physical activity, neuromotor and cardiopulmonary fitness, and dietary intake of retinol and polyunsaturated fatty acids (PUFA)). Data were obtained from the observational Amsterdam Growth and Health Study, a longitudinal study with six repeated measurements between ages 13-27 yrs (n=167). The statistical analyses were carried out with generalized estimating equations. The following "stability" coefficients were found: for forced vital capacity (FVC) in males 0.66 (95% confidence interval (CI): 0.54-0.77) and in females 0.51 (95% CI: 0.43-0.60); for forced expiratory volume in one second (FEV1) in males 0.65 (95% CI: 0.50-0.80), in females 0.53 (95% CI 0.46-0.60); for peak expiratory flow (PEF) in both males and females 0.41 (95% CI: 0.31-0.51). Positive relationships were found between alcohol consumption and FVC and FEV1 and between neuromotor fitness and PEF and (only for males) with FVC and FEV1. Physical activity was inversely related to PEF and the intake of PUFA positively related to FVC and FEV1. Smoking was related to a decrease in FVC and FEV1; changes in physical activity positively correlated to changes in FVC. In conclusion, high to moderate stability/tracking was observed for forced vital capacity and forced expiratory volume in one second; for peak expiratory flow it was slightly lower. Preventive strategies regarding improvements of lung function should focus on smoking cessation and improving daily physical activity.

Adolescent↗
PubMed1997

Tracking of risk factors for coronary heart disease over a 14-year period: a comparison between lifestyle and biologic risk factors with data from the Amsterdam Growth and Health Study.

Because the magnitude of tracking coefficients (i.e., stability coefficients and tracking for subjects at risk) greatly depends on the initial age of subjects, the number and spacing of longitudinal measurements, and the length of the total time period, it is difficult to compare tracking coefficients from different studies with each other. Because in the Amsterdam Growth and Health Study both biologic (i.e., lipoproteins, blood pressure, body fatness, and cardiopulmonary fitness) and lifestyle (i.e., dietary intake, daily physical activity, smoking, and alcohol consumption) risk factors for coronary heart disease were measured, this study gives the unique possibility of comparing tracking coefficients of biologic and lifestyle risk factors within one data set. In the Amsterdam Growth and Health Study, six repeated measurements were carried out on 181 subjects over a period from 13 to 27 years of age, beginning in 1977. The results indicated that, over a period of 14 years covering adolescence and young adulthood, both stability coefficients and tracking for subjects at risk for lifestyle risk factors were low (except for smoking), indicating low predictability of early measurements for values later in life. For the biologic risk factors cardiopulmonary fitness and blood pressure, tracking was also low, while for the lipoproteins and body fatness, tracking was much better, indicating good predictability.

Adolescent↗
PubMed1997

The longitudinal development of running economy in males and females aged between 13 and 27 years: the Amsterdam Growth and Health Study.

The purpose of this study was to describe the longitudinal development of running economy [defined as the oxygen uptake (VO2) at a submaximal running speed] in males and females from teenage to young adult age using data from the Amsterdam Growth and Health Study. Submaximal VO2 (in ml.kg-1.min-1) was measured in 84 males and 98 females while they ran on a treadmill at a constant speed of 8 km.h-1 for 6 min at three different treadmill slopes (0%, 2.5% and 5%). This test was carried out six times, on the same subjects at the ages of 13, 14, 15, 16, 21, and 27 years. The longitudinal development of running economy in males and females was analysed using a two-way analysis of variance for repeated measurements. At all three slopes, a significant decrease in VO2 with increasing age was found for both males and females, implying a significant increase in running economy for both sexes. Males showed significantly higher VO2 values than females at all ages measured and for all three slopes, suggesting that females have a significantly higher running economy than males. In order to make a better comparison of the VO2 of individuals of different sizes, allometric models were used; power function ratios were constructed in which body mass was expressed to an exponential power. Following this analysis the difference in submaximal VO2 and running economy between males and females appeared even larger.

Adolescent↗
PubMed1997

A new approach to tracking of subjects at risk for hypercholesteremia over a period of 15 years: The Amsterdam Growth and Health Study.

Because 'traditional' tracking analyses have some drawbacks, this paper presents a new method, which is based on generalized estimating equations (GEE). The new method is illustrated with data from the Amsterdam Growth and Health Study. In this observational longitudinal study six repeated measurements were carried out on 181 subjects (initial age 13 years) over a period of 15 years. Tracking was assessed for total cholesterol (TC), high density lipoprotein (HDL) and the TC/HDL ratio by calculating the odds ratio (OR) for subjects at risk at the age of 13 years regarding the development of their risk status over a 15 year period. These ORs can be interpreted as tracking coefficients. Three methods were compared: percentage of subjects who maintain their position in a certain risk group (i.e. univariate logistic regression), multivariate logistic regression and GEE. The three methods differ in the possibility of using all available data in the analysis and in the possibility of adjusting for certain covariates. Based on this, the GEE-approach seemed to be the most appropriate to calculate tracking coefficients for subjects at risk. When the risk groups were defined according to objective (absolute) risk values, for TC the GEE-OR was 10.1 (95% confidence interval (CI) 5.0-21.9), for HDL 14.4 (95% CI 7.2-28.7) and for the TC/HDL ratio 25.5 (95% CI 11.5-56.8). It can be concluded that the GEE-approach is very suitable to assess tracking for subjects at risk.

Adolescent↗
PubMed1997

The association between dietary patterns and cardio vascular disease risk indicators in healthy youngsters: results covering fifteen years of longitudinal development.

OBJECTIVE: To examine longitudinal relationships between nutrition and risk indicators for cardio vascular diseases (CVD) during adolescence and young adulthood. DESIGN: A longitudinal study over fifteen years. SUBJECTS: 98 females and 84 males, from 13 to 27 years. METHODS: By means of six interviews dietary patterns were determined. Blood samples were analyzed for serum concentration of total cholesterol (TC), and high-density-lipoprotein (HDL), blood pressure, body fat and maximal aerobic power (VO2max) were determined. The longitudinal relations were analyzed with generalized estimation equations (GEE), a statistical technique in which relations at different time-points are tested simultaneously. RESULTS: Compared to Dutch recommendations six out of seven macro nutrients appear to be unfavorable with respect to CVD. Borderline or high CVD risk values are apparent at 27 y in more than 25% of the subjects with respect to percentage body fat and serum total cholesterol in both sexes. In males 40% or more show borderline hypertension. The 'univariate' longitudinal analyses showed significantly positive relations: (1) between the intake of animal protein, saturated fat (SFA), cholesterol (Cho1) and TC, and HDL; (2) between total energy intake (EN) and systolic blood pressure, and VO2max. Significantly negative associations were found: (1) between EN, poly-unsaturated fat (PUFA) and TC concentrations; (2) between EN and sum of four skinfolds (SSF). CONCLUSIONS: With increasing age, over a period of 15 y in both sexes the SFA and Cho1 intake relate significantly to the development of a negative CVD risk profile. The intake of PUFA relates positive to a CVD risk profile. The significantly negative relation between EN intake and body fat (SSF) is partly explained by the relation between EN and VO2max.

Adolescent↗
PubMed1997

Physical characteristics as risk factors for sports injuries: a four year prospective study.

A variety of physical characteristics of athletes has been proposed to be related to the risk to sustain a sports injury. The aim of the present study was to determine the influence of flexibility, anthropometric characteristics and malalignment of the lower extremities on the risk to sustain a sports injury, using a prospective study design and subjects exposed to rather equal extrinsic risk factors. Physical education students (N = 136) were followed during their four-year education. Sixteen flexibility indices, four anthropometric characteristics and five malalignment indices of the lower extremities were assessed at the start of the study and all sports injuries sustained in that four-year period were recorded. No influence of flexibility or anthropometric variables on the total number of injuries or the number of several specific injuries (ankle sprain, muscle rupture, dislocation, shin splints, backache) could be established. Malalignments of the lower extremities (average prevalence 18% and only minor deviations) did show some but inconsistent relations with the number of (specific) injuries. For pelvic obliquity it was positive as predicted, but for malalignment of the rearfoot and a deviant footprint it appeared to be negative. Leg length inequality and malalignment of the knees were not related to injuries. The most likely explanation for these (poor) findings is the relatively low number and great variety of sports injuries recorded. Further, the homogeneity in physical characteristics of the population under study makes it difficult to find significant relationships. A study design that meets both the criterium of similar extrinsic risk factors and that of a wide range of physical characteristics in a representative sporting population, however, is not practicable.

Adolescent↗
PubMed1997

The Amsterdam Growth and Health Longitudinal Study. The past (1976-1996) and future (1997-?).

This article presents an overview of the Amsterdam Growth and Health Longitudinal Study (AGAHLS). This study was started in the 1970s, following a whole sample of 500 healthy 13-year-old boys and girls from two secondary schools. During the school period (12-17 years) annual measurements were performed with respect to anthropometrics, physiological and psychological parameters, lifestyle characteristics (activity, diet, smoking) and health parameters. A multiple longitudinal design was applied with overlapping birth cohorts and a cross-sectional measured control group to monitor for confounding factors such as time of measurement, cohort, dropout and testing effects. Emphasis is also placed on measures that enhance adherence of the subjects. The follow-up was extended with repeated measurements at age 21, 26 and 28. This enabled us to analyze the data with respect to tracking characteristics of biological and lifestyle variables over a period of 15 years between adolescence and adulthood and also to investigate quasi-causal relationships between the effects of a healthy lifestyle and indicators for cardiovascular diseases (CVD). Also new methods such as measurement of atherosclerosis and osteoporosis will be added and related to longitudinal measurements of the same subjects in the past. The main results that were obtained in the past are summarized and research questions for the near future are explained.

Adolescent↗
PubMed1997

Problems and solutions in longitudinal research: from theory to practice.

Longitudinal studies provide the only method for directly studying the natural course of human growth and development and are therefore invaluable, both to public health and clinical medicine. However, longitudinal studies are accompanied by specific problems. The purpose of this final paper is to discuss in two separate sections some of the methodological, analytical and practical issues regarding the relevance of the findings reported. Examples of such problems and their solutions are described. Methodological issues discussed concern statistical conclusion validity, internal validity and construct validity of longitudinal studies. Practical issues discussed concern the design of longitudinal studies, the recruitment and retention of subjects, and the methods used. Finally, examples of the significance of longitudinal research outcomes to public health and clinical medicine are given.

Clinical Medicine↗
PubMed1997

Sports injury surveillance systems. 'One size fits all'?

Sport is beneficial to health, but may also cause injuries. Therefore there is a need for sports injury prevention. Sports injury prevention should be based on the outcome of scientific research and should be part of the 'sequence of prevention'. In applying the 'sequence of prevention', first the incidence and severity of the sports injury problem need to be established. Secondly the aetiology and the mechanism of sports injuries need to be identified. Only based on this information can preventative measures be introduced, which must subsequently be evaluated for effectiveness. The principle of the 'sequence of prevention' cannot be applied without proper sports injury surveillance. This paper addresses the question of whether one uniform sports injury surveillance system can be used to cover all aspects of sports injury research at all stages of the 'sequence of prevention'. It is argued that a general sports injury surveillance system is useful for answering questions about the incidence and severity of the sports injury problem in various subsets of a population. It can also be used for time trend studies. If the purpose of injury surveillance is to identify the aetiology or the effectiveness of preventative measures, then sports injury surveillance should be tailored to the specific sports situation. Sports injury surveillance systems are not useful in identifying the mechanism of injury.

Athletic Injuries↗
PubMed1997

The severity of sports injuries.

In order to assess the extent of the sports injury problem, it is necessary to identify both the incidence and severity of sports injuries. In the literature, the severity of sports injuries is usually described on the basis of 6 criteria: (i) nature of sports injury; (ii) duration and nature of treatment; (iii) sporting time lost; (iv) working time lost; (v) permanent damage; and (vi) monetary cost. It is important to include information on the severity of injuries in a sports injury registration system. This kind of information will help to set targets for preventive strategies. The more severe the injuries sustained, the higher the priority will be to prevent these injuries regardless of the injury incidence. When assessing injury severity one should take into account that, in order to enhance the comparability of research data, uniform definitions are also important in this area of sports injury surveillance. This paper briefly discusses the 6 criteria used to describe the severity of sports injuries.

Absenteeism↗
PubMed1996

Myosin heavy chain isoform expression and high energy phosphate content in human muscle fibres at rest and post-exercise.

1. The relationship between myosin heavy chain (MyHC) isoforms and high energy phosphate content was studied in human muscle fibres at rest and following maximal dynamic exercise lasting 25 s. 2. Single fibre fragments were characterized as type I, type IIA, type IIX or type IIAX. These latter fibres were subdivided into five groups on the basis of the proportion of MyHC IIX isoform present. 3. Resting ATP concentration in type I fibres was 10% lower than in type II fibres (P < 0.05), but no differences were found amongst type IIA, IIX and IIAX fibre groups. Phosphocreatine (PCr) content was lower in type I than in type II fibres (P < 0.01) and, amongst type II fibres, increased progressively with the amounts of MyHC IIX expressed. 4. After 25 s of maximal dynamic exercise ATP concentration was reduced in all fibres. The decrease was approximately 25% in type I fibres and between 47 and 66% in the type II subgroups. 5. Post-exercise PCr content was low in all fibre types. Fibre groups with the lowest post-exercise PCr also had the lowest ATP and the highest inosine monophosphate contents. delta PCr (rest to post-exercise) was smallest in type I fibres and showed a progressive increase in the type II fibre groups as the proportion of the faster IIX myosin heavy chain isoform increased.

Adenosine Triphosphate↗
PubMed1996

Relation between the longitudinal development of lipoprotein levels and lifestyle parameters during adolescence and young adulthood.

The longitudinal relationship between serum levels of lipoproteins and lifestyle measures (e.g., intake of cholesterol, carbohydrates, saturated fatty acids [SFA], polyunsaturated fatty acids [PUFA], the PUFA/SFA (P:S) ratio, alcohol consumption, smoking behavior, and daily physical activity) was investigated over a period of 15 years in a cohort study (the Amsterdam Growth and Health Study). Members of the cohort were 13 years of age at commencement of the study and were 27 years old at termination. The unique feature of the study presented is that the longitudinal relations were analyzed with generalized estimating equations, a statistical technique in which the relations at different time-points are tested simultaneously. The development of the total serum cholesterol (TC) level was positively related to the intake of cholesterol and negatively to the P:S ratio. The development of high-density-lipoprotein cholesterol (HDL) level was positively related to alcohol consumption and daily physical activity and negatively to smoking behavior. The development of the TC:HDL ratio was negatively related to alcohol consumption and positively to both smoking behavior and carbohydrate intake.

Adolescent↗
PubMed1996

Rapid maturation in adolescence results in greater obesity in adulthood: the Amsterdam Growth and Health Study.

In this study, the effect of rapid and slow biological maturation on the development of obesity was investigated in boys (n = 79) and girls (n = 98), initially aged a mean of 13 y, and measured six times between 1977 and 1991. Obesity was determined by measuring body mass index (BMI; in kg/m2) and by summing four skinfold thicknesses. Biological maturation was operationalized by skeletal age, the age of peak height velocity (PHVage) for boys, and the age of menarche for girls. Multiple analyses of variance for repeated measurements showed that based on either skeletal age or PHVage, BMI for rapidly maturing boys was significantly higher than for slowly maturing boys between 13 and 27 y of age. Based on skeletal age, rapid maturers also showed higher mean sums of skinfold thicknesses over this period. For girls, BMI and sums of skinfold thicknesses for the rapidly maturing girls, based on either skeletal age or age at menarche, were also higher than for the slowly maturing girls over the entire period of study. In conclusion, individuals who matured rapidly in adolescence were, in general, more obese than slowly maturing adolescents between 13 and 27 y of age. Rapid maturation seems to have long-term consequences for obesity and should therefore be considered a risk indicator for the development of obesity.

Adolescent↗
PubMed1996

Development and tracking of central patterns of subcutaneous fat in adolescence and adulthood: the Amsterdam Growth and Health Study.

BACKGROUND: A central pattern of body fat is recognized as a risk indicator of cardiovascular diseases in adulthood. The development of this body fat pattern from childhood into adulthood however, remains to be explored. METHODS: The development of two trunk skinfolds (subscapular; supra-iliac), two extremity skinfolds (biceps; triceps), and three trunk-extremity skinfold ratios for males (n = 71) and females (n = 84), were described over a period of 17 years from 13 to 29 years of age. In addition, tracking of the skinfolds and the skinfold ratios was investigated over this period. Data for this study came from the Amsterdam Growth and Health Study, an ongoing longitudinal study in the Netherlands that started in 1977. RESULTS: In adolescence, a decrease was seen in extremity skinfolds for men but not for women. For both sexes, the trunk skinfolds increased over the entire period of study. An increase was found in trunk-extremity skinfold ratios in males, but not in females. Tracking coefficients, calculated as Pearson correlation coefficients between the initial measurement and subsequent measurements, were about 0.4 for the single skinfolds between 13 and 29 years of age for both men and women. For the skinfold ratios, these correlation coefficients were about 0.55. Longitudinal tracking coefficients, measuring the association between the initial measurement and all follow-up data simultaneously, were about 0.65 for both men and women. CONCLUSIONS: A central pattern of body fat, mainly seen in males, seems to start in adolescence. From a preventive point of view, tracking coefficients were too low to be of predictive value. In order to conclude that the roots of a central pattern of body fat are in adolescence, careful search for determinants of change of this body fat pattern is needed.

Adipose Tissue↗
PubMed1996

Relation between the longitudinal development of lipoprotein levels and biological parameters during adolescence and young adulthood in Amsterdam, The Netherlands.

STUDY OBJECTIVES: To analyse the relation between the longitudinal development of total serum cholesterol (TC), high density lipoprotein cholesterol (HDL), and the TC/ HDL ratio and the longitudinal development of the biological parameters body fatness (SSF), lean body mass (LBM), and cardiopulmonary fitness (VO2-max). The relations were analysed with generalised estimating equations (GEE). SETTING: The relations were investigated with data from the Amsterdam growth and health study, a longitudinal study in which six measurements were carried out within a period of 15 years. PARTICIPANTS: Altogether 98 females and 84 males aged 13 years at the start of the study. MAIN RESULTS: Adjusted for lifestyle and other biological parameters, the longitudinal development of TC was inversely related to the development of LBM (standardised regression coefficient beta = -0.27; p < or = 0.01) and positively to SSF (beta males = 0.32; p < or = 0.01 and beta females = 0.15; p < or = 0.01). HDL was inversely related to LBM (beta = -0.26; p < or = 0.01) and positively to VO2-max (beta = 0.08; p < or = 0.05). The TC/HDL ratio was positively related to SSF (beta males = 0.39; p < or = 0.01 and beta females = 0.13; p < or = 0.01) and inversely to VO2-max (beta = -0.09; p < or = 0.05). CONCLUSIONS: The longitudinal analyses showed that body fatness was related to a high risk profile with respect to hypercholesterolaemia, and cardiopulmonary fitness to a low risk profile. Furthermore, it was shown that using body mass index as an indicator of body fatness in relation to lipoprotein values, has some important drawbacks.

Adolescent↗
PubMed1996

Biological maturation and the distribution of subcutaneous fat from adolescence into adulthood: the Amsterdam Growth and Health Study.

OBJECTIVE: To analyze differences in the development of a trunk-oriented fat distribution pattern between 13 and 27 years of age in individuals who either matured rapidly or slowly in adolescence. DESIGN: Longitudinal, observational, four annual measurements between 1977 and 1980 and additional measurements in 1985 and 1991. SUBJECTS: 79 boys, 98 girls, health Caucasian schoolchildren, classified as rapidly, normally or slowly maturing. MEASUREMENTS: biceps, triceps, subscapular, suprailiac skinfolds resulting in two skinfold ratios, body mass index, skeletal age, peak height velocity (for boys only), age at menarche. RESULTS: No statistically significant differences were found between rapidly and slowly maturing boys and girls, based on the skeletal age or the peak height velocity. Girls with a relatively early menarche showed significant higher mean skinfold ratios between 13 and 27 years of age than girls with a relatively late menarche. CONCLUSION: Skeletal maturation of boys and girls and peak height velocity (only measured in boys) are not associated with a trunk-oriented fat distribution pattern between 13 and 27 years of age. Only a relatively early menarche in girls seems to be associated with a trunk-oriented fat distribution pattern from adolescence into adulthood.

Adipose Tissue↗