A randomized trial investigating an exercise program to prevent reduction of bone mineral density and impairment of motor performance during treatment for childhood acute lymphoblastic leukemia.

BACKGROUND: Reduced bone mineral density (BMD), altered body composition, impaired motor performance and passive ankle dorsiflexion are side effects of acute lymphoblastic leukemia (ALL) treatment. We performed a randomized study investigating whether an exercise program could prevent these side effects. PROCEDURE: At diagnosis we randomized 51 ALL patients (median age: 5.4 years) into a group receiving a 2-year exercise program or a control group receiving standard care. BMD of total body (BMD(TB)), lumbar spine (BMD(LS)) and body composition were measured using dual energy X-ray absorptiometry, motor performance with Bayley Scales of Infant Development or Movement-ABC, and passive ankle dorsiflexion with a goniometer. The investigator was blinded to the randomization. RESULTS: Body fat increased equally during treatment in both groups. One year after cessation of therapy more rapid decline of excessive body fat was observed in the intervention group than in the controls (P = 0.01). Lean body mass, BMD(TB) and BMD(LS) of both groups decreased equally during treatment and increased equally thereafter. Both groups showed a similar decrease in passive ankle dorsiflexion and motor performance during treatment. Adherence to the intervention program varied considerably. Adherence to intervention: 11% of children exercised daily, 37% > once a week, 16% once weekly, 36% < once a week. CONCLUSIONS: The exercise program was not more beneficial than standard care in preventing reduction in BMD, motor performance and passive ankle dorsiflexion than standard care, most likely due to unsatisfactory compliance. Increased BMI and body fat in the intervention group normalized faster after cessation of chemotherapy.

Relationship between fat patterns, physical fitness and blood pressure of rural South African children: Ellisras Longitudinal Growth and Health Study.

The present study investigated the relationship between blood pressure (BP), fat patterns and fitness parameters of Ellisras children aged 7-13 years. Furthermore, an assessment of body fat patterns was done to determine the subjects with the highest risk of overweight, hypertension and waist-to-hip ratio above the 90th percentile. Data were collected from 1,817 subjects (938 boys and 879 girls), aged 7-13 years, participating in the Ellisras Longitudinal Study. Anthropometric measurements were taken according to the standard procedure of the International Society for the Advancement of Kinanthropometry. The EUROFIT test items were used to test the physical fitness of 1,192 subjects (634 boys and 558 girls). Obesity was defined using the international recommended cutoff points for body mass index (BMI) in children. Hypertension was defined as the occurrence of BP levels greater or equal to the 95th percentile of height- and sex-adjusted reference levels. The prevalence of hypertension ranged from 1 to 11.4% and that of overweight 0.6-4.6%. Waist girth, BMI, triceps and subscapular skinfold showed significant (P<0.001-0.05) correlation with other fat pattern parameters (r ranging from -0.157 to 0.978) compared with significant correlations (P<0.001-0.05) with BP (r ranging from -0.071 to 0.164). Children with waist girth greater than the 90th percentile are more likely to have multiple risk factors than the children with a waist girth that is less than or equal to the 90th percentile. Longitudinal studies should verify whether changes in waist girth and skinfolds will indicate changes in cardiovascular risk factors during growth.

Development and tracking of body mass index from preschool age into adolescence in rural South African children: Ellisras Longitudinal Growth and Health Study.

The purpose of this observational prospective cohort study was to investigate the development and tracking of body mass index (BMI) of Ellisras rural children from preschool age into late adolescence from the Ellisras Longitudinal Growth and Health Study. Heights and weights of children were measured according to the standard procedures recommended by the International Society for the Advancement of Kinanthropometry twice a year from 1996 to 2003. In total, 2,225 children--550 preschool and 1,675 primary school--aged 3-10 years (birth cohorts 1993 to 1986) were enrolled at baseline in 1996 and followed through out the eight-year periodic surveys. In 2003, 1,771 children--489 preschool and 1,282 primary school--were still in the study. The prevalence of overweight was significantly higher among girls (range 1.6-15.5%) compared to boys (range 0.3-4.9%) from age 9.1 years to 14.9 years. The prevalence of thinness (severe, moderate, and mild) ranged from 7.1% to 53.7% for preschool children and from 8.0% to 47.6% for primary school children. Both preschool and primary school children showed a significant association between the first measurements of BMI and the subsequent measurement which ranged from B=0.2 (95% confidence interval [CI] 0.1-0.4) to B=0.8 (95% CI 0.6-0.9) for preschool and B=0.2 (95% CI 0.1-0.3) to B=0.7 (95% CI 0.6-0.8) for primary children. A significant tracking of BMI during 4-12 years of life was more consistent for preschool children (B=0.6 (95% CI 0.6-0.7) and for primary school children (B=0.6 (95% CI 0.5-0.6). Investigation of nutritional intake and physical activity patterns will shed light on how healthy these children are and their lifestyle.

The association of fat patterning with blood pressure in rural South African children: the Ellisras Longitudinal Growth and Health Study.

BACKGROUND: Hypertension is one of the major causes of death in developed and underdeveloped nations. Essential hypertension and obesity may have their inception in childhood, with little data in African children to support these findings. Objectives were to determine the prevalence of overweight and hypertension in rural children in South Africa. Additionally, the association between fat-patterning ratios and blood pressure (BP) was investigated. METHODS: Data were collected from 1884 subjects (967 boys and 917 girls), aged 6-13 years, participating in the Ellisras Longitudinal Study. Height; weight; and triceps, biceps, subscapular, and suprailiac skinfolds were measured according to the protocol of the International Society for the Advancement of Kinanthropometry. Skinfold ratio was used as an indicator of the central pattern of body fat. Internationally recommended cut-off points for body mass index (BMI) were used. Hypertension, defined as the average of three separate BP readings where the systolic BP or diastolic BP is >or=95th percentile for age and sex, was determined. RESULTS: The prevalence of hypertension ranged from 1 to 5.8% for boys and 3.1 to 11.4% for girls, and that of overweight from 1.1 to 2.9% for boys and 0.6 to 4.6% for girls. The association between high systolic BP and high BMI was -3.0, while that for high diastolic BP and high BMI was -0.68. CONCLUSIONS: The prevalence of hypertension is evident from the age 6 years for girls, while that of overweight was low. Overweight became evident from the age 10 to 13 years for both sexes. A significant association between high diastolic BP and high BMI was noted, while children with low BMIs were less likely to be hypertensive. Investigating habitual physical activity, fitness and dietary patterns will shed more light on the association of fat patterning and BP in this population.

Relationship of adiposity and cardiorespiratory fitness with resting blood pressure of South African adolescents: the PAHL Study.

Obesity and low level of cardiorespiratory fitness are associated with high blood pressure in both adolescents and adults. The objective of this study was to assess the relationship of adiposity and cardiorespiratory fitness with resting blood pressure in 14-year-old male and female adolescents. Cross-sectional data on 310 adolescents (31.8% boys) from six high schools, who were participating in the on-going Physical Activity and Health Longitudinal Study, were collected. Height, weight, body mass index (BMI), percentage of body fat, waist circumference, waist-to-height ratio, predicted and resting systolic (SBP) and diastolic blood pressure (DBP) were assessed according to standard procedures. The prevalence of elevated SBP and DBP were 4.9% and 6.5%, respectively. The highest prevalence of elevated blood pressure (SBP=10% and DBP=15%) were measured in overweight adolescents, who also performed poorly for predicted VO(2max)(M=26.66 ml kg(-1 )min(-1)±6.44) compared with underweight and normal-weight adolescents. Multiple regression showed that BMI was positively associated with SBP (ß=0.77, P=0.005) and VO(2max) was negatively associated with DBP (ß=-0.43, P=0.001). Overweight adolescents presented with a relatively high prevalence of elevated blood pressure and poor health-related fitness. Fatness and poor cardiorespiratory fitness were positively associated with elevated SBP and DBP, respectively. In view of the health implications of these findings, strategic interventions are needed to promote obesity-reduction programmes and physical activities in adolescents.

Body composition and physical fitness of undernourished South African rural primary school children.

OBJECTIVE: The purpose of this study was to determine the relationships between the body composition characteristics, body mass index (BMI), sum of skinfolds (SSF), % body fat (%BF), fat-free mass (FFM) and waist-to-hip ratio (WHR), and nine physical fitness items in undernourished rural primary school children in Ellisras, South Africa. DESIGN: A cross-sectional study. SETTING: The study consisted of 462 boys and 393 girls who were aged 7-14 y. MEASUREMENTS: Five body composition measures were assessed: BMI, SSF, %BF, FFM and WHR. Nine physical fitness test items were assessed: standing long jump, bent arm hang, sit-ups, 10 x 5 m shuttle run, 50 m sprint, 1600 m run, flamingo balance, sit and reach, plate tapping. RESULTS: BMI was highly correlated with FFM (r = 0.7, P < 0.001). In line with findings from Western countries, regression coefficients (B) showed that children with higher BMI or SSF performed worse in bent arm hang (girls, B = -0.84, P < 0.001, and B = -0.06, P = 0.02, respectively) and in 1600m run (B = 6.68, P < 0.001). BMI was significantly associated with flamingo balance (B = 0.26, P = 0.04). WHR was positively associated with bent arm hang (B = 9.37, P = 0.03), and inversely with sit and reach (B = -7.48, P = 0.01). In contrast, significant relationships were found between BMI and standing long jump (B = 0.74, P = 0.04), sit and reach (B = 0.51, P < 0.001), flamingo balance (B = 0.26, P = 0.04) and plate tapping (B = -19, P = 0.01). SSF was significantly associated with sit and reach (B = 0.04, P = 0.03). Significant inverse associations were found between FFM and bent arm hang (girls, B = -0.06, P = 0.05), 1600 m run (girls, B = -2.33, P = 0.003) and 50 m run (boys, B = -0.11, P = 0.006). FFM was significantly associated with standing long jump (boys, B = 0.99, P < 0.001; girls, B = 0.73, P < 0.001), flamingo balance (B = 0.17, P < 0.001), and with sit and reach (boys, B = 0.59, P = 0.03). CONCLUSION: In the present study in undernourished children, body composition was significantly related to physical fitness, but not always in the expected direction. It is therefore important to note that in this population, BMI should not be interpreted as a measure of fatness/overweight, but rather as an indicator of muscle mass.

Netherlands research programme weight gain prevention (NHF-NRG): rationale, objectives and strategies.

OBJECTIVE: To outline the rationale, objectives and strategies used in a systematically designed research programmme to study specific weight gain-inducing behaviours, their social-psychological as well as environmental determinants, and the effects of interventions aimed at the prevention of weight gain. DESIGN: The evidence for potential behavioural determinants and strategies to prevent weight gain was reviewed, and the methods applied within the Netherlands Research programme weight gain prevention (NHF-NRG) project were described. The project is designed according to the Intervention Mapping protocol. SETTING: The Netherlands. SUBJECTS: The main target groups are (a) adolescents (12-16 y) in secondary school, (b) young adults (20-40 y) at the workplace and (c) recently retired people (55-65 y) at home. INTERVENTIONS: Each intervention includes an individual component, in which computer-tailored information is provided. Additionally, interventions are aimed at changing environmental components. RESULTS: The short-term results of this project can be expected by the beginning of 2005. Guidelines for nationwide weight gain prevention, based on this research programme, will become available in 2007. CONCLUSIONS: Based on the few interventions that were evaluated to date, no robust conclusions can be drawn regarding the effectiveness of obesity prevention. The systematic and multidisciplinary design of the NHF-NRG programme enables the identification of potentially effective methods and strategies for the prevention of weight gain.

Cross-sectional and longitudinal relationships between alcohol consumption and lipids, blood pressure and body weight indices.

OBJECTIVE: Serum lipids, blood pressure and body mass may mediate the U-shaped relationship of alcohol consumption with type 2 diabetes mellitus and coronary heart disease. This study examines the cross-sectional and long-term longitudinal relationships of (changes in) alcohol consumption with (changes in) serum lipids, blood pressure and body mass indices. METHOD: In this prospective, observational cohort study, two measurements of alcohol consumption, serum total and high-density lipoprotein cholesterol, triglycerides, blood pressure, body weight, the thickness of four skinfolds and waist circumference were performed 4 years apart in healthy volunteers (143 men and 174 women, 32 years old at the first measurement). Alcohol consumption from beer, wine and distilled spirits was assessed using an extensive dietary history interview. Linear regression analyses were performed to study the cross-sectional relationships between the amount of alcohol consumed at the age of 32 years and the levels of the lipids, blood pressure and body weight indices, and to study the longitudinal relationships between the changes in the amount of alcohol consumed over the 4 years of follow-up and the concurrent changes in the lipids, blood pressure and body weight indices. Nonlinearity was investigated for the cross-sectional relationships. RESULTS: A 10-g/day difference in alcohol consumption was positively related with a 0.05 mmol/L (1.9 mg/dl) difference in high-density lipoprotein cholesterol in both cross-sectional (p = .004), and longitudinal (p < .0001) analyses. This relationship did not differ for men and women or for the consumption of beer, wine or distilled spirits. Relationships with changes in total cholesterol, triglycerides, systolic, diastolic, and pulse pressure, body weight and the sum of four skinfolds were not significant. A borderline significant inverse longitudinal relationship was found with waist circumference. The other lifestyle behaviors (tobacco smoking, physical activity and dietary habits) were major confounders of most cross-sectional relationships between alcohol and serum lipids, blood pressure and body mass indices. The longitudinal relationships, however, were not confounded by changes in the other lifestyle behaviors. A significant nonlinear relationship was found for systolic blood pressure, in which drinkers of about 30 g/day had the lowest values. CONCLUSIONS: Moderate alcohol consumption and moderate long-term changes in alcohol consumption are positively related with the levels and changes in high-density lipoprotein cholesterol in healthy adult men and women. A moderate inverse association between alcohol and waist circumference may be expected. No relationships were found with triglycerides, blood pressure, body weight and the sum of the thickness of four skinfolds. Other lifestyle behaviors confound the cross-sectional, but not the longitudinal, relationships between alcohol consumption and serum lipids, blood pressure and body mass indices. Gender and type of beverage do not modify the relationships between alcohol consumption and these indices.

Weight-bearing activity during youth is a more important factor for peak bone mass than calcium intake.

In a 15 year longitudinal study (Amsterdam Growth and Health Study) is evaluated the effect of daily calcium intake (CAI) during adolescence and young adulthood on the development of peak bone mass at age 27 when the influence of weight-bearing activity (WBA) and body weight was accounted for. A group of 84 males and 98 females were measured longitudinally from age 13 until age 28. Measurements were taken six times of anthropometric characteristics. Lifestyle was also evaluated six times by cross-check interviews of CAI and WBA. Bone mineral density (BMD) of the lumbar spine was determined at age 27 by dual x-ray absorption. Three periods were considered, that is, the adolescent period, the period 13-21 years, and the total period (13-27 years). In multiple linear regression analyses, only WBA and body weight were significant positive contributors to the final model of lumbar BMD at age 27. In all three periods WBA was the best predictor in males and body weight in females. ANOVA was performed on BMD and the highest and lowest quartiles of calcium intake with the significant predictor variables of the linear regression model as covariates. Again calcium intake appeared not a significant predictor of BMD in the three periods in both sexes. Regular weight-bearing exercise and at least a normal age-related body weight in adolescence and young adulthood are of key importance in reaching the highest lumbar peak bone mass at the age of 27 years.

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%).

A fifteen-year longitudinal study in young adults on the relation of physical activity and fitness with the development of the bone mass: The Amsterdam Growth And Health Longitudinal Study.

Although positive effects of physical activity are often reported, there are still uncertainties about the type, intensity, duration, and frequency of these activities that are most effective for (re)modeling bone mass during youth. In the Amsterdam Growth and Health Longitudinal Study, daily physical activity and fitness were monitored from age 13 to 29 years in a group of 182 males and females. At a mean age of 28 years, bone mineral density (BMD) was measured at three sites with dual X-ray absorptiometry (DXA): in the lumbar region (lumbar BMD), the femoral neck (hip BMD), and the distal radius (wrist BMD). Physical activity (PA) was estimated from a cross-check activity interview taking in consideration all daily physical activities during the last 3 months; PA was scored in two different ways: (1) metabolic physical activity score (METPA) by weighting the intensity (multiples of basic metabolic rate [METs]) and duration (minutes per week); and (2) mechanic physical activity score (MECHPA) by weighting the peak strain (ground reaction forces as multiples of body mass) irrespective of frequency and duration of the physical activities. Physical fitness was measured with a neuromotor fitness test (composite of six strength, flexibility, and speed tests) and as cardiopulmonary fitness (maximal oxygen uptake). The physical activity and fitness scores were calculated over two age periods: during adolescence (13-16 years) and during adulthood (21-27 years). The standardized regression coefficients (corrected for gender, biological age, body composition, and calcium intake) show that weight, physical activity (both METPA and MECHPA), and neuromotor fitness during adolescence and in young adulthood are significantly and positively related with the lumbar BMD (beta = 0. 11-0.40) and hip BMD (beta = 0.18-0.26), measured at the mean age of 28 years. This was not the case for cardiorespiratory fitness. No significant correlations at all are found with wrist BMD, a bone site that is less involved in physical activity and fitness. It can be concluded that daily physical activity during adolescence and in the young adult period is significantly related to the BMD at the lumbar spine and femoral neck at age 28 of males and females. Only neuromotor fitness and not cardiopulmonary fitness during adolescence and young adulthood is related to the BMD of males and females at age 28 years.

Relationship between physical activity and bone mineral status in young adults: the Northern Ireland Young Hearts Project.

Physical activity during the first three decades of life may increase peak bone mass and reduce future osteoporosis risk. The aim of this study was to determine the extent to which different components of physical activity may influence bone mineral status within a representative population sample of young men and women. Bone mineral density (BMD) and content (BMC) were determined at the lumbar spine and femoral neck in 242 men and 212 women, aged 20-25 years, by dual-energy X-ray absorptiometry. Physical activity was assessed by a self-report questionnaire designed to measure the frequency and duration of physical activity and its components (i.e., work, non-sports leisure, sports-related activities, and peak strain sports activities). Potential confounding factors such as height, weight, diet, and smoking habits were also assessed. In multivariate linear regression models, sports activity and peak strain sports activity undertaken by men were strongly associated with both lumbar spine BMD (beta = 0.35 [0.21, 0.49] and beta = 0.31 [0.17, 0.44], respectively) and BMC (beta = 0.33 [0.21, 0.45] and beta = 0.26 [0.14, 0.38], respectively) and femoral neck BMD (beta = 0.35 [0.21, 0.48] and beta = 0.27 [0.14, 0.40], respectively) and BMC (beta = 0.32 [0.19, 0.44] and beta = 0.29 [0.17, 0.41], respectively) (all p < 0.01), but work and non-sports leisure activities were not. In women, there were no associations between bone measurements and any component of physical activity. In models involving all subjects the gender/sports activity, but not the gender/peak strain, interaction term was statistically significant. Sports activity explained 10.4% of the observed variance in lumbar spine BMD in men, but <1% in women. These results demonstrate the importance of sports activities, especially those involving high peak strain, in determining peak bone status in young men. Failure to observe this association in women reflects their lower participation in such activities, but they may have the same capacity to benefit from these activities as men. Intervention studies are warranted to determine whether peak bone density in women can be improved by participating, during childhood and adolescence, in sports activities involving high peak strain.

Clustering of risk factors for coronary heart disease. the longitudinal relationship with lifestyle.

PURPOSE: The purpose of this study was to investigate whether or not clustering of biological coronary heart disease (CHD) risk factors exists and to investigate the longitudinal relationship between lifestyle parameters (dietary intake, daily physical activity, smoking behaviour, alcohol consumption) and a biological CHD risk factor clustering score. This was defined as belonging to one or more gender specific 'high risk' quartiles for the following CHD risk factors: ratio between total serum cholesterol and high density lipoprotein cholesterol (TC:HDL), mean arterial blood pressure (MABP), body fatness [sum of skinfolds (SSF)], and cardiopulmonary fitness (VO2-max). METHODS: The data were derived from the Amsterdam Growth and Health Study, an observational longitudinal study in which six repeated measurements were carried out over a period of 15 years covering adolescence and young adulthood. The longitudinal relationships were analysed with generalized estimating equations. RESULTS: The results showed significant clustering for the TC:HDL ratio, SSF, and VO(2)-max. MABP was not significantly associated with the other CHD risk factors. Daily physical activity and alcohol consumption (only for males) were both inversely related to the clustering score. None of the other lifestyle parameters showed significant relationships with the clustering score. CONCLUSIONS: Based on this small longitudinal study, it can be stated that during adolescence and young adulthood both daily physical activity and alcohol consumption were related to a healthy CHD risk profile.

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.

Longitudinal development of lipoprotein levels in males and females aged 12-28 years: the Amsterdam Growth and Health Study.

BACKGROUND: In the Amsterdam Growth and Health Study, the longitudinal development of risk factors for coronary heart disease (CHD) was investigated. METHODS: Serum cholesterol (TC), high density lipoprotein (HDL) and the TC/HDL ratio were measured at the ages of 13, 14, 15 and 16 years (adolescence) and at the ages of 21 and 27 years ([young] adulthood). RESULTS: No cohort, time of measurement, drop-out or test/learning effects were found for TC, HDL and the TC/HDL ratio. For males the longitudinal development of TC showed a dip in the adolescent period, while females showed constant values. For both males and females TC values increased during young adulthood, but females had higher (P < or = 0.001) absolute values than males. The HDL values for males decreased throughout the measurement period, while for females a stable period during adolescence was followed by a slight increase during adulthood. For the TC/HDL ratio males showed an increase during young adulthood, while females stayed more or less constant over the whole measurement period. The percentages of subjects above (or below for HDL) objective risk values increased with age: from 0% to 1% during adolescence to 11% (males) and 14% (females) for TC, 5% (males) and 1% (females) for HDL and 13% (males) and 1% (females) for the TC/HDL ratio. CONCLUSIONS: In a relatively young and healthy population TC and TC/HDL values tended to rise with age (especially in males) indicating that prevention related to these risk factors for CHD should start early in life.

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.

Comparison of a quantitative dairy questionnaire with a dietary history in young adults.

BACKGROUND: There is growing interest in the potential role of calcium in the prevention of osteoporosis. Therefore a quantitative dairy questionnaire (DQ) was developed to estimate the calcium intake from dairy products. The aim of this study was to evaluate the relative validity and reproducibility of the DQ in 27-29 year old males and females. METHODS: The DQ was validated against a cross-check dietary history method (DH) in 160 subjects, and the reproducibility was assessed in 29 subjects by repeating the administration of the DQ with a one-year interval. RESULTS: In the validity study, the nutrient calcium and the food groups cheese and milk and milk products measured by the DQ tend to show higher intakes as compared to the results of the DH. However, only for the calcium intake was the difference between the DQ and DH (7%) significant. The Bland-Altman plot showed that this bias was constant over the range of calcium intakes. The Pearson correlation coefficients between the DQ and the DH varied from 0.58 to 0.65. On average, about 52% of the subjects were classified in the same quartile in the DQ and the DH for the intake of calcium as well as dairy products. The weighted kappas were between 0.60 and 0.67. In the reproducibility study, the Pearson correlation coefficient for the calcium intake assessed by the DQ one year apart was 0.78. CONCLUSIONS: These data indicate that the DQ is reasonably accurate in young adults as a means of assessing the calcium intake from dairy products.

Validity and repeatability of a modified Baecke questionnaire on physical activity.

BACKGROUND: In a pilot study for the European Prospective Investigation into Cancer and Nutrition (EPIC) a modification of the Baecke questionnaire on physical activity was tested for repeatability and relative validity in a population of 134 men and women aged 20-70 years. METHODS: For the assessment of repeatability Pearson's correlation coefficients and percentages of agreement after classification in tertiles were computed between administrations of the questionnaire at baseline, and after 5 and 11 months. Relative validity was determined by comparing the questionnaire to a four times repeated 3-day activity diary. RESULTS: Repeatability after 5 and 11 months was good, with test-retest correlation coefficients between 0.65 and 0.89 for main sections of the questionnaire. The percentages of agreement, exceeding chance (Cohen's kappa) were 57% and 56% for men (at 5 and 11 months respectively) and 41% and 46% for women. The correlations with the diaries were 0.56 in men and 0.44 in women. Agreement apart from chance between classification in tertiles for both methods was 35% for men and 10% for women. CONCLUSIONS: These data show that repeatability is good and relative validity as compared to an activity diary is moderate but well within the range of values found in other studies. The questionnaire is more valid in men than in women.

Effect of chronic hypoxia and socioeconomic status on VO2max and anaerobic power of Bolivian boys.

The aim of this work was to analyze the effects of altitude and socioeconomic and nutritional status on maximal oxygen uptake (VO2max) and anaerobic power (P) in 11-yr-old Bolivian boys. At both high (HA) (3,600 m) and low (LA) (420 m) altitudes, the boys were divided into high (HA1, n = 23, LA1, n = 48) and low (HA2, n = 44, LA2, n = 30) socioeconomic levels. Anthropometric characteristics, VO2max, and P [maximal P (Pmax) during a force-velocity test and mean P (P) during a 30-s Wingate test] were measured. Results showed that 1) anthropometric parameters were not different between HA1 and LA1 and HA2 and LA2 boys, but HA2 and LA2 boys were two years behind HA1 and LA1 boys in development; 2) VO2max was not different in boys from the same altitude, but at HA VO2max was 10% lower than at LA (HA1 = 37.2 +/- 5.6, HA2 = 38.9 +/- 6.4, LA1 = 42.5 +/- 5.8, LA2 = 42.5 +/- 5.3 ml.min-1 x kg-1 body wt); and 3) Pmax and P were higher in well-nourished than in undernourished boys, but there was no difference in Pmax and P between HA1 and LA1 and HA2 and LA2 boys (HA1 = 6.8 +/- 1.0, HA2 = 5.5 +/- 0.8, LA1 = 7.1 +/- 1.0, LA2 = 5.3 +/- 0.9 W/kg for Pmax; HA1 = 5.2 +/- 0.8, HA2 = 4.5 +/- 0.9, LA1 = 5.2 +/- 0.7, LA2 = 4.0 +/- 0.6 W/kg for P).(ABSTRACT TRUNCATED AT 250 WORDS)

Is calculating pack-years retrospectively a valid method to estimate life-time tobacco smoking? A comparison between prospectively calculated pack-years and retrospectively calculated pack-years.

AIMS: To investigate the relative validity of retrospectively calculated pack-years (py-retro) by comparing py-retro with prospectively calculated pack-years (py-pro). DESIGN: A 23-year ongoing cohort study (1977-2000). PARTICIPANTS: One hundred and fifty-four males and females, 13 years old in 1977 and 36 years old in 2000. SETTING: Amsterdam, the Netherlands. MEASUREMENTS: To calculate py-pro, current smoking and quitting efforts were investigated nine times in a period of 23 years with the help of an interview or a questionnaire. At the age of 36, subjects filled out a comprehensive questionnaire about their smoking history, to calculate py-retro. Individual differences between py-pro and py-retro were calculated. In addition, Cohen's kappa was calculated after categorising py-pro and py-retro into three groups. FINDINGS: (1) Py-retro does not under- or overestimate life-time tobacco smoking. (2) The relative validity of py-retro was moderate due to large individual differences between py-pro and py-retro. (3) The individual differences between py-pro and py-retro became larger, the higher the number of pack-years. (4) Mean difference (and 95% limits of agreement) between py-pro and py-retro was -0.039 (-5.23, 5.32) when average pack-years was < 5.2 and -1.17 (-10.00, 14.65) when pack-years > or = 5.2. 5. Cohen's kappa between categorized py-pro and py-retro was 0.79. CONCLUSIONS: Future researchers in the field of smoking should be aware of the moderate relative validity of py-retro. Categorizing py-retro into smoking groups results in a misclassification error that is smaller than the quantitative error in continuous py-retro, but goes together with a loss of information.