R. Verschuur

Tracking of health and risk indicators of cardiovascular diseases from teenager to adult: Amsterdam growth and health study

Cardiovascular disease is recognized as a serious public health problem. Because the underlying pathological processes start shortly after birth, tracking of recognized cardiovascular disease indicators during childhood and adolescence can help in developing preventive pediatric strategies. A prospective follow-up of both genetic and behavioral lifestyle parameters (serum cholesterol, blood pressure, percentage body fat, maximal oxygen uptake (VO2max), smoking, physical inactivity, and type A behavior) was designed. In the Amsterdam Growth and Health Study a population of 93 males and 107 females was measured annually from 1977 to 1980 and a fifth measurement was made in 1985. In that way longitudinal data covering a period of 8 years was collected for a group of adolescents/adults between 13 and 21 years of age. Analyses of these parameters provided the following results: The stability over the 9 years of tracking cardiovascular disease indicators, measured as the interperiod correlations, is fairly high. It varies from 0.4 to 0.8 in percentage body fat, cholesterol, and VO2max. Blood pressure values are low (between 0.3 and 0.4). The probability of 13-year-olds having relatively high values of cardiovascular disease indicators on the basis of a quartile distribution with that at age 21 indicated a moderate to high predictive value. According to the literature, the levels of subjects that are continuously relatively high over the years are more in the direction of optimal health than risk values. The exception is for percentage body fat. Interrelation of the seven cardiovascular disease indicators in constantly relatively high-risk and relatively low-risk groups during the teenage period, measured during young adulthood (21.5 years), appeared to be weak: only males and females with a high percentage body fat and a low VO2max showed significantly high total cholesterol, low high-density lipoprotein cholesterol, and high total cholesterol/high-density lipoprotein cholesterol levels. From the three environmental cardiovascular disease indicators (smoking, physical activity, and type A/B behavior) measured in 1985, only physical activity was significantly correlated among males and females with high-density lipoprotein cholesterol, percentage body fat, and VO2max. It can be concluded that measurement of percentage body fat in the early teenage period seems to be the most important cardiovascular disease indicator in predicting risk levels in the young adult. The amount of physical activity measured at young adult age is the only behavioral parameter to show a significant interrelation with other cardiovascular disease risk indicators.(ABSTRACT TRUNCATED AT 400 WORDS)

Validity and reliability of pedometers in habitual activity research.

SummaryIn 12–18 year old boys actual steprate on a treadmill was compared to the scores of two types of mechanical pedometers (Russian and German), attached to the waist. Both types show deviations from actual steprate in running at speeds of 8 and 10 km·h−1 of ca. 5% (±9%). In walking or running at 6 km·h−1 and in running at 14 km·h−1 both types give an overestimation of ca. 8.5% (±8%). In walking at a speed of 2 and 4 km·h−1 the scores are not reliable because of the big standard deviation of ca. 34%. Oxygen uptake (ml·kg−1) and heart rate (beats·min−1) increase more in running than in walking, actual steprate (steps·min−1) however increases less in running compared to walking. If pedometers register only during running they reflect actual steprate fairly good and give a good estimation of the change in oxygen uptake as speed gathers.

17. The Pattern of Daily Physical Activity

In the formation of cylindrically shaped heat regenerators from ceramic honeycomb structures for use in gas turbine engines, a gas-impervious seal of the peripheral honeycomb cells and a high strength outer ring are formed simultaneously in an apparatus which provides for surrounding the outer wall of the honeycomb structure with a castable ceramic composition suitable for forming the outer ring, contacting a peripheral area of the upper surface of the honeycomb structure defining a predetermined number of peripheral cell openings with a (different) ceramic slurry composition, evacuating the honeycomb cells whose openings are contacted with the slurry composition through corresponding openings in the lower surface of the honeycomb structure in order to promote flow of the slurry into the evacuated cells, thereby forming a gas impervious seal of these peripheral cells, while simultaneously vibrating the honeycomb structure and castable composition in order to promote flow and intimate contact of the castable composition with the outer wall of the structure, thereby to form an outer adherent layer of the castable composition on the wall of the structure. After drying, the honeycomb structure with the filled peripheral cells and the outer adherent layer of ceramic may be fired in the conventional manner to convert the structure to a unified ceramic regenerator having a sealed outer ring.

Longitudinal study of maximal aerobic power in teenagers

On the basis of measurement of maximal aerobic power (VO2max) over a period of four years in a teenage population of boys (N = 102) and girls (N = 133), we studied the growth of VO2max in absolute values and in relative values: relative to whole body mass (VO2max/BM), to fat-free mass (VO2max/LBM) and to height squared (VO2max/H2). The changes in VO2max were studied in relation to chronological age (CA), skeletal age (SA), and age relative to peak height velocity (PA). Since no significant testing or measuring effects could be demonstrated and the reproducibility was high, the longitudinal design seems adequate to trace individual growth curves of VO2max. With CA VO2max increases in boys from 2.41/min at age 12+ to 3.81/min at age 17+. The increase in girls is less, from 2.31/min to 2.71/min over the same age range. VO2max/BM remained constant in boys (591/min.kg) and in girls it gradually decreased from 50 at age 12+ to 45 ml/min.kg at age 17+. The decrease in girls has been caused partly by an increase in body fat. When VO2max is aligned on PA, the results show that the peak increase coincides roughly with the age at peak height velocity. It demonstrates that in general in boys and girls during their teens no discrepancy between structural and functional growth occurs as far as VO2max is concerned.

Biological age and habitual physical activity in relation to physical fitness in 12- and 13-year-old schoolboys.

AbstractPurpose: The purpose of this study was to investigate the relationship between biological age, habitual physical activity and anthropometrical and physiological characteristics in 12- and 13-year-old schoolboys (n=70). Methods: At the beginning and the end of the school year 1971/72 biological age was determined by measuring skeletal age from left hand X-ray photographs. Habitual physical activity was determined by questionnaire interview and pedometers. Results: All anthropometrical characteristics showed significant correlations (P<0.05) with skeletal age except for bicipital and tricipital skinfolds. Out of 9 physical fitness tests handgrip was the only test that showed a significant correlation (0.52) with skeletal age.Pedometer scores gave significant negative correlations (P<0.05) with anthropometrical characteristics except for tricipital skinfold. The fitness tests bent arm hang, 12 min run walk, sit and reach and W170 showed significant correlations (P<0.05) with pedometer scores.