Biomedical subjects

G Beunen

Publications and source records attributed to G Beunen.

64 records · Page 4Linked to original sources

PubMedDate not supplied

The reproducibility of TW2 skeletal age assessments by a self-taught assessor.

An investigation into the reproducibility of TW2 skeletal age assessments was carried out using three observers. The first, G.B., had learned the technique without expert advice, while the second, R.H.W., was one of the originators of the technique. The third, N.C., was an experienced rater orginally trained by R.H.W. G.B. and R.H.W. were compared using a standard set of 112 X-rays arranged in a random order. G.B. was compared to N.C. using a random sample of 50 X-rays from the Leuven Growth Study of Belgian Boys. The percentage agreement in rating all 20 bones was just over 83% in both analyses. Higher percentage agreements were found in both analyses for the round bones (88% and 85.1% respectively) as opposed to the radius, ulna and short bones (81.3% 82.1% respectively). Significant differences were found in mean bone-age between G.B. and R.H.W. and between G.B. and N.C. for TW220 and carpal bone ages. No significant differences in mean bone-ages were found for RUS bone-ages. The reproducibility of the self-taught assessor was found to be as good as that of assessors trained by the originators of the technique or experienced raters.

Age Determination by Skeleton↗

PubMedDate not supplied

Chronological and biological age as related to physical fitness in boys 12 to 19 years.

The relative importance of skeletal age and chronological age in explaining body measurements and the relative importance of skeletal age, chronological age, height, weight, and their interactions in explaining motor fitness components are reported. Anthropometric, motor fitness, and skeletal maturity data have been collected in a mixed longitudinal study of Belgian school boys 12+/- - 19+/- years. At each age level multiple regression equations were calculated to evaluate the relative importance of the independent variables. Skeletal age was assessed by the TW2 method and the anthropometric measurements were taken following standard procedures. The motor fitness tests were selected on their factor loading and reliability in the same age range. Between 13 and 16 years a fairly high percentage of the variation in body dimensions is explained by skeletal age (+/-50% for stature). The percentage of explained variance reaches its maximum at 14-15 years. The highest percentage is found for linear dimensions and weight followed by bone width dimensions and circumferences. Triceps and calf skinfolds are not related to skeletal age. Chronological age as such does not contribute in the prediction of body measurements. The interaction between chronological age and skeletal age as such or in combination with height and/or weight have the highest predictive value except for trunk strength (leg lifting) and functional strength (bent arm hang). Except for static strength (arm pull), for which the explained variance ranged from 33% to 58%, the predictive value of body size, maturity, chronological age and their interactions is rather low, varying between 0% and 17%. As for body dimensions, the explained variance reaches its maximum for most motor tests at 14-15 years.

Adolescent↗

PubMedDate not supplied

Patterns of TW-1 and TW-2 skeletal age differences in 12-19-year-old Belgian boys.

The pattern of differences between TW-1 and TW-2 skeletal ages was investigated in a mixed longitudinal sample of Belgian school boys aged about 12-19 years. The differences between the TW-1 and TW-2 skeletal ages decrease from 12 years until 15 years, then increase until they stabilize at 17 years. TW-1 skeletal ages are greater than TW-2 skeletal ages, except at 14 and 15 years. This trend confirms the findings in better-off black and white Philadelphia children and in disadvantaged Mexican children (Malina and Little 1981).

Adolescent↗

PubMedDate not supplied

Stability of anthroposcopic and anthropometric estimates of physique in Belgian boys followed longitudinally from 13 to 18 years of age.

The stability of physique determined by the anthroposcopic 'Atlas' technique and the anthropometric Health-Carter method was examined in a sample of 210 healthy Belgian schoolboys studied longitudinally at yearly intervals from 13 to 18 years of age. The two rating systems were also compared. Results indicate that components of the same type in the two methods do not measure the same underlying factors, particularly for mesomorphy (anthroposcopic technique) and the second component (Health-Carter method). The methods cannot be considered as equivalent. The stability analysis reveals that the 'athletic' component tends to be less stable than the other two components, especially in the anthroposcopic Sheldon technique. In general, however, the constancy of the three somatotype components is fairly high during the growth period considered.

Adolescent↗

PubMedDate not supplied

Skeletal maturity and body size of teenage Belgian track and field athletes.

Attained skeletal maturity (TW2 RUS method), skeletal maturity relative to chronological age, and body size of national-level Belgian track and field athletes 15 to 18 years of age were considered. Among the 47 male athletes, 29 (62%) were skeletally mature, while 15 (52%) of the 29 female athletes were skeletally mature. There appeared to be a predominance of skeletally mature individuals among male sprinters and jumpers, while a majority of female sprinters were not skeletally mature. Both skeletally mature and immature individuals were rather evenly represented in the other track and field categories, with the exception of female throwers, who were skeletally mature. Mean statures and weights of skeletally mature and immature 16-, 17-and 18-year-old male athletes did not differ significantly, though the skeletally mature tended to be heavier. In contrast, the skeletally mature female athletes, on the average, were taller and heavier than the skeletally immature, although the differences among the small groups were not statistically significant.

Adolescent↗

PubMedDate not supplied

Age at menarche in Flemish girls: current status and secular change in the 20th century.

The age at menarche in a national sample of 4894 Flemish schoolgirls was surveyed in 1979-1980. The probit estimate of the mean age at menarche was 13.20 +/- 0.02 years (SD = 1.25 years). This estimate falls well within the range of reported ages at menarche for girls in northwestern Europe, but is slightly later than those for French-speaking girls in Belgium and in France. Status quo secular data for the 20th century indicate a decline in estimated mean ages at menarche of Flemish girls from about 14.3 years before World War II to 13.6 and 13.2 years, respectively, among girls born just before and during the war. Subsequently, mean ages at menarche of Flemish girls are fairly stable between 13.0 and 13.2 years. These secular changes are of the same magnitude as those observed in other European countries.

Adolescent↗

PubMedDate not supplied

Skeletal maturity in Belgian youths assessed by the Tanner-Whitehouse method (TW2).

Reference data for skeletal maturity (TW2 method) of the hand and wrist are provided for large representative samples of Belgian boys and girls. The sample of Belgian boys consisted of 21,174 boys aged 12 to 20 years studied in a nationwide cross-sectional and longitudinal study on the physical fitness of secondary schoolboys (1969-1974). The girls' sample consisted of 9698 6-19-year-old Flemish girls studied cross-sectionally (1979-1980). Both samples were multi-stage stratified cluster samples of entire school classes. All skeletal maturity assessments of the boys were made by the same observer (GB). His estimations agreed quite closely with those of the originators of the method. The skeletal age assessments of the girls were made by two observers trained by GB. Both observers showed high intraobserver reliability after training, and during the assessments. Moreover their ratings compared favourably with those of GB and the originators of the method. Smoothed percentile curves of the maturity scores (TW2-20 bone, RUS and CARP scores) were calculated by means of cubic splines using a stepwise regression procedure for the selection of suitable knots. In the boys, the TW2 scores (20 bone and RUS) increase linearly between 12 and 14.5 years of age, slow down for a while, and then increase again, while the CARP scores increase linearly between 12 and 15 years of age. In girls, the 20-bone maturity scores increase nearly linearly from 6 through 9.5 years of age, accelerate until 11.0 years followed by a smaller increase; RUS scores increase curvilinearly from 6 years of age onwards; and Carp scores increase almost linearly between 6.0 and 12.5 years of age. Belgian boys are advanced in RUS scores but are delayed for the carpal bones as compared with the British standards. The Belgian girls show advancement for both scales as compared with the British reference data. The skeletal maturation of youths from several other continental European countries corresponds more closely with the Belgian than with the British data. The reference data presented herein most probably provide suitable standards for youths of West-European countries.

Adolescent↗

PubMedDate not supplied

Motor performance during adolescence and age thirty as related to age at peak height velocity.

Relationships between motor performance, as measured by various fitness tests, and age at peak height velocity have been studied in a sample of 173 Flemish boys, measured yearly between +/- 13 and +/- 18 years and again as adults at 30 years of age. In addition to correlation studies, comparisons were made between boys with an early, average and late age at peak height velocity. To summarize the successive measurements during adolescence, a longitudinal principal component analysis was carried out. The first component can be interpreted as an average percentile level component. During adolescence, three performance tasks, namely speed of limb movement, explosive strength and static strength, are negatively related to age at peak height velocity; thus early maturers performed significantly better than late maturers. However, between late adolescence and adulthood, a cross-over of the average distance curves between 18 and 30 years of age was noted for almost all motor tasks. The late maturers not only caught up the early maturers, but there were significant differences for explosive strength and functional strength in favour of late maturers. In order to predict performance in adulthood from measures during adolescence, the following hypothesis is suggested: the best results at adulthood are obtained by those men who were already good performers during adolescence and who were late maturers, while the worst results are obtained by poor performers during adolescence who were early maturers.

Adolescent↗

PubMedDate not supplied

Maturity-associated variation in peak oxygen uptake in active adolescent boys and girls.

Maturity-associated variation in peak O2 uptake was considered in a longitudinal sample of 47 boys and 40 girls who were enrolled in sports schools. The children were followed annually from 11 to 14 years of age. O2 uptake and heart rate were measured during a maximal exercise test on a cycle ergometer. For boys, individual velocity curves were used to operationally define maturity groups: early-decreasing velocities from 11 to 14 years, n = 9; average-velocities reaching a peak and then decreasing, n = 7; and late-increasing velocities from 11 to 14 years, n = 31. The distributions of stages of genital and public hair development were consistent with early, average and late maturity status designation based on velocities of stature growth. Prospectively collected ages at menarche were used to define maturity groups in girls: early--< 12.0 years, n = 7, 10.8 +/- 0.6 years; average--12.0.12.9 years, n = 20, 12.4 +/- 0.3 years; and late-- > or = 13.0 years, n = 13, 13.5 +/- 0.4 years. Early maturing boys had a greater O2 uptake at each observation period. Early and average maturing girls did not differ in maximal O2 uptake, but both had greater O2 uptake than late maturers. When expressed per unit body mass, differences among the three maturity groups of boys were reduced and not significant. Late maturing girls tended to have greater maximal O2 uptake per unit body mass than early and average maturing girls, but the differences were not significant at all ages. However, with body mass at the first observation as the covariate in analyses of covariance, the three maturity groups of boys differed significantly in peak VO2 at each observation, while the three maturity groups of girls did not. Thus, removing the confounding effect of body mass on O2 uptake by simply dividing the measured values by mass is of limited utility.

Adolescent↗

PubMedDate not supplied

Gymnast wrist: an epidemiologic survey of ulnar variance and stress changes of the radial physis in elite female gymnasts.

The ulnar variance in female gymnasts attending the World Championship Artistic Gymnastics Rotterdam 1987 was measured. There was a marked increase in the ulnar length in adult as well as immature gymnast compared with nonathletes. The changes in relative ulnar length were correlated to weight, height, and skeletal age of the athletes. In 10% of the gymnasts' wrists we noted so-called "stress-related changes" of the distal physis of the radius. Repetitive injury and compression of the wrist leads to a premature closure of the distal radial growth plate resulting in secondary ulnar overgrowth.

Adolescent↗