Jacques Vrijens

A multidisciplinary selection model for youth soccer: the Ghent Youth Soccer Project

Objectives: To determine the relationships between physical and performance characteristics and level of skill in youth soccer players aged 12–16 years. Methods: Anthropometry, maturity status, functional and sport-specific parameters were assessed in elite, sub-elite, and non-elite youth players in four age groups: U13 (n = 117), U14 (n = 136), U15 (n = 138) and U16 (n = 99). Results: Multivariate analyses of covariance by age group with maturity status as the covariate showed that elite players scored better than the non-elite players on strength, flexibility, speed, aerobic endurance, anaerobic capacity and several technical skills (p<0.05). Stepwise discriminant analyses showed that running speed and technical skills were the most important characteristics in U13 and U14 players, while cardiorespiratory endurance was more important in U15 and U16 players. The results suggest that discriminating characteristics change with competitive age levels. Conclusions: Characteristics that discriminate youth soccer players vary by age group. Talent identification models should thus be dynamic and provide opportunities for changing parameters in a long-term developmental context.

Trends in BMI among Belgian children, adolescents and adults from 1969 to 1996

OBJECTIVE: To document secular data on changes in the distribution of body mass index (BMI), to determine the probability of overweight at 40 y of age in Belgian males in relation to the presence or absence of overweight at different ages in adolescence, and to estimate tracking of BMI in Belgian males in Belgium aged 12–40 y.DESIGN: Cross-sectional and mixed longitudinal surveys in nationally representative samples of Belgian males and females.SUBJECTS: Cross-sectional—more than 21 000 boys and 9698 girls; to examine secular trends—3164 boys and 5140 girls; to examine tracking—161 males.MEASURES: Body mass and height to determine BMI.RESULTS: In Belgian children the degree of overweight has increased between 1969 and 1993. Tracking of BMI is high in adolescence (r=0.77) and adulthood (r=0.69–0.91) and moderate from adolescence to adulthood (r=0.49). In Belgian males, the probability of overweight at 40 y of age in the presence of overweight at different ages in adolescence is important (odds ratios 5.0–6.9).CONCLUSIONS: Cross-sectional and longitudinal data, trends and tracking of BMI from 1969 until 1996 in Belgium indicate an increase in the degree of childhood overweight and obesity. Moreover, the risk of an overweight male adolescent becoming an overweight adult is substantial. Measures to restrict the Belgian overweight and obesity epidemic should be taken.

Effects of training on maximal working capacity and haemodynamic response during arm and leg-exercise in a group of paddlers

Maximal oxygen uptake and circulatory adaptation to work with legs and arms were studied in a group of 5 paddlers members of the Belgian national squad and a control-group of 9 trained subjects. The results showed that the specific armtraining of paddlers induced changes in the arm-to-leg ratio of physiological parameters at submaximal and maximal work. In the group of paddlers maximal oxygen intake and workload during arm-exercise averaged respectively 88.6% and 80.3% of the scores obtained with leg-exercise. In the control group the arm to leg ratio varied between 81.2% and 65.2%. At a submaximal load of 100 W the difference in heartfrequency was 21 beats/min in the canoë group and 35 beats/min in the control group. Oxygen consumption and ventilation during work with the arms was lower in the group of paddlers. The data of our study suggest that the specific training of paddlers do result in a effect on the haemodynamic adaptations to arm work

Cardiorespiratory response to treadmill and bicycle exercise in runners

SummaryMaximal aerobic power and related variables during submaximal work were determined on the bicycle ergometer and on the treadmill in nine long-distance runners and in nine control subjects.During submaximal work, heart rate and pulmonary ventilation were similar with the two exercise procedures in each group, but the runners had lower values than the control subjects.During maximal exercise, oxygen uptake and pulmonary ventilation reached higher levels on the treadmill than on the bicycle ergometer. The difference in

Validity of the heart rate deflection point as a predictor of lactate threshold concepts during cycling

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The influence of interval circuit exercises on physical fitness of adolescents.

max was not significant in the control subjects (4.4%), but was more pronounced (12.8%) and highly significant (p<0.01) in the runners. The intergroup differences for

Breiteentwicklung und Reife bei 14- bis 15jährigen Adoleszenten

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