Tracking of adult adiposity in early, average and late maturing children: a thirty year longitudinal growth study.

AIM: To investigate if predictability of adult adiposity is related to maturation status in youth. METHODS: Data of the longitudinal ''LEGS''-study (N = 550) from 6 to 18 years were used. At 35 years, 59 men and 60 women participated again. Early (EM), average (AM) and late (LM) maturity groups were established, using tertiles of age at peak height velocity (JPA-method). Pearson correlations between the childhood and the adult measurements were calculated. RESULTS: Female sum of 4 skinfolds (Sigma4SF) correlations increase from very low/moderate (6-9 years) to high at 11 years (EM), 15 years (AM) and 17 years (LM). The highest predictability was 65.6% for the Sigma4SF at 14 years in EM. At this age, predictability is 30.3% in AM and 0.8% in LM (P < 0.05). In EM, BMI correlations are moderate/high until 14 yrs (r2 = 0.64 at 13 years), but low until 15 years in LM. Male Sigma4SF correlations are very low/moderate in the three maturity groups. Significant correlation was found in the LM at 16 yrs. Moderate Body Mass index (BMI) correlations are reached at 9 years (LM) and 11 years (EM). At 16 years predictability = 4.9% for BMI in LM males. CONCLUSION: Predictability of adiposity at 35 years is generally better in girls than in boys. A dose-response effect of maturity on adult adiposity is found in girls but not in boys. Interventions to prevent adult obesity might be more effective in females than in males, particularly in EM females.

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.

Validity and reliability in a Flemish population of the WHO-MONICA Optional Study of Physical Activity Questionnaire.

PURPOSE: This study assessed the validity and reliability of a self-administered physical activity questionnaire used in the WHO-MONICA project. METHODS: Subjects (N = 167) were physical education and physical therapy alumni. The questionnaire (MOSPA-Q) covers a 1-yr period and measures the average weekly time and energy expenditure spent in one's occupation, transport-related activities, household chores, and leisure time activities. Test-retest reliability was reported as the intra-class correlation between calculated time or energy expenditure in different questionnaire items determined from two MOSPA-Q administrations. Validity was assessed using biometrical and physiological parameters as criterion measures. RESULTS: Test-retest reliability ranged from 0.45 to 0.92 with the highest correlation coefficients obtained for the leisure time physical activities. The correlation between calculated daily total energy expenditure (TEE, Kcal.d-1) and lean body mass was 0.53 (P < 0.001). The correlation between energy expenditure in leisure time activities (Kcal.wk-1) and VO2peak was 0.44. CONCLUSIONS: The MOSPA-Q provides a relatively valid and reliable estimate of physical activity.

Bayesian estimation of the parameters of a nonlinear model. An application to human height.

The estimation of the parameters of a nonlinear model by means of the maximum likelihood procedure is widely used in the study of growth phenomena. The accuracy with which these parameters are calculated is a function of the number of measures taken and particularly, of their distribution across the growth period. If the growth curve is only partially known, the inaccuracy can increase considerably. However, if we have information on the distribution of the parameters of a model in the population, the empirical Bayes method should be used. In this paper, the principle of this approach for nonlinear modeling was recalled. The method was then applied on data of human height. Four nonlinear models are used and their performances are compared. The results show the importance of information on the quality of estimates of growth parameters and consequently on the prediction of adult height.

Gymnastic injuries.

In the past 15 to 20 years gymnastics has become very popular. The increased participation exposes a greater number of athletes to potential injury. The risk of gymnastic injuries seems to be proportional to the level of the athletes; the higher the level of gymnastics, the more hours are spent in practice, with a greater exposure time. With the increased risk in gymnastics, the incidence of acute injuries will also increase, and as the skill level increases, the load during the workout will also increase, providing more opportunity for chronic injuries. As in many sports, the ankle is the most injured body part. Some injuries, however, seem to be specific to gymnastics. In gymnastics the upper extremities are used as weightbearing limbs, so high impact loads are distributed through the elbow and wrist joint. Back problems appear to result not only from single episodes of macrotrauma, but also from repeated microtrauma caused by specific impact loads during vaults and hyperextension. Early detection is the key to treating elbow, wrist and back pain in the gymnast. Reinjury following an acute injury may be reduced by allowing for complete rehabilitation before returning to full practice. Some studies indicate that maturation rate could play a potential role in injury predisposition. The combination of periods of rapid growth and intense training could provide for conditions where the gymnast is more injury prone.

Mechanical efficiency of the elbow flexors in rowing.

Biomechanical and especially kinesiological investigations of the mechanical efficiency of rowers are rarely found in today's literature. The coach frequently relates to skills or technical movements in terms of their aesthetic appearance rather than their mechanical effectiveness. The force output of the elbow flexors appears to be a function of the forearm position. The literature referring to the mechanical efficiency of the elbow flexors seems to favor both semiprone and supine positions, whereas the prone position appears to be discredited. It is the latter grip position that is actually employed and traditionally accepted in the sport of rowing. In fact, this technique was never challenged or scientifically researched to see whether a modified one might lead to better efficiency. Consequently, the purpose of this investigation was to analyze whether athletes' force output differed if the gripping technique was changed from pronation to a semiprone grip (one arm prone, the other semiprone). Under the specific conditions of this investigation, it was demonstrated that the semiprone position was generating greater force output and higher electrical activity, thus being superior to the classical prone grip.

Optimal duration of static stretching exercises for improvement of coxo-femoral flexibility.

The purpose of this study was to determine the effect of different durations of static stretching exercises on coxo-femoral (hip) flexibility. The experimental group, consisting of 20 sedentary women (20-30 years of age), participated in an exercise programme of static stretching exercises with emphasis on the hamstring muscles. The programme lasted for 10 weeks and consisted of two 50-min sessions per week. A control group of 15 sedentary women did not participate in the programme. Hip flexibility was determined before, during and at the end of the programme by means of a goniometric measuring technique developed by us and described elsewhere. Three sub-groups were formed, each following the same programme except that the duration of the static stretch differed (group 1, 10 s; group 2, 20 s; group 3, 30 s). The ANOVA tests showed that for all groups - the control group excepted - the hip flexibility had improved significantly after 10 weeks (P less than 0.05). No significant differences in hip flexibility were noted between the three subgroups at the end of the programme. This finding suggests that a duration of 10 s static stretching is sufficient for improving coxo-femoral flexibility.

The child and exercise: an overview.

In this paper the complex topic of 'the child and exercise' is approached from a multidisciplinary angle. Research concerned with effects of exercise on growth and development is reviewed. In spite of traditional beliefs, there is not enough evidence to support the view that regular and intense physical training promotes an increase in body size, nor is there any physiological evidence that severe training has any harmful effect on the body. Exercise capacity and aerobic power increase gradually throughout childhood. Investigations have shown that children aged 10 years or younger do not react with an increased VO2 max as one would expect from endurance activities. The trainability of endurance seems to depend on the biological maturity level of growing children. After puberty the effects of endurance training are similar to those reported for adults. Just how much physical activity is necessary or optimal during the growing years is not known because individual variation is great. Even fewer results are available on the trainability of anaerobic capacity. The trainability of other factors such as strength, speed, flexibility and coordination is amply discussed. Finally some thoughts are given to young female athletes, both early and late maturers, with respect to their sport performance and expectancies.

Anthropometric characteristics of female Olympic rowers.

Anthropometric data on 51 (23%) of the female rowers in the 1976 Montreal Olympic Games are summarized and compared to a female non-rower athletic sample and to a female Canadian university student sample. The rowers, being taller and heavier (means 174.3 cm and 67.4 kg) tended to be larger in all measures than the reference samples, with the exception that the university students had larger mean skinfold thicknesses. The Heath-Carter somatotype distribution of the rowers (mean 3.1 - 3.9 - 2.8) was compared to that of the students (4.0 - 3.5 - 2.9) and other female athletic samples. Proportionality profiles scaled to a unisex reference human or phantom showed both samples to be rather similar in proportional lengths except for longer tibiale height, wider transverse chest breadth, larger flexed arm and forearm girths, and smaller skinfold thicknesses in female rowers than in students. Fractionation of body mass by a four-component model showed the rowers to have similar percent skeletal and residual masses, lower percent fat and higher percent muscle mass than students. The anthropometric characteristics as described and analyzed in this study are submitted as the basic anthropometric reference for those interested in fostering the development of women's rowing.

A method for detecting errors in data of growth studies.

The paper describes a new method used for data cleaning in growth and development studies. The method is essentially based on the assumption that an extreme value of a certain variable might be suspicious if other highly correlated variables show low compatibility with it and that, on the other hand, an extreme but possible value tends not to be erroneous if it is reinforced by another extreme but possible value of a highly correlated variable. Each variable was therefore included in at least two ratios with the highest correlated variables. A program was designed to detect extreme values of individual variables and extreme ratio values. This procedure with ratios was used to help to detect possible errors and discriminate them from true extreme values. Seen in the light of corrected data files against existing data files, the number of corrections was approximately 4.4%. If the real number of corrected errors is compared to the total number of subjects, this percentage reached 5.5%. If, when correcting, the real value was not detected with certainty, the erroneous value was then simply deleted. From our results, there is reason to believe that with this method few detectable errors will escape from the cleaning procedure. Conclusions for future correction procedures and for future growth studies in general, are also given in the paper.