Longitudinal growth of stature in boys according to age and puberty: Prediction of adult stature from the age of 13 years.

BACKGROUND: The purpose of this study was to cross-validate and demonstrate how adult stature can be predicted in 13-year-old teenager's boys by using a new reference specific growth curve obtained from chronological age and maturity. METHODS: Stature measurements of 125 boys aged from 12 to 17.5 years were obtained over a period of five consecutive years. The maturity was based on the age of peak height velocity (APHV). An assessment of secondary pubertal stages using a simplification of the Tanner stages was also carried out. We found a connection between the secondary pubertal stage and the APHV. We carried out a prediction of the adult stature of 67 teenagers aged from 160 and 164 months. RESULTS: Significant differences between APHV enabled us to classify the adolescents into three categories according to their biological maturity: 19% of adolescents with advanced puberty, 62% with standard puberty and 19% with delayed puberty. The mean growth curves were used to predict the adult stature of 67 individuals with a good accuracy (±3 cm). The mean differences between predicted and real adult stature are -0.11 cm with 95% limits of agreement of [-3.2; + 2.8 cm]. CONCLUSIONS: The new stature growth curves developed from age and maturation enables us to accurately track individual growth kinetics.

Measuring body fat-How accurate is the extrapolation of predictive models in epidemiology?

Excess fat is a risk factor for many chronic diseases which can lead to premature mortality. Many studies have proposed predictive equations for body fat mass and body fat mass percentage based on anthropometric measures in relation to age and sex. However, the use of these predictive equations on other subject samples may not be relevant. Our objective is to assess whether the predictive equations proposed in the literature are generalizable to any population. We obtained fat mass and fat percentage on a reference population using Absorptiometry DXA. The predictive equations were applied to our population and the mean and individual differences between actual and estimated values were obtained. Predictive equations obtained from a reduced number of subjects have a very high Standard Error of Estimate (>3) and therefore their accuracy is not acceptable. Only the formulae established from a large number of individuals allow the estimation of values whose Standard Error of Estimate is less than 3. These equations, thanks to the large sample size, include a sufficiently large variability in anthropometric measurements covering the diversity of anthropometric values for the same fat value. However, predictive equations based on a large sample size, while exhibiting no current difference in variances, can show a shift in mean values. This mean-shift is the result of differences in DXA devices and needs to be corrected. It means that DXA values from a few individuals in the population under study must be obtained to calculate a corrective factor.

The same growth pattern from puberty suggests that modern human diversity results from changes during pre-pubertal development.

Patterns of human growth established for one population have rarely been tested in other populations. In a previous study, three growth curves from puberty were modelled for each sex in a longitudinal study of a Caucasian population based on stature, age at peak of growth and biological maturation. Each curve represents the canalisation of growth associated with the type of puberty. The high precision (± 3 cm) of individual adult stature predictions shows that growth kinetics are already set up at puberty and are canalised depending on biological maturity. Our aim is to assess whether this model can be extrapolated to other populations to test whether growth canalisation is a population-dependent phenomenon or if the model reflects a canalisation pattern specific to our species. The modelled curves predicted adult stature with the same high degree of precision in basketball players and the Baka pygmies. Therefore, (1) the relationship between growth kinetics and age at maturity is similar in all populations and (2) growth according to pubertal stages follows the same canalisation patterns in the populations despite the wide differences in their average adult statures. It suggests that morphological diversity in modern humans results from processes taking place in early development.

Age Estimation of Teenage Boys During Puberty.

BACKGROUND: Age estimation of a minor whose identity is unknown must be accurate enough to respond to judicial requests. The main objective of this study is to accurately determine a teenager's age from simple and reproducible criteria. SAMPLES AND METHODS: The first reference sample consists of 1720 measurements collected from 170 teenagers aged 11 to 16 years, over a period of 5 years. A second validation sample of 735 teenage boys aged 11 to 16 made it possible to verify the relevance of our estimates. The degree of maturation was determined using 4 pubertal stages: the stage below the age of puberty, the prepubescent stage, the parapubescent stage, and the pubescent stage.For each pubertal stage, an optimization of the values of the age was carried out in order to reduce the differences between the estimated and the actual age at the different age groups. RESULTS: The mean differences between estimated age and actual age from these values were -0.06 ± 0.91 years for the reference group and -0.49 ± 0.73 years for validation group. CONCLUSIONS: Our method of age estimation is simpler and accurate. It could be used routinely in a forensic frame to respond to judicial requests.

Prediction of body fat in male athletes from ultrasound and anthropometric measurements versus DXA.

BACKGROUND: To compare the accuracy of body fat percentage (BF%) measured by an ultrasound portable device and anthropometric measurements with a Dual energy X-ray absorptiometry (DXA) as the reference technique in male athletes. METHODS: A total of 100 athletes: 16 boxers, 4 rowers, 5 gymnasts, 6 base ball players, 19 judo players, 10 taekwondo players, 7 basket-ball players, 21 wrestlers, 6 cyclists on track and 6 karate expert aged from 18 to 30 years participated. All athletes were selected from the French National Institute of Sports and Physical Education. Ultrasound measurements were made with a sonographic US BOX at the mid-thigh level. We developed a multi -linear model of body fat estimation from ultrasound and anthropometric dimensions (height, weight, waist circumference) using the DXA reference method. A cross-validation study was then performed with this linear regression on 62 males athletes proportionally stratified across the sports. RESULTS: The best accuracy of BF was obtained using a multi-linear model from ultrasonic and anthropometric measurements with a concordance correlation ρc=0.941. This model was then used to estimate BF on the 62 males athletes. The concordance correlation ρc=0.931 and SEE=1.60. The 95% limits of agreement for individual BF% were [-4.1;3.6%] with symmetrically distributed deviations. CONCLUSIONS: Comparing to DXA, ultrasonic and anthropometric measurements are both accurate techniques to estimates BF%. Our results suggest that this regression model is practical to apply to different sports.

Prediction of male basketball players' adult stature from the age of 13 years using chronological age and maturity.

BACKGROUND: The purpose of this study was to cross-validate and demonstrate how adult stature can be predicted in 13-year-old basket-ball players by using a new reference specific growth curve obtained from chronological age, and maturity of sedentary boys. METHODS: The prediction of adult stature of young male basketball players was established from the results of a longitudinal study in which we developed from 125 sedentary boys aged from 12 to 17.5 years new growth curves using chronological and biological maturation. In partnership with the French basketball federation, we collected information on stature, age and secondary pubertal stages from a sample of 106 boys aged from 160 and 164 months. The participants were regional level basketball players whose adult statures were known. The association of biological maturation at a chronological age was the determining criterion to predict individual adult stature with advanced, standard and delayed puberty. RESULTS: The average longitudinal growth curves enabled the prediction of adult stature within ±3 cm, 98% of the time in male basketball players. The relationship between estimated adult stature and final stature was high (r=0.98) with a low standard error estimate (SEE=1.65 cm). Mean and standard deviation of the differences between estimated stature and adult stature were 0.7±1.7. CONCLUSIONS: This technique is a valid, nonintrusive and accurate method of predicting adult stature in adolescent basketball players. It constitutes an advance in the detection and the orientation of future basketball players.

Aerobic training suppresses exercise-induced lipid peroxidation and inflammation in overweight/obese adolescent girls.

This study aimed to determine whether aerobic training could reduce lipid peroxidation and inflammation at rest and after maximal exhaustive exercise in overweight/obese adolescent girls. Thirty-nine adolescent girls (14-19 years old) were classified as nonobese or overweight/obese and then randomly assigned to either the nontrained or trained group (12-week multivariate aerobic training program). Measurements at the beginning of the experiment and at 3 months consisted of body composition, aerobic fitness (VO2peak) and the following blood assays: pre- and postexercise lipid peroxidation (15F2a-isoprostanes [F2-Isop], lipid hydroperoxide [ROOH], oxidized LDL [ox-LDL]) and inflammation (myeloperoxidase [MPO]) markers. In the overweight/ obese group, the training program significantly increased their fat-free mass (FFM) and decreased their percentage of fat mass (%FM) and hip circumference but did not modify their VO2peak. Conversely, in the nontrained overweight/obese group, weight and %FM increased, and VO2peak decreased, during the same period. Training also prevented exercise-induced lipid peroxidation and/or inflammation in overweight/obese girls (F2-Isop, ROOH, ox-LDL, MPO). In addition, in the trained overweight/obese group, exercise-induced changes in ROOH, ox-LDL and F2-Isop were correlated with improvements in anthropometric parameters (waist-to-hip ratio, %FM and FFM). In conclusion aerobic training increased tolerance to exercise-induced oxidative stress in overweight/obese adolescent girls partly as a result of improved body composition.

Efficacy and safety of growth hormone treatment in children with hypochondroplasia: comparison with an historical cohort.

BACKGROUND/AIMS: Hypochondroplasia (HCH) is a skeletal dysplasia characterized by disproportionate short stature. The aims of the study are to evaluate efficacy and safety of recombinant human growth hormone (r-hGH) therapy in HCH children, when compared with a historical cohort of untreated HCH children. METHODS: Nineteen HCH patients with an initial height standard deviation score (SDS) ≤-2 and a mean age of 9.3 ± 3.1 years were treated with a mean r-hGH dose of 0.053 mg/kg/day over 3 years. Growth charts were derived from the historical cohort (n = 40). RESULTS: Height gain in the treated population was +0.62 ± 0.81 SDS greater than in the general population, and +1.39 ± 0.9 SDS greater than in the historical untreated HCH cohort (mean gain of 7.4 ± 6.6 cm gain). A negative correlation between height gain and age at treatment initiation was reported (p = 0.04). There was no significant difference in response between patients with fibroblast growth factor receptor 3 mutations and those without. No treatment-related serious adverse events were reported. CONCLUSIONS: r-hGH treatment is well tolerated and effective in improving growth in HCH patients, particularly when started early. The treatment effect varies greatly and must be evaluated for each patient during treatment to determine the value of continued therapy.

Age at menarche in a group of French schoolgirls.

BACKGROUND: Mean age at menarche in France decreased from 12.78 years in 1979 to 12.6 years in 1994. The aim of this study was to determine mean age at first menstruation in French adolescent girls in order to study the secular trend. METHODS: Age at first menstruation was noted to the nearest month during recording of anthropometric measurements in three secondary schools in the Aisne administrative department, France, in classes in years 7, 8, 9 and 10. A total of 339 girls aged 11-15 ½ years were examined. The majority were from a social background of workers, employees and middle managerial staff. Mean age at first menses and standard deviation were calculated using the probits method. RESULTS: Mean age was 12.5 ± 0.08 years (χ(2) γ=14 = 16.7, P > 0.05), indicating that it had remained stable for more than 15 years. CONCLUSIONS: A secular decline has already been observed in Belgium, Britain, Hungary, Scandinavia and the USA. In all these countries, age at menarche has reached a stable level at around 13 ± 0.5 years.

Body Fat Mass Assessment: A Comparison between an Ultrasound-Based Device and a Discovery A Model of DXA.

Objective. To examine measurement of body composition by ultrasound compared with a reference technique:dual energy X-ray absorptiometry (DXA). We evaluated the accuracy of a portable ultrasound-based device in estimating total body fat mass with those assessed by DXA in adult. Methods. Body fat mass has been estimated using a portable ultrasound-based device in comparison with a contemporary reference DXA apparatus: the Hologic Discovery A. Anthropometric data has been assessed in order to maximize the output of the software associated with the ultrasound-based device. A cross-validation between ultrasound technique (US) and DXA was developed in this study. Total body fat mass estimated by ultrasound was compared with this DXA model in a sample of 83 women and 41 men. Results. Ultrasound technique (US) of body fat (BF) was better correlated with DXA in both women (r (2) = 0.97, P < 0.01) and men (r (2) = 0.92, P < 0.01) with standard errors of estimates (SEE) being 2.1 kg and 2.2 kg, respectively. Conclusion. The use of a portable device based on a US produced a very accurate BF estimate in relation to DXA reference technique. As DXA absorptiometry techniques are not interchangeable, the use of our ultrasound-based device needs to be recalibrated on a more contemporary DXA.

[Secular trends in anthropometrical measurements observed in three to 11-year-old French children between 1953 and 2005]. / Évolution séculaire des dimensions anthropométriques chez des enfants français âgés de trois à 11ans, entre 1953 et 2005.

This study covers a fifty-year period between 1953 and 2005 and looks at secular trends in stature, weight and sitting height sizes among French boys and girls between the ages of 3 and 11. A special modelling in function to the age and variable for each child was established so that a comparison could be made in the kinetic growth patterns over these same two periods. Statistical analysis shows a significant increase in growth, of 0.8cm per decade in stature, characterised by a certain increase in the lower limbs and the weight (0.8kg per decade) together with a proportional increase on the body mass index. Positive secular trends of this anthropometric nature are generally thanks to improved eating and sanitary habits and this study enables us to build and elaborate new standards in growth patterns essential for monitoring auxological development in 3 to 11-year-old children in the years 2000 and onwards.

[Boxing: traumatology and prevention]. / La boxe, sport de combat, de la traumatologie à la prévention.

In 1986, a surgeon who, as an amateur boxer himself was concerned with boxers' health, approached a pioneering Parisian neuroimaging unit. Thus began a study in close cooperation with the French Boxing Federation, spanning 25 years. In a first series of 52 volunteer boxers (13 amateurs and 39 professionals), during which MRI gradually replaced computed tomography, ten risk factors were identified, which notably included boxing style: only one of 40 "stylists" with a good boxing technique had cortical atrophy (4.5 %), compared to 15 % of "sloggers". Changes to the French Boxing Federation rules placed the accent on medical prevention. The second series, of 247 boxers (81 amateurs and 266 professionals), showed a clear improvement, as lesions were suspected in 14 individuals, of which only 4 (1.35 %) were probably due to boxing. The third and fourth series were part of a protocol called "Brain-Boxing-Ageing", which included 76 boxers (11 having suffered KOs) and 120 MRI scans, with reproducible CT and MRI acquisitions (9 sequences with 1.5 T then 3 T, and CT). MRI anomalies secondary to boxing were found in 11 % of amateurs and 38 % of professionals (atrophy, high vascular T2 signal areas, 2 cases of post-KO subdural bleeding). CT revealed sinus damage in 13 % of the amateurs and 19 % of the professionals. The risk of acute and chronic facial and brain damage was underline, along with detailed precautionary measures (organization of bouts, role of the referee and ringside doctor, and application of French Boxing Federation rules).

Ultrasound measurement of total body fat in obese adolescents.

BACKGROUND/AIMS: To compare body fat (BF) measurements obtained with a new ultrasound method with those assessed by dual-energy X-ray absorptiometry (DEXA) in obese adolescents. METHODS: In 94 adolescents (57 females and 37 males) aged 12-19 years and body mass index (BMI) exceeding 30 kg.m(-2), the z-score BMI for age was 6.7 (adolescent girls) and 6.6 (adolescent boys) >97th percentile. BF was measured using DEXA and a method based on ultrasound measurements, body weight, height, abdominal circumference and mid-thigh circumference. RESULTS: Obesity class I was noted in 39%, II in 28% and III in 33% of the patients. BF by ultrasound correlated closely with BF by DEXA, in both females (r = 0.958) and males (r = 0.981), with standard errors of the estimates (SEE) being 2.9 and 2.5 kg, respectively. The ultrasound method was more accurate than the skinfold technique (n = 24; SEE: 2.2 vs. 6.5 kg, respectively). In 13 adolescents who had marked weight loss after 6 months of treatment, the decrease in DEXA-measured BF correlated closely with the decrease in ultrasound-measured BF (r = 0.95). CONCLUSIONS: Our innovative portable ultrasound technique has advantages in terms of reliability, reproducibility, accuracy and costs for screening and monitoring obese adolescents. A patent application has been submitted. Our method should prove valuable for epidemiological studies.

Influence of the weight status on bone mineral content and bone mineral density in a group of Lebanese adolescent girls.

AIM: The aim of this study was to determine the influence of being overweight on whole-body (WB) bone mineral content (BMC) and bone mineral density (BMD) in a group of Lebanese adolescent girls. METHODS: This study included 32 overweight (BMI>25 kg/m2) adolescent girls (15.3+/-2.3 years old) and 24 maturation-matched (15.7+/-1.7 years old) controls (BMI<25 kg/m2). Bone mineral area (BMA), BMC, BMD at the WB and body composition (lean mass and fat mass) were assessed by dual-energy X-ray absorptiometry (DXA). Calculation of the ratio BMC/height and bone mineral apparent density (BMAD) were completed for the WB. RESULTS: Expressed as crude values, BMA, BMC and the ratio BMC/height were higher in overweight adolescent girls compared to controls. After adjusting for body weight, there were no differences in BMC or in the ratio BMC/height between the two groups. However, BMA was lower in overweight girls compared to controls. After adjusting for either lean mass or fat mass, there were no significant differences between the two groups regarding these variables: BMC, BMA, BMD, BMC/height and BMAD. CONCLUSION: This study suggests that the positive effect of overweight on BMC is due to body weight. In fact, the difference in BMC between the overweight and the control girls disappears after adjusting for body weight. In contrast, overweight girls have lower BMA compared to controls when values are adjusted to body weight.

Ultrasound techniques applied to body fat measurement in male and female athletes.

CONTEXT: For athletes in disciplines with weight categories, it is important to assess body composition and weight fluctuations. OBJECTIVE: To evaluate the accuracy of measuring body fat percentage with a portable ultrasound device possessing high accuracy and reliability versus fan-beam, dual-energy X-ray absorptiometry (DEXA). DESIGN: Cross-validation study. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 93 athletes (24 women, 69 men), aged 23.5 +/- 3.7 years, with body mass index = 24.0 +/- 4.2 and body fat percentage via DEXA = 9.41 +/- 8.1 participated. All participants were elite athletes selected from the Institut National des Sports et de l'Education Physique. These participants practiced a variety of weight-category sports. MAIN OUTCOME MEASURE(S): We measured body fat and body fat percentage using an ultrasound technique associated with anthropometric values and the DEXA reference technique. Cross-validation between the ultrasound technique and DEXA was then performed. RESULTS: Ultrasound estimates of body fat percentage were correlated closely with those of DEXA in both females (r = 0.97, standard error of the estimate = 1.79) and males (r = 0.98, standard error of the estimate = 0.96). The ultrasound technique in both sexes had a low total error (0.93). The 95% limit of agreement was -0.06 +/- 1.2 for all athletes and did not show an overprediction or underprediction bias. We developed a new model to produce body fat estimates with ultrasound and anthropometric dimensions. CONCLUSIONS: The limits of agreement with the ultrasound technique compared with DEXA measurements were very good. Consequently, the use of a portable ultrasound device produced accurate body fat and body fat percentage estimates in relation to the fan-beam DEXA technique.

[Leptin, insulin, IGF-1 and bone mass in a group of sedentary adolescent girls]. / Leptine, insuline, IGF-1 et masse osseuse chez des adolescentes sédentaires.

AIM OF THE STUDY: To investigate the relationships between serum leptin, IGF-1, insulin and bone mineral content and density in a group of Lebanese sedentary adolescent girls. METHODS AND RESULTS: Twenty Lebanese sedentary adolescent girls participated in our study. Total body bone mineral content and density were measured by dual-energy X-ray absorptiometry (DEXA). In parallel, fasting leptin, IGF-1 and insulin concentrations were also measured. Serum leptin, IGF-1 and insulin concentrations were not associated with total body bone mineral content (BMC), total body bone mineral density (BMD) or pelvis BMD. CONCLUSION: Serum leptin, IGF-1 and insulin concentrations are not positive predictors of total body bone mineral content or density in this study group.

Validation of ultrasound techniques applied to body fat measurement. A comparison between ultrasound techniques, air displacement plethysmography and bioelectrical impedance vs. dual-energy X-ray absorptiometry.

AIMS: To evaluate the accuracy of body fat percentage (BF%) estimates from a portable, non-traumatizing ultrasound device with high accuracy and reliability compared to dual-energy X-ray absorptiometry (DEXA), the reference technique. DESIGN: Cross-validation between ultrasound technique (UT), DEXA, air displacement plethysmography (ADP) and bioelectrical impedance (BIA) was developed in the study. SUBJECTS: A total of 89 healthy subjects (41 women, 48 men), aged 48.4 +/- 17.7 (mean +/- SD), with Body mass index (28.5 +/- 7.7 kg/m(2)) and body fat DEXA (29.6 +/- 10.8 kg) participated. METHODS: BF% was measured using an UT associated with anthropometric parameters and simultaneously, with the DEXA reference technique, BIA and ADP. RESULTS: UT estimates of BF% were better correlated with those of DEXA in both males and females (r = 0.98, SEE = 2.0) than with ADP (r = 0.94, SEE = 3.7) or BIA (r = 0.92, SEE = 4.4). The UT in both genders was better (TE = 1.0) than BIA (TE = 2.6) and ADP (TE = 3.0). The 95% limits of agreement were also better for the UT (-2%; 2%) than with BIA (-5.1%; 4.9%) and ADP (-6.3%; 5.3%). CONCLUSIONS: The limits of agreement with BIA and ADP are unacceptably high compared to a DEXA measure criterion. The use of a new portable device based on a UT produced a very accurate BF% estimate in relation to the DEXA reference technique.

Optimal standards for fetal biometry: to each measurement its fitting model.

OBJECTIVE: To determine the best mathematical model to construct charts of fetal abdominal circumference (AC) and femur length (FL). METHODS: Ultrasound measurements were made on 1,336 normal fetuses in one center. Four mathematical models were compared (a linear-quadratic model, a linear-cubic model, the Rossavik model and a new two-phase model, which has been found to best fit fetal head data). RESULTS: The best fitting of AC and FL data was obtained with the linear-quadratic model without separate computing for gender. Centile charts have been computed. CONCLUSION: Fetal growth of AC and FL is much simpler than that of the head. Therefore, a unique mathematical model should not be used to fit all measurements.

[Average height of adolescents in the Dinaric Alps]. / Les Alpes Dinariques : un peuple de sujets de grande taille.

This study contributes to an update of average heights among European populations. Our investigation covering 2705 boys and 2842 girls aged 17 years, shows that, contrary to the general belief, adolescents of the Dinaric Alps are, on average, the tallest in Europe. With an average height of 185,6 cm, they are taller than Dutch adolescents (184 cm on average). Above all, the density of very tall subjects appears to be characteristic of the Dinaric Alps, since 28% measure 190 cm or more in height, as opposed to only 20% in Holland and 1.5% in France. Although our information is not complete, adolescent girls in the Dinaric Alps, with an average height of 171 cm come a close second to girls in Holland.

Only two-phase models, computed independently for males and females, are appropriate to describe fetal head growth.

OBJECTIVE: To establish an accurate mathematical model describing fetal head growth, taking into account gender differences and changes in growth rate during gestation. METHODS: Ultrasound measurements of head circumference and biparietal diameter were made on 1,336 normal fetuses (684 males and 652 females) in the Maternité Régionale de Nancy (France). A new two-phase model, taking into account an alteration in growth kinetics at 30 gestational weeks, was computed independently for male and female data. The accuracy of this model was tested and compared with three current mathematical models: a linear-quadratic, a linear-cubic, and the Rossavik and Deter (1984) models. RESULTS: In all models, including ours, the coefficients of determination (R(2)) were high (> or =0.999), so long as male and female data were computed separately. However, the standard error estimates (SEE) of our two-phase model were much lower (0.13 < or = SEE < or = 0.57) than the SEE of the three other models when computed over the whole gestational period (0.49 < or = SEE < or = 2.69); nevertheless, when these three other models were computed for these two successive periods, their SEE decreased, and data fitting was improved. CONCLUSION: Only two-phase mathematical models, computed independently for male and female data, accurately describe the kinetics of fetal head growth. They should be used to calculate growth standards and to perform an exact diagnosis of impaired growth.