Impact Exercise Increases BMC During Growth: An 8-Year Longitudinal Study

Our aim was to assess BMC of the hip over 8 yr in prepubertal children who participated in a 7-mo jumping intervention compared with controls who participated in a stretching program of equal duration. We hypothesized that jumpers would gain more BMC than control subjects. The data reported come from two cohorts of children who participated in separate, but identical, randomized, controlled, school-based impact exercise interventions and reflect those subjects who agreed to long-term follow-up (N = 57; jumpers = 33, controls = 24; 47% of the original participants). BMC was assessed by DXA at baseline, 7 and 19 mo after intervention, and annually thereafter for 5 yr (eight visits over 8 yr). Multilevel random effects models were constructed and used to predict change in BMC from baseline at each measurement occasion. After 7 mo, those children that completed high-impact jumping exercises had 3.6% more BMC at the hip than control subjects whom completed nonimpact stretching activities (p \u3c 0.05) and 1.4% more BMC at the hip after nearly 8 yr (BMC adjusted for change in age, height, weight, and physical activity; p \u3c 0.05). This provides the first evidence of a sustained effect on total hip BMC from short-term high-impact exercise undertaken in early childhood. If the benefits are sustained into young adulthood, effectively increasing peak bone mass, fracture risk in the later years could be reduced

Adolescent trajectories of aerobic fitness and adiposity as markers of cardiometabolic risk in adulthood

Purpose: The aim of this study was to investigate whether adolescent growth trajectories of aerobic fitness and adiposity were associated with mid-adulthood cardiometabolic risk (CMR). Methods: Participants were drawn from the Saskatchewan Growth and Development Study (1963-1973). Adolescent growth trajectories for maximal aerobic capacity (absolute VO2 (AbsVO2)), skinfolds (SF), representing total body (Sum6SF) and central adiposity (TrunkSF), and body mass index (BMI) were determined from 7 to 17 years of age. In mid-adulthood (40 to 50 years of age), 61 individuals (23 females) returned for follow-ups. A CMR score was calculated to group participants as displaying either high or a low CMR. Multilevel hierarchical models were constructed, comparing the adolescent growth trajectories of AbsVO2, Sum6SF, TrunkSF, and BMI between CMR groupings. Results: There were no significant differences in the adolescent development of AbsVO2, Sum6SF, TrunkSF, and BMI between adult CMR groupings (p > 0.05). Individuals with high CMR accrued 62% greater adjusted total body fat percentage from adolescence to adulthood (p=0.03). Conclusions: Growth trajectories of adolescent aerobic fitness and adiposity do not appear to be associated with mid-adulthood CMR. Individuals should be encouraged to participate in behaviours that promote healthy aerobic fitness and adiposity levels throughout life to reduce lifelong CMR

The role of growth and maturation during adolescence on team-selection and short-term sports participation

Background: During adolescence, deselection from sport occurs during team try-outs when month of birth, stage of growth and maturation may influence selection.Aim: The purpose of this study was to identify differences in growth and maturity related factors between those selected and deselected in youth sports teams and identify short-term associations with continued participation.Subjects and methods: Eight hundred and seventy participants, aged 11–17 years, were recruited from six sports try-outs in Saskatchewan, Canada: baseball, basketball, football, hockey, soccer and volleyball. Two hundred and forty-four of the initial 870 (28%) returned for follow-up at 36 months. Chronological (years from birth), biological (years from age at peak height velocity (APHV)) and relative (month of birth as it relates to the selection band) ages were calculated from measures of date of birth, date of test, height, sitting height and weight. Parental heights were measured or recalled and participant’s adult height predicted. Reference standards were used to calculate z-scores. Sports participation was self-reported at try-outs and at 36-month follow-up.Results: There was an over-representation of players across all sports born in the first and second quartiles of the selection bands (p < 0.05), whether they were selected or deselected. z-scores for predicted adult height ranged from 0.1 (1.1) to 1.8 (1.2) and were significantly different between sports (p < 0.05). Height and APHV differences (p < 0.05) were found between selected and deselected male participants. In females only weight differed between selected and deselected female hockey players (p < 0.05); no further differences were found between selected and deselected female participants. Four per cent of deselected athletes exited sports participation and 68% of deselected athletes remained in the same sport at 36 months, compared with 84% of selected athletes who remained in the same sport.Conclusions: It was found that youth who attended sports team’s try-outs were more likely to be born early in the selection year, be tall for their age, and in some sports early maturers. The majority of both the selected and deselected participants continued to participate in sport 36 months after try-outs, with the majority continuing to participate in their try-out sport

At what age do normal weight Canadian children become overweight adults? Differences according to sex and metric

Background: The prevalence of overweight and obesity doubles between adolescence and young adulthood. However, the exact age, and appropriate metric to use, to identify when overweight develops is still debated. Aim: To examine the age of onset of overweight by sex and four metrics: body mass index (BMI), fat mass (%FM), waist circumference (WC) and waist-to-height ratio (WHtR). Methods: Between 1991 and 2017, serial measures of body composition, were taken on 237 (108 males) individuals (aged 8 to 40 years of age). Hierarchical random effects models were used to develop growth curves. Curves were compared to BMI, %FM and WC overweight age and sex-specific cut-points. Results: In males the BMI growth curve crossed the cut-point at 22.0 years compared to 23.5 and 26.5 years for WHtR and %FM respectively; WC cut-off were not reached until 36 years. In females the BMI growth curve, crossed the overweight cut-point at 21.5 years compared to 14.2 years for %FM and at 21.9 and 27.5 years for WC and WHtR respectively. Conclusions: Overweight onset occurs during young adulthood with the exception of WC in males. BMI in males and %FM in females were the metric identifying overweight the earliest

Análise discriminante do desempenho motor de ginastas brasileiras de níveis competitivos distintos

This study investigates the discriminant power of the Talent Opportunity Program’s (TOPS) tests battery in elite and non-elite Brazilian female artistic gymnasts belonging to three competitive categories: pre-infantile, infantile e juvenile. The sample comprises 234 gymnasts (67 elite; 170 non-elite) aged 9-15 years from 26 Brazilian gymnastics clubs. Anthropometry, body composition, biological maturation, and training history data were collected. Motor performance was assessed with TOPS physical abilities battery (tests: handstand hold, cast, rope climb, press handstand, leg flexibility, leg lift, 20 meters sprint). Hotteling T2, and stepwise discriminant analysis was conducted in SYSTAT 13. There were significant differences (p&lt;0.001) in the vectors of means between elite and non-elite groups in each age-category. On average, elite gymnasts had significant higher performance than non-elite gymnasts in almost all tests (p&lt;0.05), but the sprint test (p&gt;0.05). The discriminant analysis identified different sub-sets of tests that differentiated elite from non-elite gymnasts: cast (pre-infantile); press handstand, rope climb and handstand hold (infantile); leg lift, leg flexibility (juvenile). Corrected re-classification was high: 84 % in pre-infantile, 79% in infantile, and 75% in juvenile categories. In conclusion, results showed significant differences in motor performance between elite and non-elite gymnasts, as well as the discriminant power of TOPS in each age category, suggesting that this may be a relevant instrument as an assessment tool in training control of Women Artistic Gymnastics, and may be a suitable instrument for decision making.O presente estudo pesquisou o poder discriminante da bateria de testes Talent Opportunity Program (TOPS) em ginastas brasileiras de elite e não-elite de três categorias competitivas: pré-infantil, infantil e juvenil. A amostra compreende 234 ginastas (67 elite e 170 não-elite) de 9 a 15 anos, provenientes de 26 clubes. Foram obtidas informações antropométricas, de composição corporal, maturação biológica e treinamento. O desempenho motor foi avaliado por meio de sete testes da bateria de capacidades físicas TOPS (parada de mãos, lançamento na barra, subida na corda, esquadro à parada de mãos, flexibilidade de pernas, elevação no espaldar, velocidade). Foram utilizados o teste T2 de Hotteling, bem como a opção stepwise da função discriminante implementada no SYSTAT 13. Há diferenças significativas (p&lt;0.001) entre os vetores de médias dos grupos elite e não-elite em cada categoria. Em média, as ginastas de elite têm desempenhos significativamente superiores às não-elite em praticamente todos os testes (p&lt;0.05), exceto na prova de velocidade (p&gt;0.05). A análise discriminante identificou os testes que separaram maximamente as ginastas do grupo elite e não-elite: lançamento na barra (categoria pré-infantil); esquadro à parada de mãos de mãos, subida na corda e parada de mãos (categoria infantil); elevação no espaldar e flexibilidade de pernas (categoria juvenil). A reclassificação nos grupos originais foi relativamente elevada: 84% na categoria pré-infantil, 79% na categoria infantil e 75% na categoria juvenil. Em conclusão, os resultados evidenciaram diferenças significativas nos níveis de desempenho motor das ginastas de elite versus não-elite, além do poder discriminante da TOPS em cada uma das categorias competitivas, sugerindo sua utilização na avaliação e controle do treino, e adjuvante nas tomadas de decisão dos selecionadores de Ginástica Artística Feminina

Physical fitness spurts in pre-adolescent boys and girls: Timing, intensity and sequencing

We aim to (1) estimate age of attainment of the peak mid-growth spurt in stature (age-at-peak MGS) in pre-adolescent boys and girls; (2) identify the timing, intensity, and sequences of physical fitness (PF) spurts aligned by the age-at-peak MGS; and (3) identify any sex differences in PF spurts aligned by age-at peak MGS. The sample included 180 Portuguese children (90 girls) aged 6 to 10 years at study entry who were followed annually for 4 years. Height, health-, and performance-related PF were assessed. Age-at peak MGS and PF spurts were estimated using a non-smooth mathematical procedure. Boys’ and girls’ age-at-peak MGS occurred at 7.8 ± 0.47 years and 8.0 ± 0.72 years, respectively. PF spurts’ timing aligned by age-at-peak MGS were as follows: (1) before age-at-peak MGS: boys – static strength, aerobic capacity, explosive leg strength, and flexibility; girls – speed, agility, aerobic capacity, and upper body strength; (2) coincident with age-at-peak MGS: girls – explosive leg strength and flexibility; (3) after age-at-peak MGS: boys – abdominal strength, upper body strength, agility, and speed; girls – abdominal strength and static strength. Boys and girls attained their MGS at relatively similar ages. However, the timing and sequences of PF spurts, aligned on age-at-MGS, were different between boys and girls.info:eu-repo/semantics/publishedVersio

Differentiating maturational influence on training-induced strength and endurance adaptations in prepubescent children

To analyze the effect of biological maturation on training-induced strength and endurance adaptations in the prepubertal growth spurt. One hundred and twenty-five healthy children (58 boys, 67 girls), aged 10-11 years old (10.8 ± 0.4 years), who were self-assessed as belonging to Tanner stages I and II, were randomly divided into two experimental groups, a strength training group (19 boys, 22 girls) and an endurance training group (21 boys, 24 girls) that would train twice a week for 8 weeks, as well as a control group (18 boys, 21 girls; no training program). After 8 weeks of training, there were improvements in all strength and endurance measures (P 0.05). These data suggest that more biologically mature prepubescent children seem to have no advantage in training-induced strength and endurance adaptations compared with their less mature peers. Additionally, gender did not affect the training-induced changes in strength or aerobic fitness. These results are meaningful for the development of optimized well-rounded training programs in prepubertal children.info:eu-repo/semantics/publishedVersio

Motor coordination of children: construction of centiles charts with LMS method by Cole and Green

The purposes of this study were 1) to construct reference values to KTK test battery; 2) to compare Vouzela childrens motor coordination with those from other Portuguese sites and international references; 3) to present pseudo-velocity curves for each KTK test. The sample comprises 811 children aged six to 11 years. Motor coordination was assessed with the four tests of the KTK Battery. Centile charts were constructed using the LMS method implemented in LMSchartmarker Pro software. Pervasive interindividual differences were noted in all coordination tests. Mean values of Vouzela childrens motor coordination were lower than German and Belgian samples. 50th percentile was similar among Vouzela, Peruvian and Azorean samples. Pseudo-velocity curves suggested a marked specificity to each test and sex, as well as decreasing of the coordinative gains per year.Os propósitos do estudo foram: 1) apresentar valores de referência percentílica às quatro provas da bateria de testes KTK; 2) comparar o desempenho coordenativo entre crianças vouzelenses e de outros estudos do país e exterior; e 3) apresentar pseudo-curvas de velocidade para cada prova. Foram avaliadas 811 crianças com idades entre os seis e os 10 anos. O desempenho coordenativo foi estimado por meio da bateria KTK. Cartas percentílicas e pseudo-curvas de velocidade foram construídas com base no método LMS, implementado no "software" LMSchartmarker Pro versão 2.54. Os valores de referência percentílicas expressam forte variabilidade interindividual do desempenho coordenativo. Em geral, os valores médios vouzelenses são inferiores aos belgas e alemães. O comportamento do percentil 50 das quatro provas do KTK é similar entre Vouzela, Peru e Açores. As pseudo-curvas de velocidade sugerem especificidade em cada prova e sexo, bem como diminuição dos ganhos coordenativos ao longo da idade

Preterm birth and adolescent bone mineral content

The purpose of this study was to determine the influence of preterm low birth weight on bone mineral content in adolescence. In 2007 to 2008, data on adolescents were obtained for study, including 16 females and 25 males who were born preterm (37 weeks' gestation) between October 1, 1989, and December 31, 1995, with a birth weight of less than 1850 g. Preterm low-birth-weight individuals were age- and sex-matched to full-term (>37 weeks) normal-birth-weight (>2500 g) controls. Total body, hip, and spine bone mineral content (BMC) was assessed using dual energy X-ray absorptiometry. Male preterm individuals had less BMC at the proximal femur in adolescence compared with controls (p < 0.05). However, once adjusted for age, maturity, height, weight, physical activity, and diet, there were no differences between groups (p < 0.05) in any bone parameters. These findings suggest that preterm birth and low birth weight did not influence bone accrual in these individuals at adolescence

Safety and feasibility of a home-based six week resistance training program in juvenile idiopathic arthritis

BACKGROUND: Juvenile idiopathic arthritis (JIA), among the most common chronic diseases of childhood, can be associated with attenuated physical activity levels, reduced fitness, decreased functionality and pain. This pilot study aimed to determine the safety, feasibility and effect of a six week resistance training program in children with JIA. METHODS: Youth (8-18 years) with JIA participated in a home-based resistance training program. Participants reported pain on an electronic diary once a day for one week prior to training, then once a day on non-exercise days and three times a day (before-exercise, after-exercise, and end-of-day) on exercise days for the subsequent six weeks of training. Secondary outcome measures included inflammation (assessed by ultrasound), muscle size (assessed by ultrasound), muscle strength (assessed by dynamometer) and functional ability (assessed by childhood health assessment questionnaire), measured at baseline and post-training. Participants were also instructed to wear an accelerometer one week prior to training to estimate baseline physical activity levels. Statistical analyses included safety (pain changes and any adverse events), feasibility (adherence to program and modifications made to exercises) and effect of program (differences in secondary measures pre and post training). An alpha level of p < 0.05 was accepted as significant. RESULTS: Seven participants completed an average of 12.7 ± 3.4 (range 8-17) exercise sessions out of a possible 18 (70.6%). No adverse events were reported and pain did not increase over the seven weeks. Secondary measures revealed a significant increase in vastus lateralis thickness from pre to post training (p < 0.05). End-of-day pain intensity was correlated to end-of-day stiffness, fatigue and mood (r = .864, r = .581, r = -.637, respectively, p < 0.001). Pain intensity was also correlated with ratings of perceived exertion of the exercise (r = 0.324, p < 0.01). Only two children met the recommended 60 minutes of moderate to vigorous physical activity per day. CONCLUSIONS: A six week home-based resistance training program is both safe (absence of pain changes or adverse events over the six weeks) and feasible (comparable adherence rates to other exercise studies involving JIA and individually modifiable) in children with JIA