scholarly journals Optimum Angle of Force Production Temporarily Changes Due to Growth in Male Adolescence

Children ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 20
Author(s):  
Junya Saeki ◽  
Satoshi Iizuka ◽  
Hiroaki Sekino ◽  
Ayahiro Suzuki ◽  
Toshihiro Maemichi ◽  
...  
Keyword(s):  
Force Production ◽  
Knee Extension ◽  
Peak Height ◽  
Height Velocity ◽  
Outcome Variable ◽  
P Value ◽  
Peak Height Velocity ◽  
Optimum Angle ◽  
The Difference ◽  
Polynomial Formula

The peak increase in lean mass in adolescents is delayed from peak height velocity (PHV), and muscle flexibility temporarily decreases as bones grow. If the decrease in muscle flexibility is caused by muscle elongation, the relationship between the exerted torque and the joint angle could change in adolescents. The purpose of this study was to investigate the change in the optimum angle of force production due to growth. Eighty-eight healthy boys were recruited for this study. Isokinetic knee extension muscle strength of the dominant leg was recorded. The outcome variable was the knee flexion angle when maximal knee extension torque was produced (optimum angle). The age at which PHV occurred was estimated from subjects’ height history. We calculated the difference between the age at measurement and the expected age of PHV (growth age). A regression analysis was performed with the optimal angle of force exertion as the dependent variable and the growth age as the independent variable. Then, a polynomial formula with the lowest p-value was obtained. A significant cubic regression was obtained between optimum angle and growth age. The results suggest that the optimum angle of force production temporarily changes in male adolescence.

scholarly journals Assessment of Reliability in Isokinetic Testing Among Adolescent Basketball Players

Medicina ◽  
2011 ◽  
Vol 47 (8) ◽  
pp. 446 ◽  
Author(s):  
Humberto Carvalho ◽  
Manuel Coelho E Silva ◽  
Enio Ronque ◽  
Rui Gonçalves ◽  
Renaat Philippaerts ◽  
...  
Keyword(s):  
Body Size ◽  
Knee Flexion ◽  
Knee Extension ◽  
Peak Height ◽  
Height Velocity ◽  
Isokinetic Strength ◽  
Peak Height Velocity ◽  
Training Experience ◽  
Basketball Players ◽  
Isokinetic Testing

Background. The reproducibility of day-to-day testing of isokinetic concentric and eccentric muscular actions among adolescent basketball players aged 14 to 16 years and relationships of mean within-subject variation in two isokinetic testing sessions with chronological age, biological maturation (estimated age at peak height velocity), training experience, body size, lower-body morphology, and initial strength performance were evaluated. Material and Methods. The sample included 27 basketball players who completed replicate test sessions of 5 repetitions of reciprocal concentric and eccentric knee extensions and flexions at 60º s–1. A randomly selected subsample of 8 players completed a third testing session to confirm reliability estimates. Results. Coefficients of variation (CV) between sessions 1 and 2 ranged from 8.1% to 17.4%, and intraclass coefficients (ICCs) ranged from 0.72 to 0.89. For sessions 1 and 3, CVs ranged from 3.9% to 6.0%, and ICCs ranged from 0.95 to 0.99. The initial level of strength of eccentric knee flexion (r=–0.43) and eccentric knee extension (r=–0.42) were correlated (P<0.05) with eccentric knee extension within-variation between two sessions. Training experience (r=–0.37, P<0.05) and initial values of concentric knee flexion (r=–0.62, P<0.01) were correlated with concentric knee flexion within-subject differences. Within-subject variation of eccentric knee extension was correlated (P<0.05) with chronologic age (r=0.41), estimated age at peak height velocity (r=–0.38), body size (r=0.41 to 0.47), and leg volume (r=0.39). Conclusions. Familiarization sessions may improve the reliability of concentric and eccentric knee isokinetic strength testing at 60º s–1 in adolescent basketball players. Age, maturity status, and training experience of young athletes should be considered when testing knee isokinetic strength at 60º s–1.

scholarly journals Age-Related Differences in Functional Hamstring/Quadriceps Ratio Following Soccer Exercise in Female Youth Players: An Injury Risk Factor

2018 ◽  
Vol 30 (3) ◽  
pp. 376-382 ◽  
Author(s):  
Mark De Ste Croix ◽  
Abigail Priestley ◽  
Rhodri Lloyd ◽  
Jon Oliver
Keyword(s):  
Knee Flexion ◽  
Injury Risk ◽  
Knee Extension ◽  
Peak Height ◽  
Height Velocity ◽  
Peak Height Velocity ◽  
Specific Exercise ◽  
Movement Velocity ◽  
Full Extension ◽  
Age Related

Purpose: Fatigue negatively alters dynamic knee control, and the functional hamstring/quadriceps ratio (H/QFUNC) plays an important role in stabilizing the joint. The aim of this study was to investigate the influence of soccer-specific exercise on H/QFUNC in under (U) 13-, U15-, and U17-year-old female soccer players. Methods: A total of 36 female players performed concentric and eccentric actions of the hamstrings at 60°, 120°, and 180°/s before and after an age group–specific field-based soccer protocol. H/QFUNC was determined in the first 30° of knee flexion. Results: Significant angle × velocity (P = .001) and time × angle (P = .033) interaction effects were found indicating a lower H/QFUNC with increased movement velocity at 0°–10° as opposed to greater knee flexion angles. Fatigue-related effects were only evident near full knee extension. Probabilistic inferences indicated that changes in H/QFUNC were generally unclear in U13s, likely detrimental in U15s, and very likely beneficial in U17s. Conclusions: Altered muscular control following soccer-specific exercise is age dependent with players’ 1-year post-peak height velocity at greatest risk of injury. Injury prevention and screening need to be age and maturation appropriate, should consider the effects of fatigue, and include movements near full extension.

scholarly journals Novel loci and mapuche genetic ancestry are associated with pubertal growth traits in Chilean boys

2021 ◽  
Author(s):  
Lucas Vicuña ◽  
Tomás Norambuena ◽  
José Patricio Miranda ◽  
Ana Pereira ◽  
Veronica Mericq ◽  
...  
Keyword(s):  
Native American ◽  
Developmental Process ◽  
Growth Traits ◽  
Association Studies ◽  
Peak Height ◽  
Height Velocity ◽  
Genome Wide Association Studies ◽  
Nucleotide Polymorphisms ◽  
Peak Height Velocity ◽  
The Difference

AbstractPuberty is a complex developmental process that varies considerably among individuals and populations. Genetic factors explain a large proportion of the variability of several pubertal traits. Recent genome-wide association studies (GWAS) have identified hundreds of variants involved in traits that result from body growth, like adult height. However, they do not capture many genetic loci involved in growth changes over distinct growth phases. Further, such GWAS have been mostly performed in Europeans, but we do not know how these findings relate to other continental populations. In this study, we analyzed the genetic basis of three pubertal traits; namely, peak height velocity (PV), age at PV (APV) and height at APV (HAPV). We analyzed a cohort of 904 admixed Chilean children and adolescents with European and Mapuche Native American ancestries. Height was measured on roughly a $$6-$$ 6 - month basis from childhood to adolescence between 2006 and 2019. We predict that the difference in HAPV between an European and a Mapuche adolescent is 4.3 cm higher in the European (P = 0.042) and APV is 0.73 years later for the European compared with the Mapuche adolescent on average (P = 0.023). Further, by performing a GWAS on 774, 433 single-nucleotide polymorphisms, we identified a genetic signal harboring 3 linked variants significantly associated with PV in boys (P$$< 5 \times 10^{-8}$$ < 5 × 10 - 8 ). This signal has never been associated with growth-related traits.

Validation of Maturity Offset in the Fels Longitudinal Study

2016 ◽  
Vol 28 (3) ◽  
pp. 439-455 ◽  
Author(s):  
Robert M. Malina ◽  
Audrey C. Choh ◽  
Stefan A. Czerwinski ◽  
Wm. Cameron Chumlea
Keyword(s):  
Longitudinal Study ◽  
Logistic Model ◽  
Peak Height ◽  
Height Velocity ◽  
Chronological Age ◽  
Peak Height Velocity ◽  
The Difference ◽  
Offset Time ◽  
Age Range

Sex-specific equations for predicting maturity offset, time before or after peak height velocity (PHV), were evaluated in 63 girls and 74 boys from the Fels Longitudinal Study. Serially measured heights (0.1 cm), sitting heights (0.1 cm), weights (0.1 kg), and estimated leg lengths (0.1 cm) from 8 to 18 years were used. Predicted age at PHV (years) was calculated as the difference between chronological age (CA) and maturity offset. Actual age at PHV for each child was derived with a triple logistic model (Bock-Thissen-du Toit). Mean predicted maturity offset was negative and lowest at 8 years and increased linearly with increasing CA. Predicted ages at PHV increased linearly with CA from 8 to 18 years in girls and from 8 to 13 years in boys; predictions varied within relatively narrow limits from 12 to 15 years and then increased to 18 years in boys. Differences between predicted and actual ages at PHV among youth of contrasting maturity status were significant across the age range in both sexes. Dependence of predicted age at PHV upon CA at prediction and on actual age at PHV limits its utility as an indicator of maturity timing and in sport talent programs.

scholarly journals Breakfast: A Crucial Meal for Adolescents’ Cognitive Performance According to Their Nutritional Status. The Cogni-Action Project

Nutrients ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 1320
Author(s):  
Humberto Peña-Jorquera ◽  
Valentina Campos-Núñez ◽  
Kabir P. Sadarangani ◽  
Gerson Ferrari ◽  
Carlos Jorquera-Aguilera ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Cognitive Performance ◽  
Cognitive Demand ◽  
Positive Association ◽  
Peak Height ◽  
The Body ◽  
Height Velocity ◽  
Peak Height Velocity ◽  
High Quality ◽  
Action Project

This study aimed to determine whether pupils who have breakfast just before a cognitive demand, do not regularly skip breakfast, and consume a high-quality breakfast present higher cognitive performance than those who do not; furthermore, to establish differences according to their nutritional status. In this study, 1181 Chilean adolescents aged 10–14 years participated. A global cognitive score was computed through eight tasks, and the body mass index z-score (BMIz) was calculated using a growth reference for school-aged adolescents. The characteristics of breakfast were self-reported. Analyses of covariance were performed to determine differences in cognitive performance according to BMIz groups adjusted to sex, peak height velocity, physical fitness global score, and their schools. A positive association was found in adolescents’ cognitive performance when they had breakfast just before cognitive tasks, did not regularly skip breakfast, presented at least two breakfast quality components, and included dairy products. No significant differences were found between breakfast components, including cereal/bread and fruits/fruit juice. Finally, pupils who were overweight/obese who declared that they skipped breakfast regularly presented a lower cognitive performance than their normal-BMIz peers. These findings suggest that adolescents who have breakfast just prior to a cognitive demand and regularly have a high quality breakfast have better cognitive performance than those who do not. Educative nutritional strategies should be prioritized, especially in “breakfast skippers” adolescents living with overweight/obesity.

scholarly journals Growth in achondroplasia, from birth to adulthood, analysed by the JPA-2 model

2020 ◽  
Vol 33 (12) ◽  
pp. 1589-1595
Author(s):  
Mariana del Pino ◽  
Virginia Fano ◽  
Paula Adamo
Keyword(s):  
General Population ◽  
Growth Curve ◽  
Growth Velocity ◽  
Adult Height ◽  
Growth Curves ◽  
Peak Height ◽  
Height Growth ◽  
Individual Growth ◽  
Height Velocity ◽  
Peak Height Velocity

AbstractObjectivesIn general population, there are three phases in the human growth curve: infancy, childhood and puberty, with different main factors involved in their regulation and mathematical models to fit them. Achondroplasia children experience a fast decreasing growth during infancy and an “adolescent growth spurt”; however, there are no longitudinal studies that cover the analysis of the whole post-natal growth. Here we analyse the whole growth curve from infancy to adulthood applying the JPA-2 mathematical model.MethodsTwenty-seven patients, 17 girls and 10 boys with achondroplasia, who reached adult size, were included. Height growth data was collected from birth until adulthood. Individual growth curves were estimated by fitting the JPA-2 model to each individual’s height for age data.ResultsHeight growth velocity curves show that after a period of fast decreasing growth velocity since birth, with a mean of 9.7 cm/year at 1 year old, the growth velocity is stable in late preschool years, with a mean of 4.2 cm/year. In boys, age and peak height velocity in puberty were 13.75 years and 5.08 cm/year and reach a mean adult height of 130.52 cm. In girls, the age and peak height velocity in puberty were 11.1 years and 4.32 cm/year and reach a mean adult height of 119.2 cm.ConclusionsThe study of individual growth curves in achondroplasia children by the JPA-2 model shows the three periods, infancy, childhood and puberty, with a similar shape but lesser in magnitude than general population.

scholarly journals Biological maturity and the anthropometric, physical and technical assessment of talent identified U16 Australian footballers

2017 ◽  
Vol 12 (3) ◽  
pp. 344-350 ◽  
Author(s):  
Ashley J Cripps ◽  
Christopher Joyce ◽  
Carl T Woods ◽  
Luke S Hopper
Keyword(s):  
Characteristic Curve ◽  
Vertical Jump ◽  
Binary Logistic Regression ◽  
Peak Height ◽  
Technical Skill ◽  
Height Velocity ◽  
State Representation ◽  
Peak Height Velocity ◽  
Biological Maturation ◽  
Australian Football

This study compared biological maturation, anthropometric, physical and technical skill measures between talent and non-talent identified junior Australian footballers. Players were recruited from the under 16 Western Australian Football League and classified as talent (state representation; n = 25, 15.7 ± 0.3 y) or non-talent identified (non-state representation; n = 25, 15.6 ± 0.4 y). Players completed a battery of anthropometric, physical and technical skill assessments. Maturity was estimated using years from peak height velocity calculations. Binary logistic regression was used to identify the variables demonstrating the strongest association with the main effect of ‘status’. A receiver operating characteristic curve was used to assess the level of discrimination provided by the strongest model. Talent identified under 16 players were biologically older, had greater stationary and dynamic leaps and superior handball skill when compared to their non-talent identified counterparts. The strongest model of status included standing height, non-dominant dynamic vertical jump and handball outcomes (AUC = 83.4%, CI = 72.1%–95.1%). Biological maturation influences anthropometric and physical capacities that are advantageous for performance in Australian football; talent identification methods should factor biological maturation as a confound in the search for junior players who are most likely to succeed in senior competition.

scholarly journals Somatic maturation and the relationship between bone mineral variables and types of sports among adolescents: cross-sectional study

2017 ◽  
Vol 135 (3) ◽  
pp. 253-259 ◽  
Author(s):  
Ricardo Ribeiro Agostinete ◽  
Igor Hideki Ito ◽  
Han Kemper ◽  
Carlos Marcelo Pastre ◽  
Mário Antônio Rodrigues-Júnior ◽  
...  
Keyword(s):  
Bone Mineral Density ◽  
Bone Mineral ◽  
Peak Height ◽  
Cross Sectional Study ◽  
Height Velocity ◽  
Whole Body ◽  
Sectional Study ◽  
Peak Height Velocity ◽  
Mineral Density ◽  
Cross Sectional

ABSTRACT CONTEXT AND OBJECTIVE: Peak height velocity (PHV) is an important maturational event during adolescence that affects skeleton size. The objective here was to compare bone variables in adolescents who practiced different types of sports, and to identify whether differences in bone variables attributed to sports practice were dependent on somatic maturation status. DESIGN AND SETTING: Cross-sectional study, São Paulo State University (UNESP). METHODS: The study was composed of 93 adolescents (12 to 16.5 years old), divided into three groups: no-sport group (n = 42), soccer/basketball group (n = 26) and swimming group (n = 25). Bone mineral density and content were measured using dual-energy x-ray absorptiometry and somatic maturation was estimated through using peak height velocity. Data on training load were provided by the coaches. RESULTS: Adolescents whose PHV occurred at an older age presented higher bone mineral density in their upper limbs (P = 0.018). After adjustments for confounders, such as somatic maturation, the swimmers presented lower values for bone mineral density in their lower limbs, spine and whole body. Only the bone mineral density in the upper limbs was similar between the groups. There was a negative relationship between whole-body bone mineral content and the weekly training hours (β: -1563.967; 95% confidence interval, CI: -2916.484 to -211.450). CONCLUSION: The differences in bone variables attributed to sport practice occurred independently of maturation, while high training load in situations of hypogravity seemed to be related to lower bone mass in swimmers.

Effects of Drop Height on Jump Performance in Male and Female Elite Adolescent Handball Players

2019 ◽  
Vol 14 (5) ◽  
pp. 674-680 ◽  
Author(s):  
Olaf Prieske ◽  
Helmi Chaabene ◽  
Christian Puta ◽  
David G. Behm ◽  
Dirk Büsch ◽  
...  
Keyword(s):  
Peak Height ◽  
Height Velocity ◽  
Medium Size ◽  
Drop Height ◽  
Peak Height Velocity ◽  
Adolescent Athletes ◽  
Male And Female ◽  
Standing Long Jump ◽  
Long Jump ◽  
Split Time

Purpose: To examine the effects of drop height on drop-jump (DJ) performance and on associations between DJ and horizontal-jump/sprint performances in adolescent athletes. Methods: Male (n = 119, 2.5 [0.6] y post-peak-height velocity) and female (n = 120, 2.5 [0.5] y post-peak-height velocity) adolescent handball players (national level) performed DJs in randomized order using 3 drop heights (20, 35, and 50 cm). DJ performance (jump height, reactive strength index [RSI]) was analyzed using the Optojump Next system. In addition, correlations were computed between DJ height and RSI with standing-long-jump and 20-m linear-sprint performances. Results: Statistical analyses revealed medium-size main effects of drop height for DJ height and RSI (P < .001, 0.63 ≤ d ≤ 0.71). Post hoc tests indicated larger DJ heights from 20 to 35 and 35 to 50 cm (P ≤ .031, 0.33 ≤ d ≤ 0.71) and better RSI from 20- to 35-cm drop height (P < .001, d = 0.77). No significant difference was found for RSI between 35- and 50-cm drop height. Irrespective of drop height, associations of DJ height and RSI were small with 5-m-split time (−.27 ≤ r ≤ .05), medium with 10-m-split time (−.44 ≤ r ≤ .14), and medium to large with 20-m sprint time and standing-long-jump distance (−.57 ≤ r ≤ .22). Conclusions: The present findings indicate that, irrespective of sex, 35-cm drop heights are best suited to induce rapid and powerful DJ performance (ie, RSI) during reactive strength training in elite adolescent handball players. Moreover, training-related gains in DJ performance may at least partly translate to gains in horizontal jump and longer sprint distances (ie, ≥20-m) and/or vice versa in male and female elite adolescent athletes, irrespective of drop height.

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