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https://www.readbyqxmd.com/read/28931173/hopping-and-landing-performance-in-male-youth-soccer-players-effects-of-age-and-maturation
#1
Paul James Read, Jon L Oliver, Gregory Myer, Mark De Ste Croix, Rhodri Lloyd
Quantifying hopping and landing performances can assist coaches in identifying young male soccer players who may be at increased risk of injury. The influence of chronological age and maturation on these measures in this population is unknown. Single leg hop for distance (SLHD) and 75% horizontal hop and stick landing force (75%Hop) were examined in a cross-sectional sample (N=400) of elite male youth soccer players. Between-group differences for both chronological age (U11-U18) and stage of maturation (pre-, circa- or post-peak height velocity (PHV)) were analyzed...
September 20, 2017: International Journal of Sports Medicine
https://www.readbyqxmd.com/read/28930932/complex-training-the-effect-of-exercise-selection-and-training-status-on-postactivation-potentiation-in-rugby-league-players
#2
David J Scott, Massimiliano Ditroilo, Phil A Marshall
Scott, DJ, Ditroilo, M, and Marshall, PA. Complex training: the effect of exercise selection and training status on postactivation potentiation in rugby league players. J Strength Cond Res 31(10): 2694-2703, 2017-This study compared the postactivation potentiation (PAP) response of the hex bar deadlift (HBD) and back squat (BS) exercises. The PAP response between different levels of athletes was also compared. Ten professional and 10 amateur rugby league players performed 2 experimental sessions. Participants performed a countermovement jump (CMJ) before and 2, 4, 6, 8, 10, 12, 14, and 16 minutes after a conditioning activity (CA) that contained 1 set of 3 repetitions at 93% 1 repetition maximum of either HBD or BS...
October 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28912731/long-term-athletic-development-in-youth-alpine-ski-racing-the-effect-of-physical-fitness-ski-racing-technique-anthropometrics-and-biological-maturity-status-on-injuries
#3
Lisa Müller, Carolin Hildebrandt, Erich Müller, Christian Fink, Christian Raschner
Alpine ski racing is known to be a sport with a high risk of injuries. Because most studies have focused mainly on top-level athletes and on traumatic injuries, limited research exists about injury risk factors among youth ski racers. The aim of this study was to determine the intrinsic risk factors (anthropometrics, biological maturity, physical fitness, racing technique) for injury among youth alpine ski racers. Study participants were 81 youth ski racers attending a ski boarding school (50 males, 31 females; 9-14 years)...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28902117/factors-influencing-spike-jump-height-in-female-college-volleyball-players
#4
Yusuke Ikeda, Yusuke Sasaki, Shingo Sorimachi, Rena Hamano
The purpose of this study was to examine factors influencing spike jump (SPJ) performance by female competitive volleyball players through comparisons of the kinematic data of SPJ with those of the standing long jump (SLJ) and vertical jump (VJ). Seventeen female competitive volleyball players were asked to perform SPJ, SLJ, and VJ. Motion data of SPJ including the approach phase were recorded. Regarding SLJ and VJ, jumping motion and ground reaction force were recorded during each performance. The results obtained showed that SPJ height correlated with vertical velocity at take-off, horizontal velocity at third step contact, and the deceleration of horizontal velocity from third step contact to take-off...
September 6, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28901657/longitudinal-patterns-in-bmi-and-percent-total-body-fat-from-peak-height-velocity-through-emerging-adulthood-into-young-adulthood
#5
Erin Barbour-Tuck, Marta Erlandson, Nazeem Muhajarine, Heather Foulds, Adam Baxter-Jones
OBJECTIVES: Emerging adulthood, a potential critical period, is an understudied period of fat mass accrual. The aim of this study was to describe patterns of fat mass accrual, and weight status, from adolescence, through emerging adulthood, into young adulthood. METHODS: One-hundred-eighteen participants (59 male) were measured repeatedly for 20 years. Annual measures of height, weight, and body composition (DXA) were taken. Calculated measures included: peak height velocity (PHV), biological age (BA; years from PHV), body mass index (BMI), and percent total body fat (%TBF)...
September 13, 2017: American Journal of Human Biology: the Official Journal of the Human Biology Council
https://www.readbyqxmd.com/read/28895692/development-of-equations-and-proposed-reference-values-to-estimate-body-fat-mass-among-chilean-children-and-adolescents
#6
Marco Cossio-Bolaños, Miguel de Arruda, José Sulla Torres, Camilo Urra Albornoz, Rossana Gómez Campos
INTRODUCTION: The assessment of body composition is relevant to establish nutritional status and identify potential health risks. OBJETIVE: a) To develop regression equations to predict fat mass (FM) using a dual-energy X-ray absorptiometry as reference method; b) to propose reference FM values based on chronological and biological age for Chilean children and adolescents. METHODOLOGY: Cross-sectional study in children and adolescents aged 5...
October 1, 2017: Archivos Argentinos de Pediatría
https://www.readbyqxmd.com/read/28895467/kinetic-and-kinematic-patterns-during-high-intensity-clean-movement-searching-for-optimal-load
#7
Achraf Ammar, Bryan L Riemann, Liwa Masmoudi, Marcel Blaumann, Osama Abdelkarim, Anita Hökelmann
The aim of the present study was to investigate loading effects on kinematic and kinetic variables among elite-weightlifters in order to identify an optimal training load to maximize power production for clean-movement. Nine elite-weightlifter (age: 24 ± 4years, body-mass: 77 ± 6.5kg, height: 176 ± 6.1cm and 1RM clean: 170 ± 5kg) performed 2 separate repetitions of the clean using 85, 90, 95% and 100%, in a randomized order, while standing on a force platform and being recorded using 3D-capture-system. Differences in kinematics (barbell displacement, velocity and acceleration) and kinetics (power, vertical ground reaction force (vGRF), rate of force development (RFD), and work) across the loads were statistically assessed...
September 12, 2017: Journal of Sports Sciences
https://www.readbyqxmd.com/read/28872525/thumb-ossification-composite-index-toci-for-predicting-peripubertal-skeletal-maturity-and-peak-height-velocity-in-idiopathic-scoliosis-a-validation-study-of-premenarchal-girls-with-adolescent-idiopathic-scoliosis-followed-longitudinally-until-skeletal-maturity
#8
Alec L H Hung, W W Chau, B Shi, Simon K Chow, Fiona Y P Yu, T P Lam, Bobby K W Ng, Y Qiu, Jack C Y Cheng
BACKGROUND: Accurate skeletal maturity assessment is important to guide clinical evaluation of idiopathic scoliosis, but commonly used methods are inadequate or too complex for rapid clinical use. The objective of the study was to propose a new simplified staging method, called the thumb ossification composite index (TOCI), based on the ossification pattern of the 2 thumb epiphyses and the adductor sesamoid bone; to determine its accuracy in predicting skeletal maturation when compared with the Sanders simplified skeletal maturity system (SSMS); and to validate its interrater and intrarater reliability...
September 6, 2017: Journal of Bone and Joint Surgery. American Volume
https://www.readbyqxmd.com/read/28871900/effects-of-a-modified-ballet-class-on-strength-and-jumping-ability-in-college-ballet-dancers
#9
Aikaterini Tsanaka, Vasiliki Manou, Spiros Kellis
The ability to jump high with precision is an important component of the ballet dancer's technique. The aim of this study was to evaluate the effect of a modified ballet class on strength and jumping ability in high level female dancers. Seventeen female ballet students were divided into two groups, experimental and control, and tested before and after an 8-week, 2 times/week intervention for peak torque of knee extensors and flexors at 60°and 180°, and jumping ability (squat jump, countermovement jump, countermovement with arm swing jump, sauté in first position, and sauté in first position with port de bras)...
September 15, 2017: Journal of Dance Medicine & Science
https://www.readbyqxmd.com/read/28870146/effects-of-altering-heel-wedge-properties-on-gait-with-the-intrepid-dynamic-exoskeletal-orthosis
#10
Andrea J Ikeda, John R Fergason, Jason M Wilken
BACKGROUND: The Intrepid Dynamic Exoskeletal Orthosis is a custom-made dynamic response carbon fiber device. A heel wedge, which sits in the shoe, is an integral part of the orthosis-heel wedge-shoe system. Because the device restricts ankle movement, the system must compensate to simulate plantarflexion and allow smooth forward progression during gait. OBJECTIVES: To determine the influence of wedge height and durometer on the walking gait of individuals using the Intrepid Dynamic Exoskeletal Orthosis...
September 1, 2017: Prosthetics and Orthotics International
https://www.readbyqxmd.com/read/28869359/monitoring-of-hemostatic-abnormalities-in-major-orthopedic-surgery-patients-treated-with-edoxaban-by-aptt-waveform
#11
M Hasegawa, H Wada, S Tone, T Yamaguchi, H Wakabayashi, M Ikejiri, M Watanabe, N Fujimoto, T Matsumoto, K Ohishi, Y Yamashita, N Katayama, A Sudo
INTRODUCTION: An analysis of the activated partial thromboplastin time (APTT) in major orthopedic surgery patients receiving edoxaban for the prevention of venous thromboembolism (VTE) was carried out. METHODS: The APTT waveform was analyzed in the above patients to monitor edoxaban administration. RESULTS: Of these 99 patients, 12 exhibited deep vein thrombosis, and 25 had massive bleeding. An increased biphasic pattern of the APTT waveform was observed after the administration of edoxaban, but there were no significant differences between the patients with and without complications...
September 4, 2017: International Journal of Laboratory Hematology
https://www.readbyqxmd.com/read/28860426/experience-with-jumping-mechanography-in-children-with-cerebral-palsy
#12
I Duran, K Martakis, C Stark, E Alberg, C Bossier, O Semler, E Schoenau
OBJECTIVES: Jumping mechanography provides robust motor function indicators among healthy children. The aim of the study was to assess the reproducibility and validity of jumping mechanography conducted as single two-legged jump (S2LJ) in children with cerebral palsy (CP). METHODS: 215 S2LJ investigations from a sample of 75 children with CP were eligible for evaluation. For the estimation of the reproducibility, only the baseline set of data per patient were used...
September 1, 2017: Journal of Musculoskeletal & Neuronal Interactions
https://www.readbyqxmd.com/read/28834796/does-a-one-year-age-gap-modify-the-influence-of-age-maturation-and-anthropometric-parameters-as-determinants-of-performance-among-youth-elite-soccer-players
#13
Iraia Bidaurrazaga-Letona, José Antonio Lekue, Markos Amado, Susana Maria Gil
Since age-groups in soccer often comprise children born within a two-year timeframe, characteristics that define the profile of a successful player may not be appropriate for the oldest or youngest players of the same age group. Therefore, this study aimed to determine to what extent performance was influenced by age, maturation and body size in elite soccer players with barely one year age gap. Anthropometry, 15-m sprint test, modified Barrow´s agility test, Yo-Yo intermittent recovery test level 1, countermovement jump, and handgrip test were conducted in players aged twelve and under (n=82, 11...
August 22, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28834567/ethnic-differences-in-peripheral-skeletal-development-among-urban-south-african-adolescents-a-ten-year-longitudinal-pqct-study
#14
S M Schoenbuchner, J M Pettifor, S A Norris, L K Micklesfield, A Prentice, K A Ward
There are no longitudinal pQCT data of bone growth and development from sub-Saharan Africa, where rapid environmental, societal and economic transitions are occurring, and where fracture rates are predicted to rise. The aim of this study was to compare skeletal development in black and white South African adolescents using longitudinal data from the Birth to Twenty study. The Birth to Twenty Bone Health sub-cohort consisted of 543 adolescents (261[178 black] girls, 282[201 black] boys). Annual pQCT measurements of the radial and tibial metaphysis and diaphysis were obtained between ages 12 and 22 years (distal metaphysis: cross-sectional area [CSA] and trabecular bone mineral density [BMD]; diaphysis: total and cortical CSA, cortical BMD and polar stress-strain index [SSIp])...
August 23, 2017: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
https://www.readbyqxmd.com/read/28818329/influence-of-different-packing-methods-on-the-hydrodynamic-stability-of-chromatography-columns
#15
M Dorn, F Eschbach, D Hekmat, D Weuster-Botz
It is well known that packing non-uniformity may cause peak asymmetry and limit the performance of packed-bed chromatographic columns. However, understanding of the reasons leading to packing non-uniformity is still limited. Therefore, the effect of different column packing methods, i.e. dynamic axial compression (DAC), flow packing, and combinations of both on the hydrodynamic packing heterogeneity and stability of packings composed of polymer-based compressible porous resins with a mean diameter of 90μm was investigated experimentally as well as in-silico...
August 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28816503/pubertal-development-of-body-size-and-soccer-specific-functional-capacities-in-adolescent-players
#16
Humberto Moreira Carvalho, José A Lekue, Susana M Gil, Iraia Bidaurrazaga-Letona
Pubertal growth in body size and functional capacities were examined in adolescent soccer players (n = 33). The average age at baseline was 10.9 (9.8-11.8 years). Peak height velocity (PHV) and growth curves for body mass and functional performance (countermovement jump, 15-m sprint, agility and Yo-Yo intermittent recovery test - level 1) were determined with Bayesian multilevel models. Estimates for PHV and age at PHV were 8.1 cm/year (95% credible interval: 4.2-18.5 cm/year) and 12.9 years (95% credible interval: 11...
August 17, 2017: Research in Sports Medicine
https://www.readbyqxmd.com/read/28792857/redistributing-load-using-wearable-resistance-during-power-clean-training-improves-athletic-performance
#17
Caleb R Marriner, John B Cronin, Paul Macadam, Adam Storey
A popular method to improve athletic performance and lower body power is to train with wearable resistance (WR), for example, weighted vests. However, it is currently unknown what training effect this loading method has on full-body explosive movements such as the power clean. The purpose of this study was to determine what effects WR equivalent to 12% body mass (BM) had on the power clean and countermovement jump (CMJ) performance. Sixteen male subjects (age: 23.2 ± 2.7 years; BM: 90.5 ± 10.3 kg) were randomly assigned to five weeks of traditional (TR) power clean training or training with 12% BM redistributed from the bar to the body using WR...
October 2017: European Journal of Sport Science
https://www.readbyqxmd.com/read/28777249/isometric-mid-thigh-pull-performance-is-associated-with-athletic-performance-and-sprinting-kinetics-in-division-i-men-and-women-s-basketball-players
#18
Jeremy R Townsend, David Bender, William Vantrease, John Hudy, Kevin Huet, Cassie Williamson, Emily Bechke, Paul Serafini, Gerald T Mangine
PURPOSE: To examine the relationships between isometric mid-thigh pull (IMTP) force, athletic performance measures, and sprint kinetics in Division I men's and women's basketball players. METHODS: Twenty-three (male = 8, female = 15) division 1 basketball players completed a maximal 20-m sprint trial while tethered to a device which provided kinetic feedback (peak and average sprinting power, velocity and force). Additionally, one repetition-maximal (1RM) front squat, 1RM hang clean, vertical jump height, and agility (pro-agility and lane agility) tests were performed...
July 31, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28763713/spatiotemporal-and-plantar-pressure-patterns-of-1000-healthy-individuals-aged-3-101-years
#19
Marnee J McKay, Jennifer N Baldwin, Paulo Ferreira, Milena Simic, Natalie Vanicek, Elizabeth Wojciechowski, Anita Mudge, Joshua Burns
OBJECTIVE: The purpose of this study was to establish normative reference values for spatiotemporal and plantar pressure parameters, and to investigate the influence of demographic, anthropometric and physical characteristics. METHODS: In 1000 healthy males and females aged 3-101 years, spatiotemporal and plantar pressure data were collected barefoot with the Zeno™ walkway and Emed(®) platform. Correlograms were developed to visualise the relationships between widely reported spatiotemporal and pressure variables with demographic (age, gender), anthropometric (height, mass, waist circumference) and physical characteristics (ankle strength, ankle range of motion, vibration perception) in children aged 3-9 years, adolescents aged 10-19 years, adults aged 20-59 years and older adults aged over 60 years...
July 18, 2017: Gait & Posture
https://www.readbyqxmd.com/read/28759890/maturity-status-influences-the-relative-age-effect-in-national-top-level-youth-alpine-ski-racing-and-soccer
#20
Lisa Müller, Christoph Gonaus, Christoph Perner, Erich Müller, Christian Raschner
Since the relative age effect (RAE) characterizes a problem in all age categories of alpine ski racing and soccer and the fact that, yet, to date the underlying factors have not been well investigated, the aim of the present study was to assess the influence of the biological maturity status on the RAE among youth alpine ski racers (YSR) and soccer players (SP). In total, 183 male and female YSR selected for national final races and 423 male SP selected for Elite Youth Development Centres were investigated...
2017: PloS One
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