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Backward Sled Pulling Load-Velocity Relationship in Youth: A Backward-Forward Comparison

Journal of Science in Sport and Exercise 2020年第4期2卷 330-335页

作者： Aaron Uthoff john cronin AUT-Sports Performance Research Institute New Zealand School of Sport and RecreationAUT MillenniumAuckland University of Technology17 Antares PlRosedaleAuckland 0632New Zealand

Purpose To establish the load-velocity relationships during backward sled pulling and compare this to forward sled pulling and determine the reliability of running speeds and associated load-velocity regression slopes in youth athletes.Methods Twenty-one boys(age,13.6±0.28 years old;height,1.72±0.09 m;mass,66.1±8.2 kg;maturity,0.57±0.72 years from peak height velocity)performed backward and forward resisted running on three occasions.Load-velocity relationships were established using an un-resisted sprint and resisted sled pull with loads of 25%-81%body mass(BM)in both directions,and the reliability of sprint times at each load and the load-velocity regression slopes were examined.Results The load-velocity data was reliable across multiple testing occasions for backward(CV≤7.2%;ICC 0.67-0.91)and forward sled pulling(CV≤7.2%;ICC 0.66-0.91).From the regression lines(R2≥0.99;P≤0.01),it was observed that averaged loads across the sample of 31%,46% and 61% BM resulted in 27%,38% and 48% decrease in velocity during backward sled pulling and 23%,33% and 43% during forward sled pulling.Increasing backward and forward loads by∼13% and~15% BM respectively,reliably resulted in∼10% decreases in velocity.Conclusion If contractile overload of the lower limbs is a focus of training then practitioners should preferentially use back-ward sled pulling.Both backward and forward sled pulling can be used in a similar manner regarding loading,though back-ward velocity is more sensitive to load and therefore overloading backward motion should be prescribed with this in mind.

关键词： Backward running Resisted sprinting Youth Exercise prescription

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The Influence of Biological Maturity on Dynamic Force-Time Variables and Vaulting Performance in Young Female Gymnasts

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Journal of Science in Sport and Exercise 2020年第4期2卷 319-329页

作者： Sylvia Moeskops Jon L.Oliver Paul J.Read john B.cronin Gregory D.Myer G.Gregory Haff Isabel S.Moore Rhodri S.Lloyd Youth Physical Development Centre Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCyncoed CampusCyncoed RoadCardiffCF52YBUK Sports Performance Research Institute New Zealand(SPRINZ) AUT UniversityAuckland 1142New Zealand Centre for Sport Science and Human Performance Waikato Institute of TechnologyHamilton 3240New Zealand Athlete Health and Performance Research Centre Aspetar Orthopaedic and Sports Medicine HospitalDohaQatar Division of Sports Medicine Cincinnati Children’s HospitalCincinnatiOH45229USA Department of Pediatrics and Orthopaedic Surgery College of MedicineUniversity of CincinnatiCincinnatiOH 45267USA The Micheli Center for Sports Injury Prevention WalthamMA 02453USA Centre for Exercise and Sports Science Edith Cowan UniversityJoondalupWA 6027Australia Australian Centre for Research into Injury in Sport and Its Prevention(ACRISP) Edith Cowan UniversityJoondalupWA 6027Australia University of Gloucestershire GloucesterGL502RHUK

Purpose This cross-sectional study investigated dynamic force-time variables and vaulting performance in young female gymnasts of different maturity status.Methods 120 gymnasts aged 5-14 years were sub-divided into maturity groupings using percent of predicted adult height(%PAH)attained.Participants performed three jumping protocols,the squat jump(SJ),countermovement jump(CMJ)and drop jump(DJ),before completing straight jump vaults that were recorded using two-dimensional video.Results Jumping performance improved with biological maturity evidenced by the most mature gymnasts’producing sig-nificantly more absolute force(P0.78),impulse(P0.75)and power(P0.91)than the least mature group,resulting in the greater jump heights(P0.70).While,no significant differences were observed in relative peak force across multiple tests,measures of relative peak power did significantly increase with maturity.Based upon regression analyses,maturation was found to influence vertical take-off velocity during vaulting,explaining 41%of the variance in each jumping protocol.Across all tests,the DJ was found to have the highest predictive ability of vaulting vertical take-off velocity,explaining 55%of the total variance.Conclusion Biological maturation impacts jump height and underpinning mechanical variables in young female gymnasts.Vaulting vertical take-off velocity appears to be influenced by maturation and various dynamic force-time variables,par-ticularly those during DJ,which had the highest explained total variance.

关键词： Youth Maturation Squat jump Countermovement jump Drop jump Gymnastics

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The metabolite BH4 controls T cell proliferation in autoimmunity and cancer

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四川生理科学杂志 2023年第10期45卷 1825-1825页

作者： Shane J F cronin IMBA Institute of Molecular Biotechnology of the Austrian Academy of Sciences Vienna Austria. Department of Neurobiology Harvard Medical School Boston MA USA. FM Kirby Neurobiology Center Boston Children's Hospital Boston MA USA. Ludwig Boltzmann Institute for Experimental and Clinical Traumatology AUVA Research Center Vienna Austria. Département de Pharmacologie et Physiologie Université de Montréal Montréal Québec Canada. Institute for Molecular Medicine University Medical Center of the Johannes Gutenberg-University Mainz Mainz Germany. Department of Internal Medicine II (Infectious Diseases Immunology Rheumatology and Pneumology) Medical University of Innsbruck Innsbruck Austria. Institute of Chemical Sciences and Engineering Institute of Bioengineering National Centre of Competence in Research (NCCR) in Chemical Biology École Polytechnique Fédérale de Lausanne (EPFL) Lausanne Switzerland. Division of Cardiovascular Medicine British Heart Foundation Centre for Research Excellence John Radcliffe Hospital University of Oxford Oxford UK. Wellcome Trust Centre for Human Genetics Roosevelt Drive University of Oxford Oxford UK. Division of Gastroenterology and Liver Center Department of Medicine Beth Israel Deaconess Medical Center (BIDMC) and Harvard Medical School (HMS) Harvard University Boston MA USA. LABOX Departamento de Bioquímica Universidade Federal de Santa Catarina Florianópolis Brazil. Research Institute of Molecular Pathology Vienna Biocenter Campus-Vienna-Biocenter 1 Vienna Austria. Karolinska Institute Department of Medicine Solna Center for Molecular Medicine Karolinska University Hospital Solna Stockholm Sweden. Department of Neuronal Control of Metabolism Max Planck Institute for Metabolism Research Cologne Germany. Department of Neurosciences Centre de Recherche de CHU de Québec-Université Laval Québec Québec Canada. Department of Molecular Medicine Faculty of Medicine Université Laval Québec Quebec Canada. Neurosurgery Departm

Genetic regulators and environmental stimuli modulate T cell activation in autoimmunity and cancer.The enzyme co-factor tetrahydrobiopterin(BH4)is involved in the production of monoamine neurotransmitters,the generati... 详细信息

关键词： BH4 cancer. autoimmunity

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Development of New COSMOS oral RepeatDose and non-cancer Threshold of Toxicological Concern（TTC） Databases to Support Alternative Assessment Methods for Cosmetics Related Chemicals

Development of New COSMOS oral RepeatDose and non-cancer Thr...

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中国毒理学会第七次全国毒理学大会暨第八届湖北科技论坛

作者： Yang C Barlow S Boobis A cronin MTD Felter SP Hollnagel HM Keller D Vitcheva V Worth AP Zhu T Altamira LLC Independent consultant Imperial College Liverpool john Moores University P&G Dow Europe GmbH Henkel EC Joint Research Center

In quantitative risk assessment,the Threshold of Toxicological Concern（TTC） approach provides a method to determine a conservative estimate of a chronic exposure below which there is a very low probability of risk.The TTC concept is a principle,which through a probabilistic approach,establishes human exposure levels for chemicals below which there would be no appreciable risk to human health.TTC is reliant on existing oral toxicity data on a multitude of chemical classes to predict the toxicological potential of non-tested chemicals.The tiered TTC approach has 6 potency tiers covering 4 orders of magnitude（Kroes et al.2004）.The upper tiers are based on non-cancer data from a reference database of over 600 chemicals analyzed by Munro et al（1996） and grouped according to the Cramer et al（1978） decision tree according to chemical structure.The utility of TTC has been well established and accepted by regulatory bodies in a number of areas e.***.food packaging migrants,flavor chemicals,genotoxic impurities in pharmaceuticals.In fact,low level constituents or contaminants in a cosmetic product often have insufficient toxicological data to make a full assessment of chronic toxicity.As one of the practical alternatives to repeated dose toxicity testing,the TTC approach is now being expanded to include cosmetics-related chemicals.TTC supports exposure-based safety assessment with a threshold for chemicals below which there is a low probability of a risk to humans.The EU Cosmetics Regulation requires replacement of animal testing of cosmetic products for repeated dose/reproductive toxicity and toxicokinetics.To this end,the COSMOS consortium within SEURAT,a joint cluster between European Commission and Cosmetics Europe,has been engaged in development of computational methods and tools.COSMOS has developed a new toxicity database enriched with oral repeated dose studies for cosmetics-related chemicals.A new Cosmetics Inventory has been defined based on the chemical records from EU COSING database and list from the US Personal

关键词： Threshold of Toxicological Concern（TTC） risk assessment cosmetics non-cancer

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