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      Maximal Eccentric Hamstrings Strength in Competitive Alpine Skiers: Cross-Sectional Observations From Youth to Elite Level

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          Abstract

          Competitive alpine skiers are subject to substantial risks of injury, especially concerning the anterior cruciate ligament (ACL). During “landing back weighted” episodes, hamstrings may partially counteract the anterior shear force acting on the tibia by eccentrically resisting the boot-induced drawer of the tibia relative to the femur. The aim of the present study was to provide novel descriptive data and sport-specific reference values on maximal eccentric hamstrings strength (MEHS) in competitive alpine skiers from youth to elite level, and to explore potential relationships with sex, age and biological maturation. 170 competitive alpine skiers were investigated: 139 youth athletes (51 females, 88 males; age: 13.8 ± 0.59 years) and 31 elite athletes (19 females, 12 males; age: 21.7 ± 2.8 years). MEHS was assessed by the (Vald Performance, Newstead, Australia). U15 female skiers presented lower MEHS compared to female elite skiers for both limbs ( R = 210 ± 44 N vs. 340 ± 48 N, respectively, p < 0.001, and L = 207 ± 46 N vs. 303 ± 35 N, respectively, p < 0.001). Similarly, lower MEHS was observed in U15 male skiers compared to male elite skiers for both limbs ( R = 259 ± 51 N vs. 486 ± 62 N, respectively, p < 0.001, and L = 258 ± 57 N vs. 427 ± 54 N, respectively, p < 0.001). Correlations between MEHS and chronological age were modestly significant only for the U15 group ( r = 0.37 and p < 0.001). When the correlations for the U15 group were performed between MHES and maturity offset (obtained from the calculation of biological age, i.e., age at peak height velocity), statistical significance was reached by all the correlations run for 3 variables (Males < 0: r = 0.59, p < 0.0001; Males > 0: r = 0.70, p < 0.0001; and Females > 0: r = 0.46, p < 0.0001, start of maturity offset = 0). This cross-sectional description of MEHS in alpine skiers from youth to elite level highlights the importance of biological maturation for MEHS values in youth athletes and presents novel data that may offer insights into new approaches for injury prevention.

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          Most cited references39

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          Eccentric hamstring strength and hamstring injury risk in Australian footballers.

          Are eccentric hamstring strength and between-limb imbalance in eccentric strength, measured during the Nordic hamstring exercise, risk factors for hamstring strain injury (HSI)?
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            Aggressive quadriceps loading can induce noncontact anterior cruciate ligament injury.

            The force responsible for noncontact anterior cruciate ligament (ACL) injuries remains controversial. The patella tendon to tibial shaft angle causes an anterior tibial shear force with quadriceps activation. An aggressive quadriceps contraction can injure the ACL. The authors characterized noncontact ACL injury and kinematics with aggressive quadriceps loading. Thirteen fresh-frozen knees were potted in a jig held in 20 degrees of flexion while a 4500 N quadriceps contraction was simulated. Knee kinematics were recorded. A KT-1000 arthrometer and a simulated active quadriceps test assessed anterior displacement. Statistics were performed using paired t tests and 1-way analysis of variance. Kinematics revealed the following mean values: anterior displacement, 19.5 mm; valgus, 2.3 degrees; and internal rotation, 5.5 degrees. Mean KT-1000 and active quadriceps test differences were 4.0 mm and 2.7 mm, respectively (statistically significant P =.002 and P =.002). Six knees showed gross ACL injury at the femoral insertion. Based on ACL injury, KT-1000 differences were statistically significant (P =.029). Aggressive quadriceps loading, with the knee in slight flexion, produces significant anterior tibial translation and ACL injury. This suggests that the quadriceps is the intrinsic force in noncontact ACL injuries, producing a model for further investigation.
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              A novel device using the Nordic hamstring exercise to assess eccentric knee flexor strength: a reliability and retrospective injury study.

              Reliability and case-control injury study.
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                Author and article information

                Contributors
                Journal
                Front Physiol
                Front Physiol
                Front. Physiol.
                Frontiers in Physiology
                Frontiers Media S.A.
                1664-042X
                18 February 2019
                2019
                : 10
                : 88
                Affiliations
                [1] 1Sports Medical Research Group, Department of Orthopaedics, Balgrist University Hospital, University of Zurich , Zurich, Switzerland
                [2] 2Laboratory for Muscle Plasticity, Department of Orthopaedics, Balgrist University Hospital, University of Zurich , Zurich, Switzerland
                [3] 3Section for Elite Sport, Swiss Federal Institute of Sport Magglingen , Magglingen, Switzerland
                [4] 4Swiss-Ski , Muri bei Bern, Switzerland
                [5] 5Balgrist Move>Med, Department of Orthopaedics, Balgrist University Hospital, University of Zurich , Zurich, Switzerland
                Author notes

                Edited by: Lars Donath, German Sport University Cologne, Germany

                Reviewed by: Trevor Chung-Ching Chen, National Taiwan Normal University, Taiwan; Kazunori Nosaka, Edith Cowan University, Australia

                *Correspondence: Martino V. Franchi, martino.franchi@ 123456balgrist.ch Jörg Spörri, joerg.spoerri@ 123456balgrist.ch

                These authors have contributed equally to this work as first authorship

                This article was submitted to Exercise Physiology, a section of the journal Frontiers in Physiology

                Article
                10.3389/fphys.2019.00088
                6388545
                30833902
                518ab7cd-37e3-49d5-8e9d-663f2645d533
                Copyright © 2019 Franchi, Ellenberger, Javet, Bruhin, Romann, Frey and Spörri.

                This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

                History
                : 13 September 2018
                : 24 January 2019
                Page count
                Figures: 6, Tables: 1, Equations: 0, References: 40, Pages: 8, Words: 0
                Categories
                Physiology
                Original Research

                Anatomy & Physiology
                conditioning,physical fitness,neuromuscular performance,testing,biological maturity status,athletes,injury prevention,alpine ski racing

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