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Belcher S, Whatman C, Brughelli M. A systematic video analysis of 21 anterior cruciate ligament injuries in elite netball players during games. Sports Biomech 2022:1-18. [PMID: 35129089 DOI: 10.1080/14763141.2022.2034928] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Accepted: 01/21/2022] [Indexed: 01/14/2023]
Abstract
This systematic video analysis of 21 anterior cruciate ligament (ACL) injuries sustained by elite-level netball players during televised games, describes the situation, movement pattern and player behaviour, providing insight regarding the injury mechanism. Seventeen of the ACL injuries occurred from jump-landing actions and only two from cutting manoeuvres. A common scenario was identified for 11 players. In this scenario, players were decelerating rapidly after jumping to receive a high pass, utilising a double-footed landing with a wide base of support (WBOS). Deceleration appeared to be applied predominantly via the injured leg with the knee extended and foot planted. Often the players appeared unbalanced on landing leaning too far back. ACL injury risk was possibly exacerbated by the players head turning away from the injured side. A further compressive knee moment may have been placed on the lateral aspect of the knee by bringing the ball from a high position to a low position at the estimated time of injury. Players may benefit from landing technique training programmes that encourage shoulder-width foot landings, with ≥30° knee flexion, a small amount of plantar-flexion and good balance. Incorporating challenges to players balance and ability to cope with perturbations may also be beneficial. Training programmes should include instruction on securing the ball in a stable above pelvis-level position after receiving a pass and bringing their whole body around during landing into the direction of their next pass, rather than simply turning their head to look.
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Affiliation(s)
- Suzanne Belcher
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
- NetballSmart New Zealand, Auckland, New Zealand
| | - Chris Whatman
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
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Edouard P, Lahti J, Nagahara R, Samozino P, Navarro L, Guex K, Rossi J, Brughelli M, Mendiguchia J, Morin JB. Low Horizontal Force Production Capacity during Sprinting as a Potential Risk Factor of Hamstring Injury in Football. Int J Environ Res Public Health 2021; 18:ijerph18157827. [PMID: 34360125 PMCID: PMC8345704 DOI: 10.3390/ijerph18157827] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/18/2021] [Accepted: 07/06/2021] [Indexed: 01/09/2023]
Abstract
Clear decreases in horizontal force production capacity during sprint acceleration have been reported after hamstring injuries (HI) in football players. We hypothesized that lower FH0 is associated with a higher HI occurrence in football players. We aimed to analyze the association between sprint running horizontal force production capacities at low (FH0) and high (V0) velocities, and HI occurrence in football. This prospective cohort study included 284 football players over one season. All players performed 30 m field sprints at the beginning and different times during the season. Sprint velocity data were used to compute sprint mechanical properties. Players' injury data were prospectively collected during the entire season. Cox regression analyses were performed using new HI as the outcome, and horizontal force production capacity (FH0 and V0) was used at the start of the season (model 1) and at each measurement time point within the season (model 2) as explanatory variables, adjusted for individual players' (model 2) age, geographical group of players, height, body mass, and previous HI, with cumulative hours of football practice as the time scale. A total of 47 new HI (20% of all injuries) were observed in 38 out of 284 players (13%). There were no associations between FH0 and/or V0 values at the start of the season and new HI occurrence during the season (model 1). During the season, a total of 801 measurements were performed, from one to six per player. Lower measured FH0 values were significantly associated with a higher risk of sustaining HI within the weeks following sprint measurement (HR = 2.67 (95% CI: 1.51 to 4.73), p < 0.001) (model 2). In conclusion, low horizontal force production capacities at low velocity during early sprint acceleration (FH0) may be considered as a potential additional factor associated with HI risk in a comprehensive, multifactorial, and individualized approach.
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Affiliation(s)
- Pascal Edouard
- UJM-Saint-Etienne, Laboratory Interuniversity of Human Movement Sciences, University Lyon, EA 7424, F-42023 Saint-Etienne, France; (J.R.); (J.-B.M.)
- Sports Medicine Unity, Department of Clinical and Exercise Physiology, Faculty of Medicine, University Hospital of Saint-Etienne, CEDEX 2, F-42055 Saint-Etienne, France
- Correspondence: ; Tel.: +33-674-574-691
| | - Johan Lahti
- LAMHESS, Université Côte d’Azur, F-06200 Nice, France;
| | - Ryu Nagahara
- Sports Research and Development Core, University of Tsukuba, Ibaraki 305-8574, Japan;
- Faculty of Sports and Budo Coaching Studies, National Institute of Fitness and Sports in Kanoya, Kagoshima 891-2393, Japan
| | - Pierre Samozino
- Laboratory Interuniversity of Human Movement Sciences, University Savoie Mont Blanc, EA 7424, F-73000 Chambéry, France;
| | - Laurent Navarro
- Mines Saint-Etienne, Centre CIS, Université de Lyon, Université Jean Monnet, INSERM, U 1059 Sainbiose, F-42023 Saint-Etienne, France;
| | - Kenny Guex
- School of Health Sciences (HESAV), HES-SO University of Applied Sciences and Arts Western Switzerland, 1011 Lausanne, Switzerland;
- Department of Sprints, Hurdles and Relays, Swiss Athletics, Haus des Sports, 3063 Ittigen, Switzerland
| | - Jérémy Rossi
- UJM-Saint-Etienne, Laboratory Interuniversity of Human Movement Sciences, University Lyon, EA 7424, F-42023 Saint-Etienne, France; (J.R.); (J.-B.M.)
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand, Auckland University of Technology, 1010 Auckland, New Zealand;
| | - Jurdan Mendiguchia
- Department of Physical Therapy, Zentrum Rehabilitation and Performance Center, 31002 Pamplona, Spain;
| | - Jean-Benoît Morin
- UJM-Saint-Etienne, Laboratory Interuniversity of Human Movement Sciences, University Lyon, EA 7424, F-42023 Saint-Etienne, France; (J.R.); (J.-B.M.)
- LAMHESS, Université Côte d’Azur, F-06200 Nice, France;
- Sports Performance Research Institute New Zealand, Auckland University of Technology, 1010 Auckland, New Zealand;
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Belcher S, Whatman C, Brughelli M, Borotkanics R. Short and long versions of a 12-week netball specific neuromuscular warm-up improves landing technique in youth netballers. Phys Ther Sport 2021; 49:31-36. [PMID: 33578359 DOI: 10.1016/j.ptsp.2021.01.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 01/25/2021] [Accepted: 01/28/2021] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To investigate the efficacy of two 'NetballSmart', netball specific warm-ups in improving landing technique measures in New Zealand secondary school netball players. DESIGN Multi-site cluster experimental trial. PARTICIPANTS 77 youth participants, mean ± SD age = 15.8 ± 0.9 were recruited from secondary school netball teams. SETTING 12 teams from 6 schools performed either the NetballSmart Dynamic Warm-up (NSDW) (n = 37); or Power warm-up (PWU) (n = 40), three times a week for 12 weeks. All players within a school (2 teams) were assigned the same warm-up, avoiding treatment contamination. MAIN OUTCOME MEASURES A series of unilateral and bilateral drop vertical jumps on to a portable force plate were completed by all participants. Measures included peak vertical ground reaction force (GRF) for single-leg and bilateral landings; frontal plane projection angle (FPPA) for right and left single-leg landings and Landing error scoring system (LESS) for bilateral landings. Paired t-tests were used to assess mean differences pre and post the warm-up. Generalised linear mixed effects models were developed to evaluate the effects between the NSDW and PWU groups. RESULTS Significant improvements were found in all the landing technique outcome measures for both warm-up groups (ES Range- GRF = -0.6 to -1.1; FPPA = 0.8 to 1.2; LESS = -1.6 to-3.2; p < 0.05). Results of mixed effects models revealed that there was only a significantly greater improvement in LESS for the PWU group (β = -0.30, p = 0.001). CONCLUSION Results show both warm-ups can improve landing technique measures in youth secondary school netball players. It is recommended that coaches should consider implementing one of the two warm-ups in their netball programmes. Their choice of warm-up will likely be dependent on their environment and time demands.
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Affiliation(s)
- Suzanne Belcher
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand; Netball New Zealand, Auckland, New Zealand.
| | - Chris Whatman
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand
| | - Robert Borotkanics
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand
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Abstract
McKenzie, CR, Whatman, C, and Brughelli, M. Performance profiling of female youth netball players. J Strength Cond Res 34(11): 3275-3283, 2020-The purpose of this study was to investigate the physical performance characteristics of New Zealand secondary school netball players to provide a physical performance profile and determine whether there are differences between playing grade and playing positions for this group. A total of 102 female netball players (mean ± SD: age 13.3 ± 0.50 years, height 166.95 ± 5.72 cm, and body mass 60.94 ± 12.80 kg) participated in this study. Measurements included anthropometry, horizontal and vertical jump performance, balance, core strength, change-of-direction speed, and split sprint times. Magnitude-based inferences were used to determine differences in all measures. Grade 1 players jumped further and higher (effect size [ES] = 0.41-1.37) and ran faster with small to moderate differences. They demonstrated faster change-of-direction speed (ES = -0.73 to -1.31), greater core strength (ES = 0.28-1.17), and a faster time-to-stabilization (ES = -0.69). Grade 2 circle players jumped further (ES = -0.29), compared with noncircle players who jumped higher (ES = 0.35). Noncircle players had faster sprint and change-of-direction speed (ES = -0.33 to -0.55) and measures of balance (ES = -0.47 to 0.55). Grade 1 circle players were found to be faster over 20 m (ES = 0.75). The results of this study showed differences in the physical performance capabilities between youth netball players competing in different grades, as well as differences between playing positions. These findings have provided a physical performance profile of female youth netball players in New Zealand, suggesting that physical performance measures could be used for position-specific training and talent identification and selection.
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Affiliation(s)
- Chloe R McKenzie
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand
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Arazi H, Salek L, Nikfal E, Izadi M, Tufano JJ, Elliott BT, Brughelli M. Comparable endocrine and neuromuscular adaptations to variable vs. constant gravity-dependent resistance training among young women. J Transl Med 2020; 18:239. [PMID: 32539753 PMCID: PMC7296723 DOI: 10.1186/s12967-020-02411-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 06/09/2020] [Indexed: 02/05/2023] Open
Abstract
Background Variable resistance has been shown to induce greater total work and muscle activation when compared to constant resistance. However, little is known regarding the effects of chronic exposure to variable resistance training in comparison with constant resistance training. The aim of the present study was therefore to examine the effects of chain-loaded variable and constant gravity-dependent resistance training on resting hormonal and neuromuscular adaptations. Methods Young women were randomly assigned to variable resistance training (VRT; n = 12; age, 23.75 ± 3.64 years; and BMI, 26.80 ± 4.21 kg m−2), constant resistance training (CRT; n = 12; age, 23.58 ± 3.84 years; BMI, 25.25 ± 3.84 kg m−2), or control (Con; n = 12; age, 23.50 ± 2.93 years; BMI, 27.12 ± 12 kg m−2) groups. CRT performed 8-week total-body free-weight training three times per week with moderate-to-high intensity (65–80% 1RM; periodized). VRT was the same as CRT but included variable resistance via chains (15% of total load). Resting serum samples were taken before and after the 8-week intervention for GH, IGF-1, cortisol, myostatin, and follistatin analyses. Results Both VRT and CRT groups displayed moderate-to-large significant increases in GH (197.1%; ES = 0.78 vs. 229.9%; ES = 1.55), IGF-1 (82.3%; ES = 1.87 vs. 66%; ES = 1.66), and follistatin (58.8%; ES = 0.80 vs. 49.15%; ES = 0.80) and decreases in cortisol (− 19.9%; ES = − 1.34 vs. − 17.1%; ES = − 1.05) and myostatin (− 26.9%; ES = − 0.78 vs. − 23.2%; ES = − 0.82). Also, VRT and CRT resulted in large significant increases in bench press (30.54%; ES = 1.45 vs. 25.08%; ES = 1.12) and squat (30.63%; ES = 1.28 vs. 24.81%; ES = 1.21) strength, with no differences between groups. Conclusions Implementing chain-loaded VRT into a periodized resistance training program can be an effective alternative to constant loading during free-weight RT among untrained young women.
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Affiliation(s)
- Hamid Arazi
- Department of Exercise Physiology, Faculty of Sport Sciences, University of Guilan, 10 th km of Tehran Road- Khalij-e-Fars Highway, Zip Code: 4199843653, Rasht, Iran.
| | - Lida Salek
- Department of Physical Education, Bandar-e-Anzali Branch, Islamic Azad University, Bandar-e-Anzali, Iran
| | - Elham Nikfal
- Department of Physical Education, Bandar-e-Anzali Branch, Islamic Azad University, Bandar-e-Anzali, Iran
| | - Mani Izadi
- Department of Exercise Physiology, Faculty of Sport Sciences, University of Guilan, 10 th km of Tehran Road- Khalij-e-Fars Highway, Zip Code: 4199843653, Rasht, Iran
| | - James J Tufano
- Faculty of Physical Education and Sport, Charles University, Prague, Czech Republic
| | - Bradley T Elliott
- Translational Physiology Research Group, School of Life Sciences, University of Westminster, London, UK
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand (SPRINZ), AUT Millennium, Auckland University of Technology, Auckland, New Zealand
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Belcher S, Whatman C, Brughelli M, Borotkanics R. Ten-year nationwide review of netball ankle and knee injuries in New Zealand. J Sci Med Sport 2020; 23:937-942. [PMID: 32461051 DOI: 10.1016/j.jsams.2020.04.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/23/2020] [Accepted: 04/03/2020] [Indexed: 01/02/2023]
Abstract
OBJECTIVES To review netball ankle and knee injuries between 2008 and 2017. DESIGN Audit of insurance injury claims. METHODS Data were divided into 5 equal year groups (2008/9, 2010/11, 2012/13, 2014/15, 2016/17), and 3 age groups (10 to 14 years, 15 to 19 years, 20 to 24 years old). Raw injury counts and injury rates per 1000 affiliated players were reported. Changes in injury rates over the 10-year period and differences between age groups were expressed as Incident rate ratios (IRRs). A Shewhart control chart was created to identify monthly injury patterns. RESULTS 10-14-year-olds showed the biggest increase in injury counts (ankle 84% increase and knee 133% increase). 20-24-year-olds had the highest mean injury rate over the ten-years (ankle = 77.8, knee = 71.6 injuries/1000 players). 10-14-year-olds had the biggest increase in risk of injury between 2008/09 to 2016/17, (ankle IRR = 2.0; knee IRR = 2.5), 15-19-year-olds (ankle IRR = 1.4; knee IRR = 1.5), 20-24 year olds (ankle IRR = 0.5; knee IRR = 1.9). The older two groups had a significantly higher mean risk of ankle and knee injury (IRR = 1.9 to 2.2; p < 0.001). Higher than expected yearly injury incidence was repeatedly seen in 10-19-year-olds. CONCLUSION Ankle and Knee injuries have increased with the biggest increase in 10-19-year-olds. Injuries in 20-24-year-olds still represent the highest cost and continue at a higher rate than in younger players. Spikes in injury are likely associated with intense periods of trialling and tournament play.
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Affiliation(s)
- Suzanne Belcher
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand; Netball New Zealand, Auckland, New Zealand.
| | - Chris Whatman
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand
| | - Robert Borotkanics
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, New Zealand
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Brown SR, Hume PA, Lorimer AV, Brughelli M, Besier TF. An individualised approach to assess the sidestep manoeuvre in male rugby union athletes. J Sci Med Sport 2020; 23:1086-1092. [PMID: 32381391 DOI: 10.1016/j.jsams.2020.03.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 12/09/2019] [Accepted: 03/27/2020] [Indexed: 11/18/2022]
Abstract
OBJECTIVES This study aimed to (1) quantitatively assess external knee abduction moments between legs, and (2) qualitatively assess anterior cruciate ligament injury risk between group mean and individual athlete data during the sidestep manoeuvre. DESIGN Descriptive cross-sectional study. METHODS Sixteen male academy-level rugby union athletes (20.4±2.7yr; 186.3±9.1cm; 99.1±14.4kg) performed three maximal effort sidesteps (>6.0ms-1) on each leg. Three-dimensional motion analysis was used to obtain external knee abduction moments, wherein the two legs were separated by the preferred and non-preferred kicking leg. Quantitative comparisons were made between legs, while qualitative comparisons were made been group mean and individual athlete data. RESULTS When sidestepping on the non-preferred leg, athletes produced 25% greater knee abduction moments (ES=0.43) and presented modified postural adjustments associated with injury risk (extended knee [ES=-0.26; -8%], more trunk lateral flexion [ES=0.42; 17%] and more distance between the centre-of-mass and ankle-joint-centre of the stance leg [ES=0.97; 11%]) compared to the preferred leg. Individually, only 9 out of 16 athletes presented a higher abduction moment in their non-preferred leg with individual asymmetries ranging between 2.2 and 47%. CONCLUSIONS Nearly half of the athletes assessed in this study showed the potential to "slip under the radar" when using the group mean for assessment. When assessing athletes for anterior cruciate ligament injury risk factors, individual athlete data should be examined in conjunction with the group mean for a more holistic view of the data.
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Affiliation(s)
- Scott R Brown
- Neuromuscular and Rehabilitation Robotics Laboratory (NeuRRo Lab), Department of Physical Medicine and Rehabilitation, Michigan Medicine, University of Michigan, USA; Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, New Zealand.
| | - Patria A Hume
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, New Zealand
| | - Anna V Lorimer
- Faculty of Health Sciences and Medicine, Bond University, Australia; Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, New Zealand
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, New Zealand
| | - Thor F Besier
- Auckland Bioengineering Institute and Department of Engineering Science, University of Auckland, New Zealand; Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, New Zealand
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Morin JB, Jiménez-Reyes P, Brughelli M, Samozino P. When Jump Height is not a Good Indicator of Lower Limb Maximal Power Output: Theoretical Demonstration, Experimental Evidence and Practical Solutions. Sports Med 2020; 49:999-1006. [PMID: 30805913 DOI: 10.1007/s40279-019-01073-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lower limb external maximal power output capacity is a key physical component of performance in many sports. During squat jump and countermovement jump tests, athletes produce high amounts of mechanical work over a short duration to displace their body mass (i.e. the dimension of mechanical power). Thus, jump height has been frequently used by the sports science and medicine communities as an indicator of the power output produced during the jump and by extension, of maximal power output capacity. However, in this article, we contend that squat jump and countermovement jump height are not systematically good indicators of power output produced during the jump and maximal power output capacity. To support our opinion, we first detail why, theoretically, jump height and maximal power output capacity are not fully related. Specifically, we demonstrate that individual body mass, push-off distance, optimal loading and the force-velocity profile confound the jump height-power relationship. We also discuss the relationship between squat jump or countermovement jump height and maximal power output capacity measured with a force plate based on data reported in the literature, which added to our own experimental evidence. Finally, we discuss the limitations of existing practical solutions (regression-based estimation equations and allometric scaling), and advocate using a valid, reliable and simple field-based procedure to compute individual power output produced during the jump and maximal power output capacity directly from jump height, body mass and push-off distance. The latter may allow researchers and practitioners to reduce bias in their assessment of lower limb mechanical power output by using jump height as an input with a simple yet accurate computation method, and not as the first/only variable of interest.
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Affiliation(s)
- Jean-Benoit Morin
- Université Côte d'Azur, LAMHESS, Nice, France. .,Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand.
| | | | - Matt Brughelli
- Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand
| | - Pierre Samozino
- Univ Savoie Mont Blanc, Laboratoire Interuniversitaire de Biologie de la Motricité, EA 7424, Chambéry, France
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Lenetsky S, Brughelli M, Nates RJ, Neville J, Cross MR, Lormier AV. Defining the Phases of Boxing Punches: A Mixed-Method Approach. J Strength Cond Res 2020; 34:1040-1051. [DOI: 10.1519/jsc.0000000000002895] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Zouhal H, Abderrahman AB, Dupont G, Truptin P, Le Bris R, Le Postec E, Sghaeir Z, Brughelli M, Granacher U, Bideau B. Effects of Neuromuscular Training on Agility Performance in Elite Soccer Players. Front Physiol 2019; 10:947. [PMID: 31396107 PMCID: PMC6664050 DOI: 10.3389/fphys.2019.00947] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Accepted: 07/09/2019] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Agility in general and change-of-direction speed (CoD) in particular represent important performance determinants in elite soccer. OBJECTIVES The objectives of this study were to determine the effects of a 6-week neuromuscular training program on agility performance, and to determine differences in movement times between the slower and faster turning directions in elite soccer players. MATERIALS AND METHODS Twenty male elite soccer players from the Stade Rennais Football Club (Ligue 1, France) participated in this study. The players were randomly assigned to a neuromuscular training group (NTG, n = 10) or an active control (CG, n = 10) according to their playing position. NTG participated in a 6-week, twice per week neuromuscular training program that included CoD, plyometric and dynamic stability exercises. Neuromuscular training replaced the regular warm-up program. Each training session lasted 30 min. CG continued their regular training program. Training volume was similar between groups. Before and after the intervention, the two groups performed a reactive agility test that included 180° left and right body rotations followed by a 5-m linear sprint. The weak side was defined as the left/right turning direction that produced slower overall movement times (MT). Reaction time (RT) was assessed and defined as the time from the first appearance of a visual stimulus until the athlete's first movement. MT corresponded to the time from the first movement until the athlete reached the arrival gate (5 m distance). RESULTS No significant between-group baseline differences were observed for RT or MT. Significant group x time interactions were found for MT (p = 0.012, effect size = 0.332, small) for the slower and faster directions (p = 0.011, effect size = 0.627, moderate). Significant pre-to post improvements in MT were observed for NTG but not CG (p = 0.011, effect size = 0.877, moderate). For NTG, post hoc analyses revealed significant MT improvements for the slower (p = 0.012, effect size = 0.897, moderate) and faster directions (p = 0.017, effect size = 0.968, moderate). CONCLUSION Our results illustrate that 6 weeks of neuromuscular training with two sessions per week included in the warm-up program, significantly enhanced agility performance in elite soccer players. Moreover, improvements were found on both sides during body rotations. Thus, practitioners are advised to focus their training programs on both turning directions.
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Affiliation(s)
- Hassane Zouhal
- Univ Rennes, M2S (Laboratoire Mouvement, Sport, Santé) – EA 1274, Rennes, France
| | | | | | - Pablo Truptin
- Univ Rennes, M2S (Laboratoire Mouvement, Sport, Santé) – EA 1274, Rennes, France
| | - Régis Le Bris
- Lorient Football Club (FCL), Lorient, France & Stade Rennais Football Club (SRFC), Rennes, France
| | - Erwan Le Postec
- Lorient Football Club (FCL), Lorient, France & Stade Rennais Football Club (SRFC), Rennes, France
| | | | - Matt Brughelli
- Sports Performance Research Institute New Zealand (SPRINZ), AUT Millennium, Auckland University of Technology, Auckland, New Zealand
| | - Urs Granacher
- Division of Training and Movement Science, University of Potsdam, Potsdam, Germany
| | - Benoit Bideau
- Univ Rennes, M2S (Laboratoire Mouvement, Sport, Santé) – EA 1274, Rennes, France
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Coppalle S, Rave G, Ben Abderrahman A, Ali A, Salhi I, Zouita S, Zouita A, Brughelli M, Granacher U, Zouhal H. Relationship of Pre-season Training Load With In-Season Biochemical Markers, Injuries and Performance in Professional Soccer Players. Front Physiol 2019; 10:409. [PMID: 31031638 PMCID: PMC6474299 DOI: 10.3389/fphys.2019.00409] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2018] [Accepted: 03/26/2019] [Indexed: 11/15/2022] Open
Abstract
INTRODUCTION There is controversy in the literature in regards of the link between training load and injury rate. Thus, the aims of this non-interventional study were to evaluate relationships between pre-season training load with biochemical markers, injury incidence and performance during the first month of the competitive period in professional soccer players. MATERIALS AND METHODS Healthy professional soccer players were enrolled in this study over two pre-season periods. Data sets were available from 26 players during the first season (2014-2015) and 24 players during the second season (2015-2016) who completed two pre-season periods (6 weeks each). External training load was assessed from all athletes during training using Global Positioning System (GPS). Internal training load was monitored after each training session using rate of perceived exertion (RPE). Before and after each pre-season, blood samples were taken to determine plasma lactate dehydrogenase (LDH), creatine kinase (CK) and C-reactive protein (CRP). Injury incidence and overall performance (ranking of the team after the first five official games of the championship) were recorded for both seasons separately. RESULTS There was no statistically significant difference in mean RPE values of the two-preparation periods (2737 ± 452 and 2629 ± 786 AU, p = 0.492). The correlational analysis did not reveal significant associations between internal and external training load (RPE and GPS data) and biological markers. There was a significant positive correlation between RPE and LDH during the 2015/2016 season (r = 0.974, p = 0.001). In addition, a significant negative correlation was found between total distance >20 km/h and CRP during the 2015-2016 season (r = -0.863, p = 0.027). The injury rates for the two seasons were 1.76 and 1.06 per 1000 h exposure for the 2014-2015 and 2015-2016 seasons, respectively (p = 0.127). CONCLUSION Our study showed that pre-season training load is not associated with overall team performance. This association is most likely multifactorial and other factors (e.g., technical and tactical level of the team, opponents, environment) may play an important role for the collective team performance. Our findings may help coaches to better prepare their athletes during pre-season.
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Affiliation(s)
- Sullivan Coppalle
- M2S (Movement, Sport and Health Sciences Laboratory), University of Rennes 2, Rennes, France
| | - Guillaume Rave
- Stade Lavallois Mayenne Football Club, Laval, France
- Department of Performance, Université d’Angers, Angers, France
| | | | - Ajmol Ali
- School of Sport, Exercise and Nutrition, Massey University, Auckland, New Zealand
| | - Iyed Salhi
- ISSEP Ksar Said, University of Manouba, Manouba, Tunisia
| | - Sghaier Zouita
- ISSEP Ksar Said, University of Manouba, Manouba, Tunisia
| | - Amira Zouita
- ISSEP Ksar Said, University of Manouba, Manouba, Tunisia
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand, AUT Millennium, Auckland University of Technology, Auckland, New Zealand
| | - Urs Granacher
- Division of Training and Movement Sciences, University of Potsdam, Potsdam, Germany
| | - Hassane Zouhal
- M2S (Movement, Sport and Health Sciences Laboratory), University of Rennes 2, Rennes, France
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12
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McKenzie CR, Whatman C, Brughelli M, Borotkanics R. The effect of the NetballSmart Dynamic Warm-up on physical performance in youth netball players. Phys Ther Sport 2019; 37:91-98. [PMID: 30904750 DOI: 10.1016/j.ptsp.2019.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 03/08/2019] [Accepted: 03/10/2019] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To investigate the efficacy of the NetballSmart Dynamic Warm-up in improving physical performance measures in New Zealand secondary school netball players. DESIGN Cluster randomised controlled trial. SETTING A seven-week intervention study in secondary school netball. PARTICIPANTS 81 youth netball players (Intervention group, n = 45; Control group, n = 36). MAIN OUTCOME MEASURES Performance measures included prone hold, change of direction, sprint, vertical and horizontal jump, Y-balance and time-to-stabilisation. Mixed effects models and t-tests were used to determine significant differences of pre and post measures between groups. RESULTS Significant improvements in prone hold (β = 20.46 s; p = 0.01) and vertical jump (β = 6.73 cm; p = 0.01) were found in the intervention group compared to the control group, while horizontal jump was found to significantly decrease (β = -9.86 cm; p = 0.03) in comparison to the control group. CONCLUSIONS The results of this study show the NetballSmart Dynamic Warm-up can improve some physical performance measures in youth netball players. It is recommended that coaches should consider implementing the warm-up in their netball programmes.
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Affiliation(s)
- Chloe R McKenzie
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand.
| | - Chris Whatman
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand
| | - Robert Borotkanics
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand
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13
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Edouard P, Mendiguchia J, Lahti J, Arnal PJ, Gimenez P, Jiménez-Reyes P, Brughelli M, Samozino P, Morin JB. Sprint Acceleration Mechanics in Fatigue Conditions: Compensatory Role of Gluteal Muscles in Horizontal Force Production and Potential Protection of Hamstring Muscles. Front Physiol 2018; 9:1706. [PMID: 30555346 PMCID: PMC6283907 DOI: 10.3389/fphys.2018.01706] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 11/13/2018] [Indexed: 12/28/2022] Open
Abstract
Aim: Hamstring muscle injury is the main injury related to sports requiring sprint acceleration. In addition, hamstring muscles have been reported to play a role in horizontal force production during sprint acceleration performance. The aim of the present study was to analyze (i) the determinants of horizontal force production and (ii) the role of hip extensors, and hamstring muscles in particular, for horizontal force production during repeated sprint-induced fatigue conditions. Method: In this experimental laboratory setting study including 14 sprint-trained male athletes, we analyzed (i) the changes in sprint mechanics, peak torque of the knee and hip extensors and flexors, muscle activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus, and sagittal plane lower limb motion, before and after twelve 6-s sprints separated by 44 s rest on an instrumented motorized treadmill, and (ii) the determinants of horizontal force production (FH ) during the sprint acceleration in a fatigue state (after 12 sprints). Results: The repeated-sprint protocol induced a decrease in maximal power output (Pmax) [-17.5 ± 8.9%; effect size (ES): 1.57, large] and in the contact-averaged horizontal force component (FH ) (-8.6 ± 8.4%; ES: 0.86, moderate) but not meaningful changes in the contact-averaged resultant (total) force (FTot ) (-3.4 ± 2.9%; ES: 0.55, small) and vertical force component (FV ) (-3.1 ± 3.2%; ES: 0.49, small). A decrease was found in concentric peak torque of the knee flexors and extensors and in gluteus and vastus lateralis muscle activity during entire swing and end-of-swing phase. An increase was found in contact time and swing time, while step frequency and knee speed before ground contact decreased. Muscular determinants associated with FH and its decrease after the repeated-sprint protocol were concentric peak torque of the hip extensors (p = 0.033) and a decrease in gluteus maximus activity at the end-of-swing (p = 0.007), respectively. Conclusion: Sprint-induced fatigue lead to changes in horizontal force production muscular determinants: hamstring muscle seems not to have the same role than in non-fatigue condition. Horizontal force production seems to be more dependent on the hip extensors and gluteus maximus function. Given the fatigue-induced decrease in hamstring muscle strength, we can hypothesize that muscle compensatory and kinematic strategies reported in a fatigued state could be an adaptation to allow/maintain performance and a protective adaptation to limit hamstring muscles constraints.
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Affiliation(s)
- Pascal Edouard
- Inter-University Laboratory of Human Movement Science (LIBM EA 7424), University of Lyon, University Jean Monnet, Saint Etienne, France.,Department of Clinical and Exercise Physiology, Sports Medicine Unity, University Hospital of Saint-Etienne, Faculty of Medicine, Saint-Étienne, France.,Medical Commission, French Athletics Federation, Paris, France
| | - Jurdan Mendiguchia
- Department of Physical Therapy, ZENTRUM Rehab and Performance Center, Barañain, Spain
| | - Johan Lahti
- Université Côte d'Azur, LAMHESS, Nice, France.,Faculty of Sports and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | | | - Philippe Gimenez
- Laboratory Culture Sport Health Society (EA 4660), University of Bourgogne Franche-Comté, Besançon, France
| | - Pedro Jiménez-Reyes
- Faculty of Sport, Catholic University of San Antonio, Murcia, Spain.,Centre for Sport Studies, King Juan Carlos University, Madrid, Spain
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand
| | - Pierre Samozino
- Univ Savoie Mont Blanc, Laboratoire Interuniversitaire de Biologie de la Motricité, EA 7424, Chambéry, France
| | - Jean-Benoit Morin
- Université Côte d'Azur, LAMHESS, Nice, France.,Sports Performance Research Institute New Zealand, School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand
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Jiménez-Reyes P, Samozino P, García-Ramos A, Cuadrado-Peñafiel V, Brughelli M, Morin JB. Relationship between vertical and horizontal force-velocity-power profiles in various sports and levels of practice. PeerJ 2018; 6:e5937. [PMID: 30479900 PMCID: PMC6238764 DOI: 10.7717/peerj.5937] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 10/16/2018] [Indexed: 11/29/2022] Open
Abstract
This study aimed (i) to explore the relationship between vertical (jumping) and horizontal (sprinting) force–velocity–power (FVP) mechanical profiles in a large range of sports and levels of practice, and (ii) to provide a large database to serve as a reference of the FVP profile for all sports and levels tested. A total of 553 participants (333 men, 220 women) from 14 sport disciplines and all levels of practice participated in this study. Participants performed squat jumps (SJ) against multiple external loads (vertical) and linear 30–40 m sprints (horizontal). The vertical and horizontal FVP profile (i.e., theoretical maximal values of force (F0), velocity (v0), and power (Pmax)) as well as main performance variables (unloaded SJ height in jumping and 20-m sprint time) were measured. Correlations coefficient between the same mechanical variables obtained from the vertical and horizontal modalities ranged from −0.12 to 0.58 for F0, −0.31 to 0.71 for v0, −0.10 to 0.67 for Pmax, and −0.92 to −0.23 for the performance variables (i.e, SJ height and sprint time). Overall, results showed a decrease in the magnitude of the correlations for higher-level athletes. The low correlations generally observed between jumping and sprinting mechanical outputs suggest that both tasks provide distinctive information regarding the FVP profile of lower-body muscles. Therefore, we recommend the assessment of the FVP profile both in jumping and sprinting to gain a deeper insight into the maximal mechanical capacities of lower-body muscles, especially at high and elite levels.
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Affiliation(s)
- Pedro Jiménez-Reyes
- Faculty of Sport, Catholic University of San Antonio, Murcia, Spain.,Centre for Sport Studies, King Juan Carlos University, Madrid, Spain
| | - Pierre Samozino
- Laboratoire Interuniversitaire de Biologie de la motricité (EA7424), University of Savoie Mont Blanc, Le Bourget du Lac, France
| | - Amador García-Ramos
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain.,Department of Sports Sciences and Physical Conditioning, Faculty of Education, CIEDE, Catholic University of the Most Holy Concepción, Concepción, Chile
| | | | - Matt Brughelli
- Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand
| | - Jean-Benoît Morin
- Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand.,Laboratoire Motricité Humaine Education Sport Santé, Université Côte d'Azur, Nice, France
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15
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Jiménez-Reyes P, Cross M, Ross A, Samozino P, Brughelli M, Gill N, Morin JB. Changes in mechanical properties of sprinting during repeated sprint in elite rugby sevens athletes. Eur J Sport Sci 2018; 19:585-594. [PMID: 30409072 DOI: 10.1080/17461391.2018.1542032] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This study aimed to analyse fatigue-induced changes in mechanical sprinting properties during a specific repeated-sprint test in elite rugby sevens athletes. Twenty elite rugby sevens players performed ten 40 m sprints on a 30 s cycle with participant's running back and forth in a marked lane. Radar was used to assess maximal overground sprint performance over each 40 m. Macroscopic mechanical properties (maximal horizontal force (F0), maximal horizontal power (Pmax), maximal ratio of horizontal force (RFpeak), decrease in the ratio of horizontal-to-total force (DRF), total force and maximal sprinting velocity (v0)) were drawn from horizontal force velocity relationships, using a validated method applied to the speed-time data. Fatigue-induced changes were analysed comparing the first sprint to an average of 2nd-4th, 5th-7th and 8th-10th. Repeated-sprint ability (RSA) testing induced substantial changes in the maximal velocity component, with a decrease (-15%) in v0 (effect size (ES) = -2.46 to -4.98), and to a lower extent (-5.9%) in the maximal force component F0 (ES = -0.59). DRF moderately decreased (14%; ES=-0.76-1.11), and RFpeak largely decreased in the later sprints (ES = -0.32 to -1.27). Fatigue observed in this RSA test appeared to have a greater effect on the technical ability to produce horizontal force at high velocities, likely due to an alteration in the ability to maintain horizontally oriented force application when velocity increases rather than during the initial acceleration phase, but also the overall force production capacity. The ability to maintain forward-oriented force at high velocities is of central importance for identifying fatigue and monitoring load.
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Affiliation(s)
- Pedro Jiménez-Reyes
- a Centre for Sport Studies , King Juan Carlos University , Madrid , Spain.,b Catholic University of San Antonio, Physical Activity and Sports Science , Murcia , Spain
| | - Matt Cross
- c Laboratoire Interuniversitaire de Biologie de la Motricité , University Savoie Mont Blanc , Chambéry , France.,d Département Scientifique et Sportif , Fédération Française de Ski , Annecy , France.,e Sports Performance Research Institute New Zealand (SPRINZ) , Auckland University of Technology , Auckland , New Zealand
| | - Alex Ross
- e Sports Performance Research Institute New Zealand (SPRINZ) , Auckland University of Technology , Auckland , New Zealand.,f Union Argentina de Rugby , Buenos Aires , Argentina
| | - Pierre Samozino
- c Laboratoire Interuniversitaire de Biologie de la Motricité , University Savoie Mont Blanc , Chambéry , France
| | - Matt Brughelli
- e Sports Performance Research Institute New Zealand (SPRINZ) , Auckland University of Technology , Auckland , New Zealand
| | - Nicholas Gill
- g Faculty of Health, Sport and Human Performance , University of Waikato , Tauranga , New Zealand
| | - Jean-Benoît Morin
- e Sports Performance Research Institute New Zealand (SPRINZ) , Auckland University of Technology , Auckland , New Zealand.,h LAMHESS , Université Côte d'Azur , Nice , France
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16
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Lenetsky S, Brughelli M, Nates RJ, Cross MR, Lormier AV. Variability and Reliability of Punching Impact Kinetics in Untrained Participants and Experienced Boxers. J Strength Cond Res 2018; 32:1838-1842. [DOI: 10.1519/jsc.0000000000002352] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Zouhal H, Abderrahman AB, Dupont G, Truptin P, Le Bris R, Le Postec E, Coppalle S, Ravé G, Brughelli M, Bideau B. Laterality Influences Agility Performance in Elite Soccer Players. Front Physiol 2018; 9:807. [PMID: 30008676 PMCID: PMC6033993 DOI: 10.3389/fphys.2018.00807] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 06/08/2018] [Indexed: 12/02/2022] Open
Abstract
Introduction: Laterality (i.e., handedness, footedness, and eyedness) could have an impact on highly repeated soccer movements and thus, could influence performance. The purpose of this study was to examine the laterality of high-level football players and its effects on 180° left and right U-turn movements. Materials and Methods: Handedness, footedness, and eyedness were determined in 72 elite football players (EFP, 18.2 ± 2.2 years) from the Stade Rennais Football Club (French League 1) and 9 amateur football players (AFP, 19.6 ± 2.1 years). Players performed a visual-motor task on a synthetic pitch consisting of 180° left and right rotations as fast as possible in response to a visual light on a computer screen. Movement times and reactive times for each left and right rotation were recorded with an accelerometer and video display. Results: Laterality profiles showed a majority (χ2 = 9.42, df = 2, p = 0.031) of crossed formulas (i.e., dominant leg or hand is controlateral to the dominant eye) for EFP (53 ± 7%) and a majority of non-crossed formulas for AFP (63 ± 9%). Reaction times were significantly faster (p = 0.028, effect size = 0.148, trivial) in EFP right-eyed (568.2 ± 55.5 ms) than in AFP (610.0 ± 43.9 ms). For the left rotation and for right-footed players, movement times were significantly different (p = 0.043, effect size = 0.413, small) between EFP (1.15 ± 0.07 s) and AFP (1.17 ± 0.07 s). A significant difference (p < 0.033) was observed between footedness and rotation movement times in the EFP. Conclusion: Our results showed that laterality profiles differed between EFP and AFP. Hence, in EFP, reaction times depended on the side of the visual stimulus. Moreover, leg laterality of EFP influenced 180° left or right rotation speed. Our results indicate the importance of determining laterality in soccer players and identifying deficits in performance when turning.
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Affiliation(s)
- Hassane Zouhal
- Movement Sport Science and Health Laboratory (M2S), UFR-STAPS, University of Rennes 2 - ENS-Rennes, Bruz, France
| | | | | | - Pablo Truptin
- Movement Sport Science and Health Laboratory (M2S), UFR-STAPS, University of Rennes 2 - ENS-Rennes, Bruz, France
| | - Régis Le Bris
- Fédération Française de Football (FFF), Paris, France.,Lorient Football Club (FCL) and Stade Rennais Football Club (SRFC), Lorient, France
| | - Erwan Le Postec
- Fédération Française de Football (FFF), Paris, France.,Lorient Football Club (FCL) and Stade Rennais Football Club (SRFC), Lorient, France
| | - Sullivan Coppalle
- Movement Sport Science and Health Laboratory (M2S), UFR-STAPS, University of Rennes 2 - ENS-Rennes, Bruz, France
| | | | - Matt Brughelli
- Stade Lavallois Mayenne Football Club, Laval, France.,Sports Performance Research Institute New Zealand (SPRINZ), AUT Millennium, Auckland University of Technology, Auckland, New Zealand
| | - Benoit Bideau
- Movement Sport Science and Health Laboratory (M2S), UFR-STAPS, University of Rennes 2 - ENS-Rennes, Bruz, France
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Abstract
The ability of the human body to generate maximal power is linked to a host of performance outcomes and sporting success. Power-force-velocity relationships characterize limits of the neuromuscular system to produce power, and their measurement has been a common topic in research for the past century. Unfortunately, the narrative of the available literature is complex, with development occurring across a variety of methods and technology. This review focuses on the different equipment and methods used to determine mechanical characteristics of maximal exertion human sprinting. Stationary cycle ergometers have been the most common mode of assessment to date, followed by specialized treadmills used to profile the mechanical outputs of the limbs during sprint running. The most recent methods use complex multiple-force plate lengths in-ground to create a composite profile of over-ground sprint running kinetics across repeated sprints, and macroscopic inverse dynamic approaches to model mechanical variables during over-ground sprinting from simple time-distance measures during a single sprint. This review outlines these approaches chronologically, with particular emphasis on the computational theory developed and how this has shaped subsequent methodological approaches. Furthermore, training applications are presented, with emphasis on the theory underlying the assessment of optimal loading conditions for power production during resisted sprinting. Future implications for research, based on past and present methodological limitations, are also presented. It is our aim that this review will assist in the understanding of the convoluted literature surrounding mechanical sprint profiling, and consequently improve the implementation of such methods in future research and practice.
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Affiliation(s)
- Matt R Cross
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand.
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - Pierre Samozino
- Inter-University Laboratory of Human Movement Biology, University Savoie Mont Blanc, Le Bourget-du-Lac, France
| | - Jean-Benoit Morin
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand.,Université Côte d'Azur, LAMHESS, Nice, France
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19
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Morin JB, Brughelli M, Brown SR, Cross MR, Samozino P. Letter to the Editor regarding «Sprint mechanics return to competition follow-up after hamstring injury on a professional soccer player: A case study with an inertial sensor unit based methodological approach» by I. Setuain, P. Lecumberri, and M. Izquierdo. J Biomech 2018; 66:198-199. [PMID: 29157659 DOI: 10.1016/j.jbiomech.2017.09.044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 09/04/2017] [Indexed: 11/18/2022]
Affiliation(s)
- Jean-Benoit Morin
- Université Côte d'Azur, LAMHESS, Nice, France; Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand.
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - Scott R Brown
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - Matthew R Cross
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand; University Savoie Mont Blanc, Laboratoire Interuniversitaire de Biologie de la Motricité, EA 7424, F-73000 Chambéry, France
| | - Pierre Samozino
- University Savoie Mont Blanc, Laboratoire Interuniversitaire de Biologie de la Motricité, EA 7424, F-73000 Chambéry, France
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Jiménez-Reyes P, Samozino P, Brughelli M, Morin JB. Effectiveness of an Individualized Training Based on Force-Velocity Profiling during Jumping. Front Physiol 2017; 7:677. [PMID: 28119624 PMCID: PMC5220048 DOI: 10.3389/fphys.2016.00677] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 12/20/2016] [Indexed: 11/20/2022] Open
Abstract
Ballistic performances are determined by both the maximal lower limb power output (Pmax ) and their individual force-velocity (F-v) mechanical profile, especially the F-v imbalance (FVimb ): difference between the athlete's actual and optimal profile. An optimized training should aim to increase Pmax and/or reduce FVimb . The aim of this study was to test whether an individualized training program based on the individual F-v profile would decrease subjects' individual FVimb and in turn improve vertical jump performance. FVimb was used as the reference to assign participants to different training intervention groups. Eighty four subjects were assigned to three groups: an "optimized" group divided into velocity-deficit, force-deficit, and well-balanced sub-groups based on subjects' FVimb , a "non-optimized" group for which the training program was not specifically based on FVimb and a control group. All subjects underwent a 9-week specific resistance training program. The programs were designed to reduce FVimb for the optimized groups (with specific programs for sub-groups based on individual FVimb values), while the non-optimized group followed a classical program exactly similar for all subjects. All subjects in the three optimized training sub-groups (velocity-deficit, force-deficit, and well-balanced) increased their jumping performance (12.7 ± 5.7% ES = 0.93 ± 0.09, 14.2 ± 7.3% ES = 1.00 ± 0.17, and 7.2 ± 4.5% ES = 0.70 ± 0.36, respectively) with jump height improvement for all subjects, whereas the results were much more variable and unclear in the non-optimized group. This greater change in jump height was associated with a markedly reduced FVimb for both force-deficit (57.9 ± 34.7% decrease in FVimb ) and velocity-deficit (20.1 ± 4.3%) subjects, and unclear or small changes in Pmax (-0.40 ± 8.4% and +10.5 ± 5.2%, respectively). An individualized training program specifically based on FVimb (gap between the actual and optimal F-v profiles of each individual) was more efficient at improving jumping performance (i.e., unloaded squat jump height) than a traditional resistance training common to all subjects regardless of their FVimb . Although improving both FVimb and Pmax has to be considered to improve ballistic performance, the present results showed that reducing FVimb without even increasing Pmax lead to clearly beneficial jump performance changes. Thus, FVimb could be considered as a potentially useful variable for prescribing optimal resistance training to improve ballistic performance.
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Affiliation(s)
| | - Pierre Samozino
- Laboratoire Interuniversitaire de Biologie de la motricité (EA7424), University of Savoie Mont BlancLe Bourget du Lac, France
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of TechnologyAuckland, New Zealand
| | - Jean-Benoît Morin
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of TechnologyAuckland, New Zealand
- Université Côte d'Azur, LAMHESSNice, France
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21
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King D, Hume P, Gissane C, Brughelli M, Clark T. The Influence of Head Impact Threshold for Reporting Data in Contact and Collision Sports: Systematic Review and Original Data Analysis. Sports Med 2016; 46:151-69. [PMID: 26545363 DOI: 10.1007/s40279-015-0423-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Head impacts and resulting head accelerations cause concussive injuries. There is no standard for reporting head impact data in sports to enable comparison between studies. OBJECTIVE The aim was to outline methods for reporting head impact acceleration data in sport and the effect of the acceleration thresholds on the number of impacts reported. METHODS A systematic review of accelerometer systems utilised to report head impact data in sport was conducted. The effect of using different thresholds on a set of impact data from 38 amateur senior rugby players in New Zealand over a competition season was calculated. RESULTS Of the 52 studies identified, 42% reported impacts using a >10-g threshold, where g is the acceleration of gravity. Studies reported descriptive statistics as mean ± standard deviation, median, 25th to 75th interquartile range, and 95th percentile. Application of the varied impact thresholds to the New Zealand data set resulted in 20,687 impacts of >10 g, 11,459 (45% less) impacts of >15 g, and 4024 (81% less) impacts of >30 g. DISCUSSION Linear and angular raw data were most frequently reported. Metrics combining raw data may be more useful; however, validity of the metrics has not been adequately addressed for sport. Differing data collection methods and descriptive statistics for reporting head impacts in sports limit inter-study comparisons. Consensus on data analysis methods for sports impact assessment is needed, including thresholds. Based on the available data, the 10-g threshold is the most commonly reported impact threshold and should be reported as the median with 25th and 75th interquartile ranges as the data are non-normally distributed. Validation studies are required to determine the best threshold and metrics for impact acceleration data collection in sport. CONCLUSION Until in-field validation studies are completed, it is recommended that head impact data should be reported as median and interquartile ranges using the 10-g impact threshold.
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Affiliation(s)
- D King
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand. .,Emergency Department, Hutt Valley District Health Board, Private Bag 31-907, Lower Hutt, New Zealand.
| | - P Hume
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
| | - C Gissane
- School of Sport, Health and Applied Science, St Mary's University, Twickenham, Middlesex, UK
| | - M Brughelli
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand
| | - T Clark
- Faculty of Human Performance, Australian College of Physical Education, Sydney Olympic Park, NSW, Australia
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Abstract
Understanding the impact of friction in sled sprinting allows the quantification of kinetic outputs and the effective loading experienced by the athlete. This study assessed changes in the coefficient of friction (µk) of a sled sprint-training device with changing mass and speed to provide a means of quantifying effective loading for athletes. A common sled equipped with a load cell was towed across an athletics track using a motorised winch under variable sled mass (33.1-99.6 kg) with constant speeds (0.1 and 0.3 m · s-1), and with constant sled mass (55.6 kg) and varying speeds (0.1-6.0 m · s-1). Mean force data were analysed, with five trials performed for each condition to assess the reliability of measures. Variables were determined as reliable (ICC > 0.99, CV < 4.3%), with normal-force/friction-force and speed/coefficient of friction relationships well fitted with linear (R2 = 0.994-0.995) and quadratic regressions (R2 = 0.999), respectively (P < 0.001). The linearity of composite friction values determined at two speeds, and the range in values from the quadratic fit (µk = 0.35-0.47) suggested µk and effective loading were dependent on instantaneous speed on athletics track surfaces. This research provides a proof-of-concept for the assessment of friction characteristics during sled towing, with a practical example of its application in determining effective loading and sled-sprinting kinetics. The results clarify effects of friction during sled sprinting and improve the accuracy of loading applications in practice and transparency of reporting in research.
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Affiliation(s)
- Matt R Cross
- a Sports Performance Research Institute New Zealand (SPRINZ), AUT Millennium , Auckland University of Technology , Auckland , New Zealand
| | - Farhan Tinwala
- a Sports Performance Research Institute New Zealand (SPRINZ), AUT Millennium , Auckland University of Technology , Auckland , New Zealand
| | - Seth Lenetsky
- a Sports Performance Research Institute New Zealand (SPRINZ), AUT Millennium , Auckland University of Technology , Auckland , New Zealand
| | - Pierre Samozino
- b Inter-university Laboratory of Human Movement Biology , University Savoie Mont Blanc , Le Bourget-du-Lac , France
| | - Matt Brughelli
- a Sports Performance Research Institute New Zealand (SPRINZ), AUT Millennium , Auckland University of Technology , Auckland , New Zealand
| | - Jean-Benoit Morin
- a Sports Performance Research Institute New Zealand (SPRINZ), AUT Millennium , Auckland University of Technology , Auckland , New Zealand.,c Université Côte d'Azur, LAMHESS , Nice , France
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Edouard P, Arnal P, Gimenez P, Samozino P, Jimenez-Reyes P, Brughelli M, Mendiguchia J, Morin JB. Athletic injury prevention: Determinants of sprint performance. Ann Phys Rehabil Med 2016. [DOI: 10.1016/j.rehab.2016.07.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Affiliation(s)
- S. Brown
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - M. Brughelli
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
| | - M. Cross
- Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand
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de Lacey J, Brughelli M, McGuigan M, Hansen K, Samozino P, Morin JB. The effects of tapering on power-force-velocity profiling and jump performance in professional rugby league players. J Strength Cond Res 2015; 28:3567-70. [PMID: 24936904 DOI: 10.1519/jsc.0000000000000572] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purpose of this study was to investigate the effects of a preseason taper on individual power-force-velocity profiles and jump performance in professional National Rugby League players. Seven professional rugby league players performed concentric squat jumps using ascending loads of 25, 50, 75, 100% body mass before and after a 21-day step taper leading into the in-season. Linear force-velocity relationships were derived, and the following variables were obtained: maximum theoretical velocity (V0), maximum theoretical force (F0), and maximum power (Pmax). The players showed likely-to-very likely increases in F0 (effect size [ES] = 0.45) and Pmax (ES = 0.85) from pre to posttaper. Loaded squat jump height also showed likely-to-most likely increases at each load (ES = 0.83-1.04). The 21-day taper was effective at enhancing maximal power output and jump height performance in professional rugby players, possibly as a result of a recovery from fatigue and thus increased strength capability after a prolonged preseason training period. Rugby league strength and conditioning coaches should consider reducing training volume while maintaining intensity and aerobic conditioning (e.g., step taper) leading into the in-season.
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Affiliation(s)
- James de Lacey
- 1Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand; 2Laboratory of Exercise Physiology, University of Savoie, Le Bourget-du-Lac, France; and 3Laboratory of Exercise Physiology, University of Lyon, Saint-Etienne, France
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Morin JB, Gimenez P, Edouard P, Arnal P, Jiménez-Reyes P, Samozino P, Brughelli M, Mendiguchia J. Sprint Acceleration Mechanics: The Major Role of Hamstrings in Horizontal Force Production. Front Physiol 2015; 6:404. [PMID: 26733889 PMCID: PMC4689850 DOI: 10.3389/fphys.2015.00404] [Citation(s) in RCA: 161] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 12/08/2015] [Indexed: 12/02/2022] Open
Abstract
Recent literature supports the importance of horizontal ground reaction force (GRF) production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG) activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024) between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability.
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Affiliation(s)
- Jean-Benoît Morin
- Laboratory of Human Motricity, Education Sport and Health (EA6312), Faculty of Sport Sciences, University of Nice Sophia Antipolis Nice, France
| | - Philippe Gimenez
- Laboratory Culture Sport Health Society (EA 4660), University of Franche-Comté Besançon, France
| | - Pascal Edouard
- Laboratory of Exercise Physiology (EA4338), University of LyonSaint-Etienne, France; Sports Medicine Unit, Department of Clinical and Exercise Physiology, Faculty of Medicine, University Hospital of Saint-EtienneSaint-Etienne, France
| | - Pierrick Arnal
- Laboratory of Exercise Physiology (EA4338), University of Lyon Saint-Etienne, France
| | - Pedro Jiménez-Reyes
- Faculty of Physical Sciences and Sport, Catholic University of San Antonio Murcia, Spain
| | - Pierre Samozino
- Laboratory of Exercise Physiology (EA4338), University Savoie Mont Blanc Le Bourget-du-Lac, France
| | - Matt Brughelli
- School of Sport and Recreation, Sports Performance Research Institute New Zealand, Auckland University of Technology Auckland, New Zealand
| | - Jurdan Mendiguchia
- Department of Physical Therapy, ZENTRUM Rehab and Performance Center Barañain, Spain
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McKenzie CR, Brughelli M, Whatman C, Brown SR. The Influence of Optimal Handheld Load on the Technical Ability to Apply Ground Reaction Forces during Horizontal Jumping in Female Netball Players. Int J Sports Med 2015; 37:318-23. [PMID: 26667926 DOI: 10.1055/s-0035-1565052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Handheld load has been reported to enhance horizontal jump performance, however little is known about its influence on ground reaction forces (GRF), especially in female athletes. This study investigated the effects of individualized optimal handheld loading on the technical and physical ability to apply GRF during horizontal jumping in female netball players. Maximal effort, single standing, horizontal jumps were performed by 13 female netballers. Participants performed the jumps under 2 conditions: 1) unloaded, and 2) loaded. Eccentric mean horizontal GRF significantly increased with loading (p<0.05; Effect Size [ES]= 0.74). The ratio of horizontal-to-total GRF significantly increased (p<0.05; ES=0.57), however resultant GRF did not, suggesting that the technical ability to apply force in the direction of intended movement may be of greater importance than the magnitude of force applied. Jump distance also increased from 188.2±16.1 cm to 196.4±13.6 cm (p<0.01; ES=0.55) with handheld load. In conclusion, individualized optimal handheld loading improved single horizontal jump performance in this population of athletes; most likely through various mechanisms that allowed for increased eccentric horizontal GRFs and the technical ability of force application. Findings could have practical implications for the strength and conditioning coach, trainer and athlete.
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Affiliation(s)
- C R McKenzie
- Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand
| | - M Brughelli
- Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand
| | - C Whatman
- Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand
| | - S R Brown
- Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand
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Mendiguchia J, Edouard P, Samozino P, Brughelli M, Cross M, Ross A, Gill N, Morin JB. Field monitoring of sprinting power–force–velocity profile before, during and after hamstring injury: two case reports. J Sports Sci 2015; 34:535-41. [DOI: 10.1080/02640414.2015.1122207] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Morin JB, Slawinski J, Dorel S, de villareal ES, Couturier A, Samozino P, Brughelli M, Rabita G. Acceleration capability in elite sprinters and ground impulse: Push more, brake less? J Biomech 2015. [DOI: 10.1016/j.jbiomech.2015.07.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Lenetsky S, Brughelli M, Harris NK. Shoulder function and scapular position in boxers. Phys Ther Sport 2015; 16:355-60. [PMID: 26239217 DOI: 10.1016/j.ptsp.2015.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 02/18/2015] [Accepted: 02/27/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVES To investigate differences in strength, shoulder range of motion and scapula position in a cohort of boxers in comparison with a control group of non-boxers. DESIGN Cross-sectional study. PARTICIPANTS 18 boxers with 3 or more years of experience (years = 5.5 ± 3.1, sessions per week = 4.3 ± 0.7, age = 27.0 ± 6.8) and 20 control participants (age = 28.3 ± 4.6). EXPERIMENTAL PROTOCOL The participants were tested for isometric internal and external rotation strength measured with a hand held dynamometer, passive internal and external rotation measured via 2D video using a digital camera, and scapular function measured with a scoliometer and visual inspection by a trained researcher. Both arms (dominant and non-dominant) were tested to allow for comparison. Magnitude based inferences were used to find meaningful differences intra and inter group. RESULTS Boxers had greater scapular dyskinesis (hazard ratio (HR) = 2.73 ×/÷ 3.37) and increased external rotation in the dominant arm (effect size (ES) = 0.70 ± 0.68) when compared to the non-boxer group. CONCLUSION Boxers with 3 or more years of experience displayed symptoms that increase their risk of upper limb injury when compared to a control group.
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Affiliation(s)
- Seth Lenetsky
- Sports Performance Research Institute New Zealand, Auckland University of Technology, AUT University, Private Bag 92006, Auckland 0627, New Zealand.
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand, Auckland University of Technology, AUT University, Private Bag 92006, Auckland 0627, New Zealand
| | - Nigel K Harris
- Sports Performance Research Institute New Zealand, Auckland University of Technology, AUT University, Private Bag 92006, Auckland 0627, New Zealand
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32
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Brughelli M, Morin JB, Mendiguchia J. Asymmetry after Hamstring Injury in English Premier League: Issue Resolved, Or Perhaps Not? Int J Sports Med 2015; 36:603. [PMID: 26076012 DOI: 10.1055/s-0035-1554628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- M Brughelli
- Sports Performance Research Institute New Zealand, AUT University, Auckland, New Zealand
| | - J-B Morin
- Laboratory of Human Motricity, Education Sport and Health, University of Nice Sophia Antipolis, Nice, France
| | - J Mendiguchia
- Department of Physical Therapy, ZENTRUM Rehab and Performance Center, Barañain, Spain
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Lenetsky S, Nates RJ, Brughelli M, Harris NK. Is effective mass in combat sports punching above its weight? Hum Mov Sci 2015; 40:89-97. [DOI: 10.1016/j.humov.2014.11.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 10/31/2014] [Accepted: 11/28/2014] [Indexed: 10/24/2022]
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King D, Hume PA, Brughelli M, Gissane C. Instrumented mouthguard acceleration analyses for head impacts in amateur rugby union players over a season of matches. Am J Sports Med 2015; 43:614-24. [PMID: 25535096 DOI: 10.1177/0363546514560876] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Direct impacts with the head (linear acceleration or pressure) and inertial loading of the head (rotational acceleration or strain) have been postulated as the 2 major mechanisms of head-related injuries such as concussion. Although data are accumulating for soccer and American football, there are no published data for nonhelmeted collision sports such as rugby union. PURPOSE To quantify head impacts via instrumented mouthguard acceleration analyses for rugby union players over a season of matches. STUDY DESIGN Descriptive epidemiology study. METHODS Data on impact magnitude and frequency were collected with molded instrumented mouthguards worn by 38 premier amateur senior rugby players participating in the 2013 domestic season of matches. RESULTS A total of 20,687 impacts >10g (range, 10.0-164.9g) were recorded over the duration of the study. The mean ± SD number of impacts per player over the duration of the season of matches was 564 ± 618, resulting in a mean ± SD of 95 ± 133 impacts to the head per player, per match over the duration of the season of matches. The impact magnitudes for linear accelerations were skewed to the lower values (Sp = 3.7 ± 0.02; P < .001), with a mean linear acceleration of 22.2 ± 16.2g. Rotational accelerations were also skewed to the lower values (Sp = 2.0 ± 0.02; P < .001), with a mean rotational acceleration of 3902.9 ± 3948.8 rad/s(2). CONCLUSION The acceleration magnitudes and number of head impacts in amateur rugby union players over a season of matches, measured via instrumented mouthguard accelerations, were higher than for most sports previously reported. Mean linear acceleration measured over a season of matches was similar to the mean linear accelerations previously reported for youth, high school, and collegiate American football players but lower than that for female youth soccer players. Mean rotational acceleration measured over a season of matches was similar to mean rotational accelerations for youth, high school, and collegiate American football players but less than those for female youth soccer players, concussed American collegiate players, collegiate American football players, and professional American football players.
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Affiliation(s)
- Doug King
- Sports Performance Research Institute New Zealand (SPRINZ) at AUT Millennium, Faculty of Health and Environmental Science, Auckland University of Technology, Auckland, New Zealand Emergency Department, Hutt Valley District Health Board, Lower Hutt, New Zealand
| | - Patria A Hume
- Sports Performance Research Institute New Zealand (SPRINZ) at AUT Millennium, Faculty of Health and Environmental Science, Auckland University of Technology, Auckland, New Zealand
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand (SPRINZ) at AUT Millennium, Faculty of Health and Environmental Science, Auckland University of Technology, Auckland, New Zealand
| | - Conor Gissane
- School of Sport Health and Applied Science, St Mary's University, Twickenham, Middlesex, UK
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35
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Cronin JB, Brughelli M, Gamble P, Brown SR, Mckenzie C. Acute kinematic and kinetic augmentation in horizontal jump performance using haltere type handheld loading. J Strength Cond Res 2015; 28:1559-64. [PMID: 24196795 DOI: 10.1519/jsc.0000000000000312] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The purposes of this study were to investigate the effects of haltere/handheld loading on the kinematics and kinetics of horizontal jumping and to determine if an optimum relative load (% body mass [BM]) exists to maximize jump distance. A repeated measures analysis of variance with post hoc contrasts was used to determine the effects of haltere loading (no external loading, 6, 8, 12, and 16 kg) on the horizontal jump performance of 16 sportsmen as quantified by an in-ground force plate. The haltere loads of 6 and 8 kg elicited significant (p < 0.05) increases in jump distance (effect size [ES] = 0.22-0.37). The incremental loads also resulted in significant increases in jump duration (ES = 1.22-1.83), peak vertical ground reaction force (GRF) (ES = 0.20-0.37), and vertical (ES = 0.69-1.22) and horizontal (ES = 0.70-0.88) impulse. There was a significant reduction in jump distance with the 16 kg load (ES = 0.45). Significant decreases in mean horizontal GRF were likewise observed with the 12 and 16 kg loads. The optimum relative load for enhancing jump distance was 9.2 ± 3.4% of BM, which resulted in a predicted augmented horizontal jump of 13.6 ± 7.7 cm (ES = 0.56). The findings clearly indicate that haltere/handheld loading augments vertical and horizontal force and impulses. This could have a number of interesting training implications if the strength profiling of athletes identify horizontal and/or vertical deficits in force production. Further longitudinal investigation is warranted to establish what chronic adaptations result with repeated application of this type of training.
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Affiliation(s)
- John B Cronin
- 1Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand; and 2School of Exercise, Biomedical and Health Science, Edith Cowan University, Perth, Australia
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Abstract
The purpose of this study was to investigate the physiological characteristics of Fédération Internationale de Football Association (FIFA) eligible international female soccer players aged 14-36 years and to determine if measures were significantly different for players selected (i.e., starters) to the starting line up for an FIFA tournament as compared with those not selected (i.e., nonstarters). Fifty-one (N = 18 Under 17; N = 18 Under 20; N = 15 Senior) international female soccer players participated in this study. The subjects underwent measurements of anthropometry (height and body mass), lower body strength (isokinetic testing), sprint kinetics and kinematics (nonmotorized treadmill), leg power (unilateral jumping), and maximal aerobic velocity (30:15 intermittent fitness test) during the final preparatory stage for an FIFA event. Outcomes of the age group data indicate that differences in physiological capacities are evident for the Under 17 players as compared with those for the Under 20 and Senior capped international players, suggesting a plateau in the acquisition of physical qualities as players mature. Starters tended to be faster (effect size [ES] = 0.55-1.0, p < 0.05) and have a higher maximal aerobic velocity (ES = 0.78-2.45, p < 0.05), along with greater eccentric leg strength (ES = 0.33-1.67, p < 0.05). Significant differences were detected between starters and nonstarters for isokinetic leg strength (ES = 0.54-1.24, p < 0.05) and maximal aerobic velocity (ES = 0.87, p < 0.05) for Under 17 players, where maximal aerobic velocity was the primary difference between starters and nonstarters (ES = 0.83-2.45, p < 0.05) for the Under 20 and Senior players. Coaches should emphasize the development of speed, maximal aerobic velocity, and leg strength in developing female soccer players.
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Affiliation(s)
- Sarah A Manson
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Science, Auckland University of Technology, Auckland, New Zealand
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King D, Gissane C, Brughelli M, Hume PA, Harawira J. Sport-related concussions in New Zealand: A review of 10years of Accident Compensation Corporation moderate to severe claims and costs. J Sci Med Sport 2014; 17:250-5. [DOI: 10.1016/j.jsams.2013.05.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 04/23/2013] [Accepted: 05/18/2013] [Indexed: 10/26/2022]
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39
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Brown SR, Brughelli M. Determining return-to-sport status with a multi-component assessment strategy: a case study in rugby. Phys Ther Sport 2014; 15:211-5. [PMID: 24768343 DOI: 10.1016/j.ptsp.2014.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 12/06/2013] [Accepted: 01/20/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND The effectiveness of rehabilitation programmes are often distorted by the athlete's desire to return and can result in injury recurrence. Athletic assessments allow for objective and reliable measurements to track rehabilitation progress. This case study used a multi-component assessment strategy to assess a rugby player's lower-extremity strength and symmetry as a primary determinate of their return-to-sport status. CASE DESCRIPTION A professional rugby league player was assessed for lower-extremity isokinetic strength and sprint kinetics pre- and 10-weeks post-rehabilitation programme following two consecutive knee injuries involving surgical intervention. OUTCOMES Pre-testing analysis showed clinical and functional strength deficits in the injured leg as high as 34% compared to the non-injured leg. Pre- to post-testing showed: increases in peak torque (49%) and decreased asymmetries by 50%; unilateral horizontal force increased (injured: 50%, non-injured: 19%) during sprinting; force production asymmetries decreased up to 18%. DISCUSSION The rugby player showed clinical and functional strength deficiencies return to normal ranges following a rehabilitation programme. A return-to-sport decision was made by the athlete's supporting health team based on the sizeable asymmetry decreases and return-to-normative ranges for knee and hip strength and sprint kinetics. The athlete returned to the 2013 National Rugby League season without any major injuries.
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Affiliation(s)
- Scott R Brown
- Sports Performance Research Institute New Zealand (SPRINZ) at AUT Millennium, Auckland University of Technology, 17 Antares Place, Level 2, Rosedale, Auckland 0632, New Zealand.
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand (SPRINZ) at AUT Millennium, Auckland University of Technology, 17 Antares Place, Level 2, Rosedale, Auckland 0632, New Zealand.
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Mendiguchia J, Samozino P, Martinez-Ruiz E, Brughelli M, Schmikli S, Morin JB, Mendez-Villanueva A. Progression of Mechanical Properties during On-field Sprint Running after Returning to Sports from a Hamstring Muscle Injury in Soccer Players. Int J Sports Med 2014; 35:690-5. [DOI: 10.1055/s-0033-1363192] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- J. Mendiguchia
- Department of Physical Therapy, ZENTRUM Rehab and Performance Center, Barañain, Spain
| | - P. Samozino
- Laboratory of Exercise Physiology (EA4338), University of Savoy, Le Bourget du Lac, France
| | - E. Martinez-Ruiz
- Chair of Sports Traumatology, Catholic University of San Antonio, Murcia, Spain
| | - M. Brughelli
- Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand
| | - S. Schmikli
- Department of Rehabilitation and Sports Medicine, Rudolf Magnus Institute of Neuroscience, Utrecht, Netherlands
| | - J.-B. Morin
- Laboratory of Exercise Physiology, University of Saint-Etienne, France
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Samozino P, Edouard P, Sangnier S, Brughelli M, Gimenez P, Morin JB. Force-velocity profile: imbalance determination and effect on lower limb ballistic performance. Int J Sports Med 2013; 35:505-10. [PMID: 24227123 DOI: 10.1055/s-0033-1354382] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
This study sought to lend experimental support to the theoretical influence of force-velocity (F-v) mechanical profile on jumping performance independently from the effect of maximal power output (P max ). 48 high-level athletes (soccer players, sprinters, rugby players) performed maximal squat jumps with additional loads from 0 to 100% of body mass. During each jump, mean force, velocity and power output were obtained using a simple computation method based on flight time, and then used to determine individual linear F-v relationships and P max values. Actual and optimal F-v profiles were computed for each subject to quantify mechanical F-v imbalance. A multiple regression analysis showed, with a high-adjustment quality (r²=0.931, P<0.001, SEE=0.015 m), significant contributions of P max , F-v imbalance and lower limb extension range (h PO ) to explain interindividual differences in jumping performance (P<0.001) with positive regression coefficients for P max and h PO and a negative one for F-v imbalance. This experimentally supports that ballistic performance depends, in addition to P max , on the F-v profile of lower limbs. This adds support to the actual existence of an individual optimal F-v profile that maximizes jumping performance, a F-v imbalance being associated to a lower performance. These results have potential strong applications in the field of strength and conditioning.
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Affiliation(s)
- P Samozino
- Laboratory of Exercise Physiology (EA4338), University of Savoie, Le Bourget du Lac, France
| | - P Edouard
- Department of Clinical and Exercise Physiology, Sports Medicine Unity, University-Hospital of Saint-Etienne, France
| | - S Sangnier
- Centre d'Etude des Transformations des Activités Physiques et Sportives (EA 3832), University of Rouen, France
| | - M Brughelli
- Sports Performance Research Institute New Zealand, AUT University, -Auckland, New Zealand
| | - P Gimenez
- Laboratory of Exercise Physiology (EA4338), University of Lyon, Saint Etienne, France
| | - J-B Morin
- Laboratory of Exercise Physiology (EA4338), University of Lyon, Saint Etienne, France
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Abstract
The purpose of this study was to determine the reliability of power outputs during maximal intensity eccentric cycling over short durations (i.e., eccentric sprint cycling) on a "motor-driven" isokinetic ergometer. Fourteen physically active male subjects performed isokinetic eccentric cycling sprints at 40, 60, 80, 100, and 120 revolutions per minute (rpm) on 4 separate occasions (T1-T4). Each sprint lasted for 6 seconds, and absolute measures of mean power (MP) and peak power (PP) per revolution were recorded. Significant increases in MP and PP were observed between T1 and subsequent trials, but no significant differences were identified between T2, T3, and T4. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) were calculated to reflect within-subject and between-session reliability of MP and PP at each cadence. The CV improved to below 10% for cadences of 60, 80, 100, and 120 rpm between T3 and T4, and the majority of ICC values improved to above 0.90. The remaining ICC values remained in the moderate range between T3 and T4 (i.e., 0.82-0.89). Coefficient of variation and ICC values for the 40 rpm cadence remained at unacceptable levels throughout the 4 trials and thus should be avoided in future investigations. The results of this study indicate that reliable power outputs may be obtained after 2 familiarization sessions during eccentric sprint cycling at cadences ranging from 60 to 120 rpm.
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Affiliation(s)
- Matt Brughelli
- Department of Biomedical Kinesiology, Faculty of Kinesiology and Rehabilitation Sciences, KU Leuven, Leuven, Belgium
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King D, Brughelli M, Hume P, Gissane C. Concussions in amateur rugby union identified with the use of a rapid visual screening tool. J Neurol Sci 2013; 326:59-63. [PMID: 23374885 DOI: 10.1016/j.jns.2013.01.012] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/07/2013] [Accepted: 01/09/2013] [Indexed: 12/20/2022]
Abstract
AIM To use the King-Devick (KD) test and Sports Concussion Assessment Tool 2 (SCAT2) in amateur rugby union players to identify witnessed and unrecognised episodes of concussion that occurred from match participation. METHODS A prospective observational cohort study was conducted on a premier club level amateur rugby union team during the 2012 competition in New Zealand. Every player completed a pre-competition questionnaire on concussion history, a baseline PCSS and two trials of the KD before they participated in any match activities. RESULTS For players reporting a concussion in the previous three years there was an average of 4.0±2.8 concussions per player. There were 22 concussive incidents recorded over the duration of the competition (46 per 1000 match hours). Five concussive incidents were witnessed (11 per 1000 match hours) and 17 unrecognised concussive incidents were identified with the KD (37 per 1000 match hours). Witnessed concussions recorded, on average, a longer KD on the day of injury (5.5±2.4s) than unrecognised concussions (4.4±0.9s) when compared with their baseline KD. DISCUSSION The KD was able to identify players that had not shown, or reported, any signs or symptoms of a concussion but who had meaningful head injury. The current rate of concussion reported was a ten-fold increase in previously reported concussion injury rates. This makes the KD suitable for rapid assessment in a limited time frame on the sideline such as a five-minute window to assess and review suspected concussed players in rugby union.
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Affiliation(s)
- Doug King
- Sports Performance Research Institute New Zealand, School of Sport and Recreation, Faculty of Health and Environmental Science, Auckland University of Technology, New Zealand.
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Cowell JF, Cronin J, Brughelli M. Eccentric Muscle Actions and How the Strength and Conditioning Specialist Might Use Them for a Variety of Purposes. Strength Cond J 2012. [DOI: 10.1519/ssc.0b013e318253f578] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Chaouachi A, Poulos N, Abed F, Turki O, Brughelli M, Chamari K, Drinkwater EJ, Behm DG. Volume, intensity, and timing of muscle power potentiation are variable. Appl Physiol Nutr Metab 2011; 36:736-47. [DOI: 10.1139/h11-079] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Whereas muscle potentiation is consistently demonstrated with evoked contractile properties, the potentiation of functional and physiological measures is inconsistent. The objective was to compare a variety of conditioning stimuli volumes and intensities over a 15-min recovery period. Twelve volleyball players were subjected to conditioning stimuli that included 10 repetitions of half squats with 70% of 1-repetition maximum (RM) (10 × 70), 5 × 70, 5 × 85, 3 × 85, 3 × 90, 1 × 90, and control. Jump height, power, velocity, and force were measured at baseline, 1, 3, 5, 10, and 15 min. Data were analysed with a 2-way repeated measure ANOVA and magnitude-based inferences. The ANOVA indicated significant decreases in jump height, power, and velocity during recovery. This should not be interpreted that no potentiation occurred. Each dependent variable reached a peak at a slightly different time: peak jump height (2.8 ± 2.3 min), mean power (3.6 ± 3.01 min), peak power (2.5 ± 1.8 min), and peak velocity (2.5 ± 1.8 min). Magnitude-based inference revealed that both the 5 × 70 and 3 × 85 protocol elicited changes that exceeded 75% likelihood of exceeding the smallest worthwhile change (SWC) for peak power and velocity. The 10 × 70 and the 5 × 70 had a substantial likelihood of potentiating peak velocity and mean power above the SWC, respectively. Magnitude-based inferences revealed that while no protocol had a substantial likelihood of potentiating the peak vertical jump, the 5 × 70 had the most consistent substantial likelihood of increasing the peak of most dependent variables. We were unable to consistently predict if these peaks occurred at 1, 3, or 5 min poststimulation, though declines after 5 min seems probable.
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Affiliation(s)
- Anis Chaouachi
- Tunisian Research Laboratory “Sports Performance Optimisation” National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia
| | - Nick Poulos
- Sport Science Department, ASPIRE, Academy for Sports Excellence, Doha, Qatar
| | - Fathi Abed
- Tunisian Research Laboratory “Sports Performance Optimisation” National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia
| | - Olfa Turki
- Tunisian Research Laboratory “Sports Performance Optimisation” National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia
- High Institute of Sport and Physical Education, Ksar-Saïd, Manouba University, Tunisia
| | - Matt Brughelli
- Sports Performance Research Institute New Zealand, AUT University, Auckland, New Zealand
| | - Karim Chamari
- Tunisian Research Laboratory “Sports Performance Optimisation” National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia
- High Institute of Sport and Physical Education, Ksar-Saïd, Manouba University, Tunisia
| | - Eric J. Drinkwater
- School of Human Movement Studies, Charles Sturt University, Panorama Avenue, Bathurst, NSW 2795, Australia
| | - David G. Behm
- School of Human Kinetics and Recreation; Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
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Buchheit M, Mendez-Villanueva A, Delhomel G, Brughelli M, Ahmaidi S. Improving repeated sprint ability in young elite soccer players: repeated shuttle sprints vs. explosive strength training. J Strength Cond Res 2011; 24:2715-22. [PMID: 20224449 DOI: 10.1519/jsc.0b013e3181bf0223] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To compare the effects of explosive strength (ExpS) vs. repeated shuttle sprint (RS) training on repeated sprint ability (RSA) in young elite soccer players, 15 elite male adolescents (14.5 ± 0.5 years) performed, in addition to their soccer training program, RS (n = 7) or ExpS (n = 8) training once a week for a total of 10 weeks. RS training consisted of 2-3 sets of 5-6 × 15- to 20-m repeated shuttle sprints interspersed with 14 seconds of passive or 23 seconds of active recovery (≈2 m·s⁻¹); ExpS training consisted of 4-6 series of 4-6 exercises (e.g., maximal unilateral countermovement jumps (CMJs), calf and squat plyometric jumps, and short sprints). Before and after training, performance was assessed by 10 and 30 m (10 and 30 m) sprint times, best (RSAbest) and mean (RSAmean) times on a repeated shuttle sprint ability test, a CMJ, and a hopping (Hop) test. After training, except for 10 m (p = 0.22), all performances were significantly improved in both groups (all p's < 0.05). Relative changes in 30 m (-2.1 ± 2.0%) were similar for both groups (p = 0.45). RS training induced greater improvement in RSAbest (-2.90 ± 2.1 vs. -0.08 ± 3.3%, p = 0.04) and tended to enhance RSAmean more (-2.61 ± 2.8 vs. -0.75 ± 2.5%, p = 0.10, effect size [ES] = 0.70) than ExpS. In contrast, ExpS tended to induce greater improvements in CMJ (14.8 ± 7.7 vs. 6.8 ± 3.7%, p = 0.02) and Hop height (27.5 ± 19.2 vs. 13.5 ± 13.2%, p = 0.08, ES = 0.9) compared with RS. Improvements in the repeated shuttle sprint test were only observed after RS training, whereas CMJ height was only increased after ExpS. Because RS and ExpS were equally efficient at enhancing maximal sprinting speed, RS training-induced improvements in RSA were likely more related to progresses in the ability to change direction.
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Affiliation(s)
- Martin Buchheit
- Research Laboratory, EA 3300, Laboratory of Exercise Physiology and Rehabilitation, Faculty of Sport Sciences, University of Picardie, Jules Verne, Amiens, France.
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