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Geneau MC, Carey DL, Gastin PB, Robertson S, James LP. Classification of Force-Time Metrics Into Lower-Body Strength Domains. J Strength Cond Res 2024:00124278-990000000-00467. [PMID: 38976311 DOI: 10.1519/jsc.0000000000004855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
ABSTRACT Geneau, MC, Carey, DL, Gastin, PB, Robertson, S, and James, LP. Classification of force-time metrics into lower-body strength domains. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this study was to classify force-time metrics into distinct lower-body strength domains using a systematic data reduction analysis. A cross-sectional design was used, whereby competitive field sport athletes (F = 39, M = 96) completed a series of drop jumps, squat jumps, countermovement jumps (CMJs), loaded CMJs, and 2 isometric tasks on portable force platforms, resulting in a total of 285 force-time performance metrics. The metrics were split into 4 test "families" and each was entered into a sparse principal component analysis (sPCA) model. A single metric from each component of each family-specific sPCA were selected based on the loading, reliability, and simplicity of the metric and entered into a second sPCA that included metrics across all tests. The final sPCA revealed 7 principal components each containing 2 metrics and explained a total of 53% variance of the dataset. The final principal components were interpreted as 7 lower-body strength domains: (a) dynamic force, (b) dynamic timing, (c) early isometric, (d) maximal isometric, (e) countermovement velocity, (f) reactive output, and (g) reactive timing. The findings demonstrate that a total of 7 metrics from a drop jump, CMJ, and isometric test can be used to represent ∼50% of variance in lower-body strength performance of field sport athletes. These results can help guide and simplify the lower-body strength diagnosis process in field sport athletes.
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Affiliation(s)
- Mary C Geneau
- Sport, Performance, and Nutrition Research Group, School of Allied Health, Human Services, and Sport, La Trobe University, Melbourne, Australia; and
| | - David L Carey
- Sport, Performance, and Nutrition Research Group, School of Allied Health, Human Services, and Sport, La Trobe University, Melbourne, Australia; and
| | - Paul B Gastin
- Sport, Performance, and Nutrition Research Group, School of Allied Health, Human Services, and Sport, La Trobe University, Melbourne, Australia; and
| | - Sam Robertson
- Institute for Health and Sport (IHES), Victoria University, Melbourne, Australia
| | - Lachlan P James
- Sport, Performance, and Nutrition Research Group, School of Allied Health, Human Services, and Sport, La Trobe University, Melbourne, Australia; and
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Cabarkapa D, Cabarkapa DV, Nagy D, Szabo K, Balogh L, Safar S, Ratgeber L. Differences in anthropometric and vertical jump force-time characteristics between U16 and U18 female basketball players. Front Sports Act Living 2024; 6:1425475. [PMID: 38983713 PMCID: PMC11231396 DOI: 10.3389/fspor.2024.1425475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 06/12/2024] [Indexed: 07/11/2024] Open
Abstract
Considering the importance of body composition and lower-body strength and power for basketball players' on-court performance, as well as a lack of sports science research focused on female athletes, the purpose of the present investigation was to record the anthropometric and countermovement vertical jump (CMJ) characteristics of top-tier U16 and U18 female basketball players and examine between-group differences in the aforementioned tests. Thirty-two athletes who were a part of the national basketball academy volunteered to participate in the present investigation. Following the body composition assessment conducted via a segmental multifrequency bioimpedance analyzer, athletes performed three CMJs while standing on a force plate system sampling at 1000 Hz. Independent t-test and Mann-Whitney U-test were used to examine between-group differences. The findings reveal significant differences in body composition and lower-body neuromuscular performance characteristics between female basketball players ages 16 and 18. Although no differences were observed in muscle and body fat percentages, the U18 group had significantly greater height, overall body mass (both muscle and fat mass), as well as greater segmental fat-free mass (trunk, both legs and arms), intracellular and extracellular water, and body mass index when compared to their U16 counterparts. On the other hand, the U18 group demonstrated longer eccentric, concentric, and braking phase duration, as well as overall contraction time when compared to the U16 players. In addition, the U18 athletes exhibited higher eccentric mean force and power, concentric impulse, peak power, and mean and peak force.
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Affiliation(s)
- Dimitrije Cabarkapa
- Jayhawk Athletic Performance Laboratory-Wu Tsai Human Performance Alliance, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, KS, United States
| | - Damjana V Cabarkapa
- Jayhawk Athletic Performance Laboratory-Wu Tsai Human Performance Alliance, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, KS, United States
| | - Dora Nagy
- Faculty of Health Sciences, Doctoral School of Health Sciences, University of Pecs, Pecs, Hungary
- Faculty of Health Sciences, Institute of Physiotherapy and Sport Science, University of Pecs, Pecs, Hungary
- Center for Basketball Methodology of Education, Pecs, Hungary
| | - Kenza Szabo
- Center for Basketball Methodology of Education, Pecs, Hungary
| | - Laszlo Balogh
- Center for Basketball Methodology of Education, Pecs, Hungary
- Institute of Sport Science, University of Debrecen, Debrecen, Hungary
| | - Sandor Safar
- Training Theory and Methodology Research Center, University of Physical Education, Budapest, Hungary
| | - Laszlo Ratgeber
- Faculty of Health Sciences, Institute of Physiotherapy and Sport Science, University of Pecs, Pecs, Hungary
- Center for Basketball Methodology of Education, Pecs, Hungary
- Department of Sport Games, Institute of Sports, University of Physical Education, Budapest, Hungary
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Hughes W, Healy R, Lyons M, Higginbotham C, Lane A, Beattie K. The Strength Characteristics of Elite and Subelite Female Gaelic Football Players. J Strength Cond Res 2024; 38:1072-1081. [PMID: 38489587 DOI: 10.1519/jsc.0000000000004741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2024]
Abstract
ABSTRACT Hughes, W, Healy, R, Lyons, M, Higginbotham, C, Lane, A, and Beattie, K. The strength characteristics of elite and subelite female Gaelic football players. J Strength Cond Res 38(6): 1072-1081, 2024-There is currently an underrepresentation of sports science research focused on the female athlete, specifically in the context of Gaelic football. The aims of this study are to (a) compare the strength characteristics of elite and subelite players and (b) establish normative-based values and percentile scores for the strength characteristics of female Gaelic football players. Ninety-two female Gaelic football players were recruited for this study and subsequently categorized as elite (intercounty n = 30, age; 25.1 ± 5.3 years, stature; 1.69 ± 0.06 m, mass; 69.5 ± 5.9 kg) or subelite (club n = 62, age; 25.4 ± 6.8 years, stature; 1.66 ± 0.06 m, mass; 65.1 ± 8.9 kg). The physical strength characteristics of the subjects were assessed through the isometric midthigh pull (IMTP), countermovement jump (CMJ), and 10-5 repeated jump test. Statistically significant differences were found in the physical strength characteristics between the groups with elite players demonstrating greater peak force (large effect), relative peak force (moderate effect), and reactive strength index (large effect). Statistically significant differences were also observed for key CMJ phase characteristics with elite players producing greater RSI mod (moderate effect), jump height (large effect), and propulsion peak power (large effect) than subelite players. This study demonstrated that there are moderate to large differences between playing standards with elite players displaying superior reactive-, explosive-, and maximal-strength than their subelite counterparts. The strength characteristics evaluated in this study may be used in conjunction with other performance indices to distinguish between elite and subelite playing standards in female Gaelic football players.
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Affiliation(s)
- William Hughes
- Department of Sport and Health Sciences, Technological University of the Shannon: Midlands Midwest, Athlone, Ireland
- SHE Research Group, Technological University of the Shannon: Midlands Midwest, Athlone, Ireland
| | - Robin Healy
- Department of Sport and Health Sciences, Technological University of the Shannon: Midlands Midwest, Athlone, Ireland
- SHE Research Group, Technological University of the Shannon: Midlands Midwest, Athlone, Ireland
| | - Mark Lyons
- Department of Physical Education and Sports Sciences, Sport and Human Performance Research Centre, University of Limerick, Limerick, Ireland
| | - Clement Higginbotham
- Department of Mechanical, Polymer, and Design, Technological University of the Shannon: Midlands Midwest, Athlone, Ireland; and
- SHE Research Group, Technological University of the Shannon: Midlands Midwest, Athlone, Ireland
| | - Aoife Lane
- Department of Sport and Health Sciences, Technological University of the Shannon: Midlands Midwest, Athlone, Ireland
- SHE Research Group, Technological University of the Shannon: Midlands Midwest, Athlone, Ireland
| | - Kris Beattie
- Department of Sport and Health Sciences, Technological University of the Shannon: Midlands Midwest, Athlone, Ireland
- SHE Research Group, Technological University of the Shannon: Midlands Midwest, Athlone, Ireland
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Sánchez-Sixto A, McMahon JJ, Floría P. Verbal instructions affect reactive strength index modified and time-series waveforms in basketball players. Sports Biomech 2024; 23:211-221. [PMID: 33404374 DOI: 10.1080/14763141.2020.1836252] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 10/08/2020] [Indexed: 10/22/2022]
Abstract
This study aimed to determine the effects of different verbal instructions, intended to affect the countermovement jump (CMJ) execution time, on the reactive strength index modified (RSIMod) and the time-series waveforms. Thirteen male basketball players performed six CMJs on a force plate with two different verbal instructions: 'jump as high as possible' (CMJhigh) and 'jump as high and as fast as possible' (CMJfast). Force-, power-, velocity-, and displacement-series waveforms, RSIMod and jump height were compared between conditions using statistical parametric mapping procedures. CMJfast showed greater values in RSIMod (p = 0.002) despite no differences in jump height (p = 0.345). Unweighting force (between 18% and 33% of total time) was lower in the CMJfast compared to CMJhigh. Larger force (between 53% and 63% of total time), velocity (between 31% and 48% of total time) and power (between 43% and 56% of total time) were found in the CMJfast compared to CMJhigh. These findings suggest that commanding athletes to jump as high and fast as possible increases rapid force production. Additionally, the results highlight the relevance of the countermovement phase in jumping and show that RSIMod could increase without power output modifications during propulsion, despite previous studies having reported positive associations between RSIMod propulsion power.
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Affiliation(s)
- Alberto Sánchez-Sixto
- Department of Sport, CEU Cardenal Spínola University, Bormujos, Spain
- Physical Performance & Sports Research Center, Pablo de Olavide University, Seville, Spain
| | - John J McMahon
- Directorate of Sport, Exercise and Physiotherapy, University of Salford, Salford, UK
| | - Pablo Floría
- Physical Performance & Sports Research Center, Pablo de Olavide University, Seville, Spain
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Donahue PT, Peel SA, Rush M, McInnis AK, Littlefield T, Calci C, Brutofsky T. Examining Countermovement Jump Strategies Between Women's NCAA Division I Sports. J Strength Cond Res 2023; 37:2052-2057. [PMID: 37639644 DOI: 10.1519/jsc.0000000000004505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
ABSTRACT Donahue, PT, Peel, SA, Rush, M, McInnis, AK, Littlefield, T, Calci, C, and Brutofsky, T. Examining countermovement jump strategies between women's NCAA Division I sports. J Strength Cond Res 37(10): 2052-2057, 2023-The purpose of this study was to examine countermovement vertical jump performance among female athletes who rely heavily on vertical jump performance within their given sport. Forty-five female athletes representing 3 teams (basketball, volleyball, and beach volleyball) competing at the NCAA Division I level completed 2 maximal effort countermovement jumps (CMJ) using a portable force platform. A 1-way analysis of variance was used to compare groups across each variable. Statistically significant differences were found between the groups regarding propulsive duration and time to takeoff with basketball showing the shortest time and beach volleyball having the longest times ( p < 0.05). In addition, differences were seen in countermovement depth and mean propulsive force between the groups with basketball displaying the smallest countermovement and highest force ( p < 0.05). No differences were seen in jump height and reactive strength index modified. Greater force and shorter durations in basketball athletes versus the low force and long durations in the beach volleyball athletes suggest that sporting backgrounds play a large role in how the CMJ is performed. This information can aid strength and conditioning practitioners in the design of training programs that are sport specific to the strategies used by the athlete.
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Affiliation(s)
- Paul T Donahue
- School of Kinesiology and Nutrition, University of Southern Mississippi, Hattiesburg, Mississippi; and
| | - Shelby A Peel
- School of Kinesiology and Nutrition, University of Southern Mississippi, Hattiesburg, Mississippi; and
| | - Megan Rush
- School of Kinesiology and Nutrition, University of Southern Mississippi, Hattiesburg, Mississippi; and
| | - Ayden Klaire McInnis
- School of Kinesiology and Nutrition, University of Southern Mississippi, Hattiesburg, Mississippi; and
| | - Thomas Littlefield
- School of Kinesiology and Nutrition, University of Southern Mississippi, Hattiesburg, Mississippi; and
| | - Courtney Calci
- School of Kinesiology and Nutrition, University of Southern Mississippi, Hattiesburg, Mississippi; and
| | - Tony Brutofsky
- Department of Athletics, University of Southern Mississippi, Hattiesburg, Mississippi
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Badby AJ, Mundy PD, Comfort P, Lake JP, McMahon JJ. The Validity of Hawkin Dynamics Wireless Dual Force Plates for Measuring Countermovement Jump and Drop Jump Variables. SENSORS (BASEL, SWITZERLAND) 2023; 23:4820. [PMID: 37430733 DOI: 10.3390/s23104820] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/06/2023] [Accepted: 05/15/2023] [Indexed: 07/12/2023]
Abstract
Force plate testing is becoming more commonplace in sport due to the advent of commercially available, portable, and affordable force plate systems (i.e., hardware and software). Following the validation of the Hawkin Dynamics Inc. (HD) proprietary software in recent literature, the aim of this study was to determine the concurrent validity of the HD wireless dual force plate hardware for assessing vertical jumps. During a single testing session, the HD force plates were placed directly atop two adjacent Advanced Mechanical Technology Inc. in-ground force plates (the "gold standard") to simultaneously collect vertical ground reaction forces produced by 20 participants (27 ± 6 years, 85 ± 14 kg, 176.5 ± 9.23 cm) during the countermovement jump (CMJ) and drop jump (DJ) tests (1000 Hz). Agreement between force plate systems was determined via ordinary least products regression using bootstrapped 95% confidence intervals. No bias was present between the two force plate systems for any of the CMJ and DJ variables, except DJ peak braking force (proportional bias) and DJ peak braking power (fixed and proportional bias). The HD system may be considered a valid alternative to the industry gold standard for assessing vertical jumps because fixed or proportional bias was identified for none of the CMJ variables (n = 17) and only 2 out of 18 DJ variables.
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Affiliation(s)
- Andrew J Badby
- Centre for Human Movement and Rehabilitation, University of Salford, Salford M6 6PU, UK
- Hawkin Dynamics, Inc., Westbrook, ME 04092, USA
| | | | - Paul Comfort
- Centre for Human Movement and Rehabilitation, University of Salford, Salford M6 6PU, UK
- School of Medical and Health Sciences, Edith Cowan University, Joondalup, WA 6027, Australia
| | - Jason P Lake
- Hawkin Dynamics, Inc., Westbrook, ME 04092, USA
- Chichester Institute of Sport, University of Chichester, Chichester PO19 6PE, UK
| | - John J McMahon
- Centre for Human Movement and Rehabilitation, University of Salford, Salford M6 6PU, UK
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Identifying and reporting position-specific countermovement jump outcome and phase characteristics within rugby league. PLoS One 2022; 17:e0265999. [PMID: 35333887 PMCID: PMC8956158 DOI: 10.1371/journal.pone.0265999] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 03/14/2022] [Indexed: 11/19/2022] Open
Abstract
The countermovement jump (CMJ) has been suggested to be an important test of neuromuscular performance for rugby league (RL) players. Identifying force platform-derived CMJ variables that may be more applicable to RL positions (e.g., forwards and backs) has yet to be fully explored in the scientific literature. The aim of this study was to identify RL position-specific CMJ force-time variables. Specifically, we aimed to compare select force-time variables from the countermovement (i.e., the combination of unweighting and braking) and propulsion phases of the CMJ between the global forwards and backs positional groups. We also aimed to compare typical (i.e., jump height) and alternative (i.e., take-off momentum) outcome CMJ variables between positional groups. Finally, we sought to visually present each individual player’s CMJ performance alongside the average data to facilitate the interpretation and reporting of the CMJ performances of RL athletes. Twenty-seven forwards and twenty-seven backs who competed in the senior men’s English RL Championship, performed three CMJs on a force platform at the beginning of the pre-season training period. There were no significant differences in any countermovement or propulsion phase variable between positions with just small effect sizes noted (P ≥0.09, d ≤0.46). Jump height (and so take-off velocity) was significantly greater for backs with moderate effects displayed (P = 0.03, d = 0.60). Take-off momentum (take-off velocity × body mass) was largely and significantly greater for forwards (P<0.01, d = 1.01). There was considerable overlap of individual player’s body mass and CMJ outcome variables across positions, despite significant differences in the mean values attained by each positional group. The results suggest that it may be beneficial for RL practitioners to identify player-specific, or at least position-specific, variables. As a minimum, it may be worthwhile selecting CMJ force-time variables based on what is considered important to individual player’s or small clusters of similar players’ projected successes during RL competition.
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Countermovement Jump Force–Time Curve Analysis between Strength-Matched Male and Female Soccer Players. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19063352. [PMID: 35329039 PMCID: PMC8949185 DOI: 10.3390/ijerph19063352] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 03/03/2022] [Accepted: 03/03/2022] [Indexed: 02/04/2023]
Abstract
The purpose of this study was to compare countermovement jump force–time measures between strength-matched male and female soccer players. Males (n = 11) and females (n = 11) were strength-matched via isometric mid-thigh pull testing, whereby peak force values were normalised to body mass. Subjects performed three maximal-effort countermovement jumps (CMJs) on a force platform from which a range of kinetic and kinematic variables were calculated via forward dynamics. Thereafter, differences in gross measures were examined via independent t-tests, while differences in force–, power–, velocity–, and displacement–time curves throughout the entire CMJ were analysed using statistical parametric mapping (SPM). Jump height, reactive strength index modified, propulsion mean force, propulsion impulse, and propulsion mean velocity were all greater for males (d = 1.50 to 3.07). Relative force– and velocity–time curves were greater for males at 86–93% (latter half of the concentric phase) and 85–100% (latter half of the concentric phase) of normalized movement time, respectively. Time to take-off, braking phase time, braking mean velocity and impulse, propulsion phase time and centre of mass displacement were similar between males and females (d = −0.23 to 0.97). This research demonstrates the strength of SPM to identify changes between entire force-time curves. Continued development and the use of SPM analysis could present the opportunity for a refined comparison of strength-matched male and female CMJ performance with the analysis of entire force–time curves.
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Jarvis P, Turner A, Read P, Bishop C. Reactive Strength Index and its Associations with Measures of Physical and Sports Performance: A Systematic Review with Meta-Analysis. Sports Med 2021; 52:301-330. [PMID: 34606061 DOI: 10.1007/s40279-021-01566-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2021] [Indexed: 01/24/2023]
Abstract
BACKGROUND Reactive strength index (RSI) is used frequently in the testing and monitoring of athletes. Associations with sports performance measures may vary dependent on the task but a literature synthesis has not been performed. OBJECTIVES The aim of this meta-analysis was to examine associations between RSI measured during rebound jumping tasks and measures of strength, linear and change of direction speed, and endurance performance. METHODS A systematic literature search with meta-analysis was conducted using databases PubMed, SPORTDiscus, Web of Science, and Ovid. Inclusion criteria required studies to (1) examine the relationship between RSI and an independent measure of physical or sporting performance for at least one variable; and (2) provide rebound test instructions to minimise ground contact time and maximise displacement of the jump. Methodological quality was assessed using a modified version of the Downs and Black Quality Index tool. Heterogeneity was examined via the Q statistic and I2. Pooled effect sizes were calculated using a random-effects model, with Egger's regression test used to assess small study bias (inclusive of publication bias). RESULTS Of the 1320 citations reviewed, a total of 32 studies were included in this meta-analysis. RSI was significantly and moderately associated with strength (isometric: r = 0.356 [95% CI 0.209-0.504]; isotonic: r = 0.365 [0.075-0.654]; pooled strength measures: r = 0.339 [0.209-0.469]) and endurance performance (r = 0.401 [0.173-0.629]). Significant moderate and negative associations were indicated for acceleration (r = - 0.426 [- 0.562 to - 0.290]), top speed (r = - 0.326 [- 0.502 to - 0.151]), and significant large negative associations were noted for change of direction speed (r = - 0.565 [- 0.726 to - 0.404]). Heterogeneity was trivial to moderate across all measures (I2 = 0-66%), and significant for isotonic strength and change of direction speed (p < 0.1). Evidence of small study bias was apparent for both acceleration and change of direction speed (p < 0.05). CONCLUSIONS We identified primarily moderate associations between RSI and independent measures of physical and sporting performance, and the strength of these relationships varied based on the task and physical quality assessed. The findings from this meta-analysis can help practitioners to develop more targeted testing and monitoring processes. Future research may wish to examine if associations are stronger in tasks that display greater specificity.
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Affiliation(s)
- Paul Jarvis
- Faculty of Science and Technology, London Sport Institute, Middlesex University, London, UK.
| | - Anthony Turner
- Faculty of Science and Technology, London Sport Institute, Middlesex University, London, UK
| | - Paul Read
- Institute of Sport, Exercise and Health, London, UK.,Division of Surgery and Interventional Science, University College London, London, UK.,School of Sport and Exercise, University of Gloucestershire, Gloucester, UK
| | - Chris Bishop
- Faculty of Science and Technology, London Sport Institute, Middlesex University, London, UK
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Vieira A, Tufano JJ. Reactive strength index-modified: reliability, between group comparison, and relationship between its associated variables. Biol Sport 2021; 38:451-457. [PMID: 34475626 PMCID: PMC8329976 DOI: 10.5114/biolsport.2021.100363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 07/30/2020] [Accepted: 09/25/2020] [Indexed: 11/18/2022] Open
Abstract
To investigate and compare the reliability of reactive strength index-modified (RSImod) and its associated variables (jump height [JH] and [time to take-off]) 20 combat fighters and 18 physically active men participated in this study. They visited the laboratory three times; firstly, for jump familiarization and two sessions for test-retest (2-7 days apart). For both groups, the between-day changes in performance were trivial to small (≤ 1.1%). The coefficient of variation (CV) comparisons (i.e. CV ratio) demonstrated that combat athletes had a lower test-retest variation for RSImod (0.87) and JH (0.80) than non-athletes. Combat athletes demonstrated a greater JH than physically active men (0.43 vs 0.37; p = 0.03, g = 0.73), but small and non-significant differences were observed for RSImod (0.60 vs 0.55; p = 0.24, g = 0.38) and TTT (0.70 vs 0.72; p = 0.32, g = 0.33). RSImod was more positively correlated with JH (r = 0.75-0.87; p < 0.001) than negatively correlated with TTT (r = 0.45-0.54; p < 0.001). This study suggests that RSImod is a reliable variable obtained during CMJ testing in combat athletes and physically active men, with scores being slightly better for combat athletes. In terms of performance, combat athletes jumped higher than physically active men, but no differences in RSImod or TTT were observed. Lastly, RSImod was more strongly related to JH than TTT, and this was more evident in athletes than nonathletes. This indicates that the combat athletes were able to better utilize their (equal) time spent jumping (higher), possibly via greater utilization of the stretch shortening cycle, faster or more optimal motor unit recruitment, or an array of other factors.
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Affiliation(s)
- Amilton Vieira
- Strength and Conditioning Laboratory, Faculty of Physical Education, University of Brasilia, Brasilia, Brazil
| | - James J. Tufano
- Faculty of Physical Education and Sport, Charles University, Prague, Czech Republic
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11
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Mohammadian M, Sadeghi H, Khaleghi Tazji M, Maloney SJ. The relationship between vertical stiffness during bilateral and unilateral hopping tests performed with different strategies and vertical jump performances. Eur J Sport Sci 2021; 22:182-189. [PMID: 33406998 DOI: 10.1080/17461391.2021.1872712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Vertical stiffness has been highlighted as a potential determinant of performance and may be estimated across a range of different performance tasks. The aim of the current study was to investigate the relationship between vertical stiffness determined during 9 different hopping tests and performance of vertical jumps. Twenty healthy, active males performed vertical hopping tests with three different strategies (self-selected, maximal, and controlled) and three different limb configurations (bilateral, unilateral preferred, and unilateral non-preferred), resulting in nine different variations, during which vertical stiffness was determined. In addition, participants performed squat jump (SQJ) and countermovement jump (CMJ) during which jump height, CMJ stiffness, and eccentric utilization ratio (EUR) were determined. Vertical stiffness in bilateral and unilateral preferred tasks performed with a self-selected and maximal, but not controlled, strategy was associated with stiffness in the CMJ (r = 0.61-0.64; p < 0.05). However, stiffness obtained during unilateral preferred and non-preferred hopping with self-selected strategy was negatively associated with performance in SQJ and CMJ tasks (r = -0.50 to -0.57; p < 0.05). These findings suggest that high levels of vertical stiffness may be disadvantageous to static vertical jumping performance. In addition, unilateral hopping with a self-selected strategy may be the most appropriate task variation if seeking to determine relationships with vertical jumping performance. HighlightsStiffness obtained during unilateral hopping with a preferred strategy was negatively associated with vertical jumping performancesStiffness obtained during hopping with preferred and maximal strategies was associated with stiffness obtained during a countermovement jumpIn this population, hopping stiffness may therefore be reflective of an individual's countermovement jump strategyHigh levels of stiffness may be disadvantageous to static-start vertical jumping.
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Affiliation(s)
- Mohammadamin Mohammadian
- Department of Biomechanics and Sports Injuries, Faculty of Physical Education and Sports Sciences, Kharazmi University, Tehran, Iran
| | - Heydar Sadeghi
- Department of Biomechanics and Sports Injuries, Faculty of Physical Education and Sports Sciences, Kharazmi University, Tehran, Iran.,Kinesiology Research Center, Department of Sports Biomechanics, Kharazmi University, Tehran, Iran
| | - Mehdi Khaleghi Tazji
- Department of Biomechanics and Sports Injuries, Faculty of Physical Education and Sports Sciences, Kharazmi University, Tehran, Iran
| | - Sean J Maloney
- Institute of Sports Science and Physical Activity Research, University of Bedfordshire, Bedford, UK
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Pérez-Castilla A, Weakley J, García-Pinillos F, Rojas FJ, García-Ramos A. Influence of countermovement depth on the countermovement jump-derived reactive strength index modified. Eur J Sport Sci 2020; 21:1606-1616. [PMID: 33131460 DOI: 10.1080/17461391.2020.1845815] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
This study aimed to investigate the effect of countermovement depth on the magnitude of the countermovement jump (CMJ) derived reactive strength index modified (RSImod), and to compare the RSImod between the CMJ performed with a self-preferred knee flexion angle (CMJpref) and the CMJ performed from a pre-determined knee flexion angle (CMJrefer) with the countermovement depth more similar to the CMJpref. Sixteen subjects (11 males and 5 females; age 25.1 ± 6.3 years, body mass 69.7 ± 10.2 kg, body height 172.9 ± 8.1 m) randomly performed in a single session the CMJpref and CMJs from five pre-determined knee flexion angles (60°, 75°, 90°, 105°, and 120°). Our results showed that lower knee flexion angles were generally associated with greater RSImod values with the CMJ performed at 60° showing the greatest RSImod (P ≤ 0.049; effect size [ES] range = 0.19-0.63). The greatest RSImod for the CMJ performed at 60° was caused by the proportionally lower values of the time to take-off (ES range = 0.65-1.91) compared to the decrease observed in jump height (ES range = 0.11-0.25). The RSImod was higher for the CMJpref compared to the CMJrefer (P < 0.001; ES = 0.34) due to a higher jump height (P = 0.021; ES = 0.14) and reduced time to take-off (P < 0.001; ES = 0.85). These results indicate that practitioners should be careful when interpreting an individual's changes in RSImod when the countermovement depth is not similar across the testing sessions. However, since the use of pre-determined knee flexion angles negatively impacts the RSImod, we encourage practitioners to use the CMJpref but only compare the RSImod when CMJs are performed using consistent countermovement depths.Highlights The magnitude of the countermovement jump-reactive reactive strength index modified is influenced by the knee flexion angle instruction.The magnitude of the countermovement jump-reactive reactive strength index tended to progressively increase with lower amounts of knee flexion.The magnitude of the countermovement jump-reactive reactive strength index is lower when an external reference is used to control the depth of the countermovement.
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Affiliation(s)
- Alejandro Pérez-Castilla
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain
| | - Jonathon Weakley
- School of Behavioural and Health Sciences, Australian Campus University, Brisbane, Australia.,Carnegie Applied Rugby Research (CARR) Centre, Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, United Kingdom
| | - Felipe García-Pinillos
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain.,Department of Physical Education, Sports and Recreation, Universidad de La Frontera, Temuco, Chile
| | - F Javier Rojas
- Department of Physical Education and Sport, Faculty of Sport Sciences, University of Granada, Granada, Spain
| | - 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, Universidad Católica de la Santísima Concepción, Concepción, Chile
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13
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Khalil LS, Matar RN, Rahman T, Franovic S, Abbas MJ, Hessburg L, Mehran N, Okoroha KR. Effect of Workload After ACL Reconstruction on Rerupture Rates in NBA Players. Orthop J Sports Med 2020; 8:2325967120964467. [PMID: 33283004 PMCID: PMC7682245 DOI: 10.1177/2325967120964467] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 06/11/2020] [Indexed: 01/15/2023] Open
Abstract
Background: Rupture of the anterior cruciate ligament (ACL) is a common and potentially career-altering injury sustained by players in the National Basketball Association (NBA). Strategies have been employed by the league to prevent reinjury of players after ACL reconstruction (ACLR), including minute restrictions and rest games; however, it remains unknown whether workload metrics after ACLR influence the risk for reinjury and revision surgery. Purpose: To evaluate whether workload changes after return to play (RTP) from primary ACLR influences the risk of rerupture in NBA players. Study Design: Case-control study; Level of evidence, 3. Methods: We identified NBA players from 1975 to 2018 who underwent primary ACLR as well as those who required revision ACLR. Primary outcomes included workload measures such as games played, games started, and minutes per game. Secondary outcomes included in-game performance statistics. Statistical analysis was used to compare relative workload and performance 3 years before and 3 years after undergoing primary ACLR. Workload was also compared between the control group of NBA players who underwent primary ACLR and those who required revision ACLR. Results: A total of 68 players who underwent primary ACLR were included, 8 of whom subsequently required revision ACLR. In their first season upon RTP, control players (primary ACLR) demonstrated a significant reduction in all workload metrics relative to the season before injury (P < .001), while the revision group demonstrated an unchanged to increased workload. In a comparison between the primary and revision groups during the first season after RTP, the primary group demonstrated significantly fewer games started (mean ± SD, 22.2 ± 3.0 vs 35.8 ± 8.3; P = .039) and minutes per game (20.5 ± 1.1 vs 27.0 ± 3.1; P = .048) than revision players. The primary ACLR group demonstrated reduced cumulative workload trends for the first 3 years after RTP relative to 3 years before injury, which was not demonstrated in the revision ACLR group, albeit statistically insignificant. Conclusion: Our study found that after ACLR, a reduction in workload parameters relative to preinjury baseline was associated with players who did not sustain rerupture. Further study is required to determine if workload measures following RTP from primary ACLR should be individualized relative to preinjury baseline.
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Affiliation(s)
- Lafi S Khalil
- Department of Orthopaedic Surgery, Henry Ford Hospital, Detroit, Michigan, USA
| | - Robert N Matar
- University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Tahsin Rahman
- Department of Orthopaedic Surgery, Henry Ford Hospital, Detroit, Michigan, USA
| | - Sreten Franovic
- Department of Orthopaedic Surgery, Henry Ford Hospital, Detroit, Michigan, USA
| | - Muhammad J Abbas
- Department of Orthopaedic Surgery, Henry Ford Hospital, Detroit, Michigan, USA
| | - Luke Hessburg
- Department of Orthopaedic Surgery, Henry Ford Hospital, Detroit, Michigan, USA
| | - Nima Mehran
- Kaiser Permanente Los Angeles Medical Center, Los Angeles, California, USA
| | - Kelechi R Okoroha
- Department of Orthopaedic Surgery, Henry Ford Hospital, Detroit, Michigan, USA
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14
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Petway AJ, Freitas TT, Calleja-González J, Torres-Ronda L, Alcaraz PE. Seasonal Variations in Game Activity Profiles and Players' Neuromuscular Performance in Collegiate Division I Basketball: Non-conference vs. Conference Tournament. Front Sports Act Living 2020; 2:592705. [PMID: 33345170 PMCID: PMC7739638 DOI: 10.3389/fspor.2020.592705] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 09/11/2020] [Indexed: 11/22/2022] Open
Abstract
Basketball has a high demand on a player's neuromuscular system due to a high volume of explosive high-intensity actions. This study aimed to examine the seasonal variations on game demands and players' neuromuscular performance during the Non-Conference (NON-CONF) and Conference (CONF) seasons in NCAA Division I Men's Basketball. Seven NCAA Division I Basketball players' (20 ± 1.2 years, 1.95 ± 0.1 m, and 94 ± 15 kg) match activity profiles were tracked in 17 home games (7 NON-CONF; 10 CONF); furthermore, players performed a repeat hop test on a force platform the day before competition to assess neuromuscular performance. A t-test for paired samples was used to analyze the differences between NON-CONF and CONF. Results indicated no significant differences in Total Distance, Peak Speed, Acceleration, and Deceleration loads when comparing NON-CONF and CONF match-play. Regarding neuromuscular performance, Jump Height (p = 0.03; ES = 0.43) was negatively affected during CONF. Moreover, a trend toward a decline in Peak Force (p = 0.06; ES = 0.38) was found in CONF. Conversely, no differences were obtained regarding Reactive Strength Index and Contact Time. In conclusion, match-play demands remained constant across the season whilst neuromuscular outputs were inhibited during the CONF season.
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Affiliation(s)
- Adam J Petway
- Philadelphia 76ers Athlete Care Department, Philadelphia, PA, United States
| | - Tomás T Freitas
- UCAM Research Center for High Performance Sport, Catholic University of Murcia, Murcia, Spain.,NAR-Nucleus of High Performance in Sport, São Paulo, Brazil
| | - Julio Calleja-González
- Physical Education and Sport Department, Faculty of Education and Sport, University of Basque Country (UPV/EHU), Vitoria, Spain.,Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia
| | | | - Pedro E Alcaraz
- UCAM Research Center for High Performance Sport, Catholic University of Murcia, Murcia, Spain.,Faculty of Sport Sciences, UCAM, Catholic University of Murcia, Murcia, Spain
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