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Gillen ZM, Burch RF, Saucier DN, Strawderman L, Luczak T, Piroli A, Petway AJ, Rath T. Effects of a Strength and Conditioning Offseason Program on Countermovement Jump Ground Reaction Forces in Division I American Football Players. J Strength Cond Res 2024; 38:e86-e95. [PMID: 38088878 DOI: 10.1519/jsc.0000000000004660] [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: 02/29/2024]
Abstract
ABSTRACT Gillen, ZM, Burch, RF, Saucier, DN, Strawderman, L, Luczak, T, Piroli, A, Petway, AJ, and Rath, T. Effects of a strength and conditioning offseason program on countermovement jump ground reaction forces in Division I American football players. J Strength Cond Res 38(3): e86-e95, 2024-The purpose of this study was to examine the effects of a 10-week strength and conditioning offseason program on the ground reaction forces (GRFs) of American football players during single-leg and double-leg countermovement jumps (SLJ and CMJ, respectively). Each subject visited the laboratory twice, once for preoffseason and once for postoffseason testing. During each visit, subjects performed CMJs and SLJs for each leg. Ground reaction forces were collected by force plates to quantify unweighting, braking, propulsive, and performance metrics for each jump. In addition, an efficiency index was calculated for each jump to examine changes in vertical jump efficiency. Dependent samples t tests compared all CMJ metrics. Two-way repeated measures analyses of variance (leg × time) compared all SLJ metrics. An alpha level of p ≤ 0.05 was considered statistically significant. For the CMJ, propulsive phase duration decreased due to the program ( p = 0.007), whereas peak braking power, peak propulsive power, mean propulsive force, and jump height increased ( p ≤ 0.012). For the SLJ, peak braking power, force at the low position, braking rate of force development, eccentric force, peak propulsive power, mean propulsive force, and jump height increased in both legs ( p ≤ 0.044). The efficiency index increased for the CMJ and the SLJ for both legs ( p ≤ 0.016). This study demonstrated that SLJ and CMJ vertical jump performance significantly increases in as few as 10 weeks of offseason strength and conditioning. Strength and conditioning programming may effectively increase vertical jump performance, as assessed by GRFs, which can be used as a simple indicator regarding changes in athletic performance.
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Affiliation(s)
- Zachary M Gillen
- Department of Kinesiology, Mississippi State University, Mississippi State, Mississippi
| | - Reuben F Burch
- Department of Industrial & Systems Engineering, Mississippi State University, Mississippi State, Mississippi
- Human Factors & Athlete Engineering, Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi
| | - David N Saucier
- Human Factors & Athlete Engineering, Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi
| | - Lesley Strawderman
- Department of Industrial & Systems Engineering, Mississippi State University, Mississippi State, Mississippi
| | - Tony Luczak
- National Strategic Planning & Analysis Research Center, Mississippi State University, Mississippi State, Mississippi
| | - Anthony Piroli
- Tampa Bay Buccaneers Strength & Conditioning, Tampa, Florida
| | - Adam J Petway
- Department of Industrial & Systems Engineering, Mississippi State University, Mississippi State, Mississippi
- Human Factors & Athlete Engineering, Center for Advanced Vehicular Systems, Mississippi State University, Mississippi State, Mississippi
- University of Louisville Strength & Conditioning, Louisville, Kentucky; and
| | - Ted Rath
- Philadelphia Eagles Strength & Conditioning, Philadelphia, Pennsylvania
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Montoro-Bombú R, Miranda-Oliveira P, Valamatos MJ, João F, Buurke TJW, Cupido Santos A, Rama L. Spatiotemporal variables comparison between drop jump and horizontal drop jump in elite jumpers and sprinters. PeerJ 2024; 12:e17026. [PMID: 38426130 PMCID: PMC10903347 DOI: 10.7717/peerj.17026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 02/07/2024] [Indexed: 03/02/2024] Open
Abstract
Background General expectations speculated that there are differences between drop jump (DJ) and horizontal drop jump (HDJ) exercises. While these criteria may be valid, we have yet to find a report that explores these differences in competitive level athletes. Objective The study aimed to compare spatiotemporal variables in the drop jump (DJ) vs. the horizontal drop jump (HDJ) in elite jumpers and sprinters. Methods Sixteen international-level male athletes performed two DJ attempts at different fall heights 0.3, 0.4, and 0.5 m (DJ30, DJ40, and DJ50), and after 2 h, they performed two HDJ attempts (HDJ30, HDJ40, HDJ50). All jumps were performed on a Kistler force plate. The variables analyzed were ground contact time (GCT), flight time (FT), eccentric phase time, concentric phase time, and time to peak concentric force. Results The GCT was found to be significantly shorter in DJ vs. HDJ (Z = 4.980; p = 0.0001; ES = 3.11). FT was significantly lower in DJ30 versus HDJ30 (Z = 4.845; p = 0.0001, d = 3.79), but significantly higher in DJ40 vs. HDJ40 (Z = 4.437; p ≤ 0.0001, d = 3.70) and in DJ50 vs. HDJ50 (Z = 4.549; p ≤ 0.0001, d = 4.72). Conclusions It is concluded that the HDJ requires more time for force production, that the eccentric component requires more time than the concentric and that it is not recommended to use the HDJ over the DJ for reactive purposes. This is the first study that comprehensively compare the differences between DJ and HDJ, which will assist coaches and researchers in the design of future training strategies.
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Affiliation(s)
- Raynier Montoro-Bombú
- University of Coimbra, Research Unit for Sport and Physical Activity (CIDAF), Faculty of Sport Sciences and Physical Education, Coímbra, Portugal
| | - Paulo Miranda-Oliveira
- Portuguese Athletics Federation (FPA), Lisboa, Lisboa, Portugal
- School of Technology and Management (ESTG), Polytechnic of Leiria, Leiria, Portugal
- Interdisciplinary Research Centre Egas Moniz (CIIEM), Egas Moniz School of Health & Science, Almada, Portugal
| | - Maria João Valamatos
- Centro Interdisciplinar para o Estudo da Performance Humana (CIPER), Faculdade de Motricidade Humana, Lisboa, Cruz-Quebrada, Portugal
- Laboratório de Biomecânica e Morfologia Funcional, Faculdade de Motricidade Humana, Universidade de Lisboa, Estrada da Costa, Lisboa, Cruz-Quebrada, Portugal
| | - Filipa João
- Centro Interdisciplinar para o Estudo da Performance Humana (CIPER), Faculdade de Motricidade Humana, Lisboa, Cruz-Quebrada, Portugal
- Laboratório de Biomecânica e Morfologia Funcional, Faculdade de Motricidade Humana, Universidade de Lisboa, Estrada da Costa, Lisboa, Cruz-Quebrada, Portugal
| | - Tom JW Buurke
- University of Groningen, University Medical Center Groningen, Department of Human Movement Sciences, Groningen, Netherlands
- KU Leuven, Department of Movement Sciences, Leuven, Belgium
| | - Amândio Cupido Santos
- University of Coimbra, Research Unit for Sport and Physical Activity (CIDAF), Faculty of Sport Sciences and Physical Education, Coímbra, Portugal
| | - Luis Rama
- University of Coimbra, Research Unit for Sport and Physical Activity (CIDAF), Faculty of Sport Sciences and Physical Education, Coímbra, Portugal
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Ino T, Samukawa M, Ishida T, Wada N, Koshino Y, Kasahara S, Tohyama H. Validity of AI-Based Gait Analysis for Simultaneous Measurement of Bilateral Lower Limb Kinematics Using a Single Video Camera. SENSORS (BASEL, SWITZERLAND) 2023; 23:9799. [PMID: 38139644 PMCID: PMC10747245 DOI: 10.3390/s23249799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 12/02/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023]
Abstract
Accuracy validation of gait analysis using pose estimation with artificial intelligence (AI) remains inadequate, particularly in objective assessments of absolute error and similarity of waveform patterns. This study aimed to clarify objective measures for absolute error and waveform pattern similarity in gait analysis using pose estimation AI (OpenPose). Additionally, we investigated the feasibility of simultaneous measuring both lower limbs using a single camera from one side. We compared motion analysis data from pose estimation AI using video footage that was synchronized with a three-dimensional motion analysis device. The comparisons involved mean absolute error (MAE) and the coefficient of multiple correlation (CMC) to compare the waveform pattern similarity. The MAE ranged from 2.3 to 3.1° on the camera side and from 3.1 to 4.1° on the opposite side, with slightly higher accuracy on the camera side. Moreover, the CMC ranged from 0.936 to 0.994 on the camera side and from 0.890 to 0.988 on the opposite side, indicating a "very good to excellent" waveform similarity. Gait analysis using a single camera revealed that the precision on both sides was sufficiently robust for clinical evaluation, while measurement accuracy was slightly superior on the camera side.
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Affiliation(s)
- Takumi Ino
- Graduate School of Health Sciences, Hokkaido University, Sapporo 0600812, Japan;
- Department of Physical Therapy, Faculty of Health Sciences, Hokkaido University of Science, Sapporo 0068585, Japan
| | - Mina Samukawa
- Faculty of Health Sciences, Hokkaido University, Sapporo 0600812, Japan
| | - Tomoya Ishida
- Faculty of Health Sciences, Hokkaido University, Sapporo 0600812, Japan
| | - Naofumi Wada
- Department of Information and Computer Science, Faculty of Engineering, Hokkaido University of Science, Sapporo 0068585, Japan;
| | - Yuta Koshino
- Faculty of Health Sciences, Hokkaido University, Sapporo 0600812, Japan
| | - Satoshi Kasahara
- Faculty of Health Sciences, Hokkaido University, Sapporo 0600812, Japan
| | - Harukazu Tohyama
- Faculty of Health Sciences, Hokkaido University, Sapporo 0600812, Japan
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Schärer C, Reinhart L, Hübner K. Age-Related Differences between Maximum Flight Height of Basic Skills on Floor, Beam and Vault and Physical Condition of Youth Female Artistic Gymnasts. Sports (Basel) 2023; 11:sports11050100. [PMID: 37234056 DOI: 10.3390/sports11050100] [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: 03/31/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/27/2023] Open
Abstract
In women's artistic gymnastics, difficult elements with great flight heights have to be performed on the apparatuses. However, the importance of the physical condition for generating flight height and its development with age remains elusive. Therefore, we investigated the age-related differences of lower body power, reactive strength, 20 m sprint speed, flight heights (basic elements on beam and floor) and run-up speed on the vault of 33 youth female gymnasts. Further, we calculated correlations between all parameters separately for different age groups (7-9 y; 10-12 y; 13-15 y). We found larger differences between the age groups 7-9 y and 10-12 y than between 10-12 y and 13-15 y on the apparatuses (10-12 y vs. 7-9 y: +23% to +52%; 13-15 y vs. 10-12 y: +2% to +24%) and for physical conditioning variables (10-12 y vs. 7-9 y: +12 to +24%; 13-15 y vs. 10-12 y: + 5% to +16%). The correlations between flight heights and physical condition were the lowest for age group 7-9 y (r: from -0.47 to 0.78; 10-12 y: r: from -0.19 to 0.80; 13-15 y: r: from -0.20 to 0.90). An optimal application of the physical condition to enhance the gymnastics-specific performance (e.g., flight height) is strongly age-dependent. Regular monitoring of jumping abilities and the derivation of training recommendations can accelerate this development and the future performance of young athletes.
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Affiliation(s)
- Christoph Schärer
- Swiss Federal Institute of Sport Magglingen, Hauptstrasse 247, 2532 Magglingen, Switzerland
| | - Luca Reinhart
- Swiss Federal Institute of Sport Magglingen, Hauptstrasse 247, 2532 Magglingen, Switzerland
| | - Klaus Hübner
- Swiss Federal Institute of Sport Magglingen, Hauptstrasse 247, 2532 Magglingen, Switzerland
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Lin J, Shen J, Zhang J, Zhou A, Guo W. Correlations between horizontal jump and sprint acceleration and maximal speed performance: a systematic review and meta-analysis. PeerJ 2023; 11:e14650. [PMID: 36748088 PMCID: PMC9899053 DOI: 10.7717/peerj.14650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 12/06/2022] [Indexed: 02/04/2023] Open
Abstract
Objectives The purpose of this study is to determine the associations between horizontal jump and sprint acceleration, as well as maximal speed performance. Methods A systematic literature search was performed using PubMed, MEDLINE (EBSCOhost), and Web of Science. The studies that were included in this review must meet the following criteria: (1) well-trained individuals over the age of 18 years old; (2) Pearson's correlation coefficients between sprint time and horizontal jump distance were provided; (3) the sprint distance was limited to 0-100 m. The quality of the studies was assessed using a modified version of the Downs and Black Quality Index test. A random-effects model was used to determine the effect sizes, and heterogeneity between studies was examined using the Q statistic and I2. Results From the identified 2,815 studies, 27 studies were included in this study (two from reference lists). The sprint time of the sprint acceleration phase was moderately and negatively correlated with the standing long jump (r = - 0.45, z = 7.48, p < 0.001), single leg standing long jump (r = - 0.48, z = 3.49, p < 0.001) and horizontal drop jump distance (r = - 0.48, z = 3.49, p < 0.001), and was largely and negatively correlated with multiple jump distance (r = - 0.69, z = 6.02, p < 0.001). Out of five studies assessed the standing triple jump, three studies reported significant positive association with the sprint acceleration performance. The sprint time of maximal speed phase was very largely and negatively associated with standing long jump distance (r = - 0.73, z = 4.44, p < 0.001) and multiple jump distance (r = - 0.76, z = 6.86, p < 0.001). Conclusions This review indicates the moderate to very large associations between horizontal jump and sprint acceleration and maximal speed performance, and the highest magnitude of associations between them is found in the multiple jump. Moreover, compared to the sprint acceleration performance, there are greater associations between maximal speed performance and standing long jump and multiple jump distance.
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Affiliation(s)
- Junlei Lin
- School of Strength and Conditioning Training, Beijing Sport University, Beijing, China
| | - Jie Shen
- School of Strength and Conditioning Training, Beijing Sport University, Beijing, China
| | - Junjie Zhang
- Capital University of Physical Education and Sports, Beijing, China
| | - Aiguo Zhou
- School of Strength and Conditioning Training, Beijing Sport University, Beijing, China
| | - Wenxia Guo
- Beijing University of Chemical Technology, Beijing, China
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Krzyszkowski J, Chowning LD, Harry JR. Phase-Specific Predictors of Countermovement Jump Performance That Distinguish Good From Poor Jumpers. J Strength Cond Res 2022; 36:1257-1263. [PMID: 32412965 DOI: 10.1519/jsc.0000000000003645] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
Abstract
ABSTRACT Krzyszkowski, J, Chowning, LD, and Harry, JR. Phase-specific predictors of countermovement jump performance that distinguish good from poor jumpers. J Strength Cond Res 36(5): 1257-1263, 2022-The modified-reactive strength index (RSImod) is commonly examined during the countermovement vertical jump (CMJ) to assess neuromuscular characteristics (i.e., explosiveness, fatigue, adaptation, etc.) of an athlete. However, both phase-specific variables explaining RSImod and corresponding differences between good and poor jumpers are not well understood in trained populations. This study sought to (a) identify predictors of RSImod during the CMJ based on phase-specific temporal and rate of force development (RFD) variables, and (b) identify differences in those predictors between performers with high and low RSImod performances from a sample of collegiate male basketball players (n = 22; 20 ± 2 years; 1.99 ± 0.06 month; 93.8 ± 7.5 kg). Subjects performed 3 maximal effort CMJ trials while ground reaction force data was recorded using 2 force platforms. Phase-specific temporal and RFD variables were calculated and entered into separate stepwise regression models using backward elimination to identify predictors RSImod. Individuals were then categorized into high (n = 11; RSImod = 0.68 ± 0.10) and low (n = 11; RSImod = 0.48 ± 0.04) RSImod groups according to the overall median RSImod (RSImod = 0.55). Independent t-tests (α = 0.05) were conducted and supplemented by Cohen's d effect sizes (d ≥ 1.2, large) to compare groups relative to significant predictors identified by the linear regression models and related variables. The temporal regression model (R2 = 0.530) retained unloading time and concentric time, whereas the RFD regression model (R2 = 0.429) retained unloading RFD and braking RFD. The high RSImod group exhibited significantly greater RSImod scores (d = 2.51, p < 0.001) and jump heights (d = 1.58, p < 0.001), shorter times to takeoff (d = 1.27, p = 0.007) and concentric times (d = 1.51, p = 0.002), and a greater braking RFD (d = 1.41, p = 0.005) than the low RSImod group. Individuals targeting enhanced CMJ performance may consider exploring strategies or interventions to develop quicker unloading and concentric phases and increasing eccentric RFD abilities.
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Affiliation(s)
- John Krzyszkowski
- Human Performance & Biomechanics Laboratory, Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, Texas
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Mangine GT, McNabb JA, Feito Y, VanDusseldorp TA, Hester GM. Increased Resisted Sprinting Load Decreases Bilateral Asymmetry in Sprinting Kinetics Among Rugby Players. J Strength Cond Res 2021; 35:3076-3083. [DOI: 10.1519/jsc.0000000000003293] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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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: 31] [Impact Index Per Article: 10.3] [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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Bell S, Howarth SJ. Effect of Drop-Piece High-Velocity, Low-Amplitude Manipulation to the Midfoot of Asymptomatic Adult Sprinters on Performance During a Unilateral Horizontal Drop-Jump Test: A Feasibility Investigation. J Manipulative Physiol Ther 2021; 44:527-534. [DOI: 10.1016/j.jmpt.2021.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 12/14/2021] [Accepted: 12/17/2021] [Indexed: 11/26/2022]
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The Reactive Bounding Coefficient as a Measure of Horizontal Reactive Strength to Evaluate Stretch-Shortening Cycle Performance in Sprinters. J Hum Kinet 2020; 73:45-55. [PMID: 32774536 PMCID: PMC7386155 DOI: 10.2478/hukin-2020-0003] [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] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Plyometric exercises such as drop jumping and bounding offer athletes a substantiated means of enhancing athletic performance. Between the two exercises, reactive measurement using bounding (reactive bounding coefficient [RBC]) has received scant attention within the domain of training and conditioning. Therefore, this study aimed to identify the viability of utilising a speed-bounding exercise to assess horizontal reactive strength. Eleven young, male elite sprinters (age: 17.8 ± 1.3 yr; body height: 1.72 ± 0.06 m; body mass: 66.05 ± 6.10 kg; best 100 m sprint time: 10.77 ± 0.32 s) were tested for static jumps (SJ), drop jumps (DJ), 10 speed-bounding (RBC10), and 50 m sprint performance. Between-group comparisons based on sprint ability (fast [FSG] vs. slow [SSG] sprint-group) and correlation coefficients were computed subsequently. The FSG (n = 5; 50 m time: 5.82 ± 0.11 s; RBC10: 7.46 ± 0.27) performed significantly better in the RBC10 (p = 0.036) than the SSG (n = 5; 50 m time: 6.09 ± 0.13 s; RBC10: 7.09 ± 0.25). A very high correlation was attained between the RBC10 and the criterion measure, the SJ (r = 0.83). Additionally, RBC10 appeared to be correlated with 30, 50, 10-30 and 30-50 m sprint times (r = -0.52 to -0.60). This positive trend, however, was not observed for the DJ reactive strength index (trivial to moderate correlations). Good reliability was shown for the RBC10 and all sprint distances (“1.5% coefficient variation). Furthermore, all sprinters attained ground contact times of 0.12-0.18 s during the RBC10 which was indicative of fast stretch-shortening cycles during movement, suggesting that the RBC10 could be utilised to assess plyometric ability and enhance sprint performance. Overall, the RBC10 seems able to discriminate between the FSG and the SSG, indicating it has acceptable levels of validity and reliability.
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Dolenec A, Milinović I, Babić V, Dizdar D. Test UHCJ20m-Measurement Procedure Standardization and Metric Characteristics Determination. SENSORS 2020; 20:s20143971. [PMID: 32708882 PMCID: PMC7411694 DOI: 10.3390/s20143971] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/11/2020] [Accepted: 07/15/2020] [Indexed: 11/16/2022]
Abstract
The purpose of the research study was to standardize the measurement procedure and determine the reliability, homogeneity, and sensitivity of a 20 m unilateral horizontal cyclic jump test (UHCJ20m) whose intentional (assumed) measurement aim is the lower extremities’ explosive strength. The subject sample consisted of 31 students from Zagreb University (20.68 ± 1.96 years of age, height 185.16 ± 7.19 cm, body mass 79.48 ± 9.23 kg) actively involved in various sports events. The UHCJ20m test was performed three times using a dominant (take-off) leg with an active rest of 15 min between the repetitions. The results showed that the UHCJ20m test had satisfactory sensitivity and a very high reliability: Cronbach α = 0.95, intraclass correlation coefficient (ICC) = 0.94 and homogeneity average intertrial correlation (AVR) = 0.88. Future research studies should be aimed at determining the metric characteristics of the UHCJ20m test with a population of athletes in sports characterized by start acceleration and maximum speed running.
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Affiliation(s)
- Aleš Dolenec
- Faculty of Sport, University of Ljubljana, Gortanova ulica 22, 1000 Ljubljana, Slovenia
- Correspondence: ; Tel.: +386-152-078-04
| | - Ivan Milinović
- Faculty of Economics & Business, University of Zagreb, Trg J.F. Kennedy 6, 10000 Zagreb, Croatia;
| | - Vesna Babić
- Faculty of Kinesiology, University of Zagreb, Horvaćanski zavoj 15, 10000 Zagreb, Croatia; (V.B.); (D.D.)
| | - Dražan Dizdar
- Faculty of Kinesiology, University of Zagreb, Horvaćanski zavoj 15, 10000 Zagreb, Croatia; (V.B.); (D.D.)
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Sharp AP, Cronin JB, Neville J. Using Smartphones for Jump Diagnostics: A Brief Review of the Validity and Reliability of the My Jump App. Strength Cond J 2019. [DOI: 10.1519/ssc.0000000000000472] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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13
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Koyama K, Yamauchi J. Comparison of lower limb kinetics, kinematics and muscle activation during drop jumping under shod and barefoot conditions. J Biomech 2018; 69:47-53. [PMID: 29397998 DOI: 10.1016/j.jbiomech.2018.01.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 07/13/2017] [Accepted: 01/08/2018] [Indexed: 11/18/2022]
Abstract
This study was to investigate the acute effects of wearing shoes on lower limb kinetics, kinematics and muscle activation during a drop jump. Eighteen healthy men performed a drop jump under barefoot and shod conditions. Vertical ground reaction force (GRF) was measured on a force plate during the contact phase of a drop jump, and GRF valuables were calculated for each condition. The angles of the knee and ankle joints, and the foot strike angle (the angle between the plantar surface of the foot and the ground during ground contact) as well as the electromyography of 7 muscles were measured. The shod condition showed a significant larger first peak GRF, longer time to first peak GRF from the initial ground contact and lower initial loading rate than the barefoot condition. The shod condition showed a significant larger ankle joint angle at initial ground contact, smaller knee joint angle between the second peak GRF and take-off as well as smaller foot strike angle at both initial ground contact and take-off than the barefoot condition. There were significant correlations between relative differences in ankle joint at the initial ground contact and relative differences in the initial loading rate. The muscle activity of all muscles during foot ground contact did not differ between two conditions; however, in the shod condition, muscle activation of 150 ms before foot ground contact was significantly higher in the rectus femoris, whereas it was lower in the biceps femoris and tibialis anterior muscles than the barefoot condition. These results indicate that wearing shoes alternates the GRF variables at initial ground contact, joint kinematics at the ground contact and muscle activation before foot ground contact during a drop jump, suggesting that the effects of wearing shoes on drop jump training differ from being barefoot.
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Affiliation(s)
- Keiji Koyama
- Department of Sport Technology, Toin University of Yokohama, Kanagawa, Japan; Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Junichiro Yamauchi
- Graduate School of Human Health Sciences, Tokyo Metropolitan University, Tokyo, Japan; Future Institute for Sport Sciences, Tokyo, Japan; Research Center in Back, Neck, Other Joint Pain and Human Performance (BNOJPH), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand.
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Kariyama Y, Hobara H, Zushi K. Differences in take-off leg kinetics between horizontal and vertical single-leg rebound jumps. Sports Biomech 2016; 16:187-200. [DOI: 10.1080/14763141.2016.1216160] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Yasushi Kariyama
- Faculty of Health and Sport Science, University of Tsukuba, Tsukuba, Japan
| | - Hiroaki Hobara
- Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan
| | - Koji Zushi
- Faculty of Health and Sport Science, University of Tsukuba, Tsukuba, Japan
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15
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Schuster D, Jones PA. Relationships between unilateral horizontal and vertical drop jumps and 20 m sprint performance. Phys Ther Sport 2016; 21:20-5. [DOI: 10.1016/j.ptsp.2016.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 01/05/2016] [Accepted: 02/24/2016] [Indexed: 10/22/2022]
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16
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Agar-Newman DJ, Klimstra MD. Efficacy of Horizontal Jumping Tasks as a Method for Talent Identification of Female Rugby Players. J Strength Cond Res 2015; 29:737-43. [DOI: 10.1519/jsc.0000000000000683] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Dobbs CW, Gill ND, Smart DJ, McGuigan MR. Relationship Between Vertical and Horizontal Jump Variables and Muscular Performance in Athletes. J Strength Cond Res 2015; 29:661-71. [DOI: 10.1519/jsc.0000000000000694] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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18
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Mangine GT, Hoffman JR, Gonzalez AM, Wells AJ, Townsend JR, Jajtner AR, McCormack WP, Robinson EH, Fragala MS, Fukuda DH, Stout JR. Speed, Force, and Power Values Produced From Nonmotorized Treadmill Test Are Related to Sprinting Performance. J Strength Cond Res 2014; 28:1812-9. [DOI: 10.1519/jsc.0000000000000316] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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19
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Lake JP, Hetzler BS, Lauder MA. Magnitude and relative distribution of kettlebell snatch force-time characteristics. J Strength Cond Res 2014; 28:3063-72. [PMID: 24845206 DOI: 10.1519/jsc.0000000000000538] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The aim of this study was to compare mechanical output from kettlebell snatch and 2-handed kettlebell swing exercise. Twenty-two men performed 3 sets of 8 kettlebell snatch and 2-handed swing exercise with a 24-kg kettlebell on a force platform. Vertical and horizontal net impulse, mean force, displacement, the magnitude, and rate of work performed displacing the kettlebell-and-lifter center of mass (CM), phase durations and impulse ratio (horizontal to resultant) were calculated from force data. The results of repeated-measures analysis of variance showed that: (a) vertical CM displacement was significantly larger during kettlebell snatch exercise (22 ± 4 vs. 18 ± 5 cm, p = 0.001), and vertical CM displacement was significantly larger than horizontal CM displacement, regardless of exercise (20 ± 3 vs. 7 ± 1 cm, p < 0.0001); (b) the magnitude (253 ± 73 vs. 3 ± 1 J, p < 0.0001) and rate of work (714 ± 288 vs. 11 ± 4 W, p < 0.0001) performed to vertically displace the CM was larger than the horizontal equivalent in both exercises, and the magnitude (5 ± 2 vs. 1 ± 1 J, p < 0.0001) and rate of work (18 ± 7 vs. 4 ± 3 W, p < 0.0001) performed to horizontally displace the CM during 2-handed swing exercise was significantly larger than the kettlebell snatch equivalent; (c) this was underpinned by the magnitude of horizontal impulse (29 ± 7 vs. 18 ± 7 N·s, p < 0.0001) and the impulse ratio (23 vs. 14%, p < 0.0001). These findings reveal that, apart from the greater emphasis, 2-handed swing exercise places on horizontal mechanical output, the mechanical output of the 2 exercises is similar. Research shows that 2-handed swing exercise improves maximum and explosive strength. These results suggest that strength and conditioning coaches should consider using kettlebell snatch and 2-handed swing exercise interchangeably for the ballistic component of athlete strength and conditioning programs.
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Affiliation(s)
- Jason P Lake
- 1Department of Sport and Exercise Sciences, University of Chichester, Chichester, United Kingdom; and 2Department of Sports Medicine and Athletic Training, Missouri State University, Springfield, Missouri
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21
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Alkjaer T, Meyland J, Raffalt PC, Lundbye-Jensen J, Simonsen EB. Neuromuscular adaptations to 4 weeks of intensive drop jump training in well-trained athletes. Physiol Rep 2013; 1:e00099. [PMID: 24303171 PMCID: PMC3841035 DOI: 10.1002/phy2.99] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 09/02/2013] [Accepted: 09/03/2013] [Indexed: 11/16/2022] Open
Abstract
This study examined the effects of 4 weeks of intensive drop jump training in well-trained athletes on jumping performance and underlying changes in biomechanics and neuromuscular adaptations. Nine well-trained athletes at high national competition level within sprinting and jumping disciplines participated in the study. The training was supervised and augmented feedback on performance was used to ensure maximal training intensity. The drop jumps were performed with minimal contact time and maximal jumping height. Assessment of performance during training showed effects of motor learning. Before and after the training intervention maximal isometric muscle strength, the biomechanics, muscle activity pattern of the lower extremities and the soleus H-reflex and V-wave during drop jumping were measured. Maximal jump height and performance index (PI) defined as jumping height divided by contact time improved significantly by 11.9% (P = 0.024) and 16.2% (P = 0.009), respectively. Combined ankle and knee joint peak power was significantly increased by 7% after training (P = 0.047). The preactivity in the soleus muscle decreased 16% (P = 0.015). The soleus H-reflex was unchanged after training, while the soleus V-wave increased significantly at 45 msec after touchdown. This may indicate an increased drive to the α-motor neuron pool following training. Muscle strength parameters were unaffected by the training. The results demonstrate that 4 weeks of intensive drop jump training can improve jumping performance also in well-trained athletes without concomitant changes in muscle strength. It is suggested that the behavioral improvement is primarily due to neural factors regulating the activation pattern controlling the drop jump movement.
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Affiliation(s)
- Tine Alkjaer
- Department of Neuroscience and Pharmacology, University of Copenhagen Copenhagen, Denmark
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22
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Okkonen O, Häkkinen K. Biomechanical Comparison Between Sprint Start, Sled Pulling, and Selected Squat-Type Exercises. J Strength Cond Res 2013; 27:2662-73. [DOI: 10.1519/jsc.0b013e31829992b0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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23
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Dyer B, Sewell P, Noroozi S, Redwood S, Broomfield S, Callaway A. Sprint prostheses used at the Paralympics: a proposal for an assessment method to maintain fairness. Prosthet Orthot Int 2012; 36:306-11. [PMID: 22918907 DOI: 10.1177/0309364612446651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Unique to sport with a disability such as those performed at the Paralympics, the need to improve the performance of lower limb prostheses can conflict with the need to provide an equal opportunity to win whilst still needing to encourage and maximise participation. OBJECTIVES This paper extends previous research by attempting to propose a method suitable for sports governing bodies to help any functional assessment of sprinting lower limb prosthesis technology in the future. STUDY DESIGN The study comprises two elements: 1) A historical review and evaluation of drop jump assessment techniques. 2) A pilot test of a candidate using two mechanically different lower limb regions. METHODS A unilateral drop jump technique is assessed historically as an evaluation technique for sprinters with a lower-limb amputation. Further, a unilateral drop jump using mechanically altered lower limbs is piloted. RESULTS The historical review provides no evidence to suggest that this technique is not suitable for athlete participants. The pilot trials show a statistically stable and repeatable method of demonstrating a mechanical deficiency of one limb to another. Six jumps are suitable to obtain stable results but the mechanical behaviour of one limb may eventually change based on accumulated fatigue. CONCLUSIONS The unilateral drop jump is shown to be viable for application to an athlete population with a lower limb unilateral amputation.
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Affiliation(s)
- Bryce Dyer
- Bournemouth University, Poole, Dorset, UK.
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24
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Ball NB, Zanetti S. Relationship Between Reactive Strength Variables in Horizontal and Vertical Drop Jumps. J Strength Cond Res 2012; 26:1407-12. [DOI: 10.1519/jsc.0b013e3182510870] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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25
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Moresi MP, Bradshaw EJ, Greene D, Naughton G. The assessment of adolescent female athletes using standing and reactive long jumps. Sports Biomech 2011; 10:73-84. [DOI: 10.1080/14763141.2011.569564] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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26
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Keogh JWL, Newlands C, Blewett S, Payne A, Chun-Er L. A kinematic analysis of a strongman-type event: the heavy sprint-style sled pull. J Strength Cond Res 2011; 24:3088-97. [PMID: 19996774 DOI: 10.1519/jsc.0b013e3181b62c2f] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study sought to (a) characterize the kinematics aspects of a popular strongman-type event, the heavy sprint-style sled pull, and (b) gain some insight into the kinematic factors that could distinguish the within- and between-subjects' fastest and slowest trials. Six resistance-trained subjects with experience in the heavy sled pull gave informed consent to participate in this study. Subjects performed three 25-m sets of sled pulls with a load of 171.2 kg with 3 minutes of rest between sets. Kinematic variables were obtained from 2 video cameras positioned perpendicularly 11 m from the intended direction of the sled pull. Camera 1 recorded the first 5 m (acceleration phase) and Camera 2 recorded the last 5 m (maximum velocity phase). Effect sizes and paired and independent t-tests were used to determine the within- and between-subject effects, respectively, with significance set at p < 0.01. Heavy sled pulls shared many kinematic similarities to acceleration phase sprinting, although the sled pull had somewhat smaller step lengths and step rates, longer ground contact times, and a more horizontal trunk. Within- and between-subject analyses of the fastest and slowest trials typically revealed more significant differences in the maximum velocity than the acceleration phase. Although the fastest trials were often characterized by significantly greater step lengths, step rates, and shorter ground contact times, differences in the segment/joint angles were less consistent. Based on the impulse-momentum relationship, our results imply that greater anteroposterior forces/impulses were produced in the fastest sled pulls. Accordingly, the heavy sled pull may improve acceleration sprinting performance in many athlete types and the ability to break and make tackles in contact sports such as American football and the rugby codes.
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Affiliation(s)
- Justin W L Keogh
- Institute of Sport and Recreation Research New Zealand, School of Sport and Recreation, AUT University, Auckland, New Zealand.
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27
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Keogh JWL, Aickin SE, Oldham ARH. Can common measures of core stability distinguish performance in a shoulder pressing task under stable and unstable conditions? J Strength Cond Res 2010; 24:422-9. [PMID: 20072059 DOI: 10.1519/jsc.0b013e3181c7c6b9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The primary purpose of this study was to determine whether a range of static core stability (CS) measures could distinguish shoulder press performance in unstable vs. stable conditions. Thirty resistance-trained men gave informed consent to participate in this study. One-repetition maximum strength (from < 6 repetitions) was predicted in the seated shoulder dumbbell press performed in unstable (Swiss ball[SB]) and stable (back-support bench) environments. Three CS muscle endurance tests were performed, with 4 CS ratios also calculated. The degree of strength decrement, referred to as the instability strength level (ISL), was calculated by dividing the predicted 1RM Unstable score by the 1RM Stable score. All subjects were categorized as high (ISL > 0.90), moderate (0.85 < or = ISL < or = 0.90), or low (ISL < 0.85). Between-group differences for the high- and low-ISL groups were assessed using analysis of variance and effect sizes. Pearson product moment correlations were then performed to examine the relationships between the CS measures and the ISL for the entire group. No significant between-group differences (p = 0.132-0.999) or large effect sizes were observed for any of the CS measures. Trunk flexion endurance was the only CS measure significantly correlated to the ISL (r = 0.477). In line with muscular strength research, these results suggest that CS exhibits relatively high levels of task specificity and that CS performance in static single-joint exercises may not be highly related to that in more dynamic multijoint activities. Core stability training (with or without a SB) may therefore only lead to significant improvements in functional dynamic performance if the postures, mode and velocity of contraction performed in training, are similar to the competitive tasks.
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Affiliation(s)
- Justin W L Keogh
- Institute of Sport and Recreation Research New Zealand, School of Sport and Recreation, AUT University, Auckland, New Zealand.
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