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Witte BC, Schouten TC, Westphal JA, VanZile AW, Jones DD, Widenhoefer TL, Dobbs WC, Jagim AR, Luedke JA, Almonroeder TG. The Modified Reactive Strength Index Is a Valid Measure of Lower-Body Explosiveness in Male and Female High School Athletes. J Strength Cond Res 2024; 38:1428-1432. [PMID: 38662946 DOI: 10.1519/jsc.0000000000004806] [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: 07/30/2024]
Abstract
ABSTRACT Witte, BC, Schouten, TC, Westphal, JA, VanZile, AW, Jones, DD, Widenhoefer, TL, Dobbs, WC, Jagim, AR, Luedke, JA, and Almonroeder, TG. The modified reactive strength index is a valid measure of lower-body explosiveness in male and female high school athletes. J Strength Cond Res 38(8): 1428-1432, 2024-The modified reactive strength index (mRSI) is a commonly used metric to quantify lower-body explosiveness during countermovement jump (CMJ) performance. However, few studies have attempted to examine its validity as a measure of explosiveness, particularly among high school athletes. The purpose of this study was to examine the validity of the mRSI as a measure of lower-body explosiveness among a relatively large sample of male and female high school athletes from various sports. As part of this study, male ( n = 132) and female ( n = 43) high school athletes performed CMJs, while ground reaction forces were recorded using a force platform. The vertical ground reaction force data collected during the CMJs were used to derive the following variables: peak force (PF), peak power, time to PF, time to take-off, peak rate of force development, and the mRSI. Principal component analysis was applied and reduced these variables into 2 components related to "force" and "speed." The mRSI loaded on both the force (loading = 0.82) and speed (loading = -0.46) components, indicating that it incorporates elements of both force and speed, although it loaded more strongly on the force component than the speed component. The observed pattern of cross-loading suggests that the mRSI is generally a valid measure of lower-body explosiveness for male and female high school athletes.
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Affiliation(s)
- Brandon C Witte
- Doctor of Physical Therapy Program, College of Health Professions, Trine University, Fort Wayne, Indiana
| | - Tyler C Schouten
- Doctor of Physical Therapy Program, College of Health Professions, Trine University, Fort Wayne, Indiana
| | - Jessica A Westphal
- Doctor of Physical Therapy Program, College of Health Professions, Trine University, Fort Wayne, Indiana
| | | | | | - Tricia L Widenhoefer
- Doctor of Physical Therapy Program, College of Health Professions, Trine University, Fort Wayne, Indiana
| | - Ward C Dobbs
- Exercise & Sport Science Program, College of Science and Health, University of Wisconsin-La Crosse, La Crosse, Wisconsin; and
| | - Andrew R Jagim
- Sports Medicine, Mayo Clinic Health System, La Crosse, Wisconsin
| | - Joel A Luedke
- Sports Medicine, Mayo Clinic Health System, La Crosse, Wisconsin
| | - Thomas G Almonroeder
- Doctor of Physical Therapy Program, College of Health Professions, Trine University, Fort Wayne, Indiana
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Peterson PA, Lovalekar M, Cruz DE, Steele E, McFadden B, Cintineo H, Arent SM, Nindl BC. Unsupervised Machine Learning in Countermovement Jump and Isometric Mid-Thigh Pull Performance Produces Distinct Combat and Physical Fitness Clusters in Male and Female U.S. Marine Corps Recruits. Mil Med 2024; 189:38-46. [PMID: 38920035 DOI: 10.1093/milmed/usad371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/30/2023] [Accepted: 09/11/2023] [Indexed: 06/27/2024] Open
Abstract
INTRODUCTION Several challenges face the U.S. Marine Corps (USMC) and other services in their efforts to design recruit training to augment warfighter mobility and resilience in both male and female recruits as part of an integrated model. Strength and power underpin many of the physical competencies required to meet the occupational demands one might face in military. As the military considers adopting force plate technology to assess indices of strength and power, an opportunity presents itself for the use of machine learning on large datasets to deduce the relevance of variables related to performance and injury risk. The primary aim of this study was to determine whether cluster analysis on baseline strength and power data derived from countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) adequately partitions men and women entering recruit training into distinct performance clusters. The secondary aim of this study is then to assess the between-cluster frequencies of musculoskeletal injury (MSKI). MATERIALS AND METHODS Five hundred and sixty-five males (n = 386) and females (n = 179) at the Marine Corps Recruit Depots located at Parris Island and San Diego were enrolled in the study. Recruits performed CMJ and IMTP tests at the onset of training. Injury data were collected via medical chart review. Combat fitness test (CFT) and physical fitness test (PFT) results were provided to the study team by the USMC. A k-means cluster analysis was performed on CMJ relative peak power, IMTP relative peak force, and dynamic strength index. Independent sample t-tests and Cohen's d effect sizes assessed between-cluster differences in CFT and PFT performance. Differences in cumulative incidence of lower extremity %MSKIs were analyzed using Fisher's exact test. Relative risk and 95% confidence intervals (CIs) were also calculated. RESULTS The overall effects of cluster designation on CMJ and IMTP outcomes ranged from moderate (relative peak power: d = -0.68, 95% CI, -0.85 to -0.51) to large (relative peak force: d = -1.69, 95% CI, -1.88 to -1.49; dynamic strength index: d = 1.20, 95% CI, 1.02-1.38), indicating acceptable k-means cluster partitioning. Independent sample t-tests revealed that both men and women in cluster 2 (C2) significantly outperformed those in cluster 1 (C1) in all events of the CFT and PFT (P < .05). The overall and within-gender effect of cluster designation on both CFT and PFT performance ranged from small (d > 0.2) to moderate (d > 0.5). Men in C2, the high-performing cluster, demonstrated a significantly lower incidence of ankle MSKI (P = .04, RR = 0.2, 95% CI, 0.1-1.0). No other between-cluster differences in MSKI were statistically significant. CONCLUSIONS Our results indicate that strength and power metrics derived from force plate tests effectively partition USMC male and female recruits into distinct performance clusters with relevance to tactical and physical fitness using k-means clustering. These data support the potential for expanded use of force plates in assessing readiness in a cohort of men and women entering USMC recruit training. The ability to pre-emptively identify high and low performers in the CFT and PFT can aid in leadership developing frameworks for tailoring training to enhance combat and physical fitness with benchmark values of strength and power.
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Affiliation(s)
- Patrick A Peterson
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15203, USA
| | - Mita Lovalekar
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15203, USA
| | - Debora E Cruz
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15203, USA
| | - Elizabeth Steele
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15203, USA
| | - Bridget McFadden
- Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA
| | - Harry Cintineo
- Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA
| | - Shawn M Arent
- Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA
| | - Bradley C Nindl
- Neuromuscular Research Laboratory, University of Pittsburgh, Pittsburgh, PA 15203, USA
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Huang Z, Ji H, Chen L, Zhang M, He J, Zhang W, Chen X, Sun J, Song J, Li D. Comparing autoregulatory progressive resistance exercise and velocity-based resistance training on jump performance in college badminton athletes. PeerJ 2023; 11:e15877. [PMID: 37576500 PMCID: PMC10414022 DOI: 10.7717/peerj.15877] [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: 03/28/2023] [Accepted: 07/18/2023] [Indexed: 08/15/2023] Open
Abstract
Objectives Jumping ability has been identified as a key factor that influences the performance of badminton athletes. Autoregulatory progressive resistance exercise (APRE) and velocity-based resistance training (VBRT) are commonly used approaches to enhance muscle strength and have been shown to accurately monitor the development of explosive power to improve jumping ability. This study aims to investigate the effects of APRE and VBRT on badminton athletes' jumping ability and to provide practical insights into improving their jumping performance during competitions. Methods Upon completing familiarization and pretesting, 18 badminton athletes were included and completed the training intervention (age, 21.4 ± 1.4 years; stature, 170.1 ± 7.3 cm; body mass, 65.9 ± 12 kg); they were randomly divided into the APRE group (n = 9) and VBRT group (n = 9). Jumping performance was assessed during the countermovement jump (CMJ), squat jump (SJ), and drop jump (DJ) via SmartJump, with CMJ 's and SJ's jump height, eccentric utilization ratio (EUR), and reactive strength index (RSI). All participants then completed a 4-week in-season resistance training intervention. Results (1) The results of the within-group indicated that only the CMJ (pre: 41.56 ± 7.84 vs post: 43.57 ± 7.85, p < 0.05) of the APRE group had significant differences, whereas the SJ, EUR, and RSI were not significantly different (p > 0.05). (2) The results of the intergroups revealed that all indicators had no significant differences (p > 0.05), but APRE had a moderate effect size on the improvement of the CMJ (η2 = 0.244) and EUR (η2 = 0.068) when compared with VBRT. Conclusions The results showed that, compared to VBRT, APRE can effectively improve the performance of the reactive athletes' lower limb explosive power in the CMJ in a shorter period of time. The findings indicate that APRE may be useful for coaches seeking to improve the CMJ performance of athletes in the short term.
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Affiliation(s)
- Zijing Huang
- Digitalized Performance Training Laboratory, Guangzhou Sport University, Guangzhou, Guangdong, China
| | - Hongshen Ji
- Sports Training Institute, Guangzhou Sport University, Guangzhou, Guangdong, China
| | - Lunxin Chen
- Digitalized Performance Training Laboratory, Guangzhou Sport University, Guangzhou, Guangdong, China
| | - Mingyang Zhang
- Digitalized Performance Training Laboratory, Guangzhou Sport University, Guangzhou, Guangdong, China
| | - Jiaxin He
- Sports Training Institute, Guangzhou Sport University, Guangzhou, Guangdong, China
| | - Wenfeng Zhang
- Digitalized Performance Training Laboratory, Guangzhou Sport University, Guangzhou, Guangdong, China
| | - Xin Chen
- Digitalized Performance Training Laboratory, Guangzhou Sport University, Guangzhou, Guangdong, China
| | - Jian Sun
- Sports Training Institute, Guangzhou Sport University, Guangzhou, Guangdong, China
| | - Junyi Song
- Graduate School, Guangzhou Sport University, Guangzhou, Guangdong, China
| | - Duanying Li
- Sports Training Institute, Guangzhou Sport University, Guangzhou, Guangdong, China
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Louder T, Thompson BJ, Woster A, Bressel E. Kinetics of Depth Jumps Performed by Female and Male National Collegiate Athletics Association Basketball Athletes and Young Adults. J Funct Morphol Kinesiol 2023; 8:108. [PMID: 37606403 PMCID: PMC10443298 DOI: 10.3390/jfmk8030108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/07/2023] [Accepted: 07/27/2023] [Indexed: 08/23/2023] Open
Abstract
The depth jump (DJ) is commonly used to evaluate athletic ability, and has further application in rehabilitation and injury prevention. There is limited research exploring sex-based differences in DJ ground reaction force (GRF) measures. This study aimed to evaluate for sex-based differences in DJ GRF measures and determine sample size thresholds for binary classification of sex. Forty-seven participants from mixed-sex samples of NCAA athletes and young adults performed DJs from various drop heights. Force platform dynamometry and 2-dimensional videography were used to estimate GRF measures. Three-way mixed analysis of variance was used to evaluate main effects and interactions. Receiver operating characteristic (ROC) curve analysis was used to evaluate the combined sensitivity and specificity of dependent measures to sex. Results revealed that reactive strength index scores and rebound jump heights were greater in males than females (p < 0.001). Additionally, young adult females showed greater peak force reduction than young adult males (p = 0.002). ROC curve analysis revealed mixed results that appeared to be influenced by population characteristics and drop height. In conclusion, sex-based differences in DJ performance were observed, and the results of this study provide direction for future DJ investigations.
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Affiliation(s)
- Talin Louder
- Department of Kinesiology and Health Science, Utah State University, Logan, UT 84322, USA; (B.J.T.); (E.B.)
- Dennis G. Dolny Movement Research Clinic, Sorenson Legacy Foundation Center for Clinical Excellence, Utah State University, Logan, UT 84322, USA
| | - Brennan J. Thompson
- Department of Kinesiology and Health Science, Utah State University, Logan, UT 84322, USA; (B.J.T.); (E.B.)
- Dennis G. Dolny Movement Research Clinic, Sorenson Legacy Foundation Center for Clinical Excellence, Utah State University, Logan, UT 84322, USA
| | - Alex Woster
- Department of Kinesiology and Health Science, Utah State University, Logan, UT 84322, USA; (B.J.T.); (E.B.)
| | - Eadric Bressel
- Department of Kinesiology and Health Science, Utah State University, Logan, UT 84322, USA; (B.J.T.); (E.B.)
- Dennis G. Dolny Movement Research Clinic, Sorenson Legacy Foundation Center for Clinical Excellence, Utah State University, Logan, UT 84322, USA
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