scholarly journals Assessing Reactive Strength Measures in Jumping and Hopping Using the Optojump™ System

2016 ◽  
Vol 54 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Robin Healy ◽  
Ian C. Kenny ◽  
Andrew J. Harrison
Keyword(s):  
Contact Time ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Flight Time ◽  
Force Platform ◽  
Regression Equations ◽  
Strength Ratio ◽  
Strength Index ◽  
Physically Active ◽  
Drop Jumps

AbstractThe aim of this study was to assess the concurrent validity of the Optojump™ system (Microgate, Bolzano, Italy) versus a force platform in the estimation of temporal and reactive strength measures. In two separate investigations, twenty physically active males performed double-leg and single-leg drop jumps from a box height of 0.3 m and a 10 s vertical bilateral hopping test. Contact time, flight time and total time (the sum of contact and flight time) were concurrently assessed during single and double-leg drop jumps and during hopping. Jump height, the reactive strength index and the reactive strength ratio were also calculated from contact time and flight time. Despite intraclass correlation coefficients (ICCs) for all variables being close to 1 (ICC > 0.975), a significant overestimation was found in contact time (0.005 ± 0.002 s) and underestimations in flight time (0.005 ± 0.003 s), the reactive strength index (0.04 ± 0.02 m·s-1) and the reactive strength ratio (0.07 ± 0.04). Overestimations in contact time and underestimations in flight time were attributed to the physical design of the Optojump™ system as the transmitter and receiver units were positioned 0.003 m above the floor level. The Optojump™ demonstrated excellent overall temporal validity with no differences found between systems for total time. Coaches are advised to be consistent with the instrumentation used to assess athletes, however, in the case of comparison between reactive strength values collected with the Optojump™ and values collected with a force platform, regression equations are provided.

scholarly journals Assessing Plyometric Ability during Vertical Jumps Performed by Adults and Adolescents

Sports ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 132 ◽  
Author(s):  
Brandon Snyder ◽  
Shawn Munford ◽  
Chris Connaboy ◽  
Hugh Lamont ◽  
Shala Davis ◽  
...  
Keyword(s):  
Contact Time ◽  
Analysis Data ◽  
Adolescent Male ◽  
Ground Contact ◽  
Strength Index ◽  
Basketball Players ◽  
Contact Phase ◽  
Adult Men ◽  
Drop Jumps ◽  
Vertical Jumps

The purpose of this study was to compare different methods for assessing plyometric ability during countermovement (CMJ) and drop jumps (DJ) in a group of adults and adolescents. Ten resistance-trained adult men (age: 22.6 ± 1.6 years) and ten adolescent male basketball players (age: 16.5 ± 0.7 years) performed a CMJ and a DJ from a height of 0.40 m. Jump height (JH), contact time, normalized work (WNORM), and power output (PONORM) during the absorption and propulsion phases were calculated from force platforms and 3-D motion analysis data. Plyometric ability was assessed using the modified reactive strength index (RSIMOD during CMJ) and the reactive strength index (RSI during DJ) as well as three indices using propulsion time, propulsion work (PWI), and propulsion power. Adults jumped significantly higher than adolescents (mean difference [MD]: 0.05 m) while JH (MD: 0.05 m) and ground contact time (MD: 0.29 s) decreased significantly from CMJ to DJ. WNORM (MD: 4.2 J/kg) and PONORM (MD: 24.2 W/kg) during the absorption phase of CMJ were significantly less than these variables during the propulsion phases of the jumps. The reactive strength index variants increased significantly from the CMJ to DJ (MD: 0.23) while all other plyometric indices decreased significantly. Neither RSIMOD nor RSI contributed significantly to the prediction of JH during CMJ and DJ, respectively, while PWI was able to explain ≥68% of the variance in JH. Variants of the reactive strength index do not reflect the changes in mechanical variables during the ground contact phase of CMJ and DJ and may not provide an accurate assessment of plyometric ability during different vertical jumps.

scholarly journals Interday Reliability and Usefulness of a Reactive Strength Index Derived From 2 Maximal Rebound Jump Tests

2019 ◽  
Vol 14 (9) ◽  
pp. 1200-1204
Author(s):  
Thomas M. Comyns ◽  
Eamonn P. Flanagan ◽  
Sean Fleming ◽  
Evan Fitzgerald ◽  
Damian J. Harper
Keyword(s):  
Female Athletes ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Strength Index ◽  
Warm Up ◽  
Intraclass Correlation Coefficients ◽  
Jump Test ◽  
Moderate Change ◽  
Familiarization Session

Purpose: To examine the interday reliability and usefulness of a reactive strength index (RSI) derived from a maximal 5-rebound jump test (5max RJT) and a maximal 10-rebound jump test (10/5 RJT). Methods: Twenty male field-sport athletes (24.5 [3.0] y, 1.78 [0.1] m, 84.9 [5.2] kg) and 15 female participants (21.1 [0.9] y, 1.65 [0.73] m, 62.0 [5.1] kg) performed 2 maximal repetitions of the 5max RJT and the 10/5 RJT on 2 testing days after a specific warm-up. A 1-wk period separated testing days, and these sessions were preceded by a familiarization session. RSI was calculated by dividing jump height (in meters) by contact time (in seconds). The 5max RJT and the 10/5 RJT trial with the highest RSI on each testing day were used for reliability and usefulness analysis. Results: Both tests were deemed reliable for determining RSI for male, female, and pooled male and female cohorts, as the intraclass correlation coefficients were ≥.80 and the coefficient of variation was ≤10%. Only the 5max RJT was rated as “good” at detecting the smallest worthwhile change in performance for female athletes (smallest worthwhile change: 0.10 > typical error: 0.07). The 5max RJT for men and the 10/5 RJT for men and women were rated “good” in detecting a moderate change in performance only. Conclusions: Both tests are reliable for the determination of RSI, but the usefulness of the tests in detecting the smallest worthwhile change is questionable.

scholarly journals Impact of acute static-stretching on the optimal height in drop jumps

2014 ◽  
Vol 20 (1) ◽  
pp. 65-70
Author(s):  
Leonardo A. Pasqua ◽  
Nilo M. Okuno ◽  
Mayara V. Damasceno ◽  
Adriano. E. Lima-Silva ◽  
Rômulo Bertuzzi
Keyword(s):  
Contact Time ◽  
Jump Condition ◽  
Static Stretching ◽  
Drop Height ◽  
Plantar Flexors ◽  
Jump Performance ◽  
Physically Active ◽  
Height Determination ◽  
Drop Jumps ◽  
Male Subjects

This study analyzed the effect of static stretching on performance during drop jumps. Furthermore, we investigated if a reduction in drop height would compensate the stretching-caused alterations. Ten physically active male subjects performed drop jumps at four different drop heights without static stretching for the optimal drop height determination. After, they performed drop jumps on two drop heights with static stretching previously. The jump height, contact time and reactive strength index were significantly affected by static stretching. However, only the contact time was significantly improved by the reduction in drop height with previous static stretching. Our results suggest that the decrement in performance after static stretching could be partially compensated by a reduction in drop height, which decreases the contact time near a non-stretching jump condition. This can be explained by the lower landing velocity and, possibly, the smaller reduction in the activation of the plantar flexors muscles. In conclusion, the reduction in drop height seems to be interesting after a static stretching session, aiming to expose the athletes to lower impact forces to maintain jump performance.

Reliability and Validity of the Fullerton Functional Fitness Test: An Independent Replication Study

1999 ◽  
Vol 7 (4) ◽  
pp. 339-353 ◽  
Author(s):  
Jacqueline M. Miotto ◽  
Wojtek J. Chodzko-Zajko ◽  
Jennifer L. Reich ◽  
Melissa M. Supler
Keyword(s):  
Discriminant Validity ◽  
Intraclass Correlation ◽  
Reliability And Validity ◽  
Correlation Coefficients ◽  
Community Dwelling ◽  
Functional Mobility ◽  
Limiting Factor ◽  
Functional Fitness ◽  
Physically Active ◽  
Fitness Test

A limiting factor in evaluating the functional status of older people is the lack of appropriate measurement tools for assessing functional mobility, muscle strength, aerobic endurance, agility, and flexibility. In this study, the reliability and validity of the seven-item Fullerton Functional Fitness Test (FFT) battery, designed for use with community-dwelling older adults, was examined. The test items were as follows: floor sit-and-reach, back scratch, 8-ft up-and-go, arm curl, 30-s chair stand. 2-min step, and 9-min walk. Seventy-nine participants (42 physically active, 37 sedentary) completed the FFT battery three times within a 2-week period. The test-retest reliability intraclass correlation coefficients were high. Construct validity analysis revealed that five of the seven FFT items discriminated between the physically active and sedentary groups. In conclusion, most of the evidence from the stability reliability and discriminant validity analyses supports the view that the Fullerton FFT battery is a reliable and valid test of functional fitness.

Assessing Interlimb Jump Asymmetry in Young Soccer Players: The My Jump 2 App

2021 ◽  
Vol 16 (1) ◽  
pp. 19-27
Author(s):  
Matheus Barbalho ◽  
Ana Francisca Rozin Kleiner ◽  
Bianca Callegari ◽  
Ramon Costa de Lima ◽  
Givago da Silva Souza ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Intraclass Correlation Coefficient ◽  
Intraclass Correlation ◽  
Flight Time ◽  
Mobile App ◽  
Force Platform ◽  
Soccer Players ◽  
Drop Jump ◽  
Time Asymmetry ◽  
Gold Standard Method

Background: Jumps are important evaluation tools for muscle strength and power and for interlimb asymmetries. Different jump tests are well related to athletic performance, prediction of injury risk, and common motor gestures of several sports such as soccer. Low-cost mobile applications (apps) have gained popularity for this measure. The authors hypothesized that the My Jump 2 app would be a valid tool to assess drop-jump performance and interlimb asymmetry in soccer players. Methods: Eleven male soccer players took part in this study (18.2 [1.3] y, 69.9 [9.5] kg, 174 [6.6] cm). The athletes performed each test twice on a force plate (gold-standard method), while the jumps were recorded through the mobile app. Measures with the My Jump 2 app were applied by 2 evaluators, independently and in duplicate (interrater and intrarater reliability). The agreement analysis between both evaluations was done using an intraclass correlation coefficient and Bland–Altman plots. Results: Compared with the force platform, the app tested showed excellent reliability for the drop jump’s flight time and interlimb asymmetry (intraclass correlation coefficient > .98). For interlimb contact-time asymmetry, the values were 18.4 (9.9) and 19.1 (9.9) milliseconds for the My Jump 2 app and the force platform, respectively (P = .88). For flight-time asymmetries, the values were 389.7 (114.3) and 396.8 (112.5) milliseconds for the My Jump 2 app and the force platform, respectively (P = .88). Conclusion: The My Jump 2 app is a valid tool to assess drop-jump and interlimb asymmetry in soccer players.

scholarly journals The 10/5 Repeated Jumps Test: Are 10 Repetitions and Three Trials Necessary?

Biomechanics ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 1-14
Author(s):  
Callum Stratford ◽  
Thomas Dos’Santos ◽  
John J. McMahon
Keyword(s):  
Repeated Measures ◽  
Intraclass Correlation ◽  
Force Plate ◽  
Correlation Coefficients ◽  
Pairwise Comparisons ◽  
Strength Index ◽  
Intraclass Correlation Coefficients ◽  
Coefficients Of Variation ◽  
Repeated Measures Analysis ◽  
Ground Contact Time

The purpose of this study was to identify whether ten repetitions and three trials were necessary to achieve stability in peak reactive strength index (RSI) during the 10/5 repeated jumps test (RJT). Twenty-five males, from multiple sports, performed three trials of the RJT on an in-ground force plate, with 90 seconds’ rest between trials. Intraclass correlation coefficients (ICC = 0.916–0.986) and coefficients of variation (CV ≤ 14.5%) were considered acceptable for all variables. Repeated-measures analysis of variance and Freidman’s tests revealed large and significant differences (p ≤ 0.006, η2 = 0.159–0.434, power ≥ 0.859) in ground contact time (GCT), jump height (JH), and subsequently RSI both between trials and repetitions. Pairwise comparisons revealed that repetitions 1–3 produced longer GCTs (p ≤ 0.05, d = 0.41–1.40), lower JHs (p ≤ 0.05, d = 0.31–0.56), and lower RSI values (p ≤ 0.05, d = 0.35–1.24). The shortest GCTs, greatest JHs and greater RSIs occurred between repetitions 7 and 10, with approximately 60% of peak RSIs occurring during these ranges. The sequential estimate technique revealed that seven repetitions were needed to attain stability in mean peak RSI. Non-significant (p = 0.554) and negligible differences (d ≤ 0.09) in the five best RSIs between trials were noted. One trial of the 10/5 RJT is sufficient to evaluate peak RSI in athletes and should reduce data collection time and fatigue.

The Development and Reliability of a Simple Field-Based Screening Tool to Assess for Scapular Dyskinesis

2016 ◽  
Vol 25 (3) ◽  
Author(s):  
Siobhan O'Connor ◽  
Noel McCaffrey ◽  
Enda Whyte ◽  
Kieran Moran
Keyword(s):  
Screening Tool ◽  
High Reliability ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Future Research ◽  
Scapular Dyskinesis ◽  
Convenience Sample ◽  
Physically Active ◽  
Overhead Athletes ◽  
Lack Of Control

Context: Scapular dyskinesis has been identified as a possible risk factor for injury in overhead athletes. There is a need to develop a simple, inexpensive, time-efficient field-based test that can establish the presence and severity of both scapular dyskinesis and its individual components in a musculoskeletal preparticipation screening. To ensure confidence in the test results, high reliability must be displayed. Objective: To establish the intertester and intratester reliability of a simple field-based screening tool for scapular dyskinesis. Design: Reliability study. Setting: Athletic therapy facilities. Participants: 15 physically active men (19.46 ± 0.63 y) free from any orthopedic or neurological disorders, recruited from a convenience sample of college students. Intervention: Testers underwent 3 training sessions where the instructions and scoring system of the test were explained, demonstrations of the tests were given, and opportunities to practice the test were provided. Three testers independently rated 3 trials, and the process was repeated at the same time the following week. Main Outcome Measures: Scapular dyskinesis was assessed using the following components: winging, loss/lack of control when lifting, loss/lack of control when lowering, and scapular asymmetry. A 0-3 rating (0 = no issue, 1 = slight issue, 2 = moderate issue, 3 = severe issue) was provided by the tester independently on each side separately and on scapular asymmetry. The intraclass correlation coefficients (ICCs), 95% confidence intervals, and standard error of measurement (SEM) were computed to establish reliability. Results: Excellent ICC values were found for intertester reliability (ICCs .80-1.00) and good to excellent intratester reliability (ICCs .60-1.00 for tester A, .63-1.00 for tester B, and .75-1.00 for tester C) for all components of the test. The SEM was not found to be clinically significant. Conclusions: The simple field-based screening tool developed to assess scapular dyskinesis demonstrates high reliability and so is a reliable tool to use in preparticipation screenings. Future research should establish its validity.

scholarly journals Reliability Analysis of Traditional and Ballistic Bench Press Exercises at Different Loads

2015 ◽  
Vol 47 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Amador García-Ramos ◽  
Paulino Padial ◽  
Miguel García-Ramos ◽  
Javier Conde-Pipó ◽  
Javier Argüelles-Cienfuegos ◽  
...  
Keyword(s):  
Recovery Time ◽  
Bench Press ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Upper Body ◽  
Physically Active ◽  
Velocity Relationship ◽  
Body Velocity ◽  
The Individual ◽  
Test Retest Reliability

Abstract The purpose of this study was to determine test–retest reliability for peak barbell velocity (Vpeak) during the bench press (BP) and bench press throw (BPT) exercises for loads corresponding to 20–70% of one-repetition maximum (1RM). Thirty physically active collegiate men conducted four evaluations after a preliminary BP 1RM determination (1RM·bw-1 = 1.02 ± 0.16 kg·kg-1). In counterbalanced order, participants performed two sessions of the BP in one week and two sessions of the BPT in another week. Recovery time between sessions within the same week was 48 hours and recovery time between sessions of different weeks was 120 hours. On each day of evaluation the individual load-velocity relationship at each tenth percentile (20–70% of 1RM) in a Smith machine for the BP or BPT was determined. Participants performed three attempts per load, but only the best repetition (highest Vpeak), registered by a linear position transducer, was analysed. The BPT resulted in a significantly lower coefficient of variation (CV) for the whole load–velocity relationship, compared to the BP (2.48% vs. 3.22%; p = 0.040). Test–retest intraclass correlation coefficients (ICCs) ranged from r = 0.94-0.85 for the BPT and r = 0.91-0.71 for the BP (p < 0.001). The reduction in the biological within-subject variation in BPT exercise could be promoted by the braking phase that obligatorily occurs during a BP executed with light or moderate loads. Therefore, we recommend the BPT exercise for a most accurate assessment of upper-body velocity.

scholarly journals Reliability and Validity of a Mobile Device Application for Use in Sports-Related Concussion Balance Assessment

2017 ◽  
Vol 04 (01) ◽  
pp. e1-e6 ◽  
Author(s):  
Mark Burghart ◽  
Jordan Craig ◽  
Jeff Radel ◽  
Jessie Huisinga
Keyword(s):  
Mobile Device ◽  
Center Of Pressure ◽  
Pearson Correlation ◽  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Force Platform ◽  
Balance Assessment ◽  
Retest Reliability ◽  
Device Application ◽  
Test Retest Reliability

Background Balance assessment is necessary when evaluating athletes after a concussion. We investigated a mobile device application (app) for providing valid, reliable, and objective measures of static balance. Objectives The mobile device app would demonstrate similar test–retest reliability to force platform center of pressure (COP) sway variables and that SWAY scores and force platform COP sway variables would demonstrate good correlation coefficients. Methods Twenty-six healthy adults performed balance stances on a force platform while holding a mobile device equipped with SWAY (Sway Medical LLC) to measure postural sway based on acceleration changes detected by the mobile device's accelerometer. Participants completed four series of three 10-second stances (feet together, tandem, and single leg), twice with eyes open and twice with eyes closed. Test–retest reliability was assessed using intraclass correlation coefficients (ICC). Concurrent validity of SWAY scores and COP sway variables were determined with Pearson correlation coefficients. Results Reliability of SWAY scores was comparable to force platform results for the same test condition (ICC = 0.21–0.57). Validity showed moderate associations between SWAY scores and COP sway variables during tandem stance (r = –0.430 to –0.493). Lower SWAY scores, indicating instability, were associated with greater COP sway. Discussion The SWAY app is a valid and reliable tool when measuring balance of healthy individuals in tandem stance. Further study of clinical populations is needed prior to assessment use. Conclusion The SWAY app has potential for objective clinical and sideline evaluations of concussed athletes, although continued evaluation is needed.

scholarly journals A Correction Equation for Jump Height Measured Using the Just Jump System

2016 ◽  
Vol 11 (4) ◽  
pp. 555-557 ◽  
Author(s):  
John J. McMahon ◽  
Paul A. Jones ◽  
Paul Comfort
Keyword(s):  
Intraclass Correlation ◽  
Correlation Coefficients ◽  
Force Platform ◽  
Coefficient Of Determination ◽  
Jump Height ◽  
Validity And Reliability ◽  
Height Measurement ◽  
Intraclass Correlation Coefficients ◽  
Future Work ◽  
Criterion Method

Purpose:To determine the concurrent validity and reliability of the popular Just Jump system (JJS) for determining jump height and, if necessary, provide a correction equation for future reference.Methods:Eighteen male college athletes performed 3 bilateral countermovement jumps (CMJs) on 2 JJSs (alternative method) that were placed on top of a force platform (criterion method). Two JJSs were used to establish consistency between systems. Jump height was calculated from flight time obtained from the JJS and force platform.Results:Intraclass correlation coefficients (ICCs) demonstrated excellent within-session reliability of the CMJ height measurement derived from both the JJS (ICC = .96, P < .001) and the force platform (ICC = .96, P < .001). Dependent t tests revealed that the JJS yielded a significantly greater CMJ jump height (0.46 ± 0.09 m vs 0.33 ± 0.08 m) than the force platform (P < .001, Cohen d = 1.39, power = 1.00). There was, however, an excellent relationship between CMJ heights derived from the JJS and force platform (r = .998, P < .001, power = 1.00), with a coefficient of determination (R2) of .995. Therefore, the following correction equation was produced: Criterion jump height = (0.8747 × alternative jump height) – 0.0666.Conclusions:The JJS provides a reliable but overestimated measure of jump height. It is suggested, therefore, that practitioners who use the JJS as part of future work apply the correction equation presented in this study to resultant jump-height values.

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