Interday Reliability of the Reactive Strength Index and Optimal Drop Height

Byrne, Damien; Browne, Declan; Byrne, Paul; Richardson, Noel

doi:10.1519/jsc.0000000000001534

Cited by 45 publications

(50 citation statements)

References 12 publications

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“…An effective method to increase this physical quality is plyometric training. 14,30 Available evidence indicates that plyometric training is used sparingly during ACL rehabilitation. 31 We encourage practitioners to include this training modality when it is appropriate to do so and propose assessment of RSI using a practically viable tool such as the 10s hop to measure lower limb SSC function.…”

Section: O N L I N E F I R S Tmentioning

confidence: 99%

Residual deficits in reactive strength indicate incomplete restoration of athletic qualities following anterior cruciate ligament reconstruction in professional soccer players

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Davies

Bishop

et al. 2020

Journal of Athletic Training

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Context: Deficits in plyometric abilities are common following anterior cruciate ligament reconstruction (ACLR). Vertical rebound tasks may provide a targeted evaluation of knee function. Objective: Examine the utility of a vertical hop test to assess function following ACLR and establish factors associated with performance. Design: Cross-sectional Setting: Rehabilitation Participants: Soccer players with a history of ACLR (N = 73) and matched controls (N = 195) Main outcome measures: 10 second vertical hop test including measures of jump height, reactive strength index (RSI) and asymmetry. We also examined possible predictors of hop performance including single leg vertical drop jump (SLDVJ), isokinetic knee extension strength, and the international knee documentation committee questionnaire. Results: Significant between-limb differences were identified for the ACLR group only and asymmetry scores increased in those with a history of ACLR (P < 0.001) compared to controls. SLDVJ RSI and knee extension torque were significant predictors of 10 second hop height (R2 = 20.1%) and RSI (R2 = 47.1%). Conclusions: Vertical hop deficits are present following ACLR even after completing a comprehensive rehabilitation program. This may be due to reduced knee extension and reactive strength. Vertical hop tests warrant inclusion as part of return to sport test battery.

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Section: O N L I N E F I R S Tmentioning

confidence: 99%

Residual deficits in reactive strength indicate incomplete restoration of athletic qualities following anterior cruciate ligament reconstruction in professional soccer players

Read

Davies

Bishop

et al. 2020

Journal of Athletic Training

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“…Such a mechanical characteristic would appear to be relevant to a variety of athletic tasks including jumping, sprint running, and change of direction and indeed the variants of RSI have been shown to differentiate between athletes from different sports [13] and identify different force-time and power-time characteristics during jumping tasks [14]. Furthermore, the RSI variants have been shown to be reliable [15,16,17,18]. These characteristics have resulted in the use of the RSI and RSI MOD to select the intensity of plyometric exercises and monitor the adaptations to plyometric training methods [10,15,19,20].…”

Section: Introductionmentioning

confidence: 99%

Assessing Plyometric Ability during Vertical Jumps Performed by Adults and Adolescents

Snyder

Munford

Connaboy

et al. 2018

Sports

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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.

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“…The DJ RSI test has been widely used as a measure of reactive strength during performance ( Byrne et al, 2017 ; Cronin and Hansen, 2005 ). This test emphasises shorter ground contact and maximum jump height which were thought to promote reflex potentiation and elastic energy recoil ( Komi and Bosco, 1978 ).…”

Section: Discussionmentioning

confidence: 99%

“…Hence, higher levels of reactive strength may be translated to better sprint performance as both variables emphasise a rapid SSC. However, the RSI test’s heavy dependence on ground contact time may not be favourable ( Barr and Nolte, 2011 ) as it may be unable to differentiate between athletes who are “contact time” dominant and those who are “jump height” dominant ( Byrne et al, 2017 ). Thus, it was suggested to utilise optimal drop height for each individual as opposed to a default drop height (as used in this study) when addressing the DJ RSI ( Byrne et al, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

“…However, the RSI test’s heavy dependence on ground contact time may not be favourable ( Barr and Nolte, 2011 ) as it may be unable to differentiate between athletes who are “contact time” dominant and those who are “jump height” dominant ( Byrne et al, 2017 ). Thus, it was suggested to utilise optimal drop height for each individual as opposed to a default drop height (as used in this study) when addressing the DJ RSI ( Byrne et al, 2017 ). Irrespective of the previous statement, a previous study found a moderate relationship between the RSI and sprint speed, it also noted that DJ height had a stronger correlation than the RSI ( Barr and Nolte, 2011 ).…”

Section: Discussionmentioning

confidence: 99%

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The Reactive Bounding Coefficient as a Measure of Horizontal Reactive Strength to Evaluate Stretch-Shortening Cycle Performance in Sprinters

Washif¹,

Kok

2020

Journal of Human Kinetics

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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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Interday Reliability of the Reactive Strength Index and Optimal Drop Height

Cited by 45 publications

References 12 publications

Residual deficits in reactive strength indicate incomplete restoration of athletic qualities following anterior cruciate ligament reconstruction in professional soccer players

Residual deficits in reactive strength indicate incomplete restoration of athletic qualities following anterior cruciate ligament reconstruction in professional soccer players

Assessing Plyometric Ability during Vertical Jumps Performed by Adults and Adolescents

The Reactive Bounding Coefficient as a Measure of Horizontal Reactive Strength to Evaluate Stretch-Shortening Cycle Performance in Sprinters

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