Relationship Between Reactive Strength Index Variants in Rugby League Players.

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Publisher: National Strength and Conditioning Association
Document Type: Report; Brief article
Length: 368 words

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Byline: John J. McMahon, Directorate of Sport, Exercise and Physiotherapy, University of Salford, Greater Manchester, United Kingdom;; Timothy J. Suchomel, Department of Human Movement Sciences, Carroll University, Waukesha, Wisconsin; and; Jason P. Lake, Department of Sport and Exercise Sciences, University of Chichester, West Sussex, United Kingdom; Paul Comfort, Directorate of Sport, Exercise and Physiotherapy, University of Salford, Greater Manchester, United Kingdom; Abstract McMahon, JJ, Suchomel, TJ, Lake, JP, and Comfort, P. Relationship between reactive strength index variants in rugby league players. J Strength Cond Res 35(1): 280-285, 2021--Two reactive strength index (RSI) variants exist, the RSI and RSI modified (RSImod), which are typically calculated during the drop jump (DJ) and countermovement jump (CMJ), respectively. Both RSI variants have been used to monitor athletes' ability to complete stretch-shortening cycle actions quickly, but they have never been compared. The purpose of this study was to determine whether they yield relatable information about reactive strength characteristics. Male professional rugby league players (n = 21, age = 20.8 Ø 2.3 years, height = 1.82 Ø 0.06 m and body mass = 94.3 Ø 8.4 kg) performed 3 DJs (30 cm) and CMJs on a force plate. Reactive strength index and RSImod were subsequently calculated by dividing jump height (JH) by ground contact time (GCT) and time to take-off (TTT), respectively. All variables were highly reliable (intraclass correlation coefficient [greater than or equal] 0.78) with acceptable levels of variability (coefficient of variation ëñ8.2%), albeit larger variability was noted for DJ variables. Moreover, there was a large relationship between RSI and RSImod (r = 0.524, p = 0.007), whereas very large relationships were noted between JHs (r = 0.762, p

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Gale Document Number: GALE|A671348314