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

Abstract

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.

Differences in anthropometric and physical performance characteristics between U17, U19, and Senior Irish female international football players

“…25,34 Coymns et al. 24 reported lower levels of RSI (1.22 ± .47 m/s) in collegiate level female team sport athletes when compared to the athletes in this current study (see Table 2). These differences may be attributed to the competition level and training status of the athletes involved in both studies (i.e.…”

“…11 Therefore, assessment of female international football player's stretch-shortening cycle capabilities is of interest to sports scientists and strength and conditioning coaches. 24 To the author's knowledge, this study is the first to report the RSI measures of female international football players across several age groups via the 10/5 repeated jump test. In this study the senior age group (1.56 ± .25 m/s) exhibited higher levels of reactive strength in comparisons to the U17 (1.31 ± .31 m/s) and U19 (1.34 ± .28 m/s) categories.…”

“…23 The 10/5 RJT has been demonstrated to be a reliable and valid assessment method of RSI in female team sport athletes. 24 The 10/5 RJT required the participants to perform a counter movement jump followed by 10 maximal rebound jumps. 23 During the test, participants were instructed to maintain hands akimbo to standardise the protocol and negate upper body interference.…”

Age-Group Differences in Reactive Strength and Measures of Intra-day Reliability in Female International Footballers

“…Currently, limited data exists detailing the reliability of reactive strength index (RSI) via 10/5 RJT in female team sport athletes. Only one study has assessed the reliability of the 10/5 RJT measurement of RSI (26). Coymns et al (2019) reported interday reliability of (CV= 10%, ICC = 0.91) in female collegiate team sport (26).…”

“…Only one study has assessed the reliability of the 10/5 RJT measurement of RSI (26). Coymns et al (2019) reported interday reliability of (CV= 10%, ICC = 0.91) in female collegiate team sport (26). While the reliability and validity of several jump tests have been assessed in elite male populations the topic has been poorly investigated in elite female populations (10,16,18,25).…”