Influence of traditional and cluster set plyometric warm-ups on reactive strength index and leg stiffness in male rugby players

BACKGROUND: Cluster set plyometrics (CSP) promise greater muscular performance than traditional set plyometrics (TSP). OBJECTIVE: The purpose of this study was to compare the influence of TSP and CSP warm-ups via bounce drop jump (BDJ) on reactive strength index (RSI), leg stiffness (K[Formula: see text]), ground contact time (CT), and jump height (JH). METHODS: Thirteen male rugby players (age, 20.92 [Formula: see text] 2.25 years; body mass, 82.88 [Formula: see text] 9.22 kg; rugby experience, 3.61 [Formula: see text] 3.04 years; training volume, 10.69 [Formula: see text] 3.75 h/week) were recruited for this study from two rugby clubs competing in the Second League in Turkey. The players completed 3 different set configurations of equal jump volume 72 h apart in a randomized, balanced order. The sets configurations were TSP (2 [Formula: see text] 10 jump with 90 s interval), CSP-1 (4 [Formula: see text] 5 jump with 30 s interval), and CSP-2 (10 [Formula: see text] 2 jump with 10 s interval). Pre and post values of RSI, K[Formula: see text], CT, and JH on each session were determined via the Myotest Pro system. RESULTS: Statistically significant changes were not found between pre- and post-values of RSI, K[Formula: see text], CT, and JH in each session, either positive or negative ([Formula: see text] 0.05), as well as among the three different set configurations in any of the outcome variables according to post-results ([Formula: see text] 0.05). These findings indicated that low-volume TSP and CSP bounce drop jump had no effect on RSI, K[Formula: see text], CT, and JH in male rugby players. CONCLUSIONS: Set configurations, jump volume, and intensity applied in this study may be too low to change muscle-tendon complex (MTC) stiffness and produce a post-activation potentiation (PAP) effect. Further research, with larger samples, is needed to determine which set configurations, jump volume ([Formula: see text] 20 jumps/session), and intensity (box height [Formula: see text] 30 cm) are the best option for enhancement of RSI, K[Formula: see text], CT, and JH.