Intra-Day and Inter-Day Reliability and Usefulness of Performance, Kinetic and Kinematic Variables during Drop Jumping in Hurling Players

The aim of this study was to estimate the intra-day and inter-day reliability and usefulness of performance (Jump height (JH), ground contact time (GCT) and reactive strength index (RSI)), kinetic (force, power, eccentric rate of force development [E-RFD] and leg stiffness [LS]) and kinematic (velocity) variables during drop jumping (DJ) in hurling players. Seventeen (n = 17; mean +/- SD; age = 23.35 +/- 5.78 years, height = 178.35 +/- 6.30 cm, body mass = 78.62 +/- 8.06 kg) male club-level hurling players completed two maximal DJs from 0.20, 0.30, 0.40, 0.50 and 0.60 m drop heights on three testing days separated by 5-9 days of rest. Reliability was assessed using the coefficient of variation percentage (CV% <= 15%) and intraclass correlation coefficient (ICC > 0.70). For intra-day reliability, GCT (0.40 m, 0.50 m and 0.60 m), peak force (absolute and relative) (0.40 m and 0.50 m) and leg stiffness (0.40 m and 0.50 m) were found to be unreliable (ICC = 0.32-0.68 and CV% = 3.67-11.83%) from those specific drop heights. All other variables were found to be reliable (ICC = 0.72-0.98 and CV% = 1.07-14.02%) intra-day. All variables were found to be reliable (ICC = 0.72-0.96 and CV% = 2.57-14.68%) inter-day except for relative peak force and absolute and relative eccentric RFD (0.30 m and 0.40 m) (ICC = 0.68-0.90 and CV% = 7.76-16.47%). Practitioners have multiple reliable DJ performance, kinetic and kinematic variables for performance testing and training purposes.