Convergent validity and reliability of a novel repeated agility protocol in junior rugby league players

Abstract

Background: Rugby league involves repeated, complex, change-of-direction movements, although there are no test protocols that specifically assesses these physical fitness profiles. Thus, the current study examined the convergent validity and reliability of a repeated Illinois Agility (RIA) protocol in adolescent Rugby League players. Methods: Twenty-two junior Rugby League players completed 4 sessions with each separated by 7 days. Initially, physical fitness characteristics at baseline (i.e., multi-stage fitness, countermovement jump, 30-m sprint, single-effort agility and repeated sprint ability [RSA]) were assessed. The second session involved a familiarisation of RIA and repeated T-agility test (RTT) protocols. During the third and fourth sessions, participants completed the RIA and RTT protocols in a randomised, counterbalanced design to examine the validity and test-retest reliability of these protocols. Results: For convergent validity, significant correlations were identified between RIA and RTT performances (r= >0.80; p<0.05). For contributors to RIA performance, significant correlations were identified between all baseline fitness characteristics and RIA (r = >0.71; p < 0.05). Reliability of the RIA protocol was near perfect with excellent intra-class correlation coefficient (0.87-0.97), good ratio limits of agreement (×/÷ 1.05-1.06) and low coefficient of variations (1.77-1.97%). Conclusions: The current study has demonstrated the RIA to be a simple, valid and reliable field test that can provide coaches with information about their athlete’s ability to sustain high intensity, multi-directional running efforts.