Veugelers, KR, Naughton, GA, Duncan, CS, Burgess, DJ, and Graham, SR. Validity and reliability of a submaximal intermittent running test in elite Australian football players. J Strength Cond Res 30(12): 3347-3353, 2016-The aim of this article was to determine the validity and reliability of a submaximal intermittent running (SIR) test in elite Australian rules football (ARF) players. Heart rate (HR) responses of 38 elite ARF players to both the SIR and the yo-yo intermittent recovery 2 (YYIR2) tests were compared over 2 trials. Linear regression analysis was used to examine the relationship between SIR test HR responses and YYIR2 test performance. Heart rate responses of 25 elite ARF players to the SIR test were monitored over 3 trials. Day-to-day reliability was determined using intraclass correlation coefficient (ICC), typical error of measurement, coefficient of variation (CV), and smallest worthwhile change. Large inverse correlations were reported between 2-, 3-, and 4-minute HR during the SIR test and YYIR2 test distance (r = -0.58 to -0.61, p < 0.01). Heart rate recovery after 2 and 3 minutes of the SIR test was moderately correlated to YYIR2 distance (r = 0.32-0.35, p ≤ 0.05). Strong correlations for ICC (r = 0.90-0.97) and low CV (1.3-9.2%) were reported for all HR variables. Monitoring HR during the SIR test is a valid and reliable indicator of YYIR2 test performance in elite ARF players. These findings support the use of the SIR test as a regular and non-fatiguing indicator of intermittent running capacity.