Malone, S, Hughes, B, and Collins, K. The influence of exercise-to-rest ratios on physical and physiological performance during hurling-specific small-sided games. J Strength Cond Res 33(1): 180–187, 2019—The current study examined the impact of different exercise-to-rest ratios on hurling-specific small-sided games (SSG). Thirty-four (n = 34) hurling players were monitored during an in-season training period. Heart rate (Polar Electro Oy, Kempele, Finland) and global positioning system technology (4-Hz; VX Sport, Lower Hutt, New Zealand) were used to analyze the physical and physiological differences between exercise-to-rest ratios across bouts of SSG. Total distance (m), high-speed distance (m) (≥17 km·h−1), very high-speed distance (≥22 km·h−1) (m), total accelerations (n), acceleration distance (m), peak velocity (km·h−1), and % maximum heart rate (%HRmax) were measured. Exercise-to-rest ratios of 2:1 (d = 0.65 ± 0.12; moderate), and 1:1 (d = 0.43 ± 0.12; small), resulted in significant reductions in high-speed distance, very high-speed distance, and acceleration distance. Exercise-to-rest ratios of 1:2 (d = 0.63 ± 0.21; moderate), and 1:3 (d = 1.23 ± 0.22; large), resulted in increased high-speed distance, very high-speed distance, and acceleration distance, but only after the third bout. The first bout of SSG resulted in the lowest %HRmax when compared with all other bouts (d = 0.63 ± 0.22; moderate). A significant bout-to-bout increase in %HRmax independent of exercise-to-rest ratio (d = 0.25 ± 0.04; small) was observed. Exercise-to-rest ratios of 2:1 (d = 0.65 ± 0.14; moderate), and 1:1 (d = 0.65 ± 0.24; moderate), resulted in significantly higher %HRmax during all SSG bouts; however, exercise-to-rest ratios of 1:2 (d = 0.25 ± 0.04; small), and 1:3 (d = 0.15 ± 0.04; trivial), resulted in lower %HRmax during SSG. Coaches should be aware that reducing the rest between bouts of SSGs (2:1 and 1:1 exercise-to-rest ratios) increases the physiological response (%HRmax) with reduced high-speed running performances. Coaches now have data to allow them tp best prepare for session needs with regard to specific SSG exercise-to-rest ratios.