Malone, S and Collins, K. Relationship between individualized training impulse and aerobic fitness measures in Hurling players across a training period. J Strength Cond Res 30(11): 3140–3145, 2016—The current study examined the association between individual internal training load (individualized training impulse, iTRIMP) and aerobic fitness variables in male hurling players. Twenty hurling players (age, 25.5 ± 3.2 years; height, 178.9 ± 3.2 cm; body mass, 78.5 ± 4.5 kg) performed treadmill testing for V[Combining Dot Above]O2max, running economy (RE), and the speed at blood lactate concentrations of 2 mmol·L−1 (S2) and 4 mmol·L−1 (S4) on separate occasions before and after an 8-week training period. The Yo-Yo intermittent recovery (Yo-YoIR1, Yo-YoIR2) test performance were also assessed before and after the training period. Individualized training impulse was calculated using the blood lactate and heart rate profile of each individual player and was further assessed for each training session across the intervention period (n = 990). The results showed that iTRIMP had large to very large association with the percentage improvements in V[Combining Dot Above]O2max (r = 0.77; p = 0.002; 95% confidence interval [CI], 0.38–0.93, very large), RE (r = 0.78; p = 0.002; 95% CI, 0.40–0.93; very large), S2 (r = 0.64; p = 0.004; 95% CI, from 0.25 to 0.85; large), S4 (r = 0.78; p = 0.003; 95% CI, 0.45–0.85; very large), Yo-YoIR1 (r = 0.69; p = 0.003; 95% CI, 0.45–0.92; large), and Yo-YoIR2 (r = 0.60; p = 0.005; 95% CI, 0.45–0.92; large) performance. The study shows that iTRIMP is a means of quantifying training load in team sports and can be used to prescribe training for the maintenance or improvement of aerobic fitness during the competitive season with strong relationships seen between weekly iTRIMP measures and improvements in aerobic fitness measures.