Sensitivity of the Load–Velocity Relationship Variables to Discriminate the Level of Fatigue Induced by Multiple Sets of the Hexagonal Barbell Deadlift Exercise

S‚ ent ¨urk, D, Akyildiz, Z, Janicijevic, D, and Garc´ıa-Ramos, A. Sensitivity of the load–velocity relationship variables to discriminate the level of fatigue induced by multiple sets of the hexagonal barbell deadlift exercise. J Strength Cond Res 39(4): 407–413, 2025—This study aimed to evaluate changes in load–velocity (L-V) relationship variables (L0, v0, and Aline) after different fatigue protocols and to determine their correlation with changes in 1 repetition maximum (1RM). After determining the hexagonal barbell deadlift (HBD) 1RM, 27 resistance-trained men randomly completed 3 sessions that only differed in the activity performed between 2 incremental loading tests that were performed at the beginning (presession) and end (postsession) of the session: (a) control protocol: no training; (b) moderate-fatigue protocol: 5 sets of the HBD exercise at 70% 1RM performing half the maximum possible number of repetitions; and (c) high-fatigue protocol: 5 sets of the HBD exercise performed to failure against the 70% 1RM. Significance was set at an alpha level of 0.05. The reduction of 1RM (p , 0.001), v0 (p 5 0.014), and Aline (p , 0.001) at postsession was greater for the high-fatigue protocol, followed by the moderate-fatigue protocol, and finally the control protocol. The changes in L0 did not differ between the fatigue protocols (p 5 0.372). The percent change in the 1RM at postsession was significantly correlated with the percent change in Aline (r 5 0.714) and L0 (r 5 0.540), but not with the percent changes in v0 (r 5 0.177). These results suggest that the L-V relationship variables offer a highly sensitive and practical solution for fatigue monitoring.