Selective effects of different fatigue protocols on the function of upper body muscles assessed through the force-velocity relationship

Purpose This study explored the feasibility of the force-velocity relationship (F-V) to detect the acute effects of different fatigue protocols on the selective changes of the maximal capacities of upper body muscles to produce force, velocity, and power. Methods After determining the bench press one-repetition maximum (1RM), participants' F-V relationships were assessed during the bench press throw exercise on five separate sessions after performing one of the following fatiguing protocols: 60% 1RM failure, 60% 1RM non-failure, 80% 1RM failure, 80% 1RM non-failure, and no-fatigue. In the non-failure protocols, participants performed half the maximum number of repetitions than in their respective failure protocols. Results The main findings revealed that (1) all F-V relationships were highly linear (median r = 0.997 and r = 0.982 for averaged across participants and individual data, respectively), (2) the fatiguing protocols were ranked based on the magnitude of power loss as follows: 60% 1RM failure > 80% 1RM failure > 60% 1RM non-failure > 80% 1RM non-failure, while (3) the assessed maximum force and velocity outputs showed a particularly prominent reduction in the protocols based on the lowest and highest levels of fatigue (i.e., 80% 1RM non-failure and 60% 1RM failure), respectively. Conclusions The results support the use of F-V to assess the effects of fatigue on the distinctive capacities of the muscles to produce force, velocity, and power output while performing multi-joint tasks, while the assessed maximum force and velocity capacities showed a particularly prominent reduction in the protocols based on the lowest and highest levels of fatigue (i.e., 80% 1RM non-failure and 60% 1RM failure), respectively.