Cornejo-Daza, PJ, Sánchez-Valdepeñas, J, Páez-Maldonado, J, Rodiles-Guerrero, L, Sánchez-Moreno, M, Gómez-Guerrero, G, León-Prados, JA, and Pareja-Blanco, F. Acute responses to different lifting velocities during squat training with and without blood flow restriction. J Strength Cond Res 39(3): 307-317, 2025-The aims of the research were to compare the acute mechanical, metabolic, neuromuscular, and muscle mechanical responses to different lifting velocities (maximal vs. half-maximal) under distinct blood flow conditions (free [FF] vs. restricted [BFR]) in full-squat (SQ). Twenty resistance-trained males performed 4 protocols that differed in the velocity at which loads were lifted (MaxV: maximal velocity vs. HalfV: half-maximal velocity) and in the blood flow condition (FF: free-flow vs. BFR: 50% of arterial occlusion pressure). The relative intensity (60% 1 repetition maximum), volume (3 sets of 8 repetitions), and resting time (2 minutes) were matched between protocols. Mean propulsive force (MPF), mean propulsive velocity (MPV), mean propulsive power (MPP), and electromyography (EMG) values were recorded for each repetition. Tensiomyography (TMG), blood lactate, countermovement jump (CMJ), maximal voluntary isometric contraction in 90° SQ, and performance with the load that elicited a 1-m·s -1 velocity at baseline measurements (V1-load) in SQ were assessed at pre-exercise and postexercise. The MaxV protocols showed significantly greater MPF, MPV, MPP, and EMG amplitude during the exercise than the HalfV protocols (velocity effect, p <
0.05). The FF protocols achieved higher MPF and MPP during exercise than BFR (BFR effect, p <
0.05). The BFR protocols induced greater blood lactate after exercise (BFR × time interaction, p = 0.02), along with higher postexercise impairments in mechanical performance (BFR × time interaction, p <
0.05). The MaxV protocols elicited superior performance and greater muscle activation during exercise. The BFR protocols resulted in lower force and power production during exercise and exhibited higher performance impairments and increased metabolic stress postexercise.