Training Effects of Traditional versus Cluster Set Configuration with and without Blood Flow Restriction.

Purpose: This study compared the effects of four different resistance training (RT) programs that differed in the set configuration (cluster vs. traditional) and the blood flow condition [free-flow (FF) vs. blood flow restriction (BFR)] on strength, neuromuscular and hypertrophic adaptations.Methods: Forty-two resistance-trained males were randomly assigned into four protocols that differed in the set configuration (TRA: without rest between repetitions vs. CLU: 30 s rest every 2 repetitions) and in the blood flow condition [FF vs. BFR (50% of arterial occlusion pressure)]. Subjects followed an 8-week RT program, twice per week, with similar intensity (55%-65% 1RM), sets (3), repetitions per set (10-6), and resting time (2 minutes) in the full-squat (SQ) exercise. Before and after the RT program, they were evaluated for: 1) muscle size of the vastus lateralis; 2) vertical jump; 3) maximal isometric contraction; 4) progressive loading test; and 5) fatigue test.Results: BFR-TRA and FF-CLU induced greater increases in 1RM, and velocity against submaximal loads than FF-TRA and BFR-CLU (BFR × time and CLU × time interactions, p = 0.02). The TRA protocols showed greater increases in maximal isometric force than CLU (CLU × time interaction, p = 0.03). BFR did not enhance jump performance unlike the FF protocols (p < 0.01). The TRA protocols induced greater hypertrophy in the distal region of the vastus lateralis than CLU protocols (CLU × time interaction, p = 0.04), with BFR-TRA producing the greatest gains in all vastus lateralis sections.Conclusions: The different combinations of set configurations and blood flow conditions resulted in highly specific adaptations that illustrate the potential of adaptation for each protocol. The divergent underlying mechanisms of CLU and BFR methodologies may offset each other when combined.