Remarkable Effects Of Continuous Blood Flow Restriction During Multiple Sets Of Low Intensity Resistance Exercise

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PURPOSE: Skeletal muscle bulk and strength are now becoming important therapeutic targets in cardiovascular rehabilitation. However, usual resistance training needs to load muscles intensively and is hard for cardiac and elder subjects. Resistance training with blood flow restriction (BFR) is a new method to effectively increase muscle bulk and strength despite using lower workload, whereas we reported that usual low-intensity resistance exercise with BFR protocol could not result in energetically sufficient stimulus. The purpose of this study was to examine the optimal low-intensity resistance exercise with 2 difference BFR protocols composed of multiple sets in terms of muscle energy metabolism. METHODS: Twelve healthy subjects (22 ± 1 yr, mean ± SE) performed 3 sets of 1-min unilateral plantar-flexion (30 repetitions) with 1-min rest intervals. Protocols were randomly performed with low-intensity exercise by using 20%1RM (L) and high-intensity exercise by using 65%1RM (H) without BFR, L with intermittent (only during exercise) BFR (L-IBFR) and L with continuous BFR (L-CBFR). Phosphocreatine (PCr) and intramuscular pH were measured using 31P-Magnetic resonance spectroscopy. RESULTS: The changes of PCr and intramuscular pH during all-sets among low-intensity conditions were significantly increased by applying BFR (L vs. L-IBFR and L-CBFR, p<0.05). In the PCr depletion (L-CBFR: 15.5 ± 1.5, L-IBFR: 25.0 ± 1.3, H: 15.9 ± 1.3 mM) and intramuscular pH decrease (L-CBFR: 6.84 ± 0.02, L-IBFR: 6.96 ± 0.02, H: 6.87 ± 0.02) at the end of final set, L-CBFR was significantly greater than those in L-IBFR (p<0.05) and similar to those in L-IBFR. Moreover, integrated PCr depletion during exercise session with rest intervals was equal level to that in H (L-CBFR: 3952 ± 315 vs. H; 4126 ± 335 sec×mM, ns). CONCLUSIONS: Effects of low-intensity resistance exercise with BFR might be sufficiently enhanced by continuous BFR with multiple sets.