title: Effect of multiple set on intramuscular metabolic stress during low-intensity resistance exercise with blood flow restriction.
abstract: Our previous study reported that intramuscular metabolic stress during low-intensity resistance exercise was significantly enhanced by combining blood flow restriction (BFR); however, they did not reach the levels achieved during high-intensity resistance exercise. That study was performed using a single set of exercise; however, usual resistance exercise consists of multiple sets with rest intervals. Therefore, we investigated the intramuscular metabolic stress during multiple-set BFR exercises, and compared the results with those during multiple-set high-intensity resistance exercise. Twelve healthy young subjects performed 3 sets of 1-min unilateral plantar flexion (30 repetitions) with 1-min intervals under 4 different conditions: low intensity (L, 20% 1 RM) and high intensity (H, 65% 1 RM) without BFR, and L with intermittent BFR (IBFR, only during exercise) and with continuous BFR (CBFR, during rest intervals as well as exercise). Intramuscular metabolic stress, defined as intramuscular metabolites and pH, and muscle fiber recruitment were evaluated by 31P-magnetic resonance spectroscopy. The changes of intramuscular metabolites and pH during IBFR were significantly greater than those in L but significantly lower than those in H. By contrast, those changes in CBFR were similar to those in H. Moreover, the fast-twitch fiber recruitment, evaluating by a splitting Pi peak, showed a similar level to H. In conclusion, the multiple sets of low-intensity resistance exercise with continuous BFR could achieve with the same metabolic stress as multiple sets of high-intensity resistance exercise.
authors.affiliation: Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Suga
authors.forename: Koichi
authors.initials: K
authors.lastname: Okita
authors.forename: Shingo
authors.initials: S
authors.lastname: Takada
authors.forename: Masashi
authors.initials: M
authors.lastname: Omokawa
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Kadoguchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Yokota
authors.forename: Kagami
authors.initials: K
authors.lastname: Hirabayashi
authors.forename: Masashige
authors.initials: M
authors.lastname: Takahashi
authors.forename: Noriteru
authors.initials: N
authors.lastname: Morita
authors.forename: Masahiro
authors.initials: M
authors.lastname: Horiuchi
authors.forename: Shintaro
authors.initials: S
authors.lastname: Kinugawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsutsui
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism*; D012039:Regional Blood Flow / Q000502:physiology*; D055070:Resistance Training; D013312:Stress, Physiological