title: Dose effect on intramuscular metabolic stress during low-intensity resistance exercise with blood flow restriction.
abstract: Our previous study reported that metabolic stress in skeletal muscle achieved by combining moderate blood flow restriction (BFR) with low-intensity resistance exercise at 20% of one repetition maximum (1 RM) could not reach the level achieved by high-intensity resistance exercise. Since the previous protocol is typical of current regimens of this type, we sought in this study to optimize the exercise protocol for low-intensity resistance exercise with BFR by examining the dose effects of exercise intensity and pressure. Twelve healthy subjects participated in this study. They were asked to perform unilateral plantar flexion for 2 min (30 repetitions/min) under six different conditions: two resistance exercises (20% 1 RM and 65% 1 RM) without BFR, and four BFR protocols. The four BFR protocols included three different exercise intensities (20, 30, and 40% 1 RM) with moderate pressure (MP) using 130% of systolic blood pressure (147+/-17 mmHg, mean+/-SD) and 20% 1 RM with high pressure at 200 mmHg. Intramuscular metabolites and pH were obtained by 31P-magnetic resonance spectroscopy. Significant dose effects on intramuscular metabolites and pH were observed for exercise intensity (P<0.001) but not for BFR pressure. The BFR protocol combining 30% 1 RM with MP had similar results as the high-intensity load at 65% 1 RM. Intramuscular metabolic stress during BFR exercise might be susceptible to increasing exercise intensity. To replace high-intensity resistance exercise, the BFR protocol might require an intensity of >or=30% 1 RM.
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: Noriteru
authors.initials: N
authors.lastname: Morita
authors.forename: Takashi
authors.initials: T
authors.lastname: Yokota
authors.forename: Kagami
authors.initials: K
authors.lastname: Hirabayashi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Horiuchi
authors.forename: Shingo
authors.initials: S
authors.lastname: Takada
authors.forename: Masashi
authors.initials: M
authors.lastname: Omokawa
authors.forename: Shintaro
authors.initials: S
authors.lastname: Kinugawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsutsui
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D001783:Blood Flow Velocity / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D013312:Stress, Physiological / Q000502:physiology*; D055815:Young Adult
chemical_list: D000255:Adenosine Triphosphate