title: Blood flow restricted and traditional resistance training performed to fatigue produce equal muscle hypertrophy.
abstract: This study investigated the hypertrophic potential of load-matched blood-flow restricted resistance training (BFR) vs free-flow traditional resistance training (low-load TRT) performed to fatigue. Ten healthy young subjects performed unilateral BFR and contralateral low-load TRT elbow flexor dumbbell curl with 40% of one repetition maximum until volitional concentric failure 3 days per week for 6 weeks. Prior to and at 3 (post-3) and 10 (post-10) days post-training, magnetic resonance imaging (MRI) was used to estimate elbow flexor muscle volume and muscle water content accumulation through training. Acute changes in muscle thickness following an early vs a late exercise bout were measured with ultrasound to determine muscle swelling during the immediate 0-48 h post-exercise. Total work was threefold lower for BFR compared with low-load TRT (P < 0.001). Both BRF and low-load TRT increased muscle volume by approximately 12% at post-3 and post-10 (P < 0.01) with no changes in MRI-determined water content. Training increased muscle thickness during the immediate 48 h post-exercise (P < 0.001) and to greater extent with BRF (P < 0.05) in the early training phase. In conclusion, BFR and low-load TRT, when performed to fatigue, produce equal muscle hypertrophy, which may partly rely on transient exercise-induced increases in muscle water content.
authors.affiliation: Section for Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Farup
authors.affiliation: Department of Biomedicine, Aarhus University, Aarhus, Denmark.
authors.forename: F
authors.initials: F
authors.lastname: de Paoli
authors.affiliation: Section for Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Bjerg
authors.affiliation: Section for Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Riis
authors.affiliation: MR-Research Centre, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Ringgard
authors.affiliation: Section for Sport Science, Department of Public Health, Aarhus University, Aarhus, Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Vissing
mesh_terms: D000328:Adult; D001132:Arm; D004576:Electromyography; D005260:Female; D006801:Humans; D006984:Hypertrophy / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000737:chemistry / Q000473:pathology* / Q000502:physiology*; D063806:Myalgia / Q000209:etiology; D009929:Organ Size; D012039:Regional Blood Flow / Q000502:physiology*; D055070:Resistance Training / Q000009:adverse effects / Q000379:methods*; D014463:Ultrasonography; D014867:Water / Q000032:analysis; D055815:Young Adult
chemical_list: D014867:Water
keywords: fiber recruitment; low-intensity resistance training; muscle volume; vascular occlusion; volitional fatigue