title: Delayed Effect of Blood Flow-restricted Resistance Training on Rapid Force Capacity.
abstract: The aim of the present study was to investigate the effect and time course of high-frequent low-load blood flow-restricted (BFR) resistance training on rapid force capacity (i.e., rate of torque development [RTD]).
  
  
  
  Ten male subjects (22.8 ± 2.3 yr) performed four sets of knee extensor exercise (20% one-repetition maximum) to concentric failure during concurrent BFR of the thigh (100 mm Hg), and eight work-matched controls (21.9 ± 3.0 yr) trained without BFR (CON). Twenty-three training sessions were performed within 19 d. Maximal slow and fast knee joint velocity muscle strength and rapid force capacity (e.g., RTD) and evoked twitch contractile parameters were assessed before (Pre) and 5 and 12 d after (Post5 and Post12) training. Muscle biopsies were obtained Pre, after 8 d (Mid8), and 3 and 10 d after (Post3 and Post10) training to examine changes in myofiber area and expression of myocellular proteins known to be modified by cellular stress (CaMKII, annexin A6, SNO-CYS).
  
  
  
  RTD remained unchanged after BFR training at Post5, while increasing 15%-20% Post12 (P < 0.01). Evoked muscle twitch parameters showed a general decline Post5 (P < 0.01) while returning to baseline levels at Post12. All contractile parameters essentially remained unchanged in CON. Elevated CaMKII was observed with BFR training at Post3 (57%) and Post10 (71%) (P < 0.05), whereas SNO-CYS increased in CON at Mid8 (P < 0.05).
  
  
  
  This study is the first to show that low-load resistance exercise performed with BFR leads to marked increases in rapid force capacity (RTD). However, a general delayed adaptive response was observed for voluntary contractile parameters (including RTD) in parallel with a decline and subsequent recovery in evoked contractile properties, suggesting the delayed gain in rapid force capacity mainly have a peripheral origin.
authors.affiliation: 1Department of Sports Science and Clinical Biomechanics and SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense, DENMARK; 2Department of Orthopedic Surgery, Odense University Hospital, Odense, DENMARK; 3Department of Orthopedic Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, DENMARK; and 4Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet Glostrup, University of Copenhagen, Copenhagen, DENMARK.
authors.forename: Jakob Lindberg
authors.initials: JL
authors.lastname: Nielsen
authors.forename: Ulrik
authors.initials: U
authors.lastname: Frandsen
authors.forename: Tatyana
authors.initials: T
authors.lastname: Prokhorova
authors.forename: Rune Dueholm
authors.initials: RD
authors.lastname: Bech
authors.forename: Tobias
authors.initials: T
authors.lastname: Nygaard
authors.forename: Charlotte
authors.initials: C
authors.lastname: Suetta
authors.forename: Per
authors.initials: P
authors.lastname: Aagaard
mesh_terms: D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009124:Muscle Proteins / Q000378:metabolism; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply*; D058748:Pain Perception / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D055070:Resistance Training / Q000379:methods*; D013848:Thigh / Q000098:blood supply; D055815:Young Adult
chemical_list: D009124:Muscle Proteins