title: Brachial blood flow under relative levels of blood flow restriction is decreased in a nonlinear fashion.
abstract: BACKGROUND
  Blood flow restriction (BFR), the application of external pressure to occlude venous return and restrict arterial inflow, has been shown to increase muscular size and strength when combined with low-load resistance exercise. BFR in the research setting uses a wide range of pressures, applying a pressure based upon an individual's systolic pressure or a percentage of occlusion pressure; not a directly determined reduction in blood flow. The relationship between relative pressure and blood flow has not been established.
  
  
  OBJECTIVE
  To measure blood flow in the arm under relative levels of BFR.
  
  
  METHODS
  Forty-five people (18-40 years old) participated. Arterial occlusion pressure in the right arm was measured using a 5-cm pneumatic cuff. Blood flow in the brachial artery was measured at rest and at pressures between 10% and 90% of occlusion using ultrasound.
  
  
  RESULTS
  Blood flow decreased in a nonlinear, stepped fashion. Blood flow decreased at 10% of occlusion and remained constant until decreasing again at 40%, where it remained until 90% of occlusion.
  
  
  CONCLUSIONS
  The decrease in brachial blood flow is not proportional to the applied relative pressure. The prescription of blood flow restriction should take into account the stimulus provided at each relative level of blood flow.
authors.affiliation: Kevser Ermin Applied Physiology Laboratory, Department of Health, Exercise Science, and Recreation Management, The University of Mississippi, University, MS, USA.
authors.forename: J Grant
authors.identifier: http://orcid.org/0000-0002-0776-0577
authors.initials: JG
authors.lastname: Mouser
authors.affiliation: Department of Kinesiology, Kansas State University, Manhattan, KS, USA.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Ade
authors.affiliation: Department of Health and Exercise Science, The University of Oklahoma, Norman, OK, USA.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Black
authors.affiliation: Department of Health and Exercise Science, The University of Oklahoma, Norman, OK, USA.
authors.forename: Debra A
authors.initials: DA
authors.lastname: Bemben
authors.affiliation: Department of Health and Exercise Science, The University of Oklahoma, Norman, OK, USA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Bemben
mesh_terms: D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007511:Ischemia / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008955:Models, Cardiovascular; D018482:Muscle, Skeletal / Q000098:blood supply*; D017711:Nonlinear Dynamics; D012039:Regional Blood Flow; D013997:Time Factors; D014111:Tourniquets; D018615:Ultrasonography, Doppler, Color; D034941:Upper Extremity; D055815:Young Adult
keywords: arterial flow; kaatsu; occlusion training; relative pressure; ultrasound