title: Blood flow restriction increases metabolic stress but decreases muscle activation during high-load resistance exercise.
abstract: BACKGROUND
  We investigated differences in metabolic stress (lactate) and muscle activation (electromyography; EMG) when high-load resistance exercise (HL) is compared with a condition in which blood flow restriction (BFR) is applied during the exercise or during the rest interval.
  
  
  METHODS
  Twelve participants performed HL with BFR during the intervals (BFR-I), during the set (BFR-S), and without BFR. Each condition consisted of 3 sets of 8 repetitions with knee extension at 70% of 1-repetition maximum. Lactate and root mean square (RMS) from the surface EMG of the vastus lateralis were calculated.
  
  
  RESULTS
  Lactate increased in all protocols but was higher with BFR-I than with BFR-S and HL. RMS decreased under all conditions, with a larger effect size in BFR-I (1.47) than in BFR-S (0.66) and HL (0.59).
  
  
  CONCLUSIONS
  BFR-I increases lactate, possibly as a result of reduced restoration of ATP. Muscle activation seems to be impacted by mechanical stress but may be reduced by metabolic stress. Muscle Nerve 57: 107-111, 2018.
authors.affiliation: School of Physical Education and Sport, University of São Paulo, Av. Prof. Mello Moraes, 65, Butantã, São Paulo, São Paulo, Brazil, 05508-030.
authors.forename: Emerson L
authors.initials: EL
authors.lastname: Teixeira
authors.affiliation: Faculty of Physical Education, University of Campinas, Campinas, São Paulo, Brazil.
authors.forename: Renato
authors.initials: R
authors.lastname: Barroso
authors.affiliation: School of Physical Education and Sport, University of São Paulo, Av. Prof. Mello Moraes, 65, Butantã, São Paulo, São Paulo, Brazil, 05508-030.
authors.forename: Carla
authors.initials: C
authors.lastname: Silva-Batista
authors.affiliation: School of Physical Education and Sport, University of São Paulo, Av. Prof. Mello Moraes, 65, Butantã, São Paulo, São Paulo, Brazil, 05508-030.
authors.forename: Gilberto C
authors.initials: GC
authors.lastname: Laurentino
authors.affiliation: Department of Health, Exercise Science, and Recreation Management, Kevser Ermin Applied Physiology Laboratory, The University of Mississippi, Oxford, Mississippi, USA.
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Loenneke
authors.affiliation: School of Physical Education and Sport, University of São Paulo, Av. Prof. Mello Moraes, 65, Butantã, São Paulo, São Paulo, Brazil, 05508-030.
authors.forename: Hamilton
authors.initials: H
authors.lastname: Roschel
authors.affiliation: School of Physical Education and Sport, University of São Paulo, Av. Prof. Mello Moraes, 65, Butantã, São Paulo, São Paulo, Brazil, 05508-030.
authors.forename: Carlos
authors.initials: C
authors.lastname: Ugrinowitsch
authors.affiliation: School of Physical Education and Sport, University of São Paulo, Av. Prof. Mello Moraes, 65, Butantã, São Paulo, São Paulo, Brazil, 05508-030.
authors.forename: Valmor
authors.initials: V
authors.lastname: Tricoli
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology; D019344:Lactic Acid / Q000378:metabolism; D007866:Leg / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism*; D052097:Quadriceps Muscle / Q000502:physiology; D012039:Regional Blood Flow; D055070:Resistance Training; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D019344:Lactic Acid; D000255:Adenosine Triphosphate
keywords: blood flow restricted exercise; high load; metabolites; motor unit recruitment; strength training