title: Hemodynamic response to upright resistance exercise: effect of load and repetition.
abstract: OBJECTIVE
  Upright resistance exercise causes large transient fluctuations in blood pressure during and immediately after the performance. We examined the effect of resistance load and the number of repetitions on the middle cerebral artery blood flow velocity (MCAv) response during and after upright squatting exercise.
  
  
  METHODS
  Healthy males (n = 12; mean ± SD: 26 ± 5 yr) completed 30%, 60%, and 90% of their six-repetition maximum load, completing two and six repetitions of these loads during two visits (order randomized). Beat-to-beat MCAv, blood pressure, and continuous end-tidal PCO2 during exercise, at nadir, and during recovery are reported as the change from preexercise standing baseline.
  
  
  RESULTS
  During exercise, MCAvmean increased 31% ± 16% (P < 0.001) across all loads (P = 0.74) and repetitions (P = 0.89), whereas mean arterial pressure (MAP) increased (all P < 0.05) as load and repetitions increased (e.g., 122 ± 9 (two repetitions) vs 135 ± 11 mm Hg (six repetitions) and 128 ± 13 vs 143 ± 14 mm Hg, at 30% and 60%, respectively). Within the six-repetition sets, peak MCAvmean remained unchanged across the set (P = 0.61), whereas MAP increased (P = 0.003). The 90% load produced the lowest MCAvmean nadir (pooled means, -18 ± 6 vs -10 ± 7 cm·s, P < 0.001 vs 30%) and MAP nadir (-34 ± 7 and -43 ± 5 mm Hg, for two and six repetitions, respectively; P < 0.001) after exercise. Postexercise MCAvmean reductions occurred via a selective, load-dependent (P < 0.001) decrease in diastolic MCAv. MCAvmean remained below baseline for the longest period after the 90% six-repetition set (10 s postexercise, P < 0.01) and took the longest to recover (14.8 ± 6.9 s, P = 0.002).
  
  
  CONCLUSIONS
  These data indicate that higher relative loads produce a greater postexercise hypotension and result in a proportionate reduction in MCAvmean.
authors.affiliation: 1School of Sport and Exercise, Massey University, Palmerston North, NEW ZEALAND; 2Department of Physiology, University of Otago, Dunedin, NEW ZEALAND; and 3School of Sport, Exercise and Rehabilitation, University of Birmingham, Birmingham, England, UNITED KINGDOM.
authors.forename: Blake G
authors.initials: BG
authors.lastname: Perry
authors.forename: Zachary J
authors.initials: ZJ
authors.lastname: Schlader
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Barnes
authors.forename: Darryl J
authors.initials: DJ
authors.lastname: Cochrane
authors.forename: Samuel J E
authors.initials: SJ
authors.lastname: Lucas
authors.forename: Toby
authors.initials: T
authors.lastname: Mündel
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D015444:Exercise / Q000502:physiology; D006801:Humans; D008297:Male; D020768:Middle Cerebral Artery / Q000502:physiology; D009520:New Zealand; D011187:Posture / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult