title: Blood flow restriction exercise in sprinters and endurance runners.
abstract: OBJECTIVE
  We demonstrated that blood flow restriction (BFR) remarkably enhances muscular metabolic stress in resistance exercise, although there is a wide range of individual differences in the responses. It is possible that these differences could be due to training status and muscular physiological characteristics. We investigated intramuscular metabolic responses during low-intensity resistance exercise with BFR between two different types of track athletes.
  
  
  METHODS
  Twelve age-matched male track athletes (sprinter group, n = 6; endurance runner group, n = 6) were recruited and performed unilateral plantarflexion (30 repetitions per minute). The exercise protocols were as follows: low-intensity exercise at 20% of one-repetition maximum (1RM) (L), high-intensity exercise at 65% 1RM without BFR (1.3 times of systolic blood pressure), L with BFR for 2 min (L-BFR), and prolonged exercise time in L-BFR for 3 min (prolonged BFR). Metabolic stress, defined as phosphocreatine and intramuscular pH decrease, and muscle fiber recruitment were evaluated using P magnetic resonance spectroscopy.
  
  
  RESULTS
  Endurance runners showed higher peak oxygen uptake and lower muscle strength than sprinters. Phosphocreatine decreases in endurance runners during exercise with BFR protocols were significantly greater than those in sprinters (P < 0.05), although those occurring during L were significantly lower than those in sprinters (P < 0.05). The changes in intramuscular pH and the incidence of fast-twitch fiber recruitment did not show a statistical difference between the two groups. Phosphocreatine decreases in L-BFR were significantly correlated with peak oxygen uptake (P < 0.05).
  
  
  CONCLUSIONS
  The effects of low-intensity resistance exercise with BFR are greater in endurance runners according to higher aerobic capacity.
authors.affiliation: Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Hokkaido, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Takada
authors.forename: Koichi
authors.initials: K
authors.lastname: Okita
authors.forename: Tadashi
authors.initials: T
authors.lastname: Suga
authors.forename: Masashi
authors.initials: M
authors.lastname: Omokawa
authors.forename: Noriteru
authors.initials: N
authors.lastname: Morita
authors.forename: Masahiro
authors.initials: M
authors.lastname: Horiuchi
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Kadoguchi
authors.forename: Masashige
authors.initials: M
authors.lastname: Takahashi
authors.forename: Kagami
authors.initials: K
authors.lastname: Hirabayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Yokota
authors.forename: Shintaro
authors.initials: S
authors.lastname: Kinugawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsutsui
mesh_terms: D000704:Analysis of Variance; D016009:Chi-Square Distribution; D003250:Constriction; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007866:Leg / Q000098:blood supply*; D016014:Linear Models; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D010725:Phosphocreatine / Q000378:metabolism; D012039:Regional Blood Flow / Q000502:physiology; D055070:Resistance Training / Q000379:methods*; D014142:Track and Field / Q000502:physiology*; D055815:Young Adult
chemical_list: D010725:Phosphocreatine