title: Dissociation between muscle metabolism and oxygen kinetics during recovery from exercise in patients with chronic heart failure.
abstract: OBJECTIVE
  To estimate muscle metabolism and oxygen delivery to skeletal muscle in patients with chronic heart failure.
  
  
  METHODS
  13 patients with chronic heart failure and 15 controls performed calf plantar flexion for six minutes at a constant workload of 50% of one repetition maximum. During recovery from exercise, skeletal muscle content of oxygenated haemoglobin (oxy-Hb) and the level of phosphocreatine (PCr) were measured by near-infrared spectroscopy and (31)P-magnetic resonance spectroscopy, respectively.
  
  
  RESULTS
  The mean (SD) time constants of PCr and oxy-Hb during recovery from exercise were significantly greater in patients with chronic heart failure than in normal subjects (tau PCr: 76.3 (30.2) s v 36.5 (5.8) s; tau oxy-Hb: 48.3 (7.3) s v 30.1 (7.7) s; p < 0.01). Both time constants were similar in normal subjects, while the tau PCr was significantly greater than the tau oxy-Hb in patients with chronic heart failure.
  
  
  CONCLUSIONS
  The slower recovery of PCr compared with oxy-Hb in patients with chronic heart failure indicates that haemoglobin resaturation is not a major rate limiting factor of PCr resynthesis. It is suggested that muscle metabolic recovery may depend more on oxygen utilisation than on haemoglobin resaturation or oxygen delivery in patients with chronic heart failure.
authors.affiliation: Department of Cardiovascular Medicine, Hokkaido University School of Medicine, Kita-15, Nishi-7, Kitaku, Sapporo 060-8638, Japan. cvext@med.hokudai.ac.jp
authors.forename: A
authors.initials: A
authors.lastname: Hanada
authors.forename: K
authors.initials: K
authors.lastname: Okita
authors.forename: K
authors.initials: K
authors.lastname: Yonezawa
authors.forename: M
authors.initials: M
authors.lastname: Ohtsubo
authors.forename: T
authors.initials: T
authors.lastname: Kohya
authors.forename: T
authors.initials: T
authors.lastname: Murakami
authors.forename: H
authors.initials: H
authors.lastname: Nishijima
authors.forename: M
authors.initials: M
authors.lastname: Tamura
authors.forename: A
authors.initials: A
authors.lastname: Kitabatake
mesh_terms: D016022:Case-Control Studies; D019069:Cell Respiration; D017079:Exercise Tolerance / Q000502:physiology*; D006333:Heart Failure / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*; D010108:Oxyhemoglobins / Q000032:analysis; D010725:Phosphocreatine / Q000032:analysis; D019265:Spectroscopy, Near-Infrared
chemical_list: D010108:Oxyhemoglobins; D010725:Phosphocreatine