title: Validity of NIR spectroscopy for quantitatively measuring muscle oxidative metabolic rate in exercise.
abstract: The purpose of this study was to examine the validity of the quantitative measurement of muscle oxidative metabolism in exercise by near-infrared continuous-wave spectroscopy (NIRcws). Twelve male subjects performed two bouts of dynamic handgrip exercise, once for the NIRcws measurement and once for the (31)P-magnetic resonance spectroscopy (MRS) measurement as a standard measure. The resting muscle metabolic rate (RMRmus) was independently measured by (31)P-MRS during 15 min of arterial occlusion at rest. During the first exercise bout, the quantitative value of muscle oxidative metabolic rate at 30 s postexercise was evaluated from the ratio of the rate of oxyhemoglobin/myoglobin decline measured by NIRcws during arterial occlusion 30 s after exercise and the rate at rest. Therefore, the absolute values of muscle oxidative metabolic rate at 30 s after exercise [VO(2NIR(30))] was calculated from this ratio multiplied by RMRmus. During the second exercise bout, creatine phosphate (PCr) resynthesis rate was measured by (31)P-MRS at 30 s postexercise [Q((30))] under the same conditions but without arterial occlusion postexercise. To determine the validity of NIRcws, VO(2NIR(30)) was compared with Q((30)). There was a significant correlation between VO(2NIR(30)), which ranged between 0.018 and 0. 187 mM ATP/s, and Q((30)), which ranged between 0.041 and 0.209 mM ATP/s (r = 0.965, P < 0.001). This result supports the application of NIRcws to quantitatively evaluate muscle oxidative metabolic rate in exercise.
authors.affiliation: Department of Preventive Medicine and Public Health, Tokyo Medical University, Shinjuku-ku, Tokyo 160-8402, Japan. sako@tokyo-med.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Sako
authors.forename: T
authors.initials: T
authors.lastname: Hamaoka
authors.forename: H
authors.initials: H
authors.lastname: Higuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Kurosawa
authors.forename: T
authors.initials: T
authors.lastname: Katsumura
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D015444:Exercise / Q000502:physiology*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D009211:Myoglobin / Q000378:metabolism; D010101:Oxygen Consumption; D010108:Oxyhemoglobins / Q000378:metabolism; D010725:Phosphocreatine / Q000096:biosynthesis; D010758:Phosphorus; D012146:Rest / Q000502:physiology; D019265:Spectroscopy, Near-Infrared / Q000592:standards*; D013997:Time Factors
chemical_list: D009211:Myoglobin; D010108:Oxyhemoglobins; D010725:Phosphocreatine; D010758:Phosphorus; D000255:Adenosine Triphosphate