title: Phosphocreatine resynthesis during recovery in different muscles of the exercising leg by 31P-MRS.
abstract: To investigate the high-energy phosphate metabolism by (31) P-nuclear magnetic resonance spectroscopy during off-transition of exercise in different muscle groups, such as calf muscles and biceps femoris muscles, seven male long-distance runners (LDR) and nine untrained males (UT) performed both submaximal constant and incremental exercises. The relative exercise intensity was set at 60% of the maximal work rate (60%W max) during both knee flexion and plantar flexion submaximal constant load exercises. The relative areas under the inorganic phosphate (Pi ) and phosphocreatine (PCr) peaks were determined. During the 5-min recovery following the 60%W max, the time constant for the PCr off-kinetics was significantly faster in the plantar flexion (LDR: 17.3 ± 3.6 s, UT: 26.7 ± 6.7 s) than in the knee flexion (LDR: 29.7 ± 4.7 s, UT: 42.7 ± 2.8 s, P < 0.05). In addition, a significantly faster PCr off-kinetics was observed in LDR than in UT for both exercises. The ratio of Pi to PCr (Pi /PCr) during exercise was significantly lower during the plantar flexion than during the knee flexion (P < 0.01). These findings indicated that the calf muscles had relatively higher potential for oxidative capacity than that of biceps femoris muscles with an association of training status.
authors.affiliation: Department of Regulatory Physiology, Graduate School of Medicine, Osaka University, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yoshida
authors.forename: D
authors.initials: D
authors.lastname: Abe
authors.forename: Y
authors.initials: Y
authors.lastname: Fukuoka
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000704:Analysis of Variance; D004734:Energy Metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D010725:Phosphocreatine / Q000096:biosynthesis*; D012420:Running / Q000502:physiology*; D055815:Young Adult
chemical_list: D010725:Phosphocreatine; D000255:Adenosine Triphosphate
keywords: 31P-MRS; PCr off-kinetics; biceps femoris muscles; calf muscles; time constant