The relationship between creatine kinase kinetics and exercise intensity in human forearm is unchanged by age

• Published in: American journal of physiology: endocrinology and metabolism 2000-08, Vol.279 (2), p.E333-E339
• Main Authors: Horska, A, Fishbein, K. W, Fleg, J. L, Spencer, R. G. S
• Format: Article
• Language: English
• Subjects: Adenosine Diphosphate - metabolism; Adenosine Triphosphate - metabolism; Adult; Aged; Aged, 80 and over; Aging - metabolism; Creatine Kinase - metabolism; Female; Forearm - physiology; Humans; Hydrogen-Ion Concentration; Longitudinal Studies; Magnetic Resonance Spectroscopy; Male; Middle Aged; Muscle, Skeletal - metabolism; Phosphates - metabolism; Phosphocreatine - metabolism; Physical Exertion - physiology; Reference Values; Regression Analysis; Sex Factors
• ISSN: 0193-1849; 1522-1555
• DOI: 10.1152/ajpendo.2000.279.2.E333

1  Gerontology Research Center, 2  Nuclear Magnetic Resonance Unit, and 3  Laboratory of Cardiovascular Sciences, National Institutes of Health, National Institute on Aging, Baltimore, Maryland 21224 Using 31 P magnetic resonance spectroscopy, creatine kinase (CK) reaction kinetics was assessed in the forearm flexor digitorum profundus muscle of healthy young ( n  = 11, age 34.7 ± 5 yr) and older ( n  = 20, age 73.5 ± 8 yr) subjects at rest, intermittent exercise at 20% maximum voluntary contraction (MVC), and 40% MVC. Exercise resulted in a significant increase in the average ratio of inorganic phosphate (P i ) to phosphocreatine (PCr) from resting values of 0.073 ± 0.031 (young) and 0.082 ± 0.037 (older) to 0.268   ± 0.140 (young, P