Effects of creatine supplementation on the energy cost of muscle contraction: a 31P-MRS study

• Published in: Journal of applied physiology (1985) 1999-07, Vol.87 (1), p.116-123
• Main Authors: Smith, Sinclair A, Montain, Scott J, Matott, Ralph P, Zientara, Gary P, Jolesz, Ferenc A, Fielding, Roger A
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Adult; Biological and medical sciences; Creatine - administration & dosage; Dietary supplements; Energy Metabolism - drug effects; Exercise - physiology; Female; Fundamental and applied biological sciences. Psychology; Humans; Magnetic Resonance Spectroscopy; Male; Muscle Contraction - drug effects; Muscle Contraction - physiology; Muscle, Skeletal - drug effects; Muscle, Skeletal - physiology; Muscular system; NMR; Nuclear magnetic resonance; Phosphates - metabolism; Phosphocreatine - metabolism; Phosphorus; Physical Endurance - drug effects; Physical Endurance - physiology; Space life sciences; Striated muscle. Tendons; Vertebrates: osteoarticular system, musculoskeletal system
• ISSN: 8750-7587; 1522-1601

1  Department of Health Sciences, Sargent College of Health and Rehabilitation Sciences, Boston University, Boston 02215; 2  United States Army Research Institute of Environmental Medicine, Natick 01760; and 3  Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115 Five women and 3 men (29.8 ± 1.4 yr) performed dynamic knee-extension exercise inside a magnetic resonance system (means ±   SE). Two trials were performed 7-14 days apart, consisting of a 4- to 5-min exhaustive exercise bout. To determine quadriceps cost of contraction, brief static and dynamic contractions were performed pre- and postexercise. 31 P spectra were used to determine pH and relative concentrations of P i , phosphocreatine (PCr), and ATP. Subjects consumed 0.3   g · kg 1 · day 1 of a placebo ( trial 1 ) or creatine ( trial 2 ) for 5 days before each trial. After creatine supplementation, resting PCr increased from 40.7 ± 1.8 to 46.6 ± 1.1 mmol/kg ( P  = 0.04) and PCr during exercise declined from 29.6 ± 2.4 to 34.1 ± 2.8 mmol/kg ( P  =   0.02). Muscle static ( ATP/N) and dynamic ( ATP/J) costs of contraction were unaffected by creatine supplementation as well as were ATP, P i , pH, PCr resynthesis rate, and muscle strength and endurance. ATP/J and ATP/N were greatest at the onset of the exercise protocol ( P