title: Reproducibility assessment of metabolic variables characterizing muscle energetics in vivo: A 31P-MRS study.
abstract: The purpose of the present study was to assess the reliability of metabolic parameters measured using (31)P magnetic resonance spectroscopy ((31)P MRS) during two standardized rest-exercise-recovery protocols. Twelve healthy subjects performed the standardized protocols at two different intensities; i.e., a moderate intensity (MOD) repeated over a two-month period and heavy intensity (HEAVY) repeated over a year's time. Test-retest reliability was analyzed using coefficient of variation (CV), limits of agreement (LOA), and intraclass correlation coefficients (ICC). During exercise and recovery periods, most of the metabolic parameters exhibited a good reliability. The CVs of individual concentration of phosphocreatine ([PCr]), concentration of adenosine diphosphate ([ADP]), and pH values recorded at end of the HEAVY exercise were lower than 15%. The CV calculated for the rate of PCr resynthesis and the maximal oxidative capacity were less than 13% during the HEAVY protocol. Inferred parameters such as oxidative and total adenosine triphosphate (ATP) production rates exhibited a good reliability (ICC approximately 0.7; CV < 15% during the HEAVY protocol). Our results demonstrated that measurement error using (31)P-MRS during a standardized exercise was low and that biological variability accounted for the vast majority of the measurement variability. In addition, the corresponding metabolic measurements can reliably be used for longitudinal studies performed even over a long period of time.
authors.affiliation: Centre de Resonance Magnetique Biologique et Medicale, UMR CNRS 6612, Faculté de Médecine de Marseille, Marseille, France.
authors.forename: Gwenael
authors.initials: G
authors.lastname: Layec
authors.forename: Aurélien
authors.initials: A
authors.lastname: Bringard
authors.forename: Yann
authors.initials: Y
authors.lastname: Le Fur
authors.forename: Christophe
authors.initials: C
authors.lastname: Vilmen
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Micallef
authors.forename: Stéphane
authors.initials: S
authors.lastname: Perrey
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Cozzone
authors.forename: David
authors.initials: D
authors.lastname: Bendahan
mesh_terms: D000328:Adult; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010725:Phosphocreatine / Q000032:analysis / Q000378:metabolism*; D010759:Phosphorus Isotopes / Q000378:metabolism; D005082:Physical Exertion / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D010759:Phosphorus Isotopes; D010725:Phosphocreatine