Reproducibility assessment of metabolic variables characterizing muscle energetics in vivo: A 31P-MRS study.
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.
Layec
Gwenael
G
Centre de Resonance Magnetique Biologique et Medicale, UMR CNRS 6612, Faculté de Médecine de Marseille, Marseille, France.
Bringard
Aurélien
A
Le Fur
Yann
Y
Vilmen
Christophe
C
Micallef
Jean-Paul
JP
Perrey
Stéphane
S
Cozzone
Patrick J
PJ
Bendahan
David
D
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
D010759:Phosphorus Isotopes; D010725:Phosphocreatine