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Reproducibility assessment of metabolic variables characterizing muscle energetics in Vivo: A 31 P‐MRS study
Author(s) -
Layec Gwenael,
Bringard Aurélien,
Le Fur Yann,
Vilmen Christophe,
Micallef JeanPaul,
Perrey Stéphane,
Cozzone Patrick J.,
Bendahan David
Publication year - 2009
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.22085
Subject(s) - reproducibility , energetics , in vivo , chemistry , nuclear magnetic resonance , chromatography , physics , biology , thermodynamics , microbiology and biotechnology
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 ≈ 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. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.