title: Comparative analysis of skeletal muscle oxidative capacity in children and adults: a 31P-MRS study.
abstract: The aim of the present study was to compare the oxidative capacity of the forearm flexor muscles in vivo between children and adults using 31-phosphorus magnetic resonance spectroscopy. Seven boys (11.7 +/- 0.6 y) and 10 men (35.6 +/- 7.8 year) volunteered to perform a 3 min dynamic finger flexions exercise against a standardized weight (15% of the maximal voluntary contraction). Muscle oxidative capacity was quantified on the basis of phosphocreatine (PCr) post-exercise recovery kinetics analysis. End-of-exercise pH was not significantly different between children and adults (6.6 +/- 0.2 vs. 6.5 +/- 0.2), indicating that indices of PCr recovery kinetics can be reliably compared. The rate constant of PCr recovery (kPCr) and the maximum rate of aerobic ATP production were about 2-fold higher in young boys than in men (kPCr: 1.7 +/- 1.2 vs. 0.7 +/- 0.2 min(-1); Vmax: 49.7 +/- 24.6 vs. 29.4 +/- 7.9 mmol.L(-1).min(-1), p < 0.05). Our results clearly illustrate a greater mitochondrial oxidative capacity in the forearm flexor muscles of young children. This larger ATP regeneration capacity through aerobic mechanisms in children could be one of the factors accounting for their greater resistance to fatigue during high-intensity intermittent exercise.
authors.affiliation: Laboratory of Exercise Biology BAPS, EA 3533, Universite Blaise Pascal, UFR STAPS, 63172 Aubiere, France. sebastien.ratel@univ-bpclermont.fr
authors.forename: Sébastien
authors.initials: S
authors.lastname: Ratel
authors.forename: Anne
authors.initials: A
authors.lastname: Tonson
authors.forename: Yann
authors.initials: Y
authors.lastname: Le Fur
authors.forename: Patrick
authors.initials: P
authors.lastname: Cozzone
authors.forename: David
authors.initials: D
authors.lastname: Bendahan
mesh_terms: D000328:Adult; D000367:Age Factors; D002648:Child; D004734:Energy Metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology; D005542:Forearm; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D010759:Phosphorus Isotopes
chemical_list: D010759:Phosphorus Isotopes; D010725:Phosphocreatine; D010100:Oxygen