title: The slow components of phosphocreatine and pulmonary oxygen uptake can be dissociated during heavy exercise according to training status.
abstract: To better understand the mechanisms underlying the pulmonary O(2) uptake (V(O(2P))) slow component during high-intensity exercise, we used (31)P magnetic resonance spectroscopy, gas exchange, surface electromyography and near-infrared spectroscopy measurements to examine the potential relationship between the slow components of V(O(2P)) and phosphocreatine (PCr), muscle recruitment and tissue oxygenation in endurance-trained athletes and sedentary subjects. Specifically, six endurance-trained and seven sedentary subjects performed a dynamic high-intensity exercise protocol during 6 min at an exercise intensity corresponding to 35-40% of knee-extensor maximal voluntary contraction. The slow component of V(O(2P))(117 ± 60 ml min(-1), i.e. 20 ± 10% of the total response) was associated with a paradoxical PCr resynthesis in endurance-trained athletes (-0.90 ± 1.27 mm, i.e. -12 ± 16% of the total response). Meanwhile, oxygenated haemoglobin increased throughout the second part of exercise and was significantly higher at the end of exercise compared with the value at 120 s (P < 0.05), whereas the integrated EMG was not significantly changed throughout exercise. In sedentary subjects, a slow component was simultaneously observed for V(O(2P)) and [PCr] time-dependent changes (208 ± 14 ml min(-1), i.e. 38 ± 18% of the total V(O(2P))response, and 1.82 ± 1.39 mm, i.e. 16 ± 13% of the total [PCr] response), but the corresponding absolute or relative amplitudes were not correlated. The integrated EMG was significantly increased throughout exercise in sedentary subjects. Taken together, our results challenge the hypothesis of a mechanistic link between [PCr] and V(O(2P)) slow components and demonstrate that, as a result of a tighter metabolic control and increased O(2) availability, the [PCr] slow component can be minimized in endurance-trained athletes while the V(O(2P)) slow component occurs.
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: Kazuya
authors.initials: K
authors.lastname: Yashiro
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; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology*; D010725:Phosphocreatine / Q000096:biosynthesis / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D057185:Sedentary Behavior; D055815:Young Adult
chemical_list: D010725:Phosphocreatine