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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.

journal_name

Exp Physiol

journal_title

Experimental physiology

authors

Layec G,Bringard A,Yashiro K,Le Fur Y,Vilmen C,Micallef JP,Perrey S,Cozzone PJ,Bendahan D

doi

10.1113/expphysiol.2011.062927

subject

Has Abstract

pub_date

2012-08-01 00:00:00

pages

955-69

issue

eissn

0958-0670

issn

1469-445X

pii

expphysiol.2011.062927

journal_volume

pub_type

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The slow components of phosphocreatine and pulmonary oxygen uptake can be dissociated during heavy exercise according to training status.