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Blood lactate exchange and removal abilities after relative high-intensity exercise: effects of training in normoxia and hypoxia |
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| Authors: | Laurent Messonnier Hubert Freund Léonard Féasson Fabrice Prieur Josiane Castells Christian Denis Marie-Thérèse Linossier André Geyssant Jean-René Lacour |
| Affiliation: | Laboratoire de Physiologie de l'Exercice, GIP Exercice, Faculté de Médecine Lyon-Sud, BP 12, 69921 Oullins Cedex, France, Pharmacologie et Physico-Chimie des Interactions Cellulaires et Moléculaires, Faculté de Pharmacie – UMR CNRS 7034, 74 Route du Rhin, BP 24, 67401 Illkirch Cedex, France, Laboratoire de Physiologie, GIP Exercice, CHU de Saint-Etienne, Pavillon 12, H?pital de Saint Jean Bonnefonds, 42055 Saint-Etienne Cedex 2, France, Laboratoire d'Analyse Multidisciplinaire des Pratiques Sportives, UFR STAPS de Liévin, Université d'Artois, Chemin des Manufactures, 62800 Liévin, France, Laboratoire de Recherche en Néphrologie et Transplantation, Faculté de Médecine Jacques Lisfranc, 15 rue Ambroise Paré, 42023 Saint-Etienne Cedex 2, France, |
| Abstract: | The effects of 4 weeks of endurance training in conditions of normoxia or hypoxia on muscle characteristics and blood lactate responses after a 5-min constant-load exercise (CLE) at 90% of the power corresponding to the maximal oxygen uptake were examined at sea-level in 13 sedentary subjects. Five subjects trained in normobaric hypoxia (HT group, fraction of oxygen in inspired gas = 13.2%), and eight subjects trained in normoxia at the same relative work rates (NT group). The blood lactate recovery curves from the CLE were fitted to a biexponential time function: La(t)=La(0)+A1(1-e-γ1·t)+A2(1-e-γ2·t), where the velocity constants γ1 and γ2 denote the lactate exchange and removal abilities, respectively, A1 and A2 are concentration parameters that describe the amplitudes of concentration variations in the space represented by the arterial blood, La( t ) is the lactate concentration at time t, and La(0) is the lactate concentration at the beginning of recovery from CLE. Before training, the two groups displayed the same muscle characteristics, blood lactate kinetics after CLE, and γ1 and γ2 values. Training modified their muscle characteristics, blood lactate kinetics and the parameters of the fits in the same direction, and proportions among the HT and the NT subjects. Endurance training increased significantly the capillary density (by 31%), citrate synthase activity (by 48%) and H isozyme proportion of lactate dehydrogenase (by 24%), and γ1 (by 68%) and γ2 (by 47%) values. It was concluded that (1) endurance training improves the lactate exchange and removal abilities estimated during recovery from exercises performed at the same relative work rate, and (2) training in normobaric hypoxia results in similar effects on lactate exchange and removal abilities to training in normoxia performed at the same relative work rates. These results, which were obtained non-invasively in vivo in humans during recovery from CLE, are comparable to those obtained in vitro or by invasive methods during exercise and subsequent recovery. Electronic Publication |
| Keywords: | Humans Recovery Normoxia Normobaric hypoxia Longitudinal study |
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