title: Significant molecular and systemic adaptations after repeated sprint training in hypoxia.
abstract: While intermittent hypoxic training (IHT) has been reported to evoke cellular responses via hypoxia inducible factors (HIFs) but without substantial performance benefits in endurance athletes, we hypothesized that repeated sprint training in hypoxia could enhance repeated sprint ability (RSA) performed in normoxia via improved glycolysis and O(2) utilization. 40 trained subjects completed 8 cycling repeated sprint sessions in hypoxia (RSH, 3000 m) or normoxia (RSN, 485 m). Before (Pre-) and after (Post-) training, muscular levels of selected mRNAs were analyzed from resting muscle biopsies and RSA tested until exhaustion (10-s sprint, work-to-rest ratio 1:2) with muscle perfusion assessed by near-infrared spectroscopy. From Pre- to Post-, the average power output of all sprints in RSA was increased (p<0.01) to the same extent (6% vs 7%, NS) in RSH and in RSN but the number of sprints to exhaustion was increased in RSH (9.4±4.8 vs. 13.0±6.2 sprints, p<0.01) but not in RSN (9.3±4.2 vs. 8.9±3.5). mRNA concentrations of HIF-1α (+55%), carbonic anhydrase III (+35%) and monocarboxylate transporter-4 (+20%) were augmented (p<0.05) whereas mitochondrial transcription factor A (-40%), peroxisome proliferator-activated receptor gamma coactivator 1α (-23%) and monocarboxylate transporter-1 (-36%) were decreased (p<0.01) in RSH only. Besides, the changes in total hemoglobin variations (Δ[tHb]) during sprints throughout RSA test increased to a greater extent (p<0.01) in RSH. Our findings show larger improvement in repeated sprint performance in RSH than in RSN with significant molecular adaptations and larger blood perfusion variations in active muscles.
authors: ISSUL-Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Switzerland. raphael.faiss@unil.ch
authors: Raphael
authors: R
authors: Faiss
authors: Bertrand
authors: B
authors: Léger
authors: Jean-Marc
authors: JM
authors: Vesin
authors: Pierre-Etienne
authors: PE
authors: Fournier
authors: Yan
authors: Y
authors: Eggel
authors: Olivier
authors: O
authors: Dériaz
authors: Grégoire P
authors: GP
authors: Millet
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D015870:Gene Expression; D006019:Glycolysis / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D000860:Hypoxia; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D012420:Running / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared
chemical_list: D006454:Hemoglobins; D012333:RNA, Messenger