title: Repeated maximal-intensity hypoxic exercise superimposed to hypoxic residence boosts skeletal muscle transcriptional responses in elite team-sport athletes.
abstract: To determine whether repeated maximal-intensity hypoxic exercise induces larger beneficial adaptations on the hypoxia-inducible factor-1α pathway and its target genes than similar normoxic exercise, when combined with chronic hypoxic exposure.
  
  
  
  Lowland elite male team-sport athletes underwent 14 days of passive normobaric hypoxic exposure [≥14 h·day-1at inspired oxygen fraction (FiO2) 14.5-14.2%] with the addition of six maximal-intensity exercise sessions either in normobaric hypoxia (FiO2~14.2%; LHTLH; n = 9) or in normoxia (FiO220.9%; LHTL; n = 11). A group living in normoxia with no additional maximal-intensity exercise (LLTL; n = 10) served as control. Before (Pre), immediately after (Post-1) and 3 weeks after (Post-2) the intervention, muscle biopsies were obtained from the vastus lateralis.
  
  
  
  Hypoxia-inducible factor-1α subunit, vascular endothelial growth factor, myoglobin, peroxisome proliferator-activated receptor-gamma coactivator 1-α and mitochondrial transcription factor A mRNA levels increased at Post-1 (all P ≤ 0.05) in LHTLH, but not in LHTL or LLTL, and returned near baseline levels at Post-2. The protein expression of citrate synthase increased in LHTLH (P < 0.001 and P < 0.01 at Post-1 and Post-2, respectively) and LLTL (P < 0.01 and P < 0.05 at Post-1 and Post-2, respectively), whereas it decreased in LHTL at Post-1 and Post-2 (both P < 0.001).
  
  
  
  Combined with residence in normobaric hypoxia, repeated maximal-intensity hypoxic exercise induces short-term post-intervention beneficial changes in muscle transcriptional factors that are of larger magnitude (or not observed) than with similar normoxic exercise. The decay of molecular adaptations was relatively fast, with most of benefits already absent 3 weeks post-intervention.
authors.affiliation: ISSUL, Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Brocherie
authors.affiliation: ISSUL, Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland.
authors.forename: G P
authors.initials: GP
authors.lastname: Millet
authors.affiliation: Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: D'Hulst
authors.affiliation: Exercise Physiology Research Group, Department of Kinesiology, KU Leuven, Leuven, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Van Thienen
authors.affiliation: Exercise Physiology Research Group, Department of Kinesiology, KU Leuven, Leuven, Belgium.|Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
authors.forename: L
authors.initials: L
authors.lastname: Deldicque
authors.affiliation: ISSUL, Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland.|ASPETAR, Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.
authors.forename: O
authors.initials: O
authors.lastname: Girard
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D056352:Athletes; D004311:Double-Blind Method; D000072696:High-Intensity Interval Training; D006688:Hockey; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000503:physiopathology; D055815:Young Adult
keywords: gene; hypoxia; maximal-intensity; oxygen sensor system; physical exercise; protein