title: Similar expression of oxidative genes after interval and continuous exercise.
abstract: OBJECTIVE
  There is a debate whether interval or traditional endurance training is the most effective stimulus of mitochondrial biogenesis. Here, we compared the effects of acute interval exercise (IE) or continuous exercise (CE) on the muscle messenger RNA (mRNA) content for several genes involved in mitochondrial biogenesis and lipid metabolism.
  
  
  METHODS
  Nine sedentary subjects cycled for 90 min with two protocols: CE (at 67% VO2max) and IE (12 s at 120% and 18 s at 20% of VO2max). The duration of exercise and work performed with CE and IE was identical. Muscle biopsies were taken before and 3 h after exercise.
  
  
  RESULTS
  There were no significant differences between the two exercise protocols in the increases in VO2 and HR, the reduction in muscle glycogen (35%-40% with both protocols) or the changes in blood metabolites (lactate, glucose, and fatty acids). The mRNA content for major regulators of mitochondrial biogenesis [peroxisome proliferator-activated receptor (PPAR) gamma coactivator 1alpha (PGC-1alpha), PGC-1-related coactivator, PPARbeta/delta] and of lipid metabolism [pyruvate dehydrogenase kinase isozyme 4 (PDK4)] increased after exercise, but there was no significant difference between IE and CE. However, the mRNA content for several downstream targets of PGC-1alpha increased significantly only after CE, and mRNA content for nuclear respiratory factor 2 was significantly higher after CE (P < 0.025 vs IE).
  
  
  CONCLUSIONS
  The present findings demonstrate that, when the duration of exercise and work performed is the same, IE and CE influence the transcription of genes involved in oxidative metabolism in a similar manner.
authors.affiliation: GIH, the Swedish School of Sport and Health Sciences, Astrands Laboratory, Stockholm, Sweden.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Niklas
authors.initials: N
authors.lastname: Psilander
authors.forename: Michail
authors.initials: M
authors.lastname: Tonkonogi
authors.forename: Shuzhe
authors.initials: S
authors.lastname: Ding
authors.forename: Kent
authors.initials: K
authors.lastname: Sahlin
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000328:Adult; D001483:Base Sequence; D015415:Biomarkers / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D006003:Glycogen / Q000032:analysis; D006801:Humans; D050356:Lipid Metabolism / Q000235:genetics; D008297:Male; D008931:Mitochondria, Muscle / Q000235:genetics; D018482:Muscle, Skeletal / Q000378:metabolism; D018384:Oxidative Stress / Q000235:genetics*; D010101:Oxygen Consumption; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000032:analysis
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger; D006003:Glycogen