title: Repeated sprints alter signaling related to mitochondrial biogenesis in humans.
abstract: OBJECTIVE
  We investigated the effects of acute and chronic repeated-sprint exercise (RSE) on the skeletal muscle messenger RNA (mRNA) expression and protein abundance/phosphorylation associated with mitochondrial biogenesis.
  
  
  METHODS
  Ten healthy young adults (seven males, three females) performed the RSE trial, comprising three sets of 5 × 4-s maximal sprints on a nonmotorized treadmill, with a 20-s recovery between sprints and 4.5 min between sets. After 4 wk of repeated-sprint training, three times per week, participants repeated the RSE. A vastus lateralis muscle biopsy was obtained at rest, immediately after, and 1 and 4 h after RSE, before and after training. Venous blood lactate and glucose were measured at rest and during recovery. Real-time reverse transcriptase polymerase chain reaction and Western blot techniques were used to measure mRNA expression and protein abundance, respectively.
  
  
  RESULTS
  Acute RSE increased the phosphorylation of acetyl-CoA carboxylase (86%, effect size (ES) = 1.4 ± 0.8, P < 0.001) and Ca calmodulin-dependent protein kinase II (69%, ES = 0.7 ± 0.6). Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α; 208%, ES = 1.5 ± 0.7, P < 0.001) and nuclear respiratory factor 1 (92%, ES = 0.7 ± 0.8) mRNA expression was increased after RSE. Four weeks of training increased the abundance of PGC-1α protein at rest (33%, ES = 0.9 ± 0.7).
  
  
  CONCLUSIONS
  Both acute and chronic RSE, despite only 60 s and 12 min of exercise, respectively, altered the molecular signaling associated with mitochondrial adaptations and PGC-1α mRNA expression in skeletal muscle. However, the small-to-moderate changes in resting PGC-1α protein abundance after training, together with the absence of changes in aerobic fitness, require further research to understand the functional significance of PGC-1α in response to RSE.
authors.affiliation: Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Australia.
authors.forename: Fabio R
authors.initials: FR
authors.lastname: Serpiello
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McKenna
authors.forename: David J
authors.initials: DJ
authors.lastname: Bishop
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Aughey
authors.forename: Marissa K
authors.initials: MK
authors.lastname: Caldow
authors.forename: David
authors.initials: D
authors.lastname: Cameron-Smith
authors.forename: Nigel K
authors.initials: NK
authors.lastname: Stepto
mesh_terms: D000103:Acetyl-CoA Carboxylase / Q000378:metabolism; D000222:Adaptation, Physiological / Q000502:physiology; D000704:Analysis of Variance; D001706:Biopsy; D001786:Blood Glucose / Q000032:analysis; D015153:Blotting, Western; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D005080:Exercise Test; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D051266:Nuclear Respiratory Factor 1 / Q000378:metabolism; D047495:PPAR gamma / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012420:Running / Q000502:physiology*; D015398:Signal Transduction; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D051266:Nuclear Respiratory Factor 1; D047495:PPAR gamma; D012333:RNA, Messenger; D019344:Lactic Acid; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D000103:Acetyl-CoA Carboxylase