title: Effects of concurrent training on oxidative capacity in rat gastrocnemius muscle.
abstract: OBJECTIVE
  Training for improvement of oxidative capacity of muscle fibers may be attenuated when concurrently training for peak power. However, because of fiber type-specific recruitment, such attenuation may only account for high-oxidative muscle fibers. Here, we investigate the effects of concurrent training on oxidative capacity (as measured by succinate dehydrogenase (SDH) activity) by using task-specific recruitment of the high- and low-oxidative compartment of rat medial gastrocnemius muscle (GM).
  
  
  METHODS
  Forty rats were subjected to 6 wk of peak power training (PT, n = 10), endurance training (ET, n = 10), concurrent peak power and endurance training (PET, n = 10), or no training (control, n = 10). SDH activity, mRNA expression of SDH, peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), receptor-interacting protein 140, and BCL2/adenovirus E1B 19 kDa-interacting protein 3 as well as PGC-1α protein levels were analyzed in the low- and high-oxidative region of the GM.
  
  
  RESULTS
  In the low-oxidative compartment, PT and PET induced a 30% decrease in SDH activity of Type IIB fibers compared with controls and ET (P < 0.001) without changes in mRNA or protein levels. In the high-oxidative compartment, after ET, SDH mRNA levels were 42% higher and RIP140 mRNA levels 33% lower compared with controls, which did not result in changes in SDH activity.
  
  
  CONCLUSIONS
  These results indicate that in compartmentalized rat GM, peak power on top of endurance training attenuated transcription of mRNA for mitochondrial proteins in high-oxidative muscle fibers. In low-oxidative Type IIB fibers, peak power training substantially decreased SDH activity, which was not related to lower SDH mRNA levels. It is concluded that PT and PET enhanced mitochondrial degradation in the low-oxidative compartment of rat GM.
authors.affiliation: MOVE Research Institute Amsterdam, VU University Amsterdam, The Netherlands.
authors.forename: Regula
authors.initials: R
authors.lastname: Furrer
authors.forename: Arnold
authors.initials: A
authors.lastname: DE Haan
authors.forename: Nathalie
authors.initials: N
authors.lastname: Bravenboer
authors.forename: Dorien
authors.initials: D
authors.lastname: Kos
authors.forename: Paul
authors.initials: P
authors.lastname: Lips
authors.forename: Richard T
authors.initials: RT
authors.lastname: Jaspers
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000818:Animals; D005260:Female; D018656:Muscle Fibers, Fast-Twitch / Q000201:enzymology / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics; D000078723:Nuclear Receptor Interacting Protein 1; D010084:Oxidation-Reduction; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010805:Physical Conditioning, Animal / Q000379:methods / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012420:Running / Q000502:physiology; D013385:Succinate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D009687:Nuclear Proteins; D000078723:Nuclear Receptor Interacting Protein 1; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C501429:Ppargc1a protein, rat; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D014157:Transcription Factors; D013385:Succinate Dehydrogenase