title: Myosin heavy-chain mRNA expression after a single session of heavy-resistance exercise.
abstract: OBJECTIVE
  This study determined the effects of a single session of heavy-resistance exercise on myosin heavy-chain (MHC) mRNA expression, along with the expression of the transcription factors Myo-D, myogenin, and Id-1.
  
  
  METHODS
  Four male subjects participated in a control group (CON) and seven in a resistance-exercise group (REX). REX performed one resistance-exercise session employing three sets of 8-10 repetitions at 75-80% one-repetition maximum on the squat, leg press, and leg extension. Vastus lateralis biopsies were obtained pre, post, and at 6 h postexercise.
  
  
  RESULTS
  In regard to CON, no significant differences were located for any criterion variable (P > 0.05). For REX, elevations of 38.19%, 45.61%, and 74.24% (P < 0.05), respectively, occurred at 6 h-post for Type I, IIa, and IIx MHC mRNA. Myo-D and myogenin mRNA were elevated 27.28% and 23.58% postexercise (P < 0.05), respectively, but no change was observed in Id-1 mRNA. Elevations at 6 h-post of 46.85% and 46.41% (P < 0.05), respectively, occurred for Myo-D and myogenin mRNA with no change in Id-1. Myo-D and myogenin protein increased 57.91% and 52.30%, respectively, postexercise and 317.56% and 254.08 at 6 h-post (P < 0.05), whereas no change was noted for Id-1. Myofibrillar protein was elevated 84.52% at 6 h-post (P < 0.05). Type I and IIa MHC mRNA at 6 h-post were correlated with myogenin mRNA and protein postexercise and 6 h-post, whereas Type IIx at 6 h-post was correlated with Myo-D mRNA and protein postexercise and 6 h-post (P < 0.05).
  
  
  CONCLUSIONS
  These results indicate that the mRNA expression of all three MHC isoforms is up-regulated after a single session of heavy-resistance exercise and that Myo-D and myogenin seem to play a role in MHC isoform gene expression.
authors.affiliation: Department of Kinesiology, Texas Christian University, TCU Box 297730, Fort Worth, TX 76129, USA. d.willoughby@tcu.edu
authors.forename: Darryn S
authors.initials: DS
authors.lastname: Willoughby
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Nelson
mesh_terms: D000704:Analysis of Variance; D015415:Biomarkers / Q000032:analysis; D016022:Case-Control Studies; D015331:Cohort Studies; D018076:DNA, Complementary / Q000032:analysis*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D015870:Gene Expression; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000032:analysis / Q000378:metabolism*; D005082:Physical Exertion; D011336:Probability; D012333:RNA, Messenger / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; D018076:DNA, Complementary; D012333:RNA, Messenger; D018995:Myosin Heavy Chains