title: Effects of oral creatine and resistance training on myosin heavy chain expression.
abstract: OBJECTIVE
  This study examined 12 wk of creatine (Cr) supplementation and heavy resistance training on muscle strength and myosin heavy chain (MHC) isoform mRNA and protein expression.
  
  
  METHODS
  Twenty-two untrained male subjects were randomly assigned to either a control (CON), placebo (PLC), or Cr (CRT) group in a double-blind fashion. Muscle biopsies were obtained before and after 12 wk of heavy resistance training. PLC and CRT trained thrice weekly using three sets of 6-8 repetitions at 85-90% 1-RM on the leg press, knee extension, and knee curl exercises. CRT ingested 6 g.d-1 of Cr for 12 wk, whereas PLC consumed the equal concentration of placebo.
  
  
  RESULTS
  There were no significant differences for percent body fat (P > 0.05). However, for total body mass, fat-free mass, thigh volume, muscle strength, and myofibrillar protein, CRT and PLC exhibited significant increases after training when compared to CON (P < 0.05), whereas CRT was also significantly greater than PLC (P < 0.05). For Type I, IIa, and IIx MHC mRNA expression, CRT was significantly greater than CON and PLC, whereas PLC was greater than CON (P < 0.05). For MHC protein expression, CRT was significantly greater than CON and PLC for Type I and IIx (P < 0.05) but was equal to PLC for IIa.
  
  
  CONCLUSIONS
  Long-term Cr supplementation increases muscle strength and size, possibly as a result of increased MHC synthesis.
authors.affiliation: Department of Kinesiology, Texas Christian University, Fort Worth, TX 76129, USA. d.Willoughby@tcu.edu
authors.forename: D S
authors.initials: DS
authors.lastname: Willoughby
authors.forename: J
authors.initials: J
authors.lastname: Rosene
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000704:Analysis of Variance; D000886:Anthropometry; D001823:Body Composition; D003401:Creatine / Q000008:administration & dosage* / Q000097:blood; D019587:Dietary Supplements; D004311:Double-Blind Method; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000502:physiology; D009210:Myofibrils / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D010806:Physical Education and Training / Q000379:methods*; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors
chemical_list: D009124:Muscle Proteins; D012333:RNA, Messenger; D018995:Myosin Heavy Chains; D003401:Creatine