title: Combined training enhances skeletal muscle mitochondrial oxidative capacity independent of age.
abstract: BACKGROUND
  Skeletal muscle from sedentary older adults exhibits reduced mitochondrial abundance and oxidative capacity.
  
  
  OBJECTIVE
  The primary objective was to determine whether 8 weeks of combined training (CT) has a more robust effect than endurance training (ET) or resistance training (RT) on mitochondrial physiology in healthy young (18-30 years) and older (≥ 65 years) adults.
  
  
  METHODS
  Thirty-four young and 31 older adults were randomly assigned to 8 weeks of ET, RT, and control/CT. Control subjects completed 8 weeks of no exercise (control) followed by 8 weeks of CT. Body composition, skeletal muscle strength, and peak oxygen uptake were measured before and after the intervention. Vastus lateralis muscle biopsy samples were obtained before and 48 hours after the intervention. Mitochondrial physiology was evaluated by high-resolution respirometry and expression of mitochondrial proteins and transcription factors by quantitative PCR and immunoblotting.
  
  
  RESULTS
  ET and CT significantly increased oxidative capacity and expression of mitochondrial proteins and transcription factors. All training modalities improved body composition, cardiorespiratory fitness, and skeletal muscle strength. CT induced the most robust improvements in mitochondria-related outcomes and physical characteristics despite lower training volumes for the ET and RT components. Importantly, most of the adaptations to training occurred independent of age.
  
  
  CONCLUSIONS
  Collectively, these results demonstrate that both ET and CT increase muscle mitochondrial abundance and capacity although CT induced the most robust improvements in the outcomes measured. In conclusion, CT provides a robust exercise regimen to improve muscle mitochondrial outcomes and physical characteristics independent of age.
authors.affiliation: Division of Endocrinology (B.A.I., I.R.L., G.D.H., K.S.N.), Endocrine Research Unit, Mayo Clinic College of Medicine, Rochester, Minnesota 55905; Department of Cancer Biology (R.R.R., B.M.S.), Dana-Farber Cancer Institute, Boston, Massachusetts 02215; and Department of Cell Biology (R.R.R., B.M.S.), Harvard Medical School, Boston, Massachusetts 02215.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Irving
authors.forename: Ian R
authors.initials: IR
authors.lastname: Lanza
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Henderson
authors.forename: Rajesh R
authors.initials: RR
authors.lastname: Rao
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Spiegelman
authors.forename: K Sreekumaran
authors.initials: KS
authors.lastname: Nair
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology; D055070:Resistance Training; D055815:Young Adult