title: The relationship between mitochondrial function and walking performance in older adults with a wide range of physical function.
abstract: Age related declines in walking performance may be partly attributable to skeletal muscle mitochondrial dysfunction as mitochondria produce over 90% of ATP needed for movement and the capacity for oxidative phosphorylation decreases with age.
  
  
  
  Participants were from two studies: an ancillary to the Lifestyle Interventions and Independence for Elders (LIFE) Study (n=33), which recruited lower functioning participants (Short Physical Performance Battery [SPPB], 7.8±1.2), and the Study of Energy and Aging-Pilot (SEA, n=29), which enrolled higher functioning (SPPB, 10.8±1.4). Physical activity was measured objectively using the Actigraph accelerometer (LIFE) and SenseWear Pro armband (SEA). Phosphocreatine recovery following muscle contraction of the quadriceps was measured using (31)P magnetic resonance spectroscopy and ATPmax (mM ATP/s) was calculated. Walking performance was defined as time (s) to walk 400m at a usual-pace. The cross-sectional association between mitochondrial function and walking performance was assessed using multivariable linear regression.
  
  
  
  Participants were 77.6±5.3years, 64.2% female and 67.2% white. ATPmax was similar in LIFE vs. SEA (0.52±0.14 vs. 0.55±0.14, p=0.31), despite different function and activity levels (1.6±2.2 vs.77.4±73.3min of moderate activity/day, p<0.01). Higher ATPmax was related to faster walk-time in SEA (r(2)=0.19, p=0.02,); but not the LIFE (r(2)<0.01, p=0.74) cohort.
  
  
  
  Mitochondrial function was associated with walking performance in higher functioning, active older adults, but not lower functioning, sedentary older adults.
authors.affiliation: Center for Aging and Population Health, Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, United States.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Santanasto
authors.affiliation: Department of Health and Physical Activity, School of Education, University of Pittsburgh, Pittsburgh, United States.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Coen
authors.affiliation: Center for Aging and Population Health, Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, United States.
authors.forename: Nancy W
authors.initials: NW
authors.lastname: Glynn
authors.affiliation: Translational Center for Metabolic Imaging, University of Washington, Seattle, United States.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Conley
authors.affiliation: Translational Center for Metabolic Imaging, University of Washington, Seattle, United States.
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Jubrias
authors.affiliation: Division of Endocrinology and Metabolism, School of Medicine, University of Pittsburgh, Pittsburgh, United States.
authors.forename: Francesca
authors.initials: F
authors.lastname: Amati
authors.affiliation: Center for Aging and Population Health, Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, United States.
authors.forename: Elsa S
authors.initials: ES
authors.lastname: Strotmeyer
authors.affiliation: Center for Aging and Population Health, Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, United States.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Boudreau
authors.affiliation: Division of Endocrinology and Metabolism, School of Medicine, University of Pittsburgh, Pittsburgh, United States.
authors.forename: Bret H
authors.initials: BH
authors.lastname: Goodpaster
authors.affiliation: Center for Aging and Population Health, Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, United States. Electronic address: newmana@edc.pitt.edu.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008019:Life Style; D016014:Linear Models; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008931:Mitochondria, Muscle / Q000502:physiology*; D051346:Mobility Limitation; D015999:Multivariate Analysis; D009119:Muscle Contraction / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology*; D014481:United States; D000070857:Walk Test; D016138:Walking / Q000502:physiology*
keywords: Aging; Mitochondrial Function; Mobility; Muscle; Physical Performance; Walking Performance