title: Aerobic Fitness and Intraindividual Reaction Time Variability in Middle and Old Age.
abstract: OBJECTIVE
  To examine whether aerobic fitness moderated age differences in within-person reaction time variability (WP RT variability) and given conceptual linkage involving the frontal cortex, whether effects were mediated by executive function.
  
  
  METHODS
  Aerobic fitness (estimated VO2max) and WP RT variability were investigated in 225 healthy, community-dwelling adults aged 50-90 years (M = 63.83) across 4 cognitive domains; psychomotor performance, executive function, visual search, and recognition.
  
  
  RESULTS
  Significant Age × Aerobic fitness interactions were found in relation to WP variability in 3 cognitive domains: psychomotor performance (4-choice RT), executive function (Flanker and Stroop arrows), and immediate recognition. Lower aerobic fitness was associated with greater RT variability, and this effect increased with age. Additionally, some of these effects were mediated by executive function.
  
  
  CONCLUSIONS
  The findings suggest that aerobic fitness moderated the association between age and intraindividual RT variability, and that executive function selectively mediated that association. It is possible that aerobic fitness helps attenuate the neurobiological decline that contributes to cognitive deficits in old age and that WP variability is a measure that may be particularly sensitive to this effect.
authors.affiliation: Institute of Psychological Sciences, Faculty of Medicine and Health, University of Leeds, UK. s.bauermeister@leeds.ac.uk.
authors.forename: Sarah
authors.initials: S
authors.lastname: Bauermeister
authors.affiliation: Institute of Psychological Sciences, Faculty of Medicine and Health, University of Leeds, UK.
authors.forename: David
authors.initials: D
authors.lastname: Bunce
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology* / Q000523:psychology*; D001288:Attention / Q000502:physiology; D056344:Executive Function / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D007206:Individuality; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D010809:Physical Fitness / Q000502:physiology* / Q000523:psychology*; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D021641:Recognition, Psychology / Q000502:physiology; D057190:Stroop Test
chemical_list: D010100:Oxygen
keywords: Aerobic fitness; Age; Cognitive function; Intraindividual variability; Physical activity; Reaction time