title: Exercise-induced oxidative stress in older adults as a function of habitual activity level.
abstract: OBJECTIVE
  It has been suggested that regular physical activity might maintain and promote the antioxidant defense capacity against oxidative stress. Therefore, we assessed exercise-induced oxidative stress in relation to habitual physical activity level (PAL) in older adults.
  
  
  METHODS
  The study included a 2-week observation period for the measurement of average daily metabolic rate (ADMR) and PAL. Exercise-induced oxidative stress was measured during a 45-minute cycling test at submaximal intensity.
  
  
  METHODS
  A university medical research center.
  
  
  METHODS
  Twenty-six subjects volunteered for the study (n = 26; mean age +/- standard deviation 60 +/- 1; body mass index 27 +/- 1 kg/m2).
  
  
  METHODS
  PAL was determined as ADMR combined with a measurement of basal metabolic rate (BMR): PAL = ADMR/BMR. ADMR was measured over 2 weeks with the doubly labeled water method, preceded by a BMR measurement with a ventilated hood. Antipyrine oxidation was used as marker for oxidative stress in vivo. Reaction of antipyrine with hydroxyl radicals results in the formation of para-hydroxyantipyrine (p-APOH) and ortho-hydroxyantipyrine (o-APOH), where o-APOH is not formed through alternative oxygenetic pathways.
  
  
  RESULTS
  PAL was inversely related to the exercise-induced increase in the ratio of o-APOH to native antipyrine (r = 0.49, P = .010). The relationship between PAL and exercise-induced increase in the ratio of p-APOH (r = 0.30, P = .140) or thiobarbituric acid reactive species (r = 0.31, P = .130) did not reach the level of significance.
  
  
  CONCLUSIONS
  Physically active older adults have a reduced exercise-induced oxidative stress than older adults with a lower level of physical activity. It seems that regular physical activity improves the antioxidant defense capacity.
authors.affiliation: Department of Human Biology, Maastricht University, The Netherlands.
authors.forename: Erwin P
authors.initials: EP
authors.lastname: Meijer
authors.forename: Annelies H C
authors.initials: AH
authors.lastname: Goris
authors.forename: Joost L J
authors.initials: JL
authors.lastname: van Dongen
authors.forename: Aalt
authors.initials: A
authors.lastname: Bast
authors.forename: Klaas R
authors.initials: KR
authors.lastname: Westerterp
mesh_terms: D000368:Aged; D000983:Antipyrine / Q000097:blood; D001481:Basal Metabolism; D015415:Biomarkers; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D006900:Hydroxylation; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D012044:Regression Analysis; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D015415:Biomarkers; D005609:Free Radicals; D017392:Thiobarbituric Acid Reactive Substances; D000983:Antipyrine