title: Effects of exercise on markers of oxidative stress: an Ancillary analysis of the Alberta Physical Activity and Breast Cancer Prevention Trial.
abstract: BACKGROUND
  Oxidative stress may contribute to cancer aetiology through several mechanisms involving damage to DNA, proteins and lipids leading to genetic mutations and genomic instability. The objective of this study was to determine the effects of aerobic exercise on markers of oxidative damage and antioxidant enzymes in postmenopausal women.
  
  
  METHODS
  The Alberta Physical Activity and Breast Cancer Prevention Trial (ALPHA) was a two-centre, two-armed randomised trial of 320 inactive, healthy, postmenopausal women aged 50-74 years. Participants were randomly assigned to a year-long exercise intervention (225 min/week) or a control group while being asked to maintain a normal diet. Fasting blood samples were obtained and plasma concentrations of two oxidative damage markers (8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-isoprostaglandin F2α (8-Iso-PGF2α)) and two antioxidant enzymes (superoxide dismutase and catalase) were measured at baseline, 6 months and 12 months. Intention-to-treat (ITT) and per-protocol analyses were performed using linear mixed models adjusted for baseline biomarker concentrations. A further exercise adherence analysis, based on mean minutes of exercise per week, was also performed.
  
  
  RESULTS
  In the ITT and per-protocol analyses, the exercise intervention did not have any statistically significant effect on either oxidative damage biomarkers or antioxidant enzyme activity.
  
  
  CONCLUSIONS
  A year-long aerobic exercise intervention did not have a significant impact on oxidative stress in healthy, postmenopausal women.
  
  
  BACKGROUND
  NCT00522262.
authors.affiliation: Department of Cancer Epidemiology and Prevention Research, CancerControl Alberta, Alberta Health Services, Calgary, Alberta, Canada; Departments of Oncology and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Friedenreich
authors.affiliation: Inter-University Laboratory of Human Movement Biology , Université Claude Bernard Lyon 1, University of Lyon , Villeurbanne , France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Pialoux
authors.affiliation: Department of Cancer Epidemiology and Prevention Research , CancerControl Alberta, Alberta Health Services , Calgary, Alberta , Canada.
authors.forename: Qinggang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Cancer Epidemiology and Prevention Research , CancerControl Alberta, Alberta Health Services , Calgary, Alberta , Canada.
authors.forename: Eileen
authors.initials: E
authors.lastname: Shaw
authors.affiliation: Department of Cancer Epidemiology and Prevention Research, CancerControl Alberta, Alberta Health Services, Calgary, Alberta, Canada; Departments of Oncology and Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Darren R
authors.initials: DR
authors.lastname: Brenner
authors.affiliation: Departments of Physiology and Pharmacology and Clinical Neurosciences , Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary , Calgary, Alberta , Canada.
authors.forename: Xavier
authors.initials: X
authors.lastname: Waltz
authors.affiliation: Cancer Prevention Institute of California , Fremont, California , USA.
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Conroy
authors.affiliation: Department of Cancer Epidemiology and Prevention Research , CancerControl Alberta, Alberta Health Services , Calgary, Alberta , Canada.
authors.forename: Rhys
authors.initials: R
authors.lastname: Johnson
authors.affiliation: Departments of Pediatrics and Obstetrics and Gynecology, Faculty of Medicine , Dalhousie University , Halifax, Nova Scotia , Canada.
authors.forename: Christy G
authors.initials: CG
authors.lastname: Woolcott
authors.affiliation: Departments of Physiology and Pharmacology and Clinical Neurosciences , Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary , Calgary, Alberta , Canada.
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Poulin
authors.affiliation: Faculty of Physical Education and Recreation , University of Alberta , Edmonton, Alberta , Canada.
authors.forename: Kerry S
authors.initials: KS
authors.lastname: Courneya
keywords: Antioxidants; Cancer; Exercise physiology; Randomised controlled trial