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.
Trial registration number NCT00522262.
- Randomised controlled trial
- Exercise physiology
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Contributors CMF, KSC, SMC, CGW, VP and MJP took part in study concept, design and funding. CMF, KSC and CGW participated in data collection. VP, XW and MJP took part in laboratory analyses. QW, ES, DRB, CMF and KSC carried out data analysis. CMF, RJ, ES, DRB and KSC reviewed the manuscript. All authors reviewed and approved the final manuscript.
Funding The Alberta Physical Activity and Breast Cancer Prevention (ALPHA) Trial was funded by research grants from the Canadian Breast Cancer Research Alliance (number 13576 and number 017468), the Alberta Cancer Foundation (number 22170) and the ALPHA Ancillary Study was funded by the Canadian Institutes for Health Research (CIHR) (number MOP-130238). CMF holds a Health Senior Scholar Award from Alberta Innovates-Health Solutions (AI-HS) and is the Alberta Cancer Foundation Weekend to End Women's Cancers Breast Cancer Chair. VP was supported by the Institut Universitaire de France. SMC was supported by postdoctoral fellowships (AI-HS) and the CIHR. DRB was supported by a postdoctoral fellowship from AI-HS and a career award from the Canadian Cancer Society Research Institute. XW was supported by postdoctoral fellowships from the Hotchkiss Brain Institute, AI-HS and the CIHR. MJP holds the Brenda Strafford Foundation Chair in Alzheimer Research. KSC was supported by the Canada Research Chairs Programme.
Competing interests None declared.
Ethics approval Alberta Cancer Research Ethics Board (Alberta Cancer Board), the Conjoint Health Research Ethics Board (University of Calgary) and the Health Research Ethics Board (University of Alberta).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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