Effects of Aerobic Exercise on Oxidative Stress in Patients Diagnosed with Cancer: A Narrative Review

Abstract

BACKGROUND Oxidative stress (OS) can bring about an imbalance between the production of free radicals (pro-oxidants) and their elimination by protective mechanisms (antioxidants). Exercise and/or physical activity (PA) may provide a mechanism to control the variation and equilibrium between pro-oxidants and antioxidants. PURPOSE  The purpose of this narrative review is to investigate the evidence regarding the effect of exercise and/or PA on OS among individuals diagnosed with cancer.  Methods: A narrative review study design involved a literature search (August 2016) across the databases: Cumulative Index of Nursing and Allied Health Literature (CINAHL), Cochrane, Excerpta Medica database (Embase), and PubMed. Articles included those published from January 2000 - August 2016; inclusive of the search terms "cancer" AND "neoplasm" AND "oncology" AND "oxidative stress" AND "exercise" AND "physical activity"; written in the English language; and utilizing human subjects. The references of the selected articles were then reviewed to identify any qualifying articles. A modified Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) review of each article was completed by two investigators. RESULTS  Eight articles met the final inclusion criteria. Moderate exercise may provide protective mechanisms against OS via increased antioxidant activity, while exhaustive exercise may be responsible for increased levels of OS, increasing the risk for malignancy. While increased OS levels are utilized by current oncologic therapies to damage malignant and premalignant cells, they also damage healthy cells (cardiac, nerve, and lymphatic). CONCLUSION Moderate levels of exercise and/or PA may provide preventative and protective qualities against the negative side effects associated with increased OS from cancer treatment.