title: Association between Leukocyte Mitochondrial DNA Copy Number and Regular Exercise in Postmenopausal Women.
abstract: BACKGROUND
  Previous studies suggest that habitual exercise can improve skeletal mitochondrial function; however, to date, the association between exercise and mitochondrial function in peripheral leukocytes has not been reported. The aim of this study was to evaluate the relationship between regular exercise and mitochondrial function by measuring leukocyte mitochondrial DNA (mtDNA) copy number in postmenopausal women.
  
  
  METHODS
  This cross-sectional study included 144 relatively healthy, non-diabetic, non-smoking, postmenopausal women. Clinical parameters, including anthropometric measurements and cardio-metabolic parameters, were assessed. Regular exercise was defined as at least 150 minutes per week of moderate-intensity activity, or an equivalent combination of moderate and vigorous-intensity activity, over a duration of at least 6 months. Leukocyte mtDNA copy numbers were measured using real-time polymerase chain reaction assays, and these were normalized to the β-globin copy number to give the relative mtDNA copy number.
  
  
  RESULTS
  The mtDNA copy number of peripheral leukocytes was significantly greater in the exercise group (1.33±0.02) than in the no exercise group (1.05±0.02, P<0.01). Stepwise multiple regression analysis showed that regular exercise was independently associated with mtDNA copy number (β=0.25, P<0.01) after adjusting for the variables age, body mass index, waist-to-hip ratio, systolic and diastolic blood pressure, homeostasis model assessment of insulin resistance value, and levels of high-density lipoprotein cholesterol, triglycerides, and homocysteine.
  
  
  CONCLUSIONS
  Regular exercise is associated with greater leukocyte mtDNA copy number in postmenopausal women.
authors.affiliation: Department of Family Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Yu Kyung
authors.initials: YK
authors.lastname: Chang
authors.affiliation: Department of Family Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Da Eun
authors.initials: DE
authors.lastname: Kim
authors.affiliation: Department of Family Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Soo Hyun
authors.initials: SH
authors.lastname: Cho
authors.affiliation: Department of Family Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Jung-Ha
authors.initials: JH
authors.lastname: Kim
keywords: DNA Copy Number; Exercise; Leukocytes; Mitochondria; Postmenopausal