title: Adiposity, muscle, and physical activity: predictors of perturbations in heart rate variability.
abstract: OBJECTIVE
  This study examines cross-sectional associations of indices of adiposity, lean body mass, and physical activity, with heart rate variability (HRV), a marker for parasympathetic cardiac vagal control.
  
  
  METHODS
  The study population consists of 360 officers from the Buffalo New York Police Department. Indices of adiposity include body mass index, waist circumference, and a fat-mass index taken from dual-energy X-ray absorptiometry (DEXA) measurements. Lean body mass indices were derived from DEXA measurements of trunk mass and extremity lean mass. Physical activity was measured using a 7-day self-report questionnaire. HRV was obtained from 5-min electrocardiogram measurements by means of parametric spectral analysis resulting in estimates for high-frequency (HF) and low-frequency (LF) HRV.
  
  
  RESULTS
  Both HF and LF HRV were significantly associated with markers for adiposity, two components of lean mass and physical activity with all associations being in the expected direction except that for trunk lean mass. This unexpected result is explained by the possibility that trunk mass is a marker for visceral adiposity rather than lean mass. Body mass index did not explain any additional variance in HRV above and beyond waist circumference and the DEXA indices.
  
  
  CONCLUSIONS
  Higher levels of physical activity, lower levels of markers for central adiposity and higher lean mass in the extremities predict higher levels of HRV in this population of police officers. This association between modifiable risk factors and markers for autonomic function suggest possible interventions that may improve health and performance.
authors.affiliation: Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505, USA. MAndrew@CDC.GOV
authors.forename: Michael E
authors.initials: ME
authors.lastname: Andrew
authors.forename: Li
authors.initials: L
authors.lastname: Shengqiao
authors.forename: Jean
authors.initials: J
authors.lastname: Wactawski-Wende
authors.forename: Joan P
authors.initials: JP
authors.lastname: Dorn
authors.forename: Anna
authors.initials: A
authors.lastname: Mnatsakanova
authors.forename: Luenda E
authors.initials: LE
authors.lastname: Charles
authors.forename: Desta
authors.initials: D
authors.lastname: Fekedulegn
authors.forename: Diane B
authors.initials: DB
authors.lastname: Miller
authors.forename: John M
authors.initials: JM
authors.lastname: Violanti
authors.forename: Cecil M
authors.initials: CM
authors.lastname: Burchfiel
authors.forename: Dan S
authors.initials: DS
authors.lastname: Sharp
mesh_terms: D000273:Adipose Tissue / Q000502:physiology*; D000328:Adult; D000367:Age Factors; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D004562:Electrocardiography; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012737:Sex Factors; D055105:Waist Circumference