title: Total and regional bone density in male runners, cyclists, and controls.
abstract: OBJECTIVE
  Male athletes who were runners (N = 12), cyclists (N = 14), or both (N = 13) were compared with nonexercising age-matched controls (N = 23) for total and regional bone mineral density (BMD). All athletic subjects had competed for a minimum of 3 yr and trained for a minimum of 4 h x wk(-1). Runners undertook no cycling and cyclists undertook no running training.
  
  
  METHODS
  All subjects were scanned for whole body and L1-L4 spine BMD using a Hologic QDR 1000W scanner (Hologic Inc., Bedford, MA).
  
  
  RESULTS
  There were no differences in age, height, weight, body mass index (BMI), % fat, or hours of training between any of the athletic groups (P > 0.05), although compared with controls, runners and cyclists had lower body mass index (P < 0.01) and all athletic groups had lower % fat (P < 0.001). Compared with controls, runners had greater total and leg BMD (P < 0.05), cyclists had reduced spine BMD (P = 0.05), and athletes of the "both" group had greater total (P < 0.05) and arm BMD (P < 0.01).
  
  
  CONCLUSIONS
  Running is associated with increased bone density, particularly in the leg, whereas cycling is associated with a mild decrease in bone density in the spine. In athletes who do both, running exerts a stronger influence than cycling.
authors.affiliation: Fitness Assessment and Sports Injury Centre, The University of Edinburgh, United Kingdom. a.d.stewart@abdn.ac.uk
authors.forename: A D
authors.initials: AD
authors.lastname: Stewart
authors.forename: J
authors.initials: J
authors.lastname: Hannan
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D001642:Bicycling; D015519:Bone Density / Q000502:physiology*; D001842:Bone and Bones / Q000502:physiology; D016022:Case-Control Studies; D006801:Humans; D008297:Male; D012420:Running