title: Sustained benefits from previous physical activity on bone mineral density in males.
abstract: BACKGROUND
  The effect of physical activity on bone mineral density (BMD) is not well investigated longitudinally after puberty in men.
  
  
  OBJECTIVE
  Our objective was to evaluate the effect of exercise and reduced exercise on BMD after puberty in men.
  
  
  METHODS
  We conducted a longitudinal study.
  
  
  METHODS
  Sixty-three healthy young athletes and 27 male controls, both with a mean age of 17 yr at baseline, participated. Also, 136 of the participants' parents were investigated to evaluate heritable influences.
  
  
  METHODS
  Total body, total hip, femoral neck, and humerus BMD (grams per square centimeter) were measured at baseline and after mean periods of 27, 68, and 94 months in the young cohort.
  
  
  RESULTS
  BMDs of control parents and athlete parents were equal, suggesting absence of selection bias. The 23 athletes that remained active throughout the study increased BMD at all sites when compared with controls (mean difference, 0.04-0.12 g/cm(2); P < 0.05) during the study period. After an average of 3 yr, 27 athletes ended their active careers. Although this group initially lost BMD at the hip compared with active athletes, the former athletes still had higher BMD than controls at the femoral neck (0.12 g/cm(2); P = 0.007), total hip (0.11 g/cm(2); P = 0.02), and humerus (0.10 g/cm(2); P = 0.02) at the final follow-up.
  
  
  CONCLUSIONS
  High sensitivity to physical loading persists after puberty in men. Reduced physical activity is associated with BMD loss in the first 3 yr in weight-bearing bone. Sustained benefits in BMD are preserved 5 yr after intensive training ends.
authors.affiliation: Sports Medicine Unit, Department of Surgical and Perioperative Sciences, Umeå University, 901 85 Umeå, Sweden. peter.nordstrom@idrott.umu.se
authors.forename: Anna
authors.initials: A
authors.lastname: Nordström
authors.forename: Tommy
authors.initials: T
authors.lastname: Olsson
authors.forename: Peter
authors.initials: P
authors.lastname: Nordström
mesh_terms: D000293:Adolescent; D015519:Bone Density / Q000235:genetics / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005272:Femur Neck; D006801:Humans; D006811:Humerus; D008137:Longitudinal Studies; D008297:Male; D011627:Puberty; D013177:Sports