title: Sport-specific association between exercise loading and the density, geometry, and microstructure of weight-bearing bone in young adult men.
abstract: In this population-based study of 24-year-old men, we have investigated the association between sport-specific exercise loading and different bone parameters. We reveal that the association between exercise loading and bone parameters is sport-specific, indicating that nonspecific resistance exercise does not impact bone density, geometry, or microstructure in young men.
  
  
  BACKGROUND
  In this cross-sectional study, the association between nonspecific resistive exercise and areal and volumetric bone density, bone geometry, or bone microstructure was investigated in young adult men.
  
  
  METHODS
  A total of 184 male athletes, 24.0 ± 0.6 years of age (mean ± SD), representing nonspecific resistive exercise and soccer (proportion of recreational athletes, 93.4 and 7.7 %, respectively), and 177 nonathletic age-matched controls were measured with dual-energy X-ray absorptiometry. Radius and tibia were measured by peripheral quantitative computed tomography (pQCT) at the diaphysis and by three-dimensional pQCT at the metaphysis.
  
  
  RESULTS
  Men in the nonspecific resistive exercise group had higher grip strength(9.1 % or 0.4 SD) and higher lean mass(5.6 % or 0.5 SD) than those in the nonathletic group(p < 0.01 and p < 0.001, respectively). However, men who participated in nonspecific resistive exercise did not have higher bone density or a more favorable bone microstructure or geometry than their nonathletic referents. In contrast, men playing soccer had higher areal bone mineral density (aBMD) at the femoral neck (19.5 % or 1.2 SD) and lumbar spine (12.6 % or 1.0 SD), as well as larger cortical cross-sectional area (16.4 % or 1.1 SD) and higher trabecular bone volume fraction (14.5 % or 0.9 SD), as a result of increased trabecular number (8.7 % or 0.6 SD) and thickness (5.7 % or 0.4 SD) at the tibia than men in the nonathletic group(p < 0.001).
  
  
  CONCLUSIONS
  Weight-bearing exercise with impacts from varying directions (playing soccer) is associated with aBMD and volumetric BMD, cortical bone geometry, as well as trabecular microstructure of weight-bearing bone. Nonspecific recreational resistance exercise does not appear to be a strong determinant of bone density, geometry, or microstructure in young adult men.
authors.affiliation: Centre for Bone and Arthritis Research at the Sahlgrenska Academy, Department of Internal Medicine, University of Gothenburg, Gothenburg, Sweden. martin.nilsson@medic.gu.se
authors.forename: M
authors.initials: M
authors.lastname: Nilsson
authors.forename: C
authors.initials: C
authors.lastname: Ohlsson
authors.forename: D
authors.initials: D
authors.lastname: Mellström
authors.forename: M
authors.initials: M
authors.lastname: Lorentzon
mesh_terms: D000328:Adult; D000886:Anthropometry / Q000379:methods; D001823:Body Composition / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D015444:Exercise / Q000502:physiology*; D005272:Femur Neck / Q000502:physiology; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000502:physiology; D011884:Radius / Q000033:anatomy & histology / Q000502:physiology; D055070:Resistance Training; D012916:Soccer / Q000502:physiology; D013177:Sports / Q000502:physiology*; D013977:Tibia / Q000033:anatomy & histology / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult