title: Effects of weight bearing and non-weight bearing exercises on bone properties using calcaneal quantitative ultrasound.
abstract: OBJECTIVE
  This study was designed to investigate bone properties using heel quantitative ultrasound (QUS) in young adults participating in various sports.
  
  
  METHODS
  A cross sectional study was performed on Chinese male students (n = 55), aged 18-22 years. Subjects with previous fractures or suffering from any diseases known to affect bone metabolism or taking any medication with such an effect, were not included. The subjects were categorised according to their main sporting activities, including soccer (n = 15) (a high impact, weight bearing exercise), dancing (n = 10) (a low impact, weight bearing exercise), and swimming (n = 15) (non-weight bearing exercise). A sedentary group acted as controls (n = 15). A reproducibility study of the velocity of sound (VOS) and the broadband ultrasound attenuation (BUA) measurement was performed and analysed using the intraclass correlation coefficient (ICC).
  
  
  RESULTS
  There was good intra-investigator and inter-investigator agreement (ICC > or = 0.8; p < 0.05) in the measurement of BUA and VOS. No significant differences in BUA and VOS (p > 0.05) were found between the dominant and non-dominant heel. Soccer players (137 +/- 4.3 dB/MHz; 1575 +/- 56 m/s; 544.1 +/- 48.4) and dancers (134.6 +/- 3.7 dB/MHz; 1538 +/- 46 m/s; 503.0 +/- 37.0) had significantly higher BUA, VOS, and stiffness index (SI) scores (p < 0.05), respectively, than swimmers (124.1 +/- 5.1 dB/MHz; 1495 +/- 42 m/s; 423.3 +/- 46.9) and the sedentary control group (119.9 +/- 6.1 dB/MHz; 1452 +/- 41 m/s; 369.9 +/- 46.4). A trend of a significant linear increase with the weight bearing and high impact exercise was revealed in all QUS parameters (p < 0.05).
  
  
  CONCLUSIONS
  This cross sectional study indicated that regular participation in weight bearing exercise in young people might be beneficial for accruing peak bone mass and optimising bone structure.
authors.affiliation: Department of Optometry and Radiography, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China.
authors.forename: P S
authors.initials: PS
authors.lastname: Yung
authors.forename: Y M
authors.initials: YM
authors.lastname: Lai
authors.forename: P Y
authors.initials: PY
authors.lastname: Tung
authors.forename: H T
authors.initials: HT
authors.lastname: Tsui
authors.forename: C K
authors.initials: CK
authors.lastname: Wong
authors.forename: V W Y
authors.initials: VW
authors.lastname: Hung
authors.forename: L
authors.initials: L
authors.lastname: Qin
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D015992:Body Mass Index; D015519:Bone Density / Q000502:physiology; D002111:Calcaneus / Q000000981:diagnostic imaging* / Q000502:physiology; D003430:Cross-Sectional Studies; D003615:Dancing / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D012916:Soccer / Q000502:physiology; D013550:Swimming / Q000502:physiology; D014463:Ultrasonography; D016474:Weight-Bearing / Q000502:physiology*