title: Biomechanical properties of isolated fascicles of the Iliopsoas and Achilles tendons in African American and Caucasian men.
abstract: OBJECTIVE
  To investigate biomechanical properties of the Iliopsoas and Achilles tendons in young African American (AA) and Caucasian (CC) men, and attempt to clarify whether the difference in Achilles tendon ruptures between AA and CC can be explained by differences in material properties.
  
  
  METHODS
  Tissue from 12 young males (AA, n=6; CC, n=6) was obtained from routine forensic autopsies. Iliopsoas and Achilles tendon samples were obtained from cadavers that were age, height and weight matched. Tendon collagen fascicles were tested micromechanically in a Deben mechanical testing rig.
  
  
  RESULTS
  Peak failure stress in Iliopsoas tendon fascicles was considerably higher (p<0.05) in AA (22.4 ± 7.2MPa) than CC (6.8 ± 2.1MPa) whereas peak strain did not differ (AA: 19.7 ± 5.2%, CC: 18.3 ± 3.5%). Likewise, Young's modulus was greater (p<0.05) in AA (165.3 ± 67.3MPa) than CC (63.6 ± 23.6MPa). In contrast, peak failure stress in Achilles tendon fascicles was similar (p>0.1) in AA (21.9 ± 9.9MPa) and CC (28.1 ± 9.8MPa), and peak strain did not differ (p>0.1) between AA (16.3 ± 3.5%) and CC (13.8 ± 4.4%). Young's modulus was slightly greater in CC (316.8 ± 110MPa) than AA (222.8 ± 84.6MPa), yet not significantly (p>0.1).
  
  
  CONCLUSIONS
  These findings indicate that Iliopsoas tendon fascicles are stronger in young AA compared to CC males, which is suggested to reflect differences in muscle mass and force generating capacity. This could not be confirmed in Achilles tendon fascicles.
authors.affiliation: Institute of Sports Medicine Copenhagen, Bispebjerg Hospital, University of Copenhagen, Denmark.
authors.forename: P
authors.initials: P
authors.lastname: Hanson
authors.forename: P
authors.initials: P
authors.lastname: Aagaard
authors.forename: S P
authors.initials: SP
authors.lastname: Magnusson
mesh_terms: D000125:Achilles Tendon / Q000293:injuries / Q000502:physiology*; D000328:Adult; D019412:Anatomy, Cross-Sectional; D001696:Biomechanical Phenomena; D044383:Black People; D002102:Cadaver; D003094:Collagen / Q000502:physiology; D055119:Elastic Modulus; D005260:Female; D006801:Humans; D008297:Male; D016658:Psoas Muscles / Q000502:physiology; D012421:Rupture; D013708:Tendon Injuries / Q000473:pathology; D013710:Tendons / Q000502:physiology*; D013718:Tensile Strength / Q000502:physiology; D044465:White People; D055815:Young Adult; D001741:Black or African American
chemical_list: D003094:Collagen