title: Increased cross-sectional area and reduced tensile stress of the Achilles tendon in elderly compared with young women.
abstract: The Achilles tendon cross-sectional area (CSA), tensile force, and stress during an isometric contraction were examined in healthy young (n = 9, age = 29 +/- 1 years, mean +/- SEM) and elderly (n = 10, 79 +/- 2 years) women. CSA area was obtained with magnetic resonance imaging 3 cm proximal to the insertion, and tendon force was obtained from the isometric ankle moment. The moment of force about the ankle joint was greater in young women (95 +/- 17 N m) than in elderly women (51 +/- 5 N m; p <.05). The Achilles tendon CSA was significantly greater in elderly women (56.3 +/- 3.0 mm(2)) than in young women (46.0 +/- 1.9 mm(2); p <.01). These data show that young women can exert a greater force than elderly women on the Achilles tendon during voluntary contraction, although elderly women have an increased (22%) tendon CSA, and a lower tendon force than young women. The greater tendon size combines to lower the stress on the tendon markedly, which may reduce the risk of injury to the tendon.
authors.affiliation: Team Danmark Test Center, Copenhagen, Denmark. P.Magnusson@mfi.ku.dk
authors.forename: S Peter
authors.initials: SP
authors.lastname: Magnusson
authors.forename: Nina
authors.initials: N
authors.lastname: Beyer
authors.forename: Heidi
authors.initials: H
authors.lastname: Abrahamsen
authors.forename: Per
authors.initials: P
authors.lastname: Aagaard
authors.forename: Kirsten
authors.initials: K
authors.lastname: Neergaard
authors.forename: Michael
authors.initials: M
authors.lastname: Kjaer
mesh_terms: D000125:Achilles Tendon / Q000502:physiology*; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000843:Ankle Joint / Q000502:physiology; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D011336:Probability; D011446:Prospective Studies; D016059:Range of Motion, Articular / Q000502:physiology; D012016:Reference Values; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013718:Tensile Strength