title: Effect of low-load resistance training on the tendon properties in middle-aged and elderly women.
abstract: OBJECTIVE
  The purposes of this study were to determine the age-related changes in the tendon-aponeurosis structures and to investigate the effects of low-load resistance training on the tendon-aponeurosis structures in middle-aged and elderly women.
  
  
  METHODS
  Fifty-one women (55.8 +/- 13.7 years, range: 21-77 years) volunteered to take part in the present study. Furthermore, 11 middle-aged and elderly women (49.7 +/- 9.2 years) performed the low-load resistance training, i.e. squat using body weight, for 6 months. The elongation of the tendon and aponeurosis of the vastus lateralis muscle was directly measured by ultrasonography, while the subjects performed ramp isometric knee extension up to the voluntary maximum, followed by a ramp relaxation. The relationship between the estimated muscle force (Fm) and tendon elongation (L) during the ascending phase was fitted to a linear regression, the slope of which was defined as stiffness. The percentage of the area within the Fm-L loop to the area beneath the curve during the ascending phase was calculated as hysteresis.
  
  
  RESULTS
  Maximal strain (L/initial tendon length) and stiffness of the tendon-aponeurosis structures decreased significantly with ageing. In contrast, the hysteresis increased significantly with ageing. In addition, low-load resistance training produced no significant change in stiffness and hysteresis, but significantly increased the maximal elongation of tendon-aponeurosis structures from 23.3 +/- 2.1 mm to 24.8 +/- 2.2 mm (P = 0.045).
  
  
  CONCLUSIONS
  These results suggest that increasing age results in a decrease in the elasticity of tendon-aponeurosis structures and an increase in their viscosity. Furthermore, the low-load resistance training made the elasticity of tendon-aponeurosis structures increase.
authors.affiliation: Department of Life Science (Sports Sciences), University of Tokyo, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kubo
authors.forename: H
authors.initials: H
authors.lastname: Kanehisa
authors.forename: M
authors.initials: M
authors.lastname: Miyatani
authors.forename: M
authors.initials: M
authors.lastname: Tachi
authors.forename: T
authors.initials: T
authors.lastname: Fukunaga
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D004548:Elasticity; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007719:Knee Joint; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology*; D013314:Stress, Mechanical; D013710:Tendons / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography; D014783:Viscosity