title: The effects of immobilization on the mechanical properties of the patellar tendon in younger and older men.
abstract: BACKGROUND
  It remains unknown if inactivity changes the mechanical properties of the human patellar tendon in younger and older healthy persons. The purpose was to examine the effects of short-term unilateral immobilization on the structural and mechanical properties of the patellar tendon in older men and younger men, in vivo.
  
  
  METHODS
  Eight older men and eight younger men underwent 14 days of unilateral immobilization. All individuals were assessed on both sides before and after the intervention. MRI was used to assess whole patellar tendon dimensions. The mechanical properties of the patellar tendon were assessed using simultaneous force and ultrasonographic measurements during isometric ramp contractions.
  
  
  RESULTS
  In older men, tendon stiffness [Pre: mean 2949 (SD 799) vs. Post: mean 2366 (SD 774) N mm(-1), P<0.01] and Young's Modulus [Pre: mean 1.2 (SD 0.3) vs. Post: mean 1.0 (SD 0.3) GPa, P<0.05] declined with immobilization on the immobilized side. On the control side, tendon stiffness [Pre: mean 3340 (SD 1209) vs. Post: mean 2230 (SD 503), P<0.01] and Young's Modulus [Pre: mean 1.5 (SD 0.4) vs. Post: mean 0.9 (SD 0.3) GPa, P<0.05] also decreased with immobilization. In younger men, tendon stiffness [Pre: 3622 (SD 1760) vs. Post: mean 2910 (SD 1528) N mm(-1), P<0.01] and Young's Modulus [Pre: mean 1.7 (SD 1.1) vs. Post: mean 1.4 (SD 0.8) GPa, P<0.05] decreased only on the immobilized side.
  
  
  CONCLUSIONS
  Short-term immobilization led to impaired mechanical properties of the patellar tendon on the immobilized side in both younger men and older men, which can influence the function of the muscle-tendon complex.
authors: Institute of Sports Medicine, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Denmark; Department of Physical Therapy, Bispebjerg Hospital, Denmark. ccouppe@gmail.com
authors: C
authors: C
authors: Couppé
authors: C
authors: C
authors: Suetta
authors: M
authors: M
authors: Kongsgaard
authors: L
authors: L
authors: Justesen
authors: L G
authors: LG
authors: Hvid
authors: P
authors: P
authors: Aagaard
authors: M
authors: M
authors: Kjær
authors: S P
authors: SP
authors: Magnusson
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D055119:Elastic Modulus / Q000502:physiology*; D006801:Humans; D007103:Immobilization; D008297:Male; D017847:Patellar Ligament / Q000502:physiology*; D013718:Tensile Strength / Q000502:physiology; D055815:Young Adult