title: Gastrocnemius muscle architecture and achilles tendon properties influence walking distance in claudicants with peripheral arterial disease.
abstract: BACKGROUND
  The extent to which gastrocnemius muscle and Achilles tendon properties contribute to the impaired walking endurance of claudicants is not known.
  
  
  METHODS
  Ultrasound images quantified muscle architecture of the lateral and medial gastrocnemius (GL and GM) and were combined with dynamometry during plantarflexor contractions to calculate tendon stress, strain, stiffness, the Young modulus, and hysteresis. Key parameters were entered into multiple regression models to explain walking endurance.
  
  
  RESULTS
  Worse disease severity was significantly associated with longer fascicle: tendon length ratios (GL R = -0.789 and GM R = -0.828) and increased tendon hysteresis (R = -0.740). Walking endurance could be explained by GL and GM pennation angle, maximum tendon force, tendon hysteresis, and disease severity (R(2)  = ∼0.6).
  
  
  CONCLUSIONS
  Peripheral arterial disease was associated with functionally important changes in muscle and tendon properties, including the usage of stored elastic energy. Interventions known to target these characteristics should be adopted as a means to improve walking endurance.
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, L3 3AF, Liverpool, United Kingdom.|Department of Sport, Health and Exercise Science, University of Hull, Yorkshire, United Kingdom.
authors.forename: Stephanie Louise
authors.initials: SL
authors.lastname: King
authors.affiliation: Department of Sport, Health and Exercise Science, University of Hull, Yorkshire, United Kingdom.|Discipline of Exercise and Sport Science, University of Sydney, Sydney, Australia.
authors.forename: Natalie
authors.initials: N
authors.lastname: Vanicek
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom Street, L3 3AF, Liverpool, United Kingdom.|School of Sport, Health and Exercise Science, Bangor University, Bangor, United Kingdom.
authors.forename: Thomas Daniel
authors.initials: TD
authors.lastname: O'Brien
mesh_terms: D000125:Achilles Tendon / Q000000981:diagnostic imaging / Q000503:physiopathology*; D000368:Aged; D055109:Ankle Brachial Index; D001696:Biomechanical Phenomena; D055119:Elastic Modulus; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D007383:Intermittent Claudication / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D058729:Peripheral Arterial Disease / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012044:Regression Analysis; D012720:Severity of Illness Index; D013314:Stress, Mechanical; D014463:Ultrasonography
keywords: efficiency; endurance; gastrocnemius; hysteresis; intermittent claudication