title: Stiffness as a Risk Factor for Achilles Tendon Injury in Running Athletes.
abstract: BACKGROUND
  Overuse injuries are multifactorial resulting from cumulative loading. Therefore, clear differences between normal and at-risk individuals may not be present for individual risk factors. Using a holistic measure that incorporates many of the identified risk factors, focusing on multiple joint movement patterns may give better insight into overuse injuries. Lower body stiffness may provide such a measure.
  
  
  OBJECTIVE
  To identify how risk factors for Achilles tendon injuries influence measures of lower body stiffness.
  
  
  METHODS
  SPORTDiscus, Web of Science, CINAHL and PubMed were searched for Achilles tendon injury risk factors related to vertical, leg and joint stiffness in running athletes.
  
  
  RESULTS
  Increased braking force and low surface stiffness, which were clearly associated with increased risk of Achilles tendon injuries, were also found to be associated with increased lower body stiffness. High arches and increased vertical and propulsive forces were protective for Achilles tendon injuries and were also associated with increased lower body stiffness. Risk factors for Achilles tendon injuries that had unclear associations were also investigated with the evidence trending towards an increase in leg stiffness and a decrease in ankle stiffness being detrimental to Achilles tendon health.
  
  
  CONCLUSIONS
  Few studies have investigated the link between lower body stiffness and Achilles injury. High stiffness is potentially associated with risk factors for Achilles tendon injuries although some of the evidence is controversial. Prospective injury studies are needed to confirm this relationship. Large amounts of high-intensity or high-speed work or running on soft surfaces such as sand may increase Achilles injury risk. Coaches and clinicians working with athletes with new or reoccurring injuries should consider training practices of the athlete and recommend reducing speed or sand running if loading is deemed to be excessive.
authors.affiliation: Sports Performance Research Institute New Zealand (SPRINZ) at AUT-Millennium, Auckland University of Technology, Private Bag 92006, Auckland, New Zealand. alorimer@aut.ac.nz.|Unitec Institute of Technology, 139 Carrington Road, Mt Albert, Auckland, 1025, New Zealand. alorimer@aut.ac.nz.
authors.forename: Anna V
authors.initials: AV
authors.lastname: Lorimer
authors.affiliation: Sports Performance Research Institute New Zealand (SPRINZ) at AUT-Millennium, Auckland University of Technology, Private Bag 92006, Auckland, New Zealand.
authors.forename: Patria A
authors.initials: PA
authors.lastname: Hume
mesh_terms: D000125:Achilles Tendon / Q000293:injuries* / Q000503:physiopathology; D056352:Athletes; D005684:Gait / Q000502:physiology; D006801:Humans; D016059:Range of Motion, Articular; D012307:Risk Factors; D012420:Running / Q000293:injuries*