title: Neuromechanical Modulation of the Achilles Tendon During Bilateral Hopping in Patients with Unilateral Achilles Tendon Rupture, Over 1 Year After Surgical Repair.
abstract: BACKGROUND
  Patients who have had an Achilles tendon (AT) rupture repaired are potentially at higher risk for re-rupture than those without previous rupture. Little attention has been given to the neuromechanical modulation of muscle-tendon interaction and muscle activation profiles during human dynamic movements after AT rupture repair.
  
  
  OBJECTIVE
  The purpose of this study was to examine muscle-tendon behavior and muscle activation during bilateral hopping.
  
  
  METHODS
  We enrolled nine subjects who had undergone surgical repair of unilateral AT rupture within the past 1-2 years. Subjects performed bilateral hopping while we took ultrasound, kinematic, and electromyogram recordings and measurements. AT behaviors were also recorded. We then compared responses between values obtained from the ruptured AT leg (LEGATR) and non-ruptured AT leg (LEGNOR).
  
  
  RESULTS
  During hopping, the AT stretching amplitudes were greater in the LEGATRthan in the LEGNOR, although the peak AT force and stiffness were smaller in the LEGATRthan in the LEGNOR. The AT negative mechanical work did not show any significant differences between both legs. However, positive works were significantly lower in the LEGATRthan in the LEGNOR. Electromyogram patterns in both soleus and tibialis anterior muscles clearly differed after ground contact for the LEGATRand the LEGNOR.
  
  
  CONCLUSIONS
  These results suggest that the repaired ruptured AT can be compliant and have insufficient Young's modulus, which can influence mechanical responses in muscle activities. The modulation of agonist-antagonist muscle activities corresponding to the different levels of stiffness between the LEGATRand the LEGNORmay not be fully functioning during the pre-activation phase.
authors.affiliation: Graduate School of Sport and Exercise Sciences, Osaka University of Health and Sport Sciences, Asashirodai 1-1, Kumatori-cho, Sennan-gun, Osaka, 590-0496, Japan. hiroyuki.oda.1005@gmail.com.|Riseisha College of Medicine and Sport, Jyusohonnmachi 3-4-21, Yodogawa-ku, Osaka, Osaka, 532-0024, Japan. hiroyuki.oda.1005@gmail.com.
authors.forename: Hiroyuki
authors.identifier: http://orcid.org/0000-0003-0150-1053
authors.initials: H
authors.lastname: Oda
authors.affiliation: Graduate School of Sport and Exercise Sciences, Osaka University of Health and Sport Sciences, Asashirodai 1-1, Kumatori-cho, Sennan-gun, Osaka, 590-0496, Japan.
authors.forename: Kanae
authors.initials: K
authors.lastname: Sano
authors.affiliation: Graduate School of Sport and Exercise Sciences, Osaka University of Health and Sport Sciences, Asashirodai 1-1, Kumatori-cho, Sennan-gun, Osaka, 590-0496, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kunimasa
authors.affiliation: Likes Research Center, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Paavo V
authors.initials: PV
authors.lastname: Komi
authors.affiliation: Graduate School of Sport and Exercise Sciences, Osaka University of Health and Sport Sciences, Asashirodai 1-1, Kumatori-cho, Sennan-gun, Osaka, 590-0496, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Ishikawa
mesh_terms: D000125:Achilles Tendon / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery*; D004576:Electromyography; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D016059:Range of Motion, Articular; D020127:Recovery of Function; D012421:Rupture; D013708:Tendon Injuries / Q000534:rehabilitation / Q000601:surgery*; D016896:Treatment Outcome