title: Strenuous resistance exercise effects on magnetic resonance diffusion parameters and muscle-tendon function in human skeletal muscle.
abstract: OBJECTIVE
  To assess the effects of strenuous exercise on magnetic resonance diffusion parameters and muscle-tendon complex function in skeletal muscle.
  
  
  METHODS
  Six men performed ankle plantar flexion exercises with eccentric contraction. The fractional anisotropy (FA), λ(1) , λ(2) , λ(3) , mean diffusivity (MD), and T(2) values in the triceps surae muscles were measured by magnetic resonance diffusion tensor and spin-echo imaging. Passive torque of plantar flexors, maximal voluntary isometric plantar flexion torques (MVIP), and Achilles tendon stiffness during MVIP were measured by combined ultrasonography and dynamometry. Plasma creatine kinase and muscle soreness were also assessed. These parameters were measured before and 1-8 days postexercise.
  
  
  RESULTS
  The medial gastrocnemius exhibited significantly decreased FA 2-5 days after, increased λ(2) 3 days after, and increased λ(3) 2 and 3 days after exercise. This muscle also showed significantly increased MD and T(2) values 3 days postexercise. MVIP significantly decreased 2 and 3 days postexercise, while passive torque significantly increased 2 days postexercise. Creatine kinase and muscle soreness increased 3-5 days and 1-5 days postexercise, respectively.
  
  
  CONCLUSIONS
  Exercise-induced muscle damage manifested as significant changes in muscle diffusion parameters with muscle-tendon complex dysfunction and delayed-onset muscle soreness.
authors.affiliation: Faculty of Sport Sciences, Waseda University, Saitama, Japan. o.yanagisawa@aoni.waseda.jp
authors.forename: Osamu
authors.initials: O
authors.lastname: Yanagisawa
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kurihara
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Kobayashi
authors.forename: Toru
authors.initials: T
authors.lastname: Fukubayashi
mesh_terms: D000125:Achilles Tendon / Q000033:anatomy & histology* / Q000502:physiology; D000843:Ankle Joint; D003402:Creatine Kinase / Q000032:analysis / Q000097:blood; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005080:Exercise Test; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology; D055070:Resistance Training; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003402:Creatine Kinase