title: Evoked spinal reflexes and force development in elite athletes with middle-portion Achilles tendinopathy.
abstract: METHODS
  Controlled laboratory study.
  
  
  OBJECTIVE
  To compare the neuromuscular function of the triceps surae muscle bilaterally in elite athletes with unilateral chronic Achilles tendinopathy.
  
  
  BACKGROUND
  Previous studies suggest that tendinopathies or chronic pain may lead to a spinal/supraspinal level modulation of the excitability or voluntary activation of ipsilateral motor units. However, this has not been studied in Achilles tendinopathy.
  
  
  METHODS
  Fourteen college athletes (mean ± SD age, 24.2 ± 1.7 years) who had unilateral chronic middle-portion tendinopathy in their Achilles tendons were recruited. Bilateral measurements of soleus reflex tests, including H-reflex and V wave, and rate of force development (RFD), as well as corresponding electromyography of the tibialis anterior and triceps surae muscles, were performed. Statistical within-subject and between-leg comparisons were made.
  
  
  RESULTS
  In the leg with tendinopathy, the V wave of the soleus muscle was significantly increased (P<.001). The side with tendinopathy also had a reduced normalized RFD (0-30, 0-50, and 0-100 ms) in plantar flexion, and concomitant higher electromyography ratios between the tibialis anterior and soleus (0-30 and 0-50 milliseconds) during the early stage of explosive contractions (P<.05). No significant differences were found for H-reflex, maximal plantar flexion and dorsiflexion torque, and absolute RFD.
  
  
  CONCLUSIONS
  Higher volitional supraspinal reflexes and lower maximal-strength independent force development occur in the triceps surae of elite athletes with unilateral middle-portion Achilles tendinopathy. These changes potentially indicate an acquired compensatory mechanism for maximal force production and deficits in explosive strength. The RFD is also suggested as a sensitive parameter to depict neuromuscular changes during treatment of chronic tendinopathies.
authors: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taiwan, Republic of China. hkwang@ntu.edu.tw
authors: Hsing-Kuo
authors: HK
authors: Wang
authors: Kwan-Hwa
authors: KH
authors: Lin
authors: Yu-Kuang
authors: YK
authors: Wu
authors: Shyh-Ching
authors: SC
authors: Chi
authors: Tifany Ting-Fang
authors: TT
authors: Shih
authors: Yung-Cheng
authors: YC
authors: Huang
mesh_terms: D000125:Achilles Tendon / Q000503:physiopathology*; D000328:Adult; D056352:Athletes; D003430:Cross-Sectional Studies; D005071:Evoked Potentials / Q000502:physiology*; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D058765:Neurofeedback; D013624:Taiwan; D052256:Tendinopathy / Q000503:physiopathology*; D055815:Young Adult