title: Preserving sarcomere number after tenotomy requires stretch and contraction.
abstract: BACKGROUND
  Passive stretch therapy is utilized to improve the range of motion of chronically shortened muscles. However, human studies show conflicting results as whether passive stretch is clinically effective.
  
  
  METHODS
  The soleus muscles of adult rats were tenotomized to induce muscle shortening adaptation. Muscles included were non-treated normal, subjected to daily static stretch, or lengthened and isometrically contracted for 20 min/day. Muscle fiber structure was analyzed histochemically. Sarcomeres per millimeter length were counted to assess the effect of treatment.
  
  
  RESULTS
  Passive stretch significantly reduced central core lesion formation, but sarcomere loss was not prevented. The addition of isometric contraction during static stretch significantly (P < 0.001) reduced sarcomere loss.
  
  
  CONCLUSIONS
  Passive stretch alone does not prevent shortening adaptation. Contraction is required in combination with stretch to preserve the number of sarcomeres in series. The combination of stretch and contraction is necessary to maintain proper muscle fiber length.
authors.affiliation: Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226, USA.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Van Dyke
authors.forename: James L W
authors.initials: JL
authors.lastname: Bain
authors.forename: Danny A
authors.initials: DA
authors.lastname: Riley
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004195:Disease Models, Animal; D004558:Electric Stimulation; D004566:Electrodes; D005081:Exercise Therapy; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D020966:Muscular Disorders, Atrophic / Q000209:etiology* / Q000473:pathology / Q000534:rehabilitation*; D009218:Myosins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012518:Sarcomeres / Q000473:pathology*; D058971:Tenotomy / Q000009:adverse effects*; D013997:Time Factors
chemical_list: D009218:Myosins