title: Stretch reduces central core lesions and calcium build-up in tenotomized soleus.
abstract: The incidence of skeletal muscle tendon rupture is increasing. The unloaded, shortened muscle undergoes rapid degeneration. Rehabilitation takes 10-12 weeks and includes stretch therapy. Outcomes may be improved by understanding the pathophysiological changes and stretch mechanisms. We investigated the effects of passive stretch on preventing central core lesions in a rat tenotomy model of simulated Achilles tendon rupture. Adult male rats were tenotomized bilaterally. At 7 days, 39% of the soleus fibers possessed central core lesions. Whole muscle calcium concentration progressively increased and plateaued by 4 days. Dantrolene, a calcium release blocker, injected daily for 7 days, reduced central core lesion formation and calcium build-up. Passive stretch, 20 min/day, inhibited central core lesion formation. Calcium increased at 4 days in mitochondria, and stretch prevented this increase. These findings indicate that stretch therapy reduces central core lesion occurrence by preventing calcium elevation in hypershortened muscles.
authors.affiliation: Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
authors.forename: David V
authors.initials: DV
authors.lastname: Baewer
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: D000125:Achilles Tendon / Q000293:injuries*; D000818:Animals; D000880:Anthraquinones; D002118:Calcium / Q000378:metabolism*; D004396:Coloring Agents; D003620:Dantrolene / Q000494:pharmacology; D008297:Male; D008854:Microscopy, Electron; D008931:Mitochondria, Muscle / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D052580:Muscle Stretching Exercises; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000880:Anthraquinones; D004396:Coloring Agents; D009125:Muscle Relaxants, Central; C004468:Alizarin Red S; D003620:Dantrolene; D002118:Calcium