title: Thermal energy enhances cell-mediated contraction of lax rat tail tendon fascicles following exercise.
abstract: BACKGROUND
  the application of thermal energy (TE) has shown promise in the treatment of tendinopathy. However, the precise mechanism(s) of action of this therapy is unclear. The loss of tendon cell homeostatic tension, due to loading-induced laxity, produces catabolic changes associated with tendinopathy. This catabolic activity can be inhibited through the re-establishment of a normal tensile environment via a cellular contraction mechanism. We hypothesized that application of TE will enhance the contraction rate of lax rat tail tendon fascicles (RTTfs) in an in vitro model.
  
  
  METHODS
  following loading, 10 lax RTTfs from each mature rat (n=5) were treated once daily for 7 days with TE by replacing the culture media at 37°C (control) with 42°C media. Using calibrated photographs, RTTf lengths were measured daily. Additional RTTfs were utilized to investigate any changes in material (n=12) and/or histological (n=12) properties with TE.
  
  
  RESULTS
  TE significantly increased the contraction rate of RTTfs (p>0.001) without altering the material or histological properties.
  
  
  CONCLUSIONS
  these results demonstrate that TE significantly enhances the contraction rate of previously exercised tendons. The ability to more quickly re-establish a normal mechanobiological environment, thus minimizing any catabolic changes, may explain the beneficial effects reported with applied TE in tendinopathy treatment.
authors: Laboratory for Comparative Orthopaedic Research, Michigan State University, USA.
authors: Michael
authors: M
authors: Lavagnino
authors: Laboratory for Comparative Orthopaedic Research, Michigan State University, USA.
authors: Kirollos
authors: K
authors: Malek
authors: Laboratory for Comparative Orthopaedic Research, Michigan State University, USA.
authors: Keri L
authors: KL
authors: Gardner
authors: Laboratory for Comparative Orthopaedic Research, Michigan State University, USA.
authors: Steven P
authors: SP
authors: Arnoczky
keywords: contraction; laxity; rat tail tendon; tendinopathy; thermal energy