For anybody interested... Here's a new article from the January 2008 issue of Medicine and Science in Sports and Exercise regarding eccentric training in regard to Achilles tendon injuries. Basically it shows that an eccentric training program increases flexibility in the calf/achilles tendon, but does not compromise the stiffness (which is a good thing). While previous research has shown eccentric loading does not change the collagen/matrix of the tendon itself in healthy individuals, this suggests that it may still have some prevention implications (and also helps explain one more mechanisms of why it works for rehab).
Author MAHIEU, NELE NATHALIE 1; MCNAIR, PETER 2; COOLS, ANN 1; D'HAEN, CAROLINE 1; VANDERMEULEN, KATRIEN 1; WITVROUW, ERIK 1
Institution (1)Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, Ghent University, Ghent, BELGIUM; and (2)Health and Rehabilitation Research Centre, Auckland University of Technology, Auckland, NEW ZEALAND
Title Effect of Eccentric Training on the Plantar Flexor Muscle-Tendon Tissue Properties.[Miscellaneous]
Source Medicine & Science in Sports & Exercise.
Status Publish Ahead of Print, POST AUTHOR CORRECTIONS, 4 December 2007
Abstract Purpose: It has been shown that eccentric training can be effective in the rehabilitation of patients with Achilles tendonopathy. The mechanism behind these results is not clear. However, there is evidence that tendons are able to respond to repeated forces by altering their structure and composition, and, thus, their mechanical properties change. In this regard, the objective of the present study was to investigate whether eccentric training affects the mechanical properties of the plantar flexor's muscle-tendon tissue properties.
Methods: Seventy-four healthy subjects were randomized into two groups: an eccentric training group and a control group. The eccentric training group performed a 6-wk eccentric training program for the calf muscles. Before and after this period, all subjects were evaluated for dorsiflexion range of motion using universal goniometry, passive resistive torque of the plantar flexors, and stiffness of the Achilles tendon. Passive resistive torque was measured during ankle dorsiflexion on an isokinetic dynamometer. Stiffness of the Achilles tendon was assessed using a dynamometer, in combination with ultrasonography.
Results: The results of the study reveal that the dorsiflexion range of motion was significantly increased only in the eccentric training group. The eccentric heel drop program also resulted in a significant decrease of the passive resistive torque of the plantar flexors (from 16.423 +/- 0.827 to 12.651 +/- 0.617 N[middle dot]m). The stiffness of the Achilles tendon did not change significantly as a result of training.
Conclusion: These findings provide evidence that an eccentric training program results in changes to some of the mechanical properties of the plantar flexor muscles. These changes were thought to be associated with modifications to structure rather than to stretch tolerance.