Effect of Eccentric Training on the Plantar Flexor Muscle-Tendon Tissue Properties

• Published in: Medicine and science in sports and exercise Vol. 40; no. 1; pp. 117 - 123
• Main Authors: NATHALIE MAHIEU, Nele, MCNAIR, Peter, COOLS, Ann, D'HAEN, Caroline, VANDERMEULEN, Katrien, WITVROUW, Erik
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 2008
• Subjects: Achilles Tendon - physiology; Adult; Ankle - physiology; Biological and medical sciences; Case-Control Studies; Female; Fundamental and applied biological sciences. Psychology; Health Surveys; Humans; Male; Muscle Stretching Exercises; Muscle, Skeletal - physiology; Range of Motion, Articular - physiology; Space life sciences; Surveys and Questionnaires; Tendons - physiology; Torque; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Human; Motion; ACHILLES; Physical training; RANGE OF MOTION; Heel; Eccentric; PASSIVE RESISTIVE TORQUE; Tissue; Sport; Plantar; Flexor muscle; Stiffness; HEEL DROP; Tendon
• ISSN: 0195-9131; 1530-0315
• DOI: 10.1249/mss.0b013e3181599254

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.
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.
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.m). The stiffness of the Achilles tendon did not change significantly as a result of training.
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.