Innovating stretch interventions that change muscle-tendon mechanics and joint mobility for people with contractures

Contractures are joint dysfunctions that are clinically characterized by a forced joint position, decreased joint range of motion, and increased joint stiffness. Involved muscles and tendons shorten and stiffen. Multiple neurological or musculoskeletal disorders can cause contractures. A commonly used treatment for contractures, aimed at increasing the joint range of motion and reducing joint stiffness, is stretching. Stretching acutely lengthens the muscle-tendon units spanning the joint. It is however unknown how this stretch is distributed among muscle belly (i.e. muscle fibers) and tendon. Even though stretch treatments are often applied, there is no clear agreement about which type (e.g. static, dynamic) or dosage (frequency, duration, magnitude) results in the best long-term outcome. The modality (i.e. equipment used for imposing stretch) and corresponding type of stretch treatment used are often based on the equipment available in the clinic and/or the preference of the attending physician, instead of on what would lead to the most beneficial outcome regarding joint range of motion, as well as adaptations in muscle and tendon.
The general aim of this project is to investigate and contrast how different types and magnitudes of stretch treatment affect joint mobility and muscle and tendon morphology and mechanics. For this purpose, we combine a systematic review and meta regression analysis of the literature with experiments in animal models and human patients.