Researchers have long sought effective strategies to manage motor impairments in children with spastic cerebral palsy, a condition characterized by excessive muscle stiffness that can hinder movement and function. In 2015, a study led by Nicola Theis, alongside Thomas Korff and Amir A. Mohagheghi, sheds new light on this topic by investigating the effects of long-term passive stretching on muscle-tendon unit mechanics.

Cerebral palsy often results in increased neural and mechanical stiffness in muscles, which is thought to contribute significantly to the functional limitations experienced by affected children. As a common therapeutic approach, passive stretching aims to reduce this stiffness, though its effectiveness remains a topic of debate due to a lack of conclusive research.

To address this, the researchers conducted a study involving 13 children aged 8 to 14 years with quadriplegic or diplegic cerebral palsy. The participants were divided into two groups: an experimental group, which underwent an additional six weeks of passive ankle dorsiflexion stretching, and a control group, which continued with their usual routines. The stretching regimen for the experimental group involved 15 minutes of stretching per leg, four days a week.

The study’s findings were significant. The experimental group showed a modest but meaningful increase of 3° in maximum ankle dorsiflexion. More importantly, there was a 13% reduction in muscle stiffness of the triceps surae, a key muscle group involved in ankle movement. Interestingly, while muscle stiffness decreased, there was no change in tendon stiffness, suggesting that the reduction in stiffness was primarily due to changes in the muscle tissue itself rather than the tendons.

Further analysis revealed that this reduction in muscle stiffness was associated with increased fascicle strain—indicating that the stretching improved the muscle’s ability to stretch without altering its resting length. This suggests that the changes occurred within the muscle’s connective tissue, rather than affecting its overall structure.

In summary, this study provides valuable evidence that long-term passive stretching can effectively reduce muscle stiffness in children with spastic cerebral palsy, potentially offering a practical intervention to improve mobility and function in this population. However, the findings also highlight the complexity of the muscle-tendon unit, underscoring the need for further research to fully understand the mechanisms at play.

Reference: Theis, N., Korff, T., & Mohagheghi, A. A. (2015). Does long-term passive stretching alter muscle–tendon unit mechanics in children with spastic cerebral palsy?. Clinical biomechanics, 30(10), 1071-1076.