A 2008 publication by the Consortium for Spinal Cord Medicine prescribes that all spinal cord injured patients receive stretching therapies beginning within the first week post-injury. This kind of therapy is targeted at preventing some serious joint and muscle problems that many spinal cord injured patients develop. These include contractures, where the range-of-motion of a joint or joints is reduced and any movement of that joint involves increased force (stiffness), muscle shortening (often associated with contractures), and muscle wasting (loss of mass and strength). Maintaining muscle and joint health early after injury is critical to long-term health and function and for participation in any future rehabilitation efforts. Despite the fact that essentially all patients with spinal cord injuries receive significant levels of stretch-based physical therapy, stretching has not been studied systematically in animal models and has been studied very little in the clinical setting. Essentially nothing is known about how stretching might influence the neural circuitry in the spinal cord, which is responsible for controlling the motor and locomotor activities of the legs.
Over the past 6 or 7 years, we have been studying activity-based rehabilitation after spinal cord injury in animal models. We have observed that the level of motor and locomotor recovery in our animal models is much greater than in the majority of human patients with roughly equivalent injuries. In order to try to determine why this is the case, we have begun to treat our animals more like patients get treated. We limit their activity by placing them in wheelchairs, we use a variety of activity-based approaches (swimming, stepping in shallow water) for rehabilitation, and we provide them with stretching-based physical therapy designed to mimic what most patients experience. To our surprise, in our animal models, restricting movement in wheelchairs and providing daily stretching makes the overall recovery of our animals worse. The goal of this project is to answer three specific questions. Does our animal model of stretching accurately mimic what is applied to most patients? Is it the overall force of the stretching or the pattern of stretching that has the largest negative influence on recovery? Finally, if the stretching is applied later after an injury is the negative influence reduced?