Background Stretching is a widely accepted standard-of-care therapy following spinal cord injury that has not been systematically studied in animal models. Objective To investigate the influence of a daily stretch-based physical therapy program on locomotor recovery in adult rats with moderate T9 contusive SCI. Methods A randomized treatment and control study of stretching in an animal model of acute spinal cord injury (SCI). Moderate spinal cord injuries were delivered with the NYU Impactor. Daily stretching (30 min./day, 5 days/wk for 8 wks) was provided by a team of animal handlers. Hindlimb function was assessed using the BBB Open Field Locomotor Scale and kinematically. Passive range-of-motion for each joint was determined weekly using a goniometer. Results Declines in hindlimb function during overground stepping were observed for the first 4 weeks. BBB scores improved weeks 5–10 but remained below the control group. Stretched animals had significant deficits in knee passive ROM starting at week 4 and for the duration of the study. Kinematic assessment showed decreased joint excursion during stepping that partially recovered beginning at week 5. Conclusion Stretch-based therapy significantly impaired functional recovery in adult rats with a moderate contusive SCI at T10. The negative impact on function was greatest acutely, but persisted even after the stretching ceased at 8 weeks post-injury.

Study Design Experimental Study Objectives To characterize the specific hindlimb electromyographic (EMG) patterns in response to muscle stretch and to measure the applied forces during stretching in the rat model of moderate SCI. Setting Kentucky Spinal Cord Injury Research Center, Louisville, KY, USA Methods Female Sprague Dawley rats (n=4) were instrumented for telemetry-based EMG recording (right Rectus Femoris and Biceps Femoris) and received a moderate T10 spinal cord injury (SCI). The major hindlimb muscle groups were stretched using our clinically modeled protocol. The EMG responses were recorded biweekly for 8 weeks. The forces applied during stretching were measured using a custom-designed glove. Locomotor function was assessed using the BBB Open Field Locomotor Scale, 3D kinematics and gait analysis. Results Three main EMG patterns in response to stretch were identified: clonic-like, air-stepping and spasms. Torques applied during stretching ranged from 0.8–6 N*cm, and did not change significantly over the weeks of stretching. Two stretching sessions a week did not result in a significant disruption to locomotor function. Conclusions Stretching evokes EMG patterns in rats similar to those reported in humans including clonus and spasms. The torques used during stretching are comparable, based on the ratio of torque to body weight, to the few previously published studies that measured the forces and/or torques applied by physical therapists when stretching patients. Future studies are warranted to fully explore the impact of muscle stretch on spinal cord function after injury. Sponsorship DoD, KSCHIRT, NIH

Seibt, Erik, "Force sensing glove for quantification of joint torques during stretching after spinal cord injury in the rat model." (2013 Instruments' LabVIEW program, the device was able to accurately measure forces, and eventually torques, applied during stretching. This study sought to explain what range of torques were being applied during stretching after SCI in the rat model in the hopes of understanding how to administer safe, effective therapeutic stretches. Six adult female Sprague-Dawley rats were mildly contused at T9 using the NYU impactor device with a 12.5 g-cm weight drop. n=2 rats were stretched 2 days per week and n=2 rats were v stretched once per week using an eight minute protocol, for the first 5 weeks post-injury while controls (n=2) received no stretch therapy. Briefly, the tibialis anterior (TA) and triceps surae (TS) muscle groups were stretched by two therapists bilaterally for a minute each, totaling 4 minutes of stretch per rat per day. Kinematic assessments of stretching were accompanied by force measurement data and were used to generate comparisons between therapeutic torque and end range of motion (ROM) of the ankle. The data suggests that both once and twice per week stretching regimens were not enough to inhibit locomotor recovery or elicit a noticeable change in end ROM in such a mild injury model. There were noticeable differences in torques applied during stretching by different therapists, confirming the findings of previous studies. More importantly, the data showed that immediately after injury the normal end ROM can be achieved by applying less torque. The torque necessary to reach the end ROM increases to baseline values by week 5, potentially due to a return of the stretch reflex during spinal shock. This study urges other aspects of stretching therapy to be considered and suggests a tool for therapists to quantitatively apply safe and consistent stretching therapies to patients.vi