The Specific Forces Applied During Robotic Training That Optimize Recovery of Locomotion in a Rat Model of Spinal Cord Injury

<i>Background</i>. Conventional physical therapy following neurological injury is an arduous task met with minimal returns and quickly plateauing recovery. Unconventional therapies, such as robotic assisted gait training (RAGT) have not produced the robust clinical gains that we all had hoped. Rodent RAGT is a nascent field, but it works on the same principles as the clinical counterpart. <i>Objective</i>. We have previously investigated the ability of RAGT to enhance the recovery of rats following a cervical spinal cord injury and found that training in a resistive field is detrimental, and training in a negative viscosity field is better than actively guiding the limbs through a healthy stepping pattern. Unfortunately, none of these treatments are particularly good at restoring unassisted overground locomotion. Previously we grouped animals based on the RAGT treatment they received. Upon further reflection, these groups are not based on what the animals actually experienced, but how the robot was programmed. <i>Methods</i>. In the work presented here we regrouped and reanalyzed our existing data bi-directionally (does level of overground recovery predict RAGT force profile experienced? does force profile predict recovery?). <i>Results</i>. This method allowed us to uncover a training force profile that optimized overground recovery, specifically, low overall forces (<±6 N), positive <i>Fy</i> and negative <i>Fx</i> during swing, and minimal forces during stance (<±2 N). <i>Conclusions</i>. This work provides new insights into the importance of the specific forces used in rehabilitation, a major shift in current clinical RAGT techniques, and could lead to improvements in patients' lives.