Interview with Kristin Musselman about Reactive Balance
Welcome to discuss. Discussions and spinal cord injury sci where we bring you interviews with researchers and clinical leaders in spinal cord injury rehabilitation. I'm rachel tappin. today. I'll be speaking with dr kristen muscleman who is last author on a recent paper in the journal spinal cord along with co co-authors. Catherine chan jaywalking less journal. Unger angela you and k musani the papers titled reactive stepping after a forward fall in people living with incomplete spinal cord injury or disease. Dr muscleman is a physical therapist and scientists with the neural engineering and therapeutics team at the cato institute which is the research arm of the toronto rehabilitation institute. She's assistant professor in the department of physical therapy and rehabilitation sciences institute at university of toronto. She's active in the canadian physiotherapy association and now of course and the american physical therapy association with this very podcast. And she's academic lead of the walking measures group and the canadian community of practice for the practice spinal cord institute so welcome. Kristen muscleman. thanks rachel so much for having me. It's a pleasure to be here. I'm so happy to have you so. Let's start by talking about balance after spinal cord injury and i wanna talk about reactive balance in particular where the person needs to recover from a loss of balance. Can you just describe for us in general. What do we know. Or i guess. More specifically what did we know prior to this to this study in this area. Sure well react to balance. It's a key part of our posture control system. And as you kind of mentioned it really is our last line of defense against a fall so to try to recover balance that's been lost and so refers to our ability to reduce control of The movement of our center of mass where or to pull our center of mass back within our basis support and we we can do this through movement at the ankles hips. You know which we've Often called the ankle hit strategies or you can do it by taking Rapid reactive steps to try to increase our base of support. And it's this Rapid reactor stepping that. We've focused on in our research and you know surprisingly we actually don't know that much about reactive balance control after spinal cord injury We do know that. In other neurological populations like individuals living with the effects of stroke. The inability to take a reactive step is associated with the occurrence of falls And as many of those listening are aware people cred injury. Do you have a lot of falls as well. So a recent meta analysis found that seventy eight percent of the ambulance chasers with spinal cord. Injury will fall each year so it's definitely reasonable to expect that reactive balance control is impaired after injury but specifically what aspects are impaired wasn't known for example are there deficits related to the timing of the movements and muscle activation or insider their spatial deficits. So you know for example. Maybe they can't take a big enough react to step to appropriately reposition their center of mass. So those are some of the questions that we had. I'm going into doing this research. Great boy and i can certainly point to as a clinician. You're supporting things that i felt like. I knew already as i would experience that in the clinic of people having lots of difficulty with reactive balance after spinal cord injury and looking to the research literature and really having a hard time understanding how to proceed so for reinforcing or validating. The experience that i've had at least you study your your group did the study. And so what did you do. And what were the results. Yes what we wanted to do was to characterize reactive stepping in and people who are living with incomplete spinal cord injury so as a first step We compared their to stepping ability to out of age and sex matched individuals who have a spinal cord injury and what we decided to do in this for study is focus on two aspects of reactor stepping so i is is a behavioral response which just simply looks at. How are the participants recovering their balance after appreciation. So can they take a single step like most people who haven't neurological damage do or do they need to take several steps to reposition that center of mass in their basis support or are they unable to recover their balanced. So that's the behavioral piece that we looked at And then the second piece we looked at were these temporal parameters of reactive stepping so this includes things like the onset of muscle activity and legs And also the reaction time so you know. How quickly can they respond for that. We look at the length of time. Between the onset of the nation and then the actual movement That's elicited so in this case you know lifting off the switch a reactive step but what we needed to figure out how to look at this behavior in a standardized way and so we use a lot based assessment That's called the released test And this has been used with the stroke population it's also been used previously in older adults And basically what it does it simulates a forward fall of course in a safe way so if you just try to picture yourself standing and you're in a safety harness that's gonna prevent us from from hitting the ground if you were to lose your balance That saves you harnesses around your trunk. And then what we do. Is we attach a horizontal cable to the back of the safety harness right around the level of your lower back and then not cable which is about a meter long. It's attached to the wall behind you and you get asked to lean forward from your ankles as best as you can until about. Ten percent of your body weight is supported by that cable.