DD SIG and JNPT Collaboration- Episode 56: Proprioceptive Reliance During Backward Walking in People with MS with Patrick Monaghan & Michael VanNostrand

Summary

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Podcast Summary: 4D Deep Dive into Degenerative Diseases – ANPT

DD SIG & JNPT Collaboration – Episode 56

Topic: Proprioceptive Reliance During Backward Walking in People with MS
Host: Carm Padgett
Guests: Dr. Michael VanNostrand & Dr. Patrick (“Patty”) Monaghan
Date: June 25, 2025

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Overview

This episode explores recent research on proprioceptive reliance during backward walking in people with Multiple Sclerosis (MS). Hosted by physical therapist Carm Padgett, the discussion features postdoctoral fellows Dr. Michael VanNostrand and Dr. Patrick Monaghan, authors of a forthcoming JNPT paper. The conversation delves into how proprioception impacts mobility—specifically backward walking—in MS, the methods and clinical implications of their research, and broader applications for physical therapy assessment and intervention.

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Guest Introductions & Research Paths

[01:50–05:14]

• Michael VanNostrand: Postdoc at Wayne State, research in real-world gait and balance using wearable sensors; interested in bridging lab and clinical assessments for neurological conditions.
• Patrick Monaghan: Background in exercise physiology and biomechanics; experience in neural control of movement in neurodegenerative conditions; seeks to bridge motor and cognitive aspects of decline in MS.

"I think my path to Wayne State is kind of unique... I'm working to better understand mobility, cognitive, and psychological factors that underpin gait and balance impairment." – Michael VanNostrand [01:50]

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Rationale: Why Backward Walking & Proprioception in MS?

[05:43–07:03]

• Mobility and sensory dysfunctions are common & burdensome in MS.
• Successful movement needs integration of sensory data from three systems (visual, vestibular, proprioceptive).
• Backward walking is more sensory-demanding and forces greater reliance on proprioception due to diminished visual cues.
• Most studies focus on forward walking—backward walking might be more sensitive for deficits.

"Backward walking is a little bit more sensory demanding... because we no longer have vision of our path of progression... So we often have to reweight our sensory reliance." – Patrick Monaghan [05:43]

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Methods: Measuring Proprioception & Mobility

[07:03–11:19]
Proprioception Assessment:

• Used a “Vibratron” to measure vibration thresholds in the great toe—a surrogate for dorsal column/ proprioceptive integrity.

"One of the assessors would have a box... individuals would put their big toe on one of two pegs and say which is vibrating... both proprioception and vibration sensation are carried by the dorsal columns." – Michael VanNostrand [07:10]

Mobility Assessment:

• Recruited 50 people with MS (all subtypes), able to walk 25 feet.
• Ambulation staged using PDDS (Patient Determined Disease Steps).
• Excluded recent relapses, instability on meds, and acute injuries.

"We tracked a detailed service... any injuries that might impact your walking or balance... anything that can impact motor performance we tried to take into account." – Patty Monaghan [09:35]

Walking Tasks:

• Timed 25-foot walk, both forward and backward at comfortable and “fast but safe” speeds, two trials averaged.

“We wanted to better understand not just our comfortable speed, but, when we have to increase our speed.” – Michael VanNostrand [10:35]

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Key Findings and Discussion

Backward Walking: Unique Hurdles and Clinical Insights

[11:26–16:45]

• Fast backward walking is novel & sometimes anxiety provoking, but most adapt quickly.
• Explored “walking speed reserve” (difference between fast and normal speeds) as indicator of speed modulation and function.
• Backward walking reserve may better correlate with measures of mobility and cognition than forward walking.

"It's just really neat to try to think outside the box a little bit... might have enhanced predictive risk validity, for things like falls or physical activity." – Patrick Monaghan [14:38]

Correlations with Cognition

[19:05–22:03]

• Backward walking, particularly speed reserve, tracks with multiple cognitive domains (e.g., attention, info processing).
• Higher cognitive demand and “non-automaticity” of backward walking may make it a sensitive marker for deficits (e.g., impulsivity).

“There’s this mismatch... between perceived subjective motor capacity versus actual lab performance, which can impact function and risk behaviors.” – Patrick Monaghan [19:54]

Backward Walking: A Superior Predictor?

[14:09–17:54]

• Backward walking velocity can outperform forward walking in predicting falls (70% vs ~50% predictive validity).

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Main Research Results: Proprioception & Walking Performance

[23:01–28:09]

• Proprioception (as measured by higher vibration thresholds) is significantly correlated with walking performance in both directions—but the correlation is stronger for backward walking.
• Regression analysis:
  • Forward walking: Ambulation disability (PDDS) was the strongest predictor, then proprioception.
  • Backward walking: Proprioception became the main contributor.
• Fall history: Those classified as “recurrent fallers” (≥2 falls/year) had significantly worse proprioception.

"In the backwards walking direction, that correlation was higher, meaning that individuals with worse proprioception tended to walk slower... main contributor was proprioception." – Michael VanNostrand [23:01]

Defining “Fallers”

[28:14–28:52]

• Fallers: ≥2 falls in past year; Non-fallers: 0 or 1 fall.

"Research tends to use, especially when you're using retrospective falls, two or more to classify individuals as fallers." – Michael VanNostrand [28:32]

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Interpretation & Clinical Implications

[29:48–36:13]

• Backward walking tasks may enhance fall risk screening—especially in populations with proprioceptive loss.
• Vibration threshold measurement is promising but backward walking is more practical in clinics.
• Ongoing research aims to broaden assessments to include all sensory systems while walking (not only standing).

Practical Applications

• Backward walking can serve as both assessment and intervention, with evidence of safety and feasibility even for higher disability levels.
• May improve proprioceptive reliance and overall functional mobility.

"Backward walking training might in fact be part of that intervention that they need. If we can better train this system... that might in return improve their proprioception." – Michael VanNostrand [33:45]

• Not a “one size fits all” solution—best as part of a balanced neuro rehab toolkit.

“It's not that backward walking is the one and only. Alongside other established practices, it can be part of a really effective motor composite to include.” – Patrick Monaghan [34:58]

Broader Benefits

• Backward walking taxes lower extremity musculature and cardiovascular system more than forward walking.
• Offers “real world” challenge and may aid translation to daily tasks.

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Notable Quotes & Memorable Moments

• On Proprioception and MS:

  “MS is a demyelinating disease. This lends further credence for why backwards walking could be a clinically accessible measure to identify those at risk for falls.” – Michael VanNostrand [29:48]

• Clinical Takeaway:

  “If we always do what we've always done, we'll always get what we always got. Is there a more sensitive, perhaps demanding task?” – Patrick Monaghan [14:38]

• Aphorisms & Puns:

  “Sometimes it's okay to take a step back to move forward. If you need any puns, Mike and I are here all night.” – Patrick Monaghan [40:30] “We do tend to like to say that backward could be the way forward, forwards.” – Michael VanNostrand [22:11]

• On Clinical Utility:

  “I always time the backward walking because I feel like it just gives me insight that I would otherwise [miss]... and I'm doing it anyway. So why not?” – Carm Padgett [35:23]

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Key Takeaways for Clinicians

• Backward walking assessments should be considered in MS and other neurological populations—especially for those with proprioceptive deficits.
• Backward walking is feasible, safe, more “real world,” and possibly more sensitive to subtle deficits than forward walking or traditional tests.
• Combine backward walking with other established assessments/interventions for best functional outcomes.
• Insight into proprioceptive loss may inform fall risk and guide targeted interventions.

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For More Information

• The research paper discussed will be published in JNPT in July 2025.
• Ongoing projects at Wayne State’s Neuroimaging and Neurorehabilitation Lab are broadening the scope to multi-sensory integration during walking.
• Stay tuned for future episodes as new results are published!

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Timestamps for Key Segments

• [01:50] Guest Introductions & Research Background
• [05:43] Why Backward Walking and Proprioception in MS?
• [07:10] Methodology: Measuring Proprioception
• [10:35] Walking Assessment Procedures
• [13:30] Walking Speed Reserve & Cognitive Associations
• [14:38] Backward Walking as a Fall Predictor
• [23:01] Main Findings: Proprioception & Walking Performance
• [28:14] Fallers vs. Non-fallers
• [33:45] Clinical Application & Recommendations

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Original podcast produced by the Academy of Neurologic Physical Therapy Degenerative Diseases Special Interest Group (DDSIG).

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Transcript

[A]

This is for informational and educational purposes only. It does not constitute and should not be used as a substitute for medical advice, diagnosis, rehabilitation or treatment. Patients and other members of the general public should always seek the advice of a qualified healthcare professional regarding personal health and medical conditions.

[B]

Welcome to 4D Deep Dive into degenerative diseases, gaining insights through casual and amusing clinical conversations.

[A]

Welcome to 4D, a podcast brought to you by the Degenerative Diseases Special Interest Group of the Academy of Neurologic Physical Therapy, a component of apta. I'm Carm Padgett, a physical therapist in the outpatient Neuro clinic at Dartmouth Hitchcock Medical center, and I am joined today by Mike Van Nostrand and Patty Monaghan, postdoctoral fellows at Wayne State University. We are here to talk about their recent paper, examination of proprioceptive reliance during backward walking in individuals with multiple sclerosis. This paper is to be published in JNPT in July of 2025 and these gentlemen have authored it with Dr. Nora Fritz, who has been a guest on 4D in the past. So let's get to it. And Mike and Patty, I'm going to have you introduce yourselves, tell us a little bit about, you know, your pathway to Wayne State and kind of what your role is there. And so Mike, why don't we start with you?

[B]

Yeah, so. So thanks for having me on today. So, Michael Van Ostrin. So I'm a postdoctoral research fellow with Dr. Nora Fritz in the Neuroimaging and Neurorehabilitation Lab. Prior to that, I received my PhD in Rehabilitation Science at University of Vermont. And I think my path to to Wayne State is kind of unique. As I was looking for for new ventures and another postdoc, I was fortunate enough to actually meet Nora's previous PhD student, Aaron Edwards. And when this opportunity came to me, I jumped on it and I was lucky enough and fortunate enough to get the position. And it's been almost two years since then. So in the lab now, kind of continuing to work and develop my own independent line of research. So I work a lot on trying to better understand the mobility, cognitive and psychological factors that underpin gait and balance impairment in neurological conditions, but with a real focus on capturing that data in the real world, understanding the limitations of current lab based assessments, and trying to better capture that data in the real world. So to do that, I leverage wearable sensors to try and capture measures such as physical activity or gait speed, stride variability to try and better inform the development of clinical assessments.

[A]

Great. We love that. We're always looking for better, more precise, faster clinical assessments. So that's awesome. And, Patti, what about you?

[C]

Yeah. So I was born and raised in a small little village in Ireland in the northeast coast of Ireland. And I was lucky enough when I was 17 to receive an athletic scholarship as a distance runner at Mississippi State University. And then I did my undergraduate degree there in clinical exercise physiology. And then in 2017, I swapped Mississippi for the Front Range of the Rockies. So I did my master's degree at Colorado State University in Fort Collins, Colorado. Particularly there, I worked with Dr. Brett Fling in the sensory neuromotor imaging lab, where we got my feet wet in training with neuroimaging neuromodulatory approaches in general motor control principles in individuals with multiple sclerosis. In 2019, I loved the south so much, I headed back down south, and I got my PhD at Auburn University in biomechanics with Dr. Jamie Roper in the locomotor and movement control lab. My research focus still working on individuals with neurologic conditions, but it shifted subtly. I hadn't gained an initial appreciation for the neural control of movement or perhaps how the nervous system doesn't control movement as well as a result of some form of pathology. I shifted towards a more biomechanics focused. In my PhD, I could see how walking and balance impairments might be clinically manifested in a lab or in a clinic setting as a result of neural alterations. So I did that from 2023. And then the last piece of the puzzle to really sort of take the next step in my training was to understand the role of cognition. So looking at this complex interplay between motor and cognitive decline, both throughout the typical aging process, but also as a result of neuropathology. So I was fortunate enough, as Mike mentioned, to join Nora, Dr. Fritz, up here in her neuroimaging and rehabilitation lab, where I've been since 2023, and again, really been enjoying the work that we've been able to do over the short couple of years that we've been up here.

[A]

Yeah, great. All right, you guys have a lot of interest, which is really fabulous, and maybe we'll get to some of those that are outside the paper, but let's focus for a little bit on this backward walking paper. And so tell me a little bit about how this idea of looking at proprioception and backward walking came to be.

[C]

We've always known that mobility impairments are often one of the first reported and most burdensome symptoms that individuals with multiple sclerosis would report. We also know that sensory dysfunction can also be incredibly prevalent as well. And many individuals can experience some form of sensory impairment. And we know that successful integration of sensory information from our three different sensory systems is an integral component of being able to have successful mobility. Whether it's walking, whether it's balancing, we have to be able to reweigh it and take the information in from our three different senses and then reweight it as appropriate for successful movement and motor performance. Part of our lab, we've done always with backwards walking. And we find that backwards walking is a little bit more sensory demanding compared to typical forward walking because we no longer have vision of our path of progression. So we often have to reweight our sensory reliance to focus more on proprioceptive cues because our vision has been manipulated. But within individuals with ms, the majority of the literature has really focused on standard forward walking or standing balance assessments. Again, that really gave us a thought process to be like, what is the association between our ability to use proprioceptive information and this backwards walking task, which we think is more proprioceptively demanding?

[A]

Okay, so how did you measure people's proprioception?

[B]

Yeah, so we measured individuals proprioceptions looking at something known as a vibration threshold, Using what's known as a Vibratron device. Can think about this as a research grade tuning fork, essentially. So we use what's known as a two alternative force choice procedure. So essentially, one of the assessors would have a box in front of us, and on that box we would be changing a vibration threshold. And individuals in their big toe would put their big toe on one of two pegs labeled A or B, and they would essentially tell us which one is vibrating. And the reason this is a good measure of proprioception is because both proprioception and vibration sensation are carried by the dorsal columns.

[A]

And.

[B]

And vibration sensation can really be a good indicator of dorsal column health and really, by extension, proprioception. So individuals who can't sense as low vibration thresholds, they by proxy have worse proprioception.

[A]

Okay, so their vibration threshold would be higher if you have proprioceptive deficit.

[B]

Correct.

[A]

Okay, and so who did you recruit for this study?

[B]

I think here at Wayne State, we always like to brag about how our participants are really just some of the best. They always come back. They're really active in our research. So we were able to recruit from existing studies that we have as well as other ongoing trials, we have this as part of the procedure. So we were recruiting individuals with Ms. From the community, and we had. It was both relapsing remitting primary and secondary progressive that participated in the study. And this was 50 people in total.

[A]

Okay. And then you didn't use the EDSS to sort of stage people. Right. You used something else. What was that?

[B]

We use the, the PDDs. The patient determined disease says it's really, it's basically a self report measure of EDSS and study. Previous studies have shown that they're pretty highly correlated.

[A]

Okay. All right. And so what were you looking for in terms of people's like mobility? I mean, they needed to be ambulatory, right?

[B]

Correct. They needed to be able to walk at least 25ft with or without an assistive device.

[A]

Okay.

[C]

We also tracked, we took in at intake RBS line visit, a pretty detailed service which included a sort of medical history where we would get all sorts of information concerning their DMT use as well. And we also screened out any sort of relapse within the past six months would have been an exclusion or have to be stable on a new immunotherapy for at least three months. And also, you know, maybe the little mundane things that we often overlook, but you know, have you had any sort of injuries or any or the PD conditions that might impact your walking or balance on, you know, on this day? You know, whether it's something as simple like rolling your ankle or doing something. So anything that can impact the motor performance we dread to take into account before enrolling in the study. And I should say alongside that too, we also individuals could use an assistive device as well.

[A]

Okay. All right, so take me through like what you did with the participants. I mean, you took me through sort of the vibration part and then. And then you also assessed their walking.

[B]

Yeah. So we had these individuals perform the TIME 25 foot walk test, a common mobility assessment in individuals with Ms. It's exactly as it sounds. We timed how long it took them to complete a 25 foot long pathway. We did this in both the forward and backwards direction as well as their comfortable or normal everyday walking speed, as well as their fastest but safest speed. Because assessments have utilized both speed paradigms and we know the importance of speed and speed modulation in the real world. So we wanted to better understand not just our comfortable speed, but, but when we have to increase our speed so that fast pace.

[A]

And you did comfortable and fast, both forward and backward?

[B]

That's correct. Yes, we did. We had individuals perform two trials of each and we took the average of those two trials.

[A]

Okay. So I have to say I do assess backward walking and I'll often give it as intervention. You Know, for, for people with neurologic disorders in general, but you know, certainly for people with Ms. That can handle it. But I never do fast backward walking. It like it scares me to think about. So what, like you guys have like experience doing this with people, right? How does it go?

[C]

Yeah, that's a great point. And it can be, you know, when you tell individuals after they do it at the, at the normal typical speed, and then, you know, it's like, okay, now we want you to go as fast but as safe as you can. You know, sometimes the reaction can be, you know, a little bit anxiety filling because it is a little bit novel. But it is also remarkable how quickly people adapt to the task even in walking in the fast condition. Again, we also always highlight that if your fast is the same as your normal in the backwards direction, that is totally fine. We also. So to get at that angle a little bit more too, we also had a paper published last year where we looked at to this degree this, what's called the walking speed reserve. We looked at the difference between someone's fastest walking speed and their comfortable walking speed, both in the forward and the backwards direction. Because we thought that this measure of speed modulation, if we can measure someone's difference between how fast they walked, when we asked them to increase their walking speed on demand, that might be a sign of greater speed modulation capacity. We actually did that after because we had this rich data set of individuals working at their comfortable as well as their fastest and maximal speed. This gave us a great insight to develop this novel and innovative metric that I think, as Mike mentioned earlier, has real world significant implications for optimally functioning in our external surroundings. But individuals do get accustomed to the fast forward walking. Some people are able to walk a lot faster than others. Some people, their backwards walking fast speed is somewhat close to their normal, but it can be a little bit of a daunting task.

[A]

Absolutely, yeah. I mean you find the same thing in forward walking too, right? Like comfortable versus fast. Some people can really ramp it up and be really different and other people can't.

[C]

Yeah, absolutely. And I think it all depends too, right? You know, you look at individuals, their psychology or their psychological mix. Some people are motivated, they have the grid, they're like, bring it on, let's do it. That's, you know, you know, sometimes they'd be like, do you want me to walk even faster? You know, there's some people, we have to tell them, okay, we're walking, we're not running even in the backwards direction. So I think that's Another aspect that I love of working with Ms. Too is just the heterogeneity and the variability that you see with individuals that come into the lab.

[A]

So in that other paper, like how much reserve did you see in the backward walking direction? Was it different than forward?

[B]

Yeah, so we did, we did find that individuals, these individuals did have less reserve. Part of that is that we just tend to walk slower in the backwards direction. So that smaller reserve is really could just be a reflection of walking slower innately in the backwards direction, given that it is this non automatic motor task in itself.

[C]

Yeah, we find with that metric too that, you know, we did some concurrent validity testing and find that it was strongly valid with other clinically well established measures of functional mobility. So you know, with the tug it was highly correlated and associated with, with the timed up and go performance individuals that had a better feed modulation capacity. So a higher reserve were also associated with having a faster time to completion within the timed up and go. We also seen interestingly that it's also a cognitively demanding task as well, both the reserve and just typical backwards walking. We find that this walking speed reserve measure tracked with cognitive functioning too. We've seen again, better speed modulation capacity was associated with enhanced multi domain cognitive functioning, including information processing and unattentional performance. And I think it's just really neat to try to think outside the box a little bit and try to develop and come up with insightful metrics that, you know, might have enhanced predictive risk validity for things like falls or physical activity. Because what we find when we first started delving into the backwards walking literature was forward walking velocity had a predictive validity of maybe around 50%. So you know, that's no greater than chance. But backwards walking, you know, it can increase upwards of 70%. So I mean, you know, if we always do what we've always done, we'll always get what we always got. So, you know, trying to think about is there a more sensitive, perhaps demanding task that you know, might be able to, you know, reduce the risk of a fall occurring, you know, before it actually happens or something like that. So that's also some of the rationale behind looking at these tasks.

[A]

Yeah. Okay, couple things. One is all this work is being done in people with Ms. Correct. And you're looking always at this 25 foot walk time. Do you guys ever convert that to an actual gait speed? You know, I don't see a ton of people with Ms. And so like my brain just goes to like gate speed and it kind of drives me crazy. The 25 foot time to walk test. I'm like, can you just figure out the gate speed and like all be talking the same language.

[B]

Yeah. So we actually, since you mentioned that, since a lot of our work is in ms, as Patty and I are both national Ms. Society funded postdocs, but we actually recently conducted a scoping review of the utility of backwards walking, both as an assessment and intervention in neurological conditions. So we were looking at stroke, Parkinson's, Mississippi, of course, spinal cord injury, as well as some supranuclear palsy literature. And across neurological conditions of results time and time again, we're reinforcing this idea that backwards walking might have increased utility for things ranging from fall risk prediction in Ms. And Parkinson's to better identifying mobility impairment in those newly diagnosed with Parkinson's. And when we get to the intervention side, we saw time and time again that at least that backwards walking or multidirectional walking showed greater improvements in mobility performance, both static and dynamically, compared to traditional, I guess they would call it. Yeah, traditional therapy or forwards walking, whatever traditional therapy is.

[C]

Right, yeah, absolutely. And to get to the. I agree with the git speed, we do also, you know, so we, we measure the length of our walkway in meters and then we also can convert it to a walking speed in meters per second as well. So we also published last year in the International Journal of Ms. Care the measurement properties that are associated with this backward walking assessment. So we did reported on the sensitivity, the validity, the responsiveness off back, not just backwards walking velocity, but as well as a range of spatial temporal parameters of backwards gate. So anything from step length variabilities to stance time, single stance time. We tested the test retest reliability of all of these metrics and also deciphered minimal detectable change values. So we can really, you know, before we implement it in a vast array across the clinic, I think it's important to know, you know, what are the properties of this assessment and also across the literature too, it can help increase the interpretive capacity when, you know, you know, someone's backward walking speed increased by 0.09 meters per second. But how clinically meaningful is that? You know, so we did some work with that too to try to establish these sort of metrics that we can help to help to increase the interpretation of the outcomes.

[A]

Okay, and I, I promise we're going to get back to proprioception. But one more thing. So you said that there was some correlation with all the domains of cognition. To you, does that kind of mean that like there's the potential for the patient to have, or your the person to have more insight into kind of what you're asking and maybe less impulsivity type of behavior. If in backwards walking, like sometimes I've done it with people and they're, you know, people that are more impulsive, go faster, have worse control, you know, I feel they need to be closer too. Right. So I'm just wondering like if you've noticed that at all.

[C]

Yeah. Part of the rationale behind this sort of neuropsychological assessments or the other multi domain cognitive perception was one prior literature we've shown, and some of Taylor, who you had on here previously has shown that there's distinct cognitive contributors to backwards walking in domains such as visuospatial memory. The literature has pointed towards it being a more cognitively demanding task compared to forwards walking. So again perhaps this might lead down the line to if we're doing a backwards walking intervention, for example, we would like to hope that people get better at backwards walking, but there might be also some translatable and generalizable outcomes to aspects like cognition and proprioception. Because we know that the functional task itself requires a higher demand, a cognitive demand or sensory demand. And we also, we're currently doing a project now where we're looking at this angle of doing sort of discordance. So it's what an individual perceives their physiological capacity to be, you know, via a self reported server versus when you bring them actually into the lab and you objectively test their gait speed or their balance. Sometimes, often than not, we have found, collaborating with previous literature, that one in four individuals with multiple sclerosis will have this discordance or this mismatch or this irrationality between their perceived subjective motor capacity versus we bring you in your lab and maybe they walk faster or slower, which we showed can also really impact function. Like you said, it might put individuals at risk. If they have this increased impulsivity, they're more likely to take risks. Therefore they may more than likely perhaps unfortunately put themselves in a situation where a fall may occur. But even conversely, in individuals on the opposite discordant profile, they're what we might call these fearful unnecessary avoiders because they may perceive themselves to be at greater risk than they actually are. And so they may not engage with insufficient physical activity, they may not go out and participate within their communities. They may have an increased social isolation. So there's also this sort of potential downstream vicious cycle that can occur from that too. So that was also another part of the Reason behind the cognitive assessments as well.

[A]

Yeah. Well, you guys are going deep on this backward walking thing.

[B]

We do tend to like to say that backwards could be the way forward, forwards, and is the way forwards.

[C]

We.

[A]

Yeah, I love that. Okay. This is great. It's great. I'm. I. It's gonna help me so much with my patients and getting them to buy in. Right. I do love, though, to. To bring up all the literature around this because I think it really helps people to understand, like, why I'm asking them to do something crazy that they say, well, I never walked backwards. I'm like, well, actually, you do. All right, let's get back to proprioception. So we're comparing. In this paper that's coming out next month in jnpt, you're looking at people's proprioceptive capacity and their backward walking performance. Right. And so what did you find?

[B]

Yes, so the results were really interesting. So first we just looked at correlations between proprioception as measured by vibration thresholds and walking performance. And we found, unsurprisingly, that proprioception was significantly correlated with walking performance in both the forward and backwards direction. Not groundbreaking there. It's. This is expected. It is one of those three sensory systems. We do expect that it does have some significant correlation to walking in both directions. But interestingly, what we did find was that in the backwards walking direction, that correlation was higher, meaning that individuals had worse. Proprioception did tend to walk slower during that backwards walking test at both the comfortable and fast pace. So then we used another statistical approach known as linear regression to try and better understand not just the correlation between proprioception and walking performance in both the forward and backwards direction, but really how much it contributes to that performance. After correcting for things such as age, sex, and the pdds or ambulation disability, and again for the forward direction and the backwards direction, we did find that proprioception significantly contributed. But the results got really interesting when we looked further into the data and looked at the contributions for that. So, in the forward direction, while vibration sensation, or by proxy, proprioception did significantly contribute at both a comfortable and a fast pace, its contributions were not as much as ambulation disability. So those who reported higher ambulation disability, that variable tended to contribute more to forward walking compared to proprioception. Conversely, when we look at backwards walking at both the comfortable and fast speed, Both proprioception and PDDs did significantly attribute, but the main contributor was proprioception. It was interesting in the backwards direction that this heightened reliance on proprioception given the reduced, as Patti had mentioned earlier, this reduced visual. Visual input. So. Right. We no longer see our path of progression. It makes us rely more heavily on proprioception, as the results of our study indicated.

[A]

Right. So, yeah, I mean, I guess in a way that makes sense. Right. Because not only do you not have vision, but you don't have the typical automaticity that you have in the forward direction either. And so when you're backward walking, right. A deficit in proprioception is going to impact your backward walking more because you need to rely on that more, you have less vision and you don't have the type of automaticity that you have in the forward direction. Is that fair to say?

[C]

Yeah, absolutely. I would say too, we're also doing a. It's. You have your vision, but it's just manipulated vision.

[A]

Right.

[C]

We're currently doing a trial now where we're having people walk backwards with their eyes closed so that we can, you know, further tease apart the sensory contributions to the. I love the word you used to the non automaticity. That's. I think that's one of the key driving homes that we think really makes backwards walking this potent clinical tool because of its non automaticity.

[A]

Right. The thing I like about it is I think it's not automatic, but it is kind of translatable, 100%. So, you know, forward walking, which is like kind of nothing else. Right?

[C]

Yeah. So during my PhD, I did a little bit of split belt treadmill walking, which was in older adults and individuals with essential tremor. And it was a similar. Right. We, we drove one leg three times faster than the other to create this non automatic complex movement strategy. But again, we're doing it on a fancy treadmill that costs, you know, $250,000 versus we've got backwards walking, which is a similar non automatic complex movement strategy that is very clinically feasible and like you said, scalable and hopefully translatable.

[A]

Yeah, yeah. Okay. So in the paper, right, you bring up these hypotheses and one of them is that an increase in vibration threshold will. Would result in a decrease in backward walking performance. And then another one is that vibration threshold will have a stronger association with backward walking compared to forward walking. And both of those things is what you found, Is that fair to say?

[B]

Yeah, so we found both of those things to be true. But there was an additional hypothesis that we wanted to explore and whether individuals with worse proprioception were considered fallers versus non fallers. So we had split this population up on retrospective fall history and we wanted to Better understand if there was difference in proprioception for these two. And we also found that to be significant. So those with a higher vibrations threshold and by proxy worse proprioception, they were the fallers where the non fallers did tend to have lower vibration sensation or better proprioception.

[A]

Okay, so how did you define a faller versus a non faller?

[B]

Yeah, so we had asked individuals if they had fallen and if they had experienced a fall within the past year. So we used retrospective fall history and we split them based on whether or not they had experienced two or more falls. So being a recurrent faller.

[A]

Okay, so if you had one fall, you were a non faller.

[B]

Yeah. So we understand that the context around falls is really multifaceted. If you ask me if I fall within the past year, the answer is probably yes. Yeah, so research tends to use, especially when you're using retrospective falls, two or more to classify individuals as fallers versus non fallers, understanding that the context surrounding falls is multifaceted.

[A]

Right.

[C]

And also with this one too, you know, we're using retrospective falls, which might be subject to, you know, potential recall bias and, you know, protect mammary issues. So in our current studies and other ones published in the past year, we've made a really concerted effort to prospectively track individuals, and we follow up with them each week to really try to get a, perhaps a better insight into the real world function and prospective fall risk as opposed to having individuals recall over the previous year.

[A]

Okay. And so when you looked at that the fallers versus non fallers and their vibration threshold, there was a clear distinction. And so I'm wondering, like, do you see a future where we might be able to use vibration as a like, predictor of falls?

[B]

So there, there could be a future where vibration is used as a predictor of falls. But I think this work and what we're trying to get at is it lends further credence to backwards walking as a clinically accessible measure that can be used to identify fallers versus non fallers. This idea of increased proprioceptive reliance for backwards walking really just continues to build on that literature. And it's interesting when we look at it, because previous studies have actually shown that individuals with Ms. Have this increased reliance on proprioception for balance maintenance. And this increased reliance on proprioception with the combined slowed signal transduction. Ms. Is a demyelinating disease. This lends further credence for why backwards walking could be a clinically accessible measure to identify those who would be at risk for falls.

[A]

Yeah, and this, I think it's bringing up this concept of Ms. Being a demyelinating disease also makes me think of like, you know, walking and balance are so multifactorial in terms of both sort of sensory input, motor control, all that stuff. I mean, I know in the paper you talk about the limitation of not really considering people who might have a coordination ataxia problem or vestibular issue, which could, I would think, significantly impact their balance and their ability to backward walk. So what's the banter around your lab about that?

[C]

This study really kickstarted another project that Mike and I have just really started up in the past couple of months. It was a pilot grant funded from the CMSE or the Consortium of Ms. Centers, where we're doing just that. We're looking at not just proprioception, but the contribution of all other sensory systems and not just focusing on standing balance. So a lot of the common clinical. I know some of the, like the mini bests and the DGI and FGA have some aspects of turning your head and pivoting when you're walking. But the majority of these, the sensory organization test, the clinical test, they're all withstanding balance, they're all withstanding still. But we know that a lot of falls also occur when we're moving. So we start up a project now where we're trying to look at sensory integration, sensory reweighting, basically creating a walking equivalent of the sort of sit sip so we can tease apart, like you said, these other sensory systems that are incredibly important to. To function as well. But this was. This paper really kind of got us kickstarted. And you're right, we looked at it and we're like, yeah, we're isolating proprioception here, but we know that, you know, it doesn't function in isolation, that the ability to. To reweight and to successfully have the ability to reweight information dependent on our context and especially considering our everyday environments are so dynamic. Right. I mean, our different types of terrain, so having the ability to effectively and efficiently switch reliance when needed to. To perhaps prevent a fall or even just a function in our own surroundings. So this paper really gave us the sort of impetus to keep pushing forward.

[A]

Yeah, that's cool. That's. I'm very interested in that. And we'll be psyched to talk to you guys.

[C]

Yeah.

[A]

All right. So when I think about, you know, tomorrow when I go to work in the clinic and I'm seeing patients and I'm trying to sort of apply this. What would be your approach if you know, that somebody has a proprioceptive sensory deficit. Right. Would you still consider backward walking as an intervention? Would you focus on strengthening other systems of balance? What do you think? How do you think we can use this information?

[B]

Yeah, so that's a great question. And when we think about the clinical utility of backwards walking as both an assessment and as an intervention, I think it's really important to understand that people will come in with different needs. Right. There's no one size fits all. Or if there is, we haven't really found it yet. But I think what we're really showing is that backwards walking has its place in intervention. So if an individual comes in with decreased proprioception, then backwards walking training might in fact be part of that intervention that they need. If we can better train this system and better train balance and some sort of intervention that puts an increased reliance on that, that might in return improve their proprioception. That's something we're currently looking at in our randomized controlled trial comparing forward to backwards walking, and maybe something we can publish on here in the future as that trial comes to a close. So I think we're just trying to really build up the literature and get the word out that there's real utility for backwards walking. It's been shown time and time again that it's safe and feasible, even for individuals at higher disability levels, and it might have added benefits that traditional training or forwards walking doesn't give.

[C]

Yeah, And I kind of want to echo. I think I just reinforce a point that Mike made as well, that it's not that I sound like we're pushing it. The backwards walking is the one and only. Like, replace everything you're doing with just backwards walking. I think it. Yeah, I think alongside other, you know, commonly, well, clinically established, it doesn't take long to do.

[A]

Right.

[C]

You know, I think it can be part of a really effective motor composite that might be worth including.

[A]

So, yeah, for sure. When I do the fga, I always time the backward walking because I feel like it just gives me insight that I would otherwise, and I'm doing it anyway. Right. So why not?

[C]

Yeah, absolutely. And there's also been prior work that is shown sort of the transfer effects or, you know, it's translatable, where backwards walking is a lot more taxing for our, you know, lower extremity muscular strength as well for our lower extremity muscles, too, because now suddenly we're working different set of muscles that we're not commonly used to walking in that way. So some literature has also Shown that, you know, it can have additional benefits. It is very specific to you. I mean, if you also get faster at walking backwards because, you know, you do it a lot. And it's also got more cardiovascular demands as well, too. It's gotta have a sort of holistic potential effects.

[A]

Yeah. Cool. All right, well, you guys have given us a lot to think about and some things to try in the clinic, which is what we're always kind of looking for. We did not forewarn you, but we do have a tradition here at 4D to ask people what they like to do when they're not doing their main job. For you guys working in the lab. So let's go with Mike. Mike, what do you like to do when you're not working?

[B]

Yeah, so when I'm not working and at home, hanging out with my dog. So big time dog lover here. So as I had mentioned before, I'm a Northeast transplant. I always call it Vermont home. And when I came to the Midwest, I lost. I lost my mountains. So it's. It's very flat here. So I have recently taken up doing a lot more rock climbing. So it's something that I find really fun, really outdoorsy, really engaging, really cognitively demanding, and something that I truly enjoy doing. So if I'm not hanging out with the dog, you'll probably find me rock climbing.

[A]

Great. And Patty, how about you?

[C]

So I'm a growing up, a runner. You know, I grew up running track, so I love to run. Perhaps for a lot of the other reasons opposite from why Mike likes to rock climb. I like that it's not demanding, like cognitively demanding. I can escape for a little bit out in the open. I can think about nothing for a little bit of time. But it is also nice to be able to run recreationally. And I can decide how far I want to go and how fast I want to go. I don't have a coach with a stopwatch timing me, so I really enjoyed that aspect of post collegiate running, of just. Just getting outside the door, tying up your shoelaces and seeing where the road takes you.

[A]

Yeah, fun. So thank you both so much for joining us and sharing this information with you. And for sure, we would love to have you back when you have more of these studies done and more good information to share with us. So thanks so much.

[C]

Absolutely. Thank you so much for having us.

[B]

Yeah. Thank you for the opportunity.

[A]

Thanks for joining us and thanks to our guests today, Mike Van Nonstrand and Patty Monahan. This podcast was produced and edited by the Ampt Degenerative Diseases Special Interest Group Podcast Team. For more information on this SIG and ANPT, visit neuropt.org Our podcast team includes Sarah Zoller, Christina Burke, Jeff Schmidt, Shannon Brown, Skyler Rost, and Ken Binocco. And thanks to Olivia Visaggio who helped with article review for this podcast. I'm Carm Padgett. Thanks to Jimmy McKay for providing music and please share this episode with a colleague. Today, the Academy of Neurologic Physical Therapy and its collaborators disclaim any liability to any party for any loss or damage by errors or omissions in this publication. The views or opinions expressed are those of the individual creators and do not necessarily represent the position of the Academy of Neurological Physical Therapy.

[B]

It's. It's the reason. Sorry. There's your first blue.

[C]

Oh yeah, Potty is ter Perfectly fine. Patrick's like, when I'm in trouble, I know. You know? So usually always. Potty is totally fine.

[A]

Actually, when I was reading your paper, I was like, I wonder if they referenced sue at all. In his face.

[B]

I reference sue quite a bit in a lot of my work. I'm familiar. The PDDS. It's the patient reported version of the EDSS.

[A]

Right. But there's two Ds and one just like Patty.

[C]

Yeah, you could just think of Patty 2Ds PDDS.

[A]

And the EDSS has two Ss.

[C]

Oh, you see now that is misleading. That is bad. We need to do better world.

[A]

Yeah. So if you had one fall, you were okay. You were not okay.

[C]

I knew. Were we cliche?

[A]

No, no, no. Not at all.

[C]

Sometimes it's okay to take a step back to move forward. If you need any puns, you know, Mike and I are here all night. Oh, I love. I haven't heard the term banter in a while. I loved it.