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

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.

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]

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]

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]

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).

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]

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.

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]

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.

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!

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

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