Targeting Paretic Propulsion and Walking Speed With a Soft Robotic Exosuit: A Consideration-of-Concept Trial

Abstract

Background: Soft robotic exosuits can facilitate immediate increases in short- and long-distance walking speeds in people with post-stroke hemiparesis. We sought to assess the feasibility and rehabilitative potential of applying propulsion-augmenting exosuits as part of an individualized and progressive training program to retrain faster walking and the underlying propulsive strategy.Methods: A 54-yr old male with chronic hemiparesis completed five daily sessions of Robotic Exosuit Augmented Locomotion (REAL) gait training. REAL training consists of high-intensity, task-specific, and progressively challenging walking practice augmented by a soft robotic exosuit and is designed to facilitate faster walking by way of increased paretic propulsion. Repeated baseline assessments of comfortable walking speed over a 2-year period provided a stable baseline from which the effects of REAL training could be elucidated. Additional outcomes included paretic propulsion, maximum walking speed, and 6-minute walk test distance.Results: Comfortable walking speed was stable at 0.96 m/s prior to training and increased by 0.30 m/s after training. Clinically meaningful increases in maximum walking speed (Δ: 0.30 m/s) and 6-minute walk test distance (Δ: 59 m) were similarly observed. Improvements in paretic peak propulsion (Δ: 2.80 %BW), propulsive power (Δ: 0.41 W/kg), and trailing limb angle (Δ: 6.2 degrees) were observed at comfortable walking speed (p's < 0.05). Likewise, improvements in paretic peak propulsion (Δ: 4.63 %BW) and trailing limb angle (Δ: 4.30 degrees) were observed at maximum walking speed (p's < 0.05).Conclusions: The REAL training program is feasible to implement after stroke and capable of facilitating rapid and meaningful improvements in paretic propulsion, walking speed, and walking distance.

Design and evaluation of an independent 4‐week, exosuit‐assisted, post‐stroke community walking program

“…The two LPP participants also had a therapeutic benefit in which they improved their NS paretic propulsion by 33% (P1: first 4 weeks) and 21% (P4: second 4 weeks) after the completion of the cREAL program (Figure 4). These outcomes are on par with a 24% propulsion improvement reported from a study in which a single participant completed high‐intensity, task‐specific, and progressively challenging walking practice with an exosuit for five daily 30‐min sessions with a physical therapist 15 . We could not compare our therapeutic benefit to nonexosuit‐based community walking programs as those results are primarily focused on walking speed and did not report changes in propulsion 2,3 .…”

“…For individuals post‐stroke, exoskeletons and exosuits offer an opportunity to complement traditional therapy by providing targeted assistance to the paretic ankle to promote more typical gait mechanics and encourage neuromuscular rehabilitation 14–17 . Exosuits can provide immediate within‐session locomotor benefits (i.e., orthotic benefit), including faster walking speeds, reduced energy use, and reduced maladaptive compensatory patterns 14,16–18 .…”

“…Focused training and practice are important for stroke recovery 19 and effective exosuit use 20 . Thus, more recent studies in the lab/clinic have investigated the effect of massed, multisession, ankle exosuit‐assisted stepping practice in post‐stroke gait 13,15 . An in‐lab, consideration‐of‐concept trial study in which a post‐stroke participant was provided 5 days of progressive speed training with an ankle‐assisting exosuit showed improvements in unassisted walking speed, distance, and paretic propulsion after training (i.e., therapeutic effect) 15 .…”

Opportunities and challenges in the development of exoskeletons for locomotor assistance

“…Furthermore, learning outcomes may be improved by appropriate intervention scheduling 259 through intermittent exposure and by increasing the variability of training through the introduction of perturbations 260,261 . Challenging the user is also important, and an 'optimal' challenge may maximize retention 261 ; for example, increasing propulsion demands using inclined split-belt treadmill training improves gait symmetry post-adaptation more than flat split-belt treadmill training in people post-stroke 262 ; also, high-intensity robot-assisted gait training increases walking speed 263 . In addition to implicit learning pathways, rehabilitation schemes often also incorporate explicit learning through task-specific instructions or biofeedback, which are known to improve learning and rehabilitation outcomes 264,265 .…”

Soft Wearable Robots: Development Status and Technical Challenges

“…Walking performance: Apparently this test only applies to lower extremity systems. Through measuring and analyzing walking speed, walking distance, ground clearance and other parameters, the actual effect of gait recovery and ambulation training will be illustrated [ 129 ]. The exosuit has a significant positive effect on improving walking performance.…”