This was a case series of participants with spasticity from chronic stroke or SCI. Participants were included if they had upper or lower limb spasticity that impacted function and gait and were able to walk with minimal or no assistance (ie, Functional Ambulatory Category [FAC] scores of 2‐5) [20]. Exclusion criteria included preexisting medical conditions preventing safe use of the EMS, such as the presence of implanted electromagnetic devices (eg, shunts, pacemakers, and intrathecal baclofen pumps), epilepsy, malignancy, uncontrolled cardiac conditions, and poor skin condition. Patients with recent initiation of oral muscle relaxants or botulinum toxin injections in the past 6 months were also excluded. A convenience sample was identified by the study team and contacted by the principal investigator for participation.

An interview for goal selection was performed for each participant before the study. All outcome measures were performed before and after a single session of stimulation with the suit.

Participants were fitted with appropriately sized suits to ensure good contact between the electrodes and the skin. They donned and doffed the EMS with assistance, ensuring that it was correctly worn—for example, zippers were positioned on the outside of the forearm, forming a straight line between the elbow and the little finger, and the seam was placed above the knee. Stimulation parameters were determined by an experienced physical therapist from Exopulse based on the results of the initial clinical assessment. The stimulation parameters were individualized and set to stimulate the antagonists of spastic muscles. A preset program was used to adjust the intensity of electrical stimulation across levels 6 to 22, depending on both the size of the target muscle group and severity of spasticity. Higher-frequency electrical stimulation is used for larger muscle groups or to manage more severe spasticity. Participants wore the suit for 60 minutes. This intervention period included 30 minutes of standardized goal-directed activities performed in two 15-minute blocks, interspersed with 15-minute rest breaks. These light activities simulated daily activities, such as food preparation or walking, and were goal directed. Figure 1 shows a participant walking with a broad-based quad stick while wearing the EMS. Figure 2 depicts the living room–like setting where the study was conducted.

Outcome measures before and after stimulation included measures of spasticity, using the Modified Tardieu Scale (MTS) [21] paired with surface electromyography (sEMG). Assessments of mobility included FAC [20], 10-meter walk test (10MWT) [22] for walking speed, five times sit-to-stand test [23] for transfer skills, and step test [24] for dynamic balance were scored. All outcomes were assessed by an experienced physiotherapist not involved in determining the stimulation parameters for the participants.

sEMG signals were recorded during high-velocity passive stretch movements (V3) during MTS measurements using Cometa EMG system (version 8.7.6.0; Cometa SRL) via lightweight wireless electromyography electrodes placed on the muscle belly of a standardized set of target muscles. The sampling rate for sEMG was 2000 Hz. Raw sEMG data were then processed by (1) low-pass filtering at 500 Hz with an eighth-order Butterworth filter and high-pass filtering at 20 Hz with a ninth-order Butterworth filter, (2) full wave rectification, and (3) smoothing with the root mean square (RMS) method. The time domain RMS feature of the sEMG signals was extracted. Three indexes were used for spasticity measurement: (1) The RMS (sEMG) of the agonist signal, (2) the RMS (sEMG) of the antagonist signal, and (3) spasticity index [25]:

For example, the sEMG index of biceps measured during passive elbow extension =RMS of triceps/RMS of triceps +RMS of biceps, while the sEMG index of the gastrocnemius measured during passive knee flexion = RMS of gastrocnemius/RMS of rectus femoris+RMS of gastrocnemius.

The spasticity angle derived from the MTS was corroborated with the sEMG index. A larger sEMG index indicates less spasticity.

Full-body sagittal plane videos of participants walking at comfortable walking speed, were recorded using an iPad Pro (Apple) at a height of approximately 1.5 m from the ground before and after use of the EMS. These were used for observational gait analysis, as well as quantification of spatiotemporal gait parameters using a markerless vision-based motion capture system. The system used OpenPose BODY25 pose estimation model [26] for 25-keypoint human pose estimation, gait events detection, and derivation of gait parameters via the coordinate-based treadmill algorithm method [27]. The system had previously been validated to detect gait abnormalities [28,29]. A single most accurately captured gait cycle from each walking trial was used to assess spatiotemporal parameters. Additionally, to quantify gait symmetry of participants with stroke, ratio index (RI) of step length was calculated [30].

RI=X1/X2, where X1 is the step length of left lower limb and X2 is the step length of the right lower limb [31]. In participants with stroke, the step length of the paretic lower limb is used as the numerator.

The Assistive Technology Usability Questionnaire for People With Neurological Diseases (NATU Quest) [32] was used to assess acceptability and perceived effectiveness of the EMS and was performed by the same study team member that performed the initial assessment. Scores range from 0 to 5, with 0 to 2 reflecting negative outcomes and 3 to 5 indicating positive ones. An average score of 3 indicates marginal usability, while scores of 4 or 5 denote high usability.

The study has been reviewed and approved by the Domain Specific Review Board, part of the National Healthcare Group (2023/00832) in Singapore.

Seven participants took part in the study. All participants were male due to recruitment constraints, which may limit generalizability. The characteristics of the participants, patient-defined goals, and goal-directed activities performed during the trial, are outlined in Table 1. Four participants had spastic hemiparesis due to stroke, while 3 had spastic tetraparesis due to cervical SCI. All patients had goals focused on improving function, either related to walking or performing activities of daily living.

Only 1 participant with stroke and 1 participant with SCI demonstrated improvement in MTS greater than minimal detectable change of 17.16° [33] (Table 2). The sEMG index corroborated the reduction in spasticity in these muscles (Multimedia Appendix 1).

An overall outcome was deemed positive if the EMS met the individualized goals specified in Table 1, and negative if these goals were not accomplished. Three participants with SCI and 1 participant with stroke had positive outcomes. Table 6 summarizes the quantitative outcomes and qualitative feedback on the EMS for each patient.

Our study investigated the acute effects of individualized electrostimulation using a single session with the EMS on spasticity and ambulatory function in participants with stroke and SCI. While improvements in objective measures of spasticity at rest were modest, improvements in ambulatory function and gait parameters were observed.

Four of 7 (57.1%) participants improved in walking speed (10MWT), with only participants with SCI exceeding the minimal clinically important difference of 0.06 m/s [41-43]. The limited response in participants with stroke may be due to the responsiveness of the test, particularly in more severely impaired participants [44]. The limited dose of intervention, as well as other factors impacting on mobility including weakness, impaired muscle synergies, sensory impairment, and impaired endurance may also be contributory. Furthermore, participants who were dependent on physical assistance or had slower walking speed did not show improvements on 10MWT. Functional endurance also influences performance in 10MWT particularly when walking requires considerable effort [45,46]. Outcomes were measured immediately after the EMS session, when participants may have experienced fatigue from the standardized goal-directed activities. Nevertheless, improvements were noted in step test (4 of 7 participants), reflecting better dynamic balance during weight shift and paretic lower-extremity motor control; as well as step-length symmetry (n=6, 85.7%), reflecting increased energy efficiency during walking [47]. Furthermore, step test and step-length symmetry are both predictors of falls risk [48-50]. A trend toward increased single-support time and decreased double-support times in our cohort also suggests improved balance and neuromuscular control [51].

Our findings of modest improvement in spasticity measures (n=2, 28.6%) at rest, including MTS and sEMG indices, corroborated with a previous double-blind crossover study which compared the EMS at 2 different frequencies (20 Hz and 30 Hz) with sham stimulation in patients with chronic stroke and reported no observed reduction in spasticity [52]. In contrast, Palmcrantz et al [53] reported the effectiveness of repeated sessions with the EMS in decreasing wrist flexor spasticity in patients with chronic stroke in a home setting (60 minutes every second day for 6 weeks; total 21 sessions). These disparate findings highlight the need for further investigation into the dose-response relationship and the potential for cumulative effects with repeated EMS sessions. Participants within our cohort who had clinically significant improvements in MTS were also those with greater spasticity, as indicated by larger spasticity angles. Pennati et al [52] also reported high interindividual variability in response to the EMS and suggested that it might be more efficacious in severe spasticity.

The observed improvements in gait symmetry among participants with stroke (3/4, 75%) are encouraging, as they suggest the potential for enhanced walking efficiency. The more pronounced improvements in gait parameters among participants with SCI warrant further investigation into possible differences in the mechanisms of response to the EMS between stroke and SCI populations. These differences may relate to differences in spinal and supraspinal mechanisms of spasticity, as well as varying extent of involvement of the descending pathways responsible for spasticity and its subsequent adaptations [54]. Additionally, presynaptic inhibition of Ia afferent terminals in muscles may remain unchanged in patients with hemiplegic stroke, which could influence responsiveness to the EMS [55]. In this limited series, more participants with SCI reported a favorable response to the EMS compared with participants with stroke. To our knowledge, this is the first report of the effects of the EMS in participants with SCI.

Qualitative feedback was mixed, with a median rating of 2 for ease of donning and doffing, mirroring that of a previous structured interview in patients with stroke and cerebral palsy who had spasticity, who described difficulty in wearing the suit at home for self-administered electrotherapy [56]. This is not unexpected as the rubber electrodes used in the EMS may cause friction against the skin but are necessary to manage impedance and ensure effective electrostimulation [57]. Concerns regarding the ease of donning and doffing, ergonomics, and functionality highlight significant barriers to self-administration and adherence and should be addressed in future iterations of the device to support wider adoption for home use. However, this score should also be interpreted with caution as it reflects the initial impression with a single-session trial. Nevertheless, most participants expressed satisfaction with the session. Others have reported improved patient well-being and muscle-relaxing effect during stimulation [58].

We recognize that the absence of a control group and the small sample size in our study limit the reproducibility and generalizability of our findings. Future studies should also aim for greater gender representation. Observed gains in spasticity, gait, and mobility measures could have been confounded by practice effects or neuromuscular warm-up. These factors may directly confound mobility and gait outcomes and hence preclude definitive attribution of the observed changes to EMS use. We designed a structured and clearly defined protocol to standardize the duration of the EMS to 60 minutes for all patients, comprising 30 minutes of standardized light activities performed in two 15-minute blocks, interspersed with 15-minute rest intervals. Furthermore, the use of fixed activity durations and rest periods enhances reproducibility and facilitates replicability in future studies. Study rigor was further strengthened by the involvement of experienced physiotherapists from Exopulse in determining the stimulation parameters, as this process requires specialized expertise. The team from Exopulse had also supported previously published studies [52,53]. In addition, the physiotherapist responsible for outcome assessment was blinded to the stimulation parameters, thereby minimizing the risk of cognitive bias and strengthening the internal validity of the study. To our knowledge, this is the first study to report spatiotemporal gait parameters with EMS use. Future controlled studies with repeated sessions should aim to confirm the efficacy of the EMS in defined patient populations. In addition, further qualitative studies of patient experience may provide insights into functional benefits in real-life activities and participation that are not fully captured by standardized quantitative measures.

With an individualized approach, a single 60-minute session of EMS use may enhance functional mobility and gait quality in some participants with spasticity resulting from stroke or SCI. User qualitative feedback on EMS usability was mixed, with reported challenges in donning and doffing likely reflecting initial experiences with a novel intervention. This finding underscores the need for design enhancements and comprehensive patient onboarding and training to ensure competencies to improve user experience, support compliance, and facilitate independent use at home. Further studies are needed to validate its effectiveness. Overall, the EMS demonstrates potential as a therapeutic, nonpharmacological option for spasticity management, particularly for individuals who require accessible care beyond traditional clinical settings.