Physiological Responses to Upper Limb NMES

NCT07635979 | Completed

• 1 other identifier: FFR-ARM-002
• Study Type: interventional
• Target: 10
• Locations: 1 country
• Sites: 1

Brief Summary

The primary objective of this study is to explore the application of the Firefly® device for delivering NMES to anatomically defined regions of the upper limb and to observe associated physiological changes. Specifically, the study will assess alterations in arterial and venous blood flow, as well as local muscle oxygen saturation, as potential indicators of muscle perfusion during NMES.

Conditions

Healthy Adult Participants

Keywords

Blood Circulation; Neuromuscular Electrical Stimulation; Muscle Contraction; Hemodynamics

Outcome Measures

Primary Outcomes (5)

• Change in upper-limb blood flow volume during NMES (ON vs OFF)

  Within-subject change in upper-limb blood flow volume (mL/min) measured using Doppler ultrasound during neuromuscular electrical stimulation (NMES) delivered via the Firefly device, comparing stimulation ON versus OFF conditions. Measurements will be collected across repeated stimulation cycles at predefined upper-limb stimulation zones and vascular assessment sites.

  During single study visit (approximately 2 hours), across repeated stimulation ON/OFF cycles

• Change in upper-limb peak systolic velocity during NMES (ON vs OFF)

  Within-subject change in upper-limb peak systolic velocity (PSV; cm/s) measured using Doppler ultrasound during NMES delivered via the Firefly device, comparing stimulation ON versus OFF conditions across repeated stimulation cycles at predefined upper-limb stimulation zones and vascular assessment sites.

  During a single study visit (approximately 2 hours), across repeated stimulation ON/OFF cycles.

• Change in upper-limb end-diastolic velocity during NMES (ON vs OFF)

  Within-subject change in upper-limb end-diastolic velocity (EDV; cm/s) measured using Doppler ultrasound during NMES delivered via the Firefly device, comparing stimulation ON versus OFF conditions across repeated stimulation cycles at predefined upper-limb stimulation zones and vascular assessment sites.

  During a single study visit (approximately 2 hours), across repeated stimulation ON/OFF cycles.

• Change in upper-limb resistive index during NMES (ON vs OFF)

  Within-subject change in upper-limb resistive index (RI; unitless ratio) derived from Doppler ultrasound measurements during NMES delivered via the Firefly device, comparing stimulation ON versus OFF conditions across repeated stimulation cycles at predefined upper-limb stimulation zones and vascular assessment sites.

  During a single study visit (approximately 2 hours), across repeated stimulation ON/OFF cycles.

• Change in upper-limb muscle oxygen saturation during NMES (ON vs OFF)

  Within-subject change in upper-limb muscle oxygen saturation (SmO₂; %) measured continuously using functional near-infrared spectroscopy (fNIRS) during NMES delivered via the Firefly device, comparing stimulation ON versus OFF conditions across repeated stimulation cycles at predefined upper-limb stimulation zones and assessment sites.

  During a single study visit (approximately 2 hours), across repeated stimulation ON/OFF cycles.

Secondary Outcomes (1)

• Incidence of adverse events and device-related effects

  During single study visit (approximately 2 hours)

Study Arms (1)

Single experimental arm: Firefly NMES

EXPERIMENTAL

Device: Firefly NMES device

Interventions

Firefly NMES device DEVICE

Firefly NMES device applied to the upper limb during a single-visit exploratory pysiological study

Single experimental arm: Firefly NMES

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• Aged 18 to 45 years (inclusive)
• No known history of vascular or neurological conditions affecting the upper extremities
• Able to read, understand, and communicate in English to ensure informed consent and safe participation in the study

You may not qualify if:

• Presence of any condition that contraindicates the use of neuromuscular electrical stimulation (e.g., implanted pacemaker, epilepsy)
• Current or recent injury to the upper limbs that may interfere with stimulation or measurement
• Anatomical variations in the brachial artery or axillary vein, specifically vascular branching outside expected anatomical locations, as identified by ultrasound, which may impair accurate blood flow measurement or device placement
• Currently participating in another interventional or physiological research study or having done so within the past 30 days.
• Currently pregnant

Sponsors & Collaborators

• Kieron.Day: lead

Study Sites (1)

Firstkind

High Wycombe, Buckinghamshire, HP11 1JX, United Kingdom

Location

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Head of Clinical Affairs

Model Details: This is a single-centre, within-subject exploratory study designed to evaluate the physiological effects of NMES applied to the upper limb using the Firefly® device. A repeated-measures design will be used to compare physiological parameters under alternating stimulation OFF and ON conditions.

Study Record Dates

• First Submitted: April 10, 2026
• First Posted: June 9, 2026
• Study Start: September 19, 2025
• Primary Completion: October 3, 2025
• Study Completion: October 3, 2025
• Last Updated: June 9, 2026

Record last verified: 2026-06

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, ICF

Locations

GB (1)