Physiological Responses to Upper Limb NMES

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.

Inclusion Criteria: * 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 Exclusion Criteria: * 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