Preconditioning Effects of Neuromuscular Electrical Stimulation in Patients with Symptomatic Peripheral Arterial Disease.

Aims: Intermittent claudication is a major barrier to establishing an exercise routine in patients with peripheral artery disease (PAD). This study investigated the preconditioning effects of neuromuscular electrical stimulation (NMES) on walking capacity in patients with PAD and intermittent claudication. Additionally, it aimed to determine the optimal NMES settings and the underlying mechanisms of its effects.

Methods: A total of 15 patients with PAD (Fontaine II) participated in a crossover study. Each patient underwent 10-min sessions of NMES at two frequencies (4 and 20 Hz) and two intensities (moderate and high), plus a sham condition, before treadmill walking tests using the modified Gardner protocol.

Results: Pain-free walking distance significantly increased after a single session of 20 Hz high-intensity NMES (259.2±27.5 m; p＜0.05) relative to the sham group (201.9±23.6 m). The maximum walking distance also improved significantly after 4 and 20 Hz high-intensity NMES. The vascular endothelial function, assessed by flow-mediated dilation, was significantly enhanced following 20 Hz moderate- and high-intensity NMES, as well as 4 Hz high-intensity NMES, relative to the sham group. Additionally, lower extremity blood flow, as measured via transcutaneous partial pressure of oxygen, improved significantly in all NMES conditions. However, serum markers such as myeloperoxidase, hepatocyte growth factor, vascular endothelial growth factor, and CD34^＋/CD133^＋ progenitor cell counts did not differ significantly between the NMES and sham groups.

Conclusion: High-intensity 20 Hz NMES is an effective preconditioning strategy for instantaneously enhancing the walking capacity in patients with PAD, likely due to nitric oxide-mediated vasodilation. These findings suggest that NMES is a promising therapeutic approach for PAD rehabilitation.