Neuromuscular electrical stimulation with blood flow restriction shows preliminary effects on abductor hallucis muscle size and toe flexor strength: a pilot randomized controlled trial

Purpose: To examine the effects of neuromuscular electrical stimulation (NMES) combined with blood flow restriction (BFR) on abductor hallucis (ABH) cross-sectional area (CSA) compared with NMES alone in a pilot randomized controlled trial. Toe flexor strength (TFS) and foot posture were also examined as secondary and exploratory outcomes, respectively. Methods: Thirty participants were randomly allocated to either an NMES + BFR group or an NMES-alone group. Both groups received 15 min of ABH NMES three times weekly for 6 weeks, while the NMES + BFR group additionally received BFR. ABH CSA, TFS, and Foot Posture Index-6 (FPI-6) scores were assessed pre- and post-intervention by a blinded assessor. Post-intervention between-group differences were analyzed using baseline-adjusted analysis of covariance. Results: The NMES + BFR group showed greater post-intervention ABH CSA than the NMES group (adjusted mean difference [95% confidence interval] = 0.19 [0.08–0.30] cm², p = 0.001). The between-group difference in TFS favored the NMES + BFR group but was not statistically significant (1.83 [− 0.09–3.75] kg, p = 0.061). Exploratory analysis showed lower post-intervention FPI-6 scores in the NMES + BFR group than in the NMES group (− 1.59 [− 2.46–−0.72] points, p = 0.001). No adverse events or intolerance leading to discontinuation occurred. Conclusion: Six weeks of NMES combined with BFR showed preliminary favorable effects on ABH CSA compared with NMES alone, whereas evidence for superior improvement in TFS was inconclusive. All findings, including the exploratory foot posture results, require confirmation in larger studies with more complete intervention-dose reporting. Trial registration: Registration number (date): UMIN000054853 (August 1, 2024). © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2026.