Frontiers in Aging · Jun 15, 2026

Acute changes in ankle dorsiflexor strength and fNIRS-Derived cortical activation following a single session of neuromuscular electrical stimulation in healthy older adults

By Li Y, Wang L, Wang C et al.

BACKGROUND: Neuromuscular electrical stimulation (NMES) is widely used to improve neuromuscular function, but most studies in healthy older adults have focused on longer-term outcomes such as muscle strength, mass, or architecture. Whether a single NMES session can induce measurable immediate changes in ankle-related neuromuscular performance and task-evoked cortical activity in healthy older adults remains unclear. METHODS: Twenty-seven healthy older adults participated in this within-participant pre-post design study. A single 20-min NMES session was applied to the right tibialis anterior (40 Hz, maximum tolerable intensity, 2 s on/10 s off), with intensity individualized to maximal tolerable contraction (mean ± SD: 28.5 ± 6.2 mA; range: 18-42 mA). Before and after NMES, maximal ankle dorsiflexion performance was assessed on a dynamometer, and passive muscle biomechanical properties were quantified with MyotonPro. Whole-brain fNIRS was recorded during the dorsiflexion task. HbO signals were analyzed using a GLM with channel- and ROI-level inference, effect sizes, and false discovery rate (FDR) correction. RESULTS: NMES increased ankle dorsiflexion strength immediately after stimulation, whereas passive muscle mechanical properties showed no measurable short-term change. Task-related cortical activation was observed in both the pre-intervention and post-intervention sessions. Although exploratory analyses suggested some localized post-pre differences, no cortical effects survived correction for multiple comparisons. Exploratory brain-behavior correlations were observed, but none remained significant after correction. CONCLUSION: A single session of NMES improved ankle dorsiflexion strength immediately in healthy older adults, while passive muscle mechanical properties did not change over the same period. Cortical activation was observed in both sessions, but no pre-post differences survived correction for multiple comparisons. The strength findings support an acute neuromuscular effect of NMES, whereas the cortical findings remain inconclusive.

doi.org/10.3389/fragi.2026.1726632 Open access PubMed 42375386 Interventions