Study Demonstrates Neural Connections Between Lower Limb Sensory Nerves and Pelvic Floor Muscles
Researchers demonstrated that electrical stimulation of lower limb nerves can evoke measurable reflex responses in the pelvic floor muscles of neurologically intact adults. The study tested stimulation of the tibial and superficial peroneal nerves at varying intensities in 21 participants, finding that tibial nerve stimulation produced intensity-dependent reflex amplitudes and that bilateral stimulation yielded stronger responses than unilateral. These findings suggest a neural pathway between leg sensory inputs and pelvic floor motor neurons that could eventually be exploited to treat urinary incontinence in people who cannot perform voluntary pelvic floor exercises.
A preprint study posted to bioRxiv investigated whether cutaneous (skin-level) nerve stimulation in the lower limb could induce reflex activity in the pelvic floor muscles (PFM), which are central to urinary continence and are typically trained through voluntary contraction exercises. Twenty-one neurologically intact adults underwent electrical stimulation of the right distal tibial nerve, bilateral distal tibial nerves, or the right superficial peroneal nerve while standing, with electromyography recording muscle responses in both the PFM and lower leg. Stimulation was delivered at sub-motor-threshold, 1.2×, and 1.5× motor threshold intensities. Both nerve sites evoked PFM reflex responses, but only tibial nerve stimulation showed a clear dose-response relationship, with reflex amplitude rising as stimulus intensity increased; superficial peroneal stimulation did not show this pattern. Bilateral tibial stimulation produced larger PFM responses than unilateral stimulation, pointing to summation effects in the shared neural circuitry. The authors argue these results confirm functional neural connections between lower limb afferents and PFM motoneurons, and propose that sensory-based stimulation strategies could one day supplement or replace voluntary training for patients with neurological conditions such as spinal cord injury who struggle to volitionally activate the pelvic floor.
What's missing
The study was conducted exclusively in neurologically intact adults, so it remains unknown whether the same reflex pathways are preserved, enhanced, or disrupted in the target population (people with neurological disorders such as spinal cord injury). The study also does not address whether evoked reflexes translate into clinically meaningful improvements in continence outcomes, nor does it report long-term or repeated-stimulation effects. As a preprint, the work has not yet undergone formal peer review.
What different sources said
- bioRxivCenter
Spinal reflex modulation in the pelvic floor muscles through sensory stimulation from the lower limb
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