100 Section - Active arms, reactive legs: insight into promoting neural coupling during walking

Wednesday, May 20, 2026

6:00 PM - 7:30 PM PT

Presenting Author/Autor expositor(s)

FE

Francisco Espinoza, MS

PhD student
University of Arizona
Tucson, Arizona, United States

Co-Author/Coautor(s)

CB

Colin Benites, n/a

Undergraduate Researcher
University of Arizona
Tucson, Arizona, United States

Corresponding Author/Autor a quien dirigir la corr(s)

CA

Christopher J. Arellano, PhD

Associate Professor
Dept. of Orthopedic Surgery and Dept. of Biomedical Engineering, University of Arizona
Tucson, Arizona, United States

Objectives : Interventions that enhance walking recovery and promote functional independence after an incomplete spinal cord injury (iSCI) have the potential to lessen the lifetime economic burden these injuries impose. One promising approach is to leverage the neural coupling that governs coordinated arm-leg movements during walking. To date, it has been shown that actively engaging the arms can alter spinal cord excitability, leading to increases in leg muscle activity. However, these insights have been restricted to seated and standing devices. Understanding how to engage arm-leg neural coupling during walking could better promote walking recovery after an iSCI, but this has remained relatively unexplored.

Design: To explore this idea, we first studied young healthy adults (n = 10; 4/6 male/female; mass = 68.12 ± 8.14 kg; height = 171.25 ± 9.8 cm) under conditions where they actively increased arm activity by cyclically lifting and lowering loads (via a simple rope pulley system) while treadmill walking without and with body weight support. During each trial, electromyographic (EMG) activity was recorded from 6 upper and 5 lower limb muscles while pseudorandomized cutaneous reflexes were evoked by electrical stimulation at the right leg’s distal tibial nerve.

Results: We discovered that increased arm activity selectively modulated both spinal cord excitability and leg muscle activity throughout the walking gait cycle. With greater loads, the arm’s posterior deltoid exhibited the largest increase in activation, which had a modulatory effect on the leg’s gastrocnemius and tibialis anterior muscles.

Conclusion: Because the gastrocnemius contributes to propulsion during late stance, this arm-driven modulation may facilitate the stance-to-swing transition. Similarly, enhanced tibialis anterior activity during swing suggests potential benefits for foot clearance. These insights set the foundation for future experiments aimed at understanding the effects that increased arm activity has on modulating spinal cord excitability and improving walking recovery in individuals with iSCIs.