Spinal and supraspinal mechanisms affecting torque development at different joint angles

Maria Papaiordanidou (1) , Valérie Mustacchi (1) , Jean-Damien Stevenot (1) , Michele Vanoncini (1) , Alain Martin (2)

1 ISM - Institut des Sciences du Mouvement Etienne Jules Marey
2 CAPS - Cognition, Action, et Plasticité Sensorimotrice [Dijon - U1093]

INTRODUCTION: We examined the neural mechanisms responsible for plantar flexion torque changes at different joint positions. METHODS: Nine subjects performed maximal voluntary contractions (MVC) at 6 ankle-knee angle combinations [3 ankle angles (dorsiflexion, anatomic position, plantar flexion) and 2 knee angles (flexion, full extension)]. Neural mechanisms were determined by V-wave, H-reflex (at rest and during MVC), and electromyography during MVC (RMS), normalized to the muscle compound action potential (V/Msup , Hmax /Mmax , Hsup /Msup and RMS/Msup ) and voluntary activation (VA), while muscle function was assessed by doublet amplitude. RESULTS: MVC and doublet amplitude were significantly lower at plantar flexion (P < 0.01), while VA was significantly lower at dorsiflexion and full knee extension (P < 0.05). V/Msup and RMS/Msup were significantly lower at knee extension (P < 0.01), while Hsup /Msup was not affected by joint angle. CONCLUSIONS: These results indicate that joint positions leading to muscle lengthening produce reduced neural drive, due mainly to supraspinal mechanisms.

Mots clés: spinal excitability; twitch interpolation; electromyography; muscle mechanical properties; neural activation

Domaines: Neurosciences [q-bio.NC]

Maria Papaiordanidou, Valérie Mustacchi, Jean-Damien Stevenot, Michele Vanoncini, Alain Martin. Spinal and supraspinal mechanisms affecting torque development at different joint angles. Muscle & nerve. Supplement., 2016, 53 (4), pp.626-632. ⟨10.1002/mus.24895⟩. ⟨hal-01302972⟩