{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T20:09:10Z","timestamp":1792786150284,"version":"4.5.0"},"reference-count":52,"publisher":"The Royal Society","issue":"243","license":[{"start":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T00:00:00Z","timestamp":1791936000000},"content-version":"vor","delay-in-days":7,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"ISB International Travel Grant"},{"name":"The Company of Biologists Travelling Fellowship","id":[{"id":"https:\/\/ror.org\/0033z1132","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,10,7]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Wearable assistive devices have potential to improve human balance, but their effectiveness remains limited by an incomplete understanding of how mechanical assistance influences neuromuscular control. This study aimed to determine the neural adaptations in the control of lower leg muscles in response to passive ankle exoskeleton assistance during standing balance tasks with varying levels of difficulty. Lower limb kinematics and kinetics were recorded to assess changes in joint dynamics and balance performance. Neural drive to the muscles was assessed by decomposing high-density electromyography signals into motor unit spike trains. Ankle exoskeleton assistance, provided by a simple spring-loaded passive device, did not alter or improve balance performance and had minimal effects on lower limb kinematics. However, exoskeleton assistance affected triceps surae neural control, but only in the soleus, by reducing neural drive, while the gastrocnemii showed no detectable changes in neural control. Together, these results demonstrate that passive exoskeleton assistance alters neural control of the triceps surae in a muscle-specific manner during balance. Understanding muscle-specific adaptations can support more effective exoskeleton design and the development of their control strategies informed by myoelectrical signals.<\/jats:p>","DOI":"10.1098\/rsif.2025.1305","type":"journal-article","created":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T00:09:06Z","timestamp":1791936546000},"source":"Crossref","is-referenced-by-count":0,"title":["Passive ankle exoskeleton assistance selectively modulates triceps surae neural control during balance"],"prefix":"10.1098","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-4438-6414","authenticated-orcid":false,"given":"Rapha\u00ebl","family":"Hamard","sequence":"first","affiliation":[{"name":"Universit\u00e9 Bourgogne Europe 1 , INSERM CAPS UMR 1093, Dijon, France"},{"name":"School of Biomedical Sciences, The University of Queensland 2 , Brisbane, Queensland, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6432-558X","authenticated-orcid":false,"given":"Fran\u00e7ois","family":"Hug","sequence":"additional","affiliation":[{"name":"School of Biomedical Sciences, The University of Queensland 2 , Brisbane, Queensland, Australia"},{"name":"Universit\u00e9 C\u00f4te d'Azur, LAMHESS, Nice, France 3"},{"name":"Institut Universitaire de France 4 , Paris, \u00cele-de-France, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7662-9716","authenticated-orcid":false,"given":"Taylor J. M.","family":"Dick","sequence":"additional","affiliation":[{"name":"School of Biomedical Sciences, The University of Queensland 2 , Brisbane, Queensland, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"175","published-online":{"date-parts":[[2026,10,14]]},"reference":[{"key":"2026102010570805600_RSIF20251305C1","doi-asserted-by":"crossref","first-page":"467","DOI":"10.1016\/j.neucli.2008.09.001","article-title":"Balance disorders in the elderly","volume":"38","author":"Sturnieks","year":"2008","journal-title":"Neurophysiol. Clin. Neurophysiol."},{"key":"2026102010570805600_RSIF20251305C2","doi-asserted-by":"crossref","first-page":"439","DOI":"10.1016\/j.neucli.2008.09.008","article-title":"Clinical tools for assessing balance disorders","volume":"38","author":"Yelnik","year":"2008","journal-title":"Neurophysiol. Clin. Neurophysiol."},{"key":"2026102010570805600_RSIF20251305C3","doi-asserted-by":"crossref","first-page":"4428","DOI":"10.1109\/TNSRE.2023.3330846","article-title":"The effects of exoskeleton assistance at the ankle on sensory integration during standing balance","volume":"31","author":"Canete","year":"2023","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"2026102010570805600_RSIF20251305C4","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1186\/s12984-018-0393-8","article-title":"Effects of a powered ankle-foot orthosis on perturbed standing balance","volume":"15","author":"Emmens","year":"2018","journal-title":"J. NeuroEng. Rehabil."},{"key":"2026102010570805600_RSIF20251305C5","doi-asserted-by":"crossref","first-page":"46721","DOI":"10.1038\/srep46721","article-title":"An ecologically-controlled exoskeleton can improve balance recovery after slippage","volume":"7","author":"Monaco","year":"2017","journal-title":"Sci. Rep."},{"key":"2026102010570805600_RSIF20251305C6","doi-asserted-by":"crossref","first-page":"295","DOI":"10.1113\/jphysiol.2004.076307","article-title":"Human postural sway results from frequent, ballistic bias impulses by soleus and gastrocnemius","volume":"564","author":"Loram","year":"2005","journal-title":"J. Physiol."},{"key":"2026102010570805600_RSIF20251305C7","first-page":"023001","article-title":"Closing the loop between wearable technology and human biology: a new paradigm for steering neuromuscular form and function","volume":"3","author":"Sartori","year":"2021","journal-title":"Prog. Biomed. Eng."},{"key":"2026102010570805600_RSIF20251305C8","doi-asserted-by":"crossref","first-page":"1329","DOI":"10.1038\/nn1986","article-title":"Optimal sensorimotor transformations for balance","volume":"10","author":"Lockhart","year":"2007","journal-title":"Nat. Neurosci."},{"key":"2026102010570805600_RSIF20251305C9","doi-asserted-by":"crossref","first-page":"026111","DOI":"10.1063\/1.3142245","article-title":"Neuromechanical tuning of nonlinear postural control dynamics","volume":"19","author":"Ting","year":"2009","journal-title":"Chaos"},{"key":"2026102010570805600_RSIF20251305C10","doi-asserted-by":"crossref","first-page":"230590","DOI":"10.1098\/rsos.230590","article-title":"Effects of passive ankle exoskeletons on neuromuscular function during exaggerated standing sway","volume":"11","author":"Farris","year":"2024","journal-title":"R. Soc. Open Sci."},{"key":"2026102010570805600_RSIF20251305C11","doi-asserted-by":"crossref","first-page":"102625","DOI":"10.1016\/j.jelekin.2021.102625","article-title":"Differential activation of the plantar flexor muscles in balance control across different feet orientations on the ground","volume":"62","author":"de Oliveira","year":"2022","journal-title":"J. Electromyogr. Kinesiol."},{"key":"2026102010570805600_RSIF20251305C12","doi-asserted-by":"crossref","first-page":"140","DOI":"10.1152\/japplphysiol.00906.2013","article-title":"Absence of lateral gastrocnemius activity and differential motor unit behavior in soleus and medial gastrocnemius during standing balance","volume":"116","author":"H\u00e9roux","year":"2014","journal-title":"J. Appl. Physiol."},{"key":"2026102010570805600_RSIF20251305C13","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1007\/BF00228159","article-title":"Different activations of the soleus and gastrocnemii muscles in response to various types of stance perturbation in man","volume":"80","author":"Nardone","year":"1990","journal-title":"Exp. Brain Res."},{"key":"2026102010570805600_RSIF20251305C14","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1007\/s00221-019-05696-8","article-title":"Regional modulation of the ankle plantarflexor muscles associated with standing external perturbations across different directions","volume":"238","author":"Cohen","year":"2020","journal-title":"Exp. Brain Res."},{"key":"2026102010570805600_RSIF20251305C15","doi-asserted-by":"crossref","first-page":"2569","DOI":"10.1007\/s00221-021-06154-0","article-title":"Maintenance of standing posture during multi-directional leaning demands the recruitment of task-specific motor units in the ankle plantarflexors","volume":"239","author":"Cohen","year":"2021","journal-title":"Exp. Brain Res."},{"key":"2026102010570805600_RSIF20251305C16","doi-asserted-by":"crossref","first-page":"272","DOI":"10.1152\/jn.00336.2022","article-title":"Differential behavior of distinct motoneuron pools that innervate the triceps surae","volume":"129","author":"Cohen","year":"2023","journal-title":"J. Neurophysiol."},{"key":"2026102010570805600_RSIF20251305C17","doi-asserted-by":"crossref","first-page":"1321","DOI":"10.1152\/jn.00068.2023","article-title":"Regional recruitment and differential behavior of motor units during postural control in older adults","volume":"130","author":"Cohen","year":"2023","journal-title":"J. Neurophysiol."},{"key":"2026102010570805600_RSIF20251305C18","doi-asserted-by":"crossref","first-page":"3366","DOI":"10.1016\/j.jbiomech.2008.09.029","article-title":"Inversion\u2013eversion moment arms of gastrocnemius and tibialis anterior measured in vivo","volume":"41","author":"Lee","year":"2008","journal-title":"J. Biomech."},{"key":"2026102010570805600_RSIF20251305C19","doi-asserted-by":"crossref","first-page":"753","DOI":"10.1111\/j.1469-7580.2006.00558.x","article-title":"An allometric analysis of the number of muscle spindles in mammalian skeletal muscles","volume":"208","author":"Banks","year":"2006","journal-title":"J. Anat."},{"key":"2026102010570805600_RSIF20251305C20","doi-asserted-by":"crossref","first-page":"259","DOI":"10.1007\/BF01003594","article-title":"Muscle fibre type populations of human leg muscles","volume":"7","author":"Edgerton","year":"1975","journal-title":"Histochem. J."},{"key":"2026102010570805600_RSIF20251305C21","doi-asserted-by":"crossref","first-page":"2183","DOI":"10.1109\/TRO.2023.3236958","article-title":"Evaluation of a fused sonomyography and electromyography-based control on a cable-driven ankle exoskeleton","volume":"39","author":"Zhang","year":"2023","journal-title":"IEEE Trans. Robot."},{"key":"2026102010570805600_RSIF20251305C22","doi-asserted-by":"crossref","first-page":"808","DOI":"10.1152\/japplphysiol.01041.2020","article-title":"Surface EMG cross talk quantified at the motor unit population level for muscles of the hand, thigh, and calf","volume":"131","author":"Germer","year":"2021","journal-title":"J Appl. Physiol."},{"key":"2026102010570805600_RSIF20251305C23","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1152\/japplphysiol.00587.2022","article-title":"Common synaptic input between motor units from the lateral and medial posterior soleus compartments does not differ from that within each compartment","volume":"134","author":"Aeles","year":"2023","journal-title":"J. Appl. Physiol."},{"key":"2026102010570805600_RSIF20251305C24","doi-asserted-by":"crossref","first-page":"342","DOI":"10.1152\/japplphysiol.00635.2020","article-title":"Muscles from the same muscle group do not necessarily share common drive: evidence from the human triceps surae","volume":"130","author":"Hug","year":"2021","journal-title":"J. Appl. Physiol."},{"key":"2026102010570805600_RSIF20251305C25","doi-asserted-by":"crossref","first-page":"e0702242024","DOI":"10.1523\/JNEUROSCI.0702-24.2024","article-title":"The volitional control of individual motor units is constrained within low-dimensional neural manifolds by common inputs","volume":"44","author":"Rossato","year":"2024","journal-title":"J. Neurosci."},{"key":"2026102010570805600_RSIF20251305C26","doi-asserted-by":"crossref","first-page":"1071","DOI":"10.3390\/machines11121071","article-title":"Exploring the impact of passive ankle exoskeletons on lower-limb neuromechanics during walking on sloped surfaces: implications for device design","volume":"11","author":"Williamson","year":"2023","journal-title":"Machines"},{"key":"2026102010570805600_RSIF20251305C27","doi-asserted-by":"crossref","first-page":"1041","DOI":"10.1113\/jphysiol.2002.025049","article-title":"Direct measurement of human ankle stiffness during quiet standing: the intrinsic mechanical stiffness is insufficient for stability","volume":"545","author":"Loram","year":"2002","journal-title":"J. Physiol."},{"key":"2026102010570805600_RSIF20251305C28","doi-asserted-by":"crossref","first-page":"439","DOI":"10.1016\/j.gaitpost.2012.04.001","article-title":"Testing single and double limb standing balance performance: comparison of COP path length evaluation between two devices","volume":"36","author":"Donath","year":"2012","journal-title":"Gait. Posture."},{"key":"2026102010570805600_RSIF20251305C29","doi-asserted-by":"crossref","first-page":"20210201","DOI":"10.1098\/rspb.2021.0201","article-title":"Series elasticity facilitates safe plantar flexor muscle\u2013tendon shock absorption during perturbed human hopping","volume":"288","author":"Dick","year":"2021","journal-title":"Proc. R. Soc. B"},{"key":"2026102010570805600_RSIF20251305C30","doi-asserted-by":"crossref","first-page":"1940","DOI":"10.1109\/TBME.2007.901024","article-title":"OpenSim: open-source software to create and analyze dynamic simulations of movement","volume":"54","author":"Delp","year":"2007","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"2026102010570805600_RSIF20251305C31","doi-asserted-by":"crossref","first-page":"2068","DOI":"10.1109\/TBME.2016.2586891","article-title":"Full-body musculoskeletal model for muscle-driven simulation of Human gait","volume":"63","author":"Rajagopal","year":"2016","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"2026102010570805600_RSIF20251305C32","doi-asserted-by":"crossref","first-page":"102886","DOI":"10.1016\/j.jelekin.2024.102886","article-title":"Tutorial on MUedit: an open-source software for identifying and analysing the discharge timing of motor units from electromyographic signals","volume":"77","author":"Avrillon","year":"2024","journal-title":"J. Electromyogr. Kinesiol."},{"key":"2026102010570805600_RSIF20251305C33","doi-asserted-by":"crossref","first-page":"102426","DOI":"10.1016\/j.jelekin.2020.102426","article-title":"Tutorial: analysis of motor unit discharge characteristics from high-density surface EMG signals","volume":"53","author":"Del Vecchio","year":"2020","journal-title":"J. Electromyogr. Kinesiol."},{"key":"2026102010570805600_RSIF20251305C34","doi-asserted-by":"crossref","first-page":"016003","DOI":"10.1088\/1741-2552\/ab4d05","article-title":"Interfacing the neural output of the spinal cord: robust and reliable longitudinal identification of motor neurons in humans","volume":"17","author":"Del Vecchio","year":"2019","journal-title":"J. Neural. Eng."},{"key":"2026102010570805600_RSIF20251305C35","doi-asserted-by":"crossref","first-page":"394","DOI":"10.1152\/japplphysiol.00075.2023","article-title":"A comparison of neural control of the biarticular gastrocnemius muscles between knee flexion and ankle plantar flexion","volume":"135","author":"Hamard","year":"2023","journal-title":"J. Appl. Physiol."},{"key":"2026102010570805600_RSIF20251305C36","doi-asserted-by":"crossref","first-page":"1479","DOI":"10.1113\/JP273662","article-title":"Tracking motor units longitudinally across experimental sessions with high-density surface electromyography","volume":"595","author":"Martinez-Valdes","year":"2017","journal-title":"J. Physiol."},{"key":"2026102010570805600_RSIF20251305C37","doi-asserted-by":"crossref","first-page":"1","DOI":"10.18637\/jss.v067.i01","article-title":"Fitting linear mixed-effects models using lme4","volume":"67","author":"Bates","year":"2015","journal-title":"J. Stat. Softw."},{"key":"2026102010570805600_RSIF20251305C38","doi-asserted-by":"crossref","first-page":"425","DOI":"10.1016\/j.gaitpost.2005.05.004","article-title":"An improved powered ankle\u2013foot orthosis using proportional myoelectric control","volume":"23","author":"Ferris","year":"2006","journal-title":"Gait Posture"},{"key":"2026102010570805600_RSIF20251305C39","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1186\/s12984-015-0086-5","article-title":"Learning to walk with an adaptive gain proportional myoelectric controller for a robotic ankle exoskeleton","volume":"12","author":"Koller","year":"2015","journal-title":"J. NeuroEng. Rehabil."},{"key":"2026102010570805600_RSIF20251305C40","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1186\/s12984-019-0523-y","article-title":"Mechanics and energetics of post-stroke walking aided by a powered ankle exoskeleton with speed-adaptive myoelectric control","volume":"16","author":"McCain","year":"2019","journal-title":"J. NeuroEng. Rehabil."},{"key":"2026102010570805600_RSIF20251305C41","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1249\/JES.0000000000000204","article-title":"Exoskeletons improve locomotion economy by reducing active muscle volume","volume":"47","author":"Beck","year":"2019","journal-title":"Exerc. Sport Sci. Rev."},{"key":"2026102010570805600_RSIF20251305C42","doi-asserted-by":"crossref","first-page":"20200431","DOI":"10.1098\/rspb.2020.0431","article-title":"Cyclically producing the same average muscle-tendon force with a smaller duty increases metabolic rate","volume":"287","author":"Beck","year":"2020","journal-title":"Proc. R. Soc. B"},{"key":"2026102010570805600_RSIF20251305C43","doi-asserted-by":"crossref","first-page":"2211","DOI":"10.1016\/j.jbiomech.2008.04.020","article-title":"Assessment of muscle volume and physiological cross-sectional area of the human triceps surae muscle in vivo","volume":"41","author":"Albracht","year":"2008","journal-title":"J. Biomech."},{"key":"2026102010570805600_RSIF20251305C44","doi-asserted-by":"crossref","first-page":"926","DOI":"10.1002\/jor.1100100623","article-title":"Physiological cross-sectional area of human leg muscles based on magnetic resonance imaging","volume":"10","author":"Fukunaga","year":"1992","journal-title":"J. Orthop. Res."},{"key":"2026102010570805600_RSIF20251305C45","doi-asserted-by":"crossref","first-page":"158","DOI":"10.1152\/jappl.1996.80.1.158","article-title":"Specific tension of human plantar flexors and dorsiflexors","volume":"80","author":"Fukunaga","year":"1996","journal-title":"J. Appl. Physiol."},{"key":"2026102010570805600_RSIF20251305C46","doi-asserted-by":"crossref","first-page":"1370","DOI":"10.1186\/s12889-019-7679-z","article-title":"Time spent cycling, walking, running, standing and sedentary: a cross-sectional analysis of accelerometer-data from 1670 adults in the Copenhagen City Heart Study","volume":"19","author":"Johansson","year":"2019","journal-title":"BMC Public Health"},{"key":"2026102010570805600_RSIF20251305C47","doi-asserted-by":"crossref","first-page":"3604","DOI":"10.1038\/s41598-020-60360-4","article-title":"Ultrasound imaging links soleus muscle neuromechanics and energetics during human walking with elastic ankle exoskeletons","volume":"10","author":"Nuckols","year":"2020","journal-title":"Sci. Rep."},{"key":"2026102010570805600_RSIF20251305C48","doi-asserted-by":"crossref","first-page":"1378","DOI":"10.1152\/jn.00458.2022","article-title":"Voluntary muscle coactivation in quiet standing elicits reciprocal rather than coactive agonist-antagonist control of reactive balance","volume":"129","author":"Martino","year":"2023","journal-title":"J. Neurophysiol."},{"key":"2026102010570805600_RSIF20251305C49","doi-asserted-by":"crossref","first-page":"102656","DOI":"10.1016\/j.jelekin.2022.102656","article-title":"Consensus for experimental design in electromyography (CEDE) project: high-density surface electromyography matrix","volume":"64","author":"Gallina","year":"2022","journal-title":"J. Electromyogr. Kinesiol."},{"key":"2026102010570805600_RSIF20251305C50","doi-asserted-by":"crossref","first-page":"R143","DOI":"10.1088\/0967-3334\/35\/7\/R143","article-title":"Blind source identification from the multichannel surface electromyogram","volume":"35","author":"Holobar","year":"2014","journal-title":"Physiol. Meas."},{"key":"2026102010570805600_RSIF20251305C51","doi-asserted-by":"crossref","first-page":"ENEURO.0064","DOI":"10.1523\/ENEURO.0064-23.2023","article-title":"Larger and denser: an optimal design for surface grids of EMG electrodes to identify greater and more representative samples of motor units","volume":"10","author":"Caillet","year":"2023","journal-title":"eNeuro"},{"key":"2026102010570805600_RSIF20251305C52","article-title":"Supplementary material from: Passive ankle exoskeleton assistance selectively modulates triceps surae neural control during balance","author":"Hamard","year":"2026"}],"container-title":["Journal of the Royal Society Interface"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/royalsocietypublishing.org\/rsif\/article-pdf\/doi\/10.1098\/rsif.2025.1305\/6170445\/rsif.2025.1305.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/royalsocietypublishing.org\/rsif\/article-pdf\/doi\/10.1098\/rsif.2025.1305\/6170445\/rsif.2025.1305.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,20]],"date-time":"2026-10-20T14:57:17Z","timestamp":1792508237000},"score":1,"resource":{"primary":{"URL":"https:\/\/royalsocietypublishing.org\/rsif\/article\/23\/243\/20251305\/483636\/Passive-ankle-exoskeleton-assistance-selectively"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,10,7]]},"references-count":52,"journal-issue":{"issue":"243","published-print":{"date-parts":[[2026,10,7]]}},"URL":"https:\/\/doi.org\/10.1098\/rsif.2025.1305","relation":{},"ISSN":["1742-5689","1742-5662"],"issn-type":[{"value":"1742-5689","type":"print"},{"value":"1742-5662","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,10,7]]},"article-number":"20251305"}}