{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,10]],"date-time":"2026-10-10T09:15:34Z","timestamp":1791623734701,"version":"4.3.4"},"reference-count":45,"publisher":"Public Library of Science (PLoS)","issue":"1","license":[{"start":{"date-parts":[[2021,1,22]],"date-time":"2021-01-22T00:00:00Z","timestamp":1611273600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001807","name":"Funda\u00e7\u00e3o de Amparo \u00e0 Pesquisa do Estado de S\u00e3o Paulo","doi-asserted-by":"publisher","award":["2018\/16103-7"],"award-info":[{"award-number":["2018\/16103-7"]}],"id":[{"id":"10.13039\/501100001807","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000268","name":"Biotechnology and Biological Sciences Research Council","doi-asserted-by":"publisher","award":["BB\/L02103X\/1"],"award-info":[{"award-number":["BB\/L02103X\/1"]}],"id":[{"id":"10.13039\/501100000268","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000855","name":"University of Birmingham","doi-asserted-by":"crossref","award":["University of Birmingham Scholarship for Research Excellence, Brazil"],"award-info":[{"award-number":["University of Birmingham Scholarship for Research Excellence, Brazil"]}],"id":[{"id":"10.13039\/501100000855","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:p>When standing, intrinsic ankle stiffness is smaller when measured using large perturbations, when sway size is large, and when background torque is low. However, there is a large variation in individual intrinsic ankle stiffness. Here we determine if individual variation has consequences for postural control. We examined the relationship between ankle stiffness, ankle torque and body sway across different individuals. Ankle stiffness was estimated in 19 standing participants by measuring torque responses to small, brief perturbations. Perturbation sizes of 0.2 &amp; 0.9 degrees (both lasting 140 ms) measured short- and long-range stiffness respectively, while participants either stood quietly on a fixed platform or were imperceptibly tilted to reduce stability (0.1 Hz sinusoid; 0.2 &amp; 0.4 deg). The spontaneous body sway component (natural random relatively rapid postural adjustments) and background ankle torque were averaged from sections immediately before perturbations. The results show that, first, intrinsic ankle stiffness is positively associated with ankle torque, and that this relationship is stronger for long-range stiffness. Second, intrinsic ankle stiffness is negatively associated with body sway, but, in contrast to the relationship with torque, this relationship is stronger for short-range stiffness. We conclude that high short-range intrinsic ankle stiffness is associated with reduced spontaneous sway, although the causal relationship between these two parameters is unknown. These results suggest that, in normal quiet standing where sway is very small, the most important determinant of intrinsic ankle stiffness may be stillness. In less stable conditions, intrinsic ankle stiffness may be more dependent on ankle torque.<\/jats:p>","DOI":"10.1371\/journal.pone.0244993","type":"journal-article","created":{"date-parts":[[2021,1,22]],"date-time":"2021-01-22T22:10:53Z","timestamp":1611353453000},"page":"e0244993","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":25,"title":["Individual differences in intrinsic ankle stiffness and their relationship to body sway and ankle torque"],"prefix":"10.1371","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3518-0198","authenticated-orcid":true,"given":"Tania E.","family":"Sakanaka","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martin","family":"Lakie","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Raymond F.","family":"Reynolds","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2021,1,22]]},"reference":[{"key":"pone.0244993.ref001","first-page":"545","article-title":"The forces operating at the human ankle joint during standing","volume":"91","author":"JW Smith","year":"1957","journal-title":"J. Anat"},{"key":"pone.0244993.ref002","first-page":"496","article-title":"Dynamics of equilibrium of the vertical posture in man","volume":"17","author":"VS Gurfinkel","year":"1972","journal-title":"Biophysics (Oxf)"},{"key":"pone.0244993.ref003","doi-asserted-by":"crossref","first-page":"533","DOI":"10.1113\/jphysiol.1992.sp019278","article-title":"Ankle stiffness of standing humans in response to imperceptible perturbation: Reflex and task-dependent components","volume":"1","author":"RC Fitzpatrick","year":"1992","journal-title":"J. Physiol"},{"key":"pone.0244993.ref004","doi-asserted-by":"crossref","first-page":"915","DOI":"10.1111\/j.1469-7793.1999.915ad.x","article-title":"Feedforward ankle strategy of balance during quiet stance in adults","volume":"514","author":"P Gatev","year":"1999","journal-title":"J. Physiol"},{"key":"pone.0244993.ref005","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1007\/BF00235249","article-title":"Adapting reflexes controlling the human posture","volume":"26","author":"LM Nashner","year":"1976","journal-title":"Exp. Brain Res"},{"key":"pone.0244993.ref006","doi-asserted-by":"crossref","first-page":"308","DOI":"10.1007\/BF00229788","article-title":"Open-loop and closed-loop control of posture: A random-walk analysis of center-of-pressure trajectories","volume":"95","author":"JJ Collins","year":"1993","journal-title":"Exp. Brain Res"},{"key":"pone.0244993.ref007","doi-asserted-by":"crossref","first-page":"479","DOI":"10.1113\/jphysiol.1993.sp019824","article-title":"Effect of vision and stance width on human body motion when standing: Implications for afferent control of lateral sway","volume":"469","author":"BL Day","year":"1993","journal-title":"J. Physiol"},{"key":"pone.0244993.ref008","doi-asserted-by":"crossref","first-page":"225","DOI":"10.1080\/00222895.1989.10735479","article-title":"Form and exploration of mechanical stability limits in erect stance","volume":"21","author":"G McCollum","year":"1989","journal-title":"J. Mot. Behav"},{"key":"pone.0244993.ref009","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1017\/S0140525X00020008","article-title":"The organization of human postural movements: A formal basis and experimental synthesis","volume":"8","author":"LM Nashner","year":"1985","journal-title":"Behav. Brain Sci"},{"key":"pone.0244993.ref010","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1016\/0966-6362(96)82849-9","article-title":"Human balance and posture control during standing and walking","volume":"3","author":"DA Winter","year":"1995","journal-title":"Gait Posture"},{"key":"pone.0244993.ref011","doi-asserted-by":"crossref","first-page":"1097","DOI":"10.1152\/jn.2002.88.3.1097","article-title":"Sensorimotor integration in human postural control","volume":"88","author":"RJ Peterka","year":"2002","journal-title":"J. Neurophysiol"},{"key":"pone.0244993.ref012","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":"ID Loram","year":"2002","journal-title":"J. Physiol"},{"key":"pone.0244993.ref013","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1007\/s00221-005-0256-y","article-title":"Multisensory control of human upright stance","volume":"171","author":"C Maurer","year":"2006","journal-title":"Exp. Brain Res"},{"key":"pone.0244993.ref014","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1016\/j.humov.2004.06.001","article-title":"Respiration and postural sway: detection of phase synchronizations and interactions","volume":"23","author":"M Schmid","year":"2004","journal-title":"Hum. Mov. Sci"},{"key":"pone.0244993.ref015","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1016\/j.mbs.2013.02.002","article-title":"Modeling human postural sway using an intermittent control and hemodynamic perturbations","volume":"245","author":"T Nomura","year":"2013","journal-title":"Math. Biosci"},{"key":"pone.0244993.ref016","doi-asserted-by":"crossref","first-page":"1622","DOI":"10.1152\/jn.1999.82.3.1622","article-title":"Can muscle stiffness alone stabilize upright standing?","volume":"82","author":"PG Morasso","year":"1999","journal-title":"J. Neurophysiol"},{"key":"pone.0244993.ref017","doi-asserted-by":"crossref","first-page":"410","DOI":"10.1016\/j.gaitpost.2004.05.005","article-title":"Direct measurement of ankle stiffness during quiet standing: Implications for control modelling and clinical application","volume":"21","author":"M Casadio","year":"2005","journal-title":"Gait Posture"},{"key":"pone.0244993.ref018","doi-asserted-by":"crossref","first-page":"661","DOI":"10.1113\/jphysiol.2007.140046","article-title":"The passive, human calf muscles in relation to standing: The non-linear decrease from short range to long range stiffness","volume":"584","author":"ID Loram","year":"2007","journal-title":"J. Physiol"},{"key":"pone.0244993.ref019","doi-asserted-by":"crossref","first-page":"781","DOI":"10.1113\/JP271137","article-title":"Sway-dependent changes in standing ankle stiffness caused by muscle thixotropy","volume":"594","author":"TE Sakanaka","year":"2016","journal-title":"J. Physiol"},{"key":"pone.0244993.ref020","doi-asserted-by":"crossref","first-page":"677","DOI":"10.1113\/jphysiol.2007.140053","article-title":"The passive, human calf muscles in relation to standing: The short range stiffness lies in the contractile component","volume":"584","author":"ID Loram","year":"2007","journal-title":"J. Physiol"},{"key":"pone.0244993.ref021","doi-asserted-by":"crossref","first-page":"1258","DOI":"10.1016\/j.jbiomech.2015.03.004","article-title":"Direct measurement of the intrinsic ankle stiffness during standing","volume":"48","author":"M Vlutters","year":"2015","journal-title":"J. Biomech. Elsevier"},{"key":"pone.0244993.ref022","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1016\/j.jbiomech.2019.01.009","article-title":"Ankle intrinsic stiffness changes with postural sway","volume":"85","author":"P Amiri","year":"2019","journal-title":"J. Biomech. Elsevier Ltd"},{"key":"pone.0244993.ref023","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1371\/journal.pone.0193850","article-title":"Intrinsic ankle stiffness during standing increases with ankle torque and passive stretch of the Achilles tendon","volume":"13","author":"TE Sakanaka","year":"2018","journal-title":"PLoS One"},{"key":"pone.0244993.ref024","doi-asserted-by":"crossref","first-page":"753","DOI":"10.1016\/0021-9290(82)90090-2","article-title":"Dynamics of human ankle stiffness: Variation with displacement amplitude","volume":"15","author":"RE Kearney","year":"1982","journal-title":"J. Biomech"},{"key":"pone.0244993.ref025","doi-asserted-by":"crossref","first-page":"463","DOI":"10.1007\/s002210000603","article-title":"Reciprocal angular acceleration of the ankle and hip joints during quiet standing in humans","volume":"136","author":"Y Aramaki","year":"2001","journal-title":"Exp. Brain Res"},{"key":"pone.0244993.ref026","unstructured":"Sakanaka TE. Causes of variation in intrinsic ankle stiffness and the consequences for standing. University of Birmingham; 2016."},{"key":"pone.0244993.ref027","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/0306-4522(95)00136-7","article-title":"Kinesthetic reference for human orthograde posture","volume":"68","author":"VS Gurfinkel","year":"1995","journal-title":"Neuroscience"},{"key":"pone.0244993.ref028","doi-asserted-by":"crossref","first-page":"166","DOI":"10.1115\/1.3426285","article-title":"Compliance of the human ankle joint","volume":"99","author":"GC Agarwal","year":"1977","journal-title":"J. Biomech. Eng"},{"key":"pone.0244993.ref029","doi-asserted-by":"crossref","first-page":"747","DOI":"10.1016\/0021-9290(82)90089-6","article-title":"Dynamics of human ankle stiffness: Variation with mean ankle torque","volume":"15","author":"IW Hunter","year":"1982","journal-title":"J. Biomech"},{"key":"pone.0244993.ref030","doi-asserted-by":"crossref","first-page":"1211","DOI":"10.1152\/jn.1998.80.3.1211","article-title":"Stiffness control of balance in quiet standing","volume":"80","author":"DA Winter","year":"1998","journal-title":"J. Neurophysiol"},{"key":"pone.0244993.ref031","doi-asserted-by":"crossref","first-page":"347","DOI":"10.1002\/ajpa.1330240318","article-title":"The influence of sex and age on postural sway of man","volume":"24","author":"FA Hellebrandt","year":"1939","journal-title":"Am. J. Phys. Anthropol"},{"key":"pone.0244993.ref032","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":"ID Loram","year":"2005","journal-title":"J. Physiol"},{"key":"pone.0244993.ref033","doi-asserted-by":"crossref","first-page":"48","DOI":"10.1016\/j.gaitpost.2003.11.006","article-title":"The assessment of body sway and the choice of the stability parameter(s)","volume":"21","author":"JA Raymakers","year":"2005","journal-title":"Gait Posture"},{"key":"pone.0244993.ref034","first-page":"183","article-title":"Revision of posturography based on force plate for balance evaluation","volume":"14","author":"M Duarte","year":"2010","journal-title":"Rev. Bras. Fisioter"},{"key":"pone.0244993.ref035","first-page":"290","article-title":"Clinical stabilometry standardization. Basic definitions\u2014Acquisition interval\u2014Sampling frequency","volume":"37","author":"F Scoppa","year":"2013","journal-title":"Gait Posture. Elsevier B.V."},{"key":"pone.0244993.ref036","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1037\/0033-2909.112.1.155","article-title":"A power primer","volume":"112","author":"J Cohen","year":"1992","journal-title":"Psychol. Bull"},{"key":"pone.0244993.ref037","first-page":"195","volume-title":"Fundam. Biomech. Equilibrium, Motion, Deform","author":"N \u00d6zkaya","year":"1999","edition":"2"},{"key":"pone.0244993.ref038","doi-asserted-by":"crossref","first-page":"1790","DOI":"10.1152\/japplphysiol.00788.2018","article-title":"Muscle thixotropy\u2013where are we now?","volume":"126","author":"M Lakie","year":"2019","journal-title":"J. Appl. Physiol"},{"key":"pone.0244993.ref039","doi-asserted-by":"crossref","first-page":"957","DOI":"10.33549\/physiolres.931238","article-title":"Age-related changes of human balance during quiet stance","volume":"8408","author":"D Abrahamov\u00e1","year":"2008","journal-title":"Physiol. Res"},{"key":"pone.0244993.ref040","doi-asserted-by":"crossref","first-page":"134","DOI":"10.1016\/0013-4694(84)90172-X","article-title":"Quantification of postural sway in normals and patients with cerebellar diseases","volume":"57","author":"HC Diener","year":"1984","journal-title":"Electroencephalogr. Clin. Neurophysiol"},{"key":"pone.0244993.ref041","first-page":"896","article-title":"Intrasession reliability of center of pressure measures of postural steadiness in healthy elderly people","volume":"85","author":"D Lafond","year":"2004","journal-title":"Arch. Phys. Med. Rehabil"},{"key":"pone.0244993.ref042","doi-asserted-by":"crossref","first-page":"347","DOI":"10.1016\/S0021-9290(96)00165-0","article-title":"Center of mass velocity-position predictions for balance control","volume":"30","author":"YC Pai","year":"1997","journal-title":"J. Biomech"},{"key":"pone.0244993.ref043","first-page":"126","article-title":"Stabilization of human posture during induced oscillations of the body","volume":"45","author":"HC Diener","year":"1982","journal-title":"Exp. Brain Res"},{"key":"pone.0244993.ref044","doi-asserted-by":"crossref","first-page":"937","DOI":"10.1016\/j.jelekin.2015.10.011","article-title":"A new method to assess passive and active ankle stiffness during quiet upright stance","volume":"25","author":"H Zhang","year":"2015","journal-title":"J. Electromyogr. Kinesiol"},{"key":"pone.0244993.ref045","first-page":"371","article-title":"The contribution of foot deformation to the changes of muscular length and angle in the ankle joint during standing in man","volume":"43","author":"VS Gurfinkel","year":"1994","journal-title":"Physiol. Res"}],"container-title":["PLOS ONE"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0244993","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,12,12]],"date-time":"2022-12-12T23:12:11Z","timestamp":1670886731000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0244993"}},"subtitle":[],"editor":[{"given":"Yury P.","family":"Ivanenko","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2021,1,22]]},"references-count":45,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2021,1,22]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0244993","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,1,22]]}}}