{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,9]],"date-time":"2026-01-09T13:22:58Z","timestamp":1767964978594,"version":"3.49.0"},"reference-count":49,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2023,2,17]],"date-time":"2023-02-17T00:00:00Z","timestamp":1676592000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003329","name":"Ministerio de Econom\u00eda y Competitividad, Gobierno de Espa\u00f1a","doi-asserted-by":"publisher","award":["DEP2013\u201344160\u2013P"],"award-info":[{"award-number":["DEP2013\u201344160\u2013P"]}],"id":[{"id":"10.13039\/501100003329","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Motor variability is a prominent feature of the human movement that, nowadays, can be easily measured through different sensors and analyzed using different types of variables, and it seems to be related to functional and adaptative motor behavior. It has been stated that motor variability is related to the system\u2019s flexibility needed to choose the right degrees of freedom (DoFs) to adapt to constant environmental changes. However, the potential relationship between motor variability and DoFs is unknown. The aim of this study was to analyze how motor variability, both the amount and structure, changes depending on the mechanical DoFs involved in the movement control. For this purpose, movement variability was assessed by a tracking sensor in five tasks with different DoFs, and the amount, using standard deviation, and the structure of variability, through fuzzy entropy and detrended fluctuation analysis, were also assessed. The results showed a higher amount of variability and a less predictable and more auto-correlated variability structure in the long-term when more mechanical DoFs are implied. The studies that analyze motor variability should consider the type of movement and the DoFs involved in the analyzed task since, as the findings have shown, both factors have a noticeable influence on the amount and the structure of motor variability.<\/jats:p>","DOI":"10.3390\/s23042256","type":"journal-article","created":{"date-parts":[[2023,2,17]],"date-time":"2023-02-17T01:59:24Z","timestamp":1676599164000},"page":"2256","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Human Motor Noise Assessed by Electromagnetic Sensors and Its Relationship with the Degrees of Freedom Involved in Movement Control"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7624-232X","authenticated-orcid":false,"given":"Carla","family":"Caballero","sequence":"first","affiliation":[{"name":"Sport Sciences Department, Miguel Hernandez University of Elche, 03202 Alicante, Spain"},{"name":"Alicante Institute for Health and Biomedical Research (ISABIAL), 03010 Alicante, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4314-9185","authenticated-orcid":false,"given":"David","family":"Barbado","sequence":"additional","affiliation":[{"name":"Sport Sciences Department, Miguel Hernandez University of Elche, 03202 Alicante, Spain"},{"name":"Alicante Institute for Health and Biomedical Research (ISABIAL), 03010 Alicante, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2520-892X","authenticated-orcid":false,"given":"Francisco J.","family":"Moreno","sequence":"additional","affiliation":[{"name":"Sport Sciences Department, Miguel Hernandez University of Elche, 03202 Alicante, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,2,17]]},"reference":[{"key":"ref_1","unstructured":"Zelaznik, H.N. (1996). Advances in Motor Learning and Control, Human Kinetics."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1295","DOI":"10.3389\/fpsyg.2020.01295","article-title":"Changes in Movement Coordination Associated with Skill Acquisition in Baseball Batting: Freezing\/Freeing Degrees of Freedom and Functional Variability","volume":"11","author":"Gray","year":"2020","journal-title":"Front. Psychol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"301","DOI":"10.1123\/mcj.10.4.301","article-title":"Functional Degrees of Freedom","volume":"10","author":"Li","year":"2006","journal-title":"Mot. Control"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"267","DOI":"10.2522\/ptj.20080130","article-title":"Movement Variability and the Use of Nonlinear Tools: Principles to Guide Physical Therapist Practice","volume":"89","author":"Harbourne","year":"2009","journal-title":"Phys. Ther."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"224","DOI":"10.1080\/14763140701322994","article-title":"Is movement variability important for sports biomechanists?","volume":"6","author":"Bartlett","year":"2007","journal-title":"Sport. Biomech."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"64","DOI":"10.1097\/JES.0b013e318259beb5","article-title":"Changing up the Routine Intervention-Induced Variability in Motor Learning","volume":"41","author":"Ranganathan","year":"2013","journal-title":"Exerc. Sport Sci. Rev."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"596","DOI":"10.1037\/xhp0000303","article-title":"Can the structure of motor variability predict learning rate?","volume":"43","author":"Barbado","year":"2017","journal-title":"J. Exp. Psychol. Hum. Percept. Perform."},{"key":"ref_8","unstructured":"Bernstein, N.A. (1967). The Co-Ordination and Regulation of Movements, Pergamon Press."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1016\/S0167-9457(02)00177-X","article-title":"Learning to coordinate redundant degrees of freedom in a dynamic balance task","volume":"22","author":"Ko","year":"2003","journal-title":"Hum. Mov. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"642","DOI":"10.1016\/j.humov.2009.11.002","article-title":"Stages in learning motor synergies: A view based on the equilibrium-point hypothesis","volume":"29","author":"Latash","year":"2010","journal-title":"Hum. Mov. Sci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"276","DOI":"10.1123\/mcj.11.3.276","article-title":"Toward a New Theory of Motor Synergies","volume":"11","author":"Latash","year":"2007","journal-title":"Mot. Control"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1097\/00003677-200201000-00006","article-title":"Motor Control Strategies Revealed in the Structure of Motor Variability","volume":"30","author":"Latash","year":"2002","journal-title":"Exerc. Sport Sci. Rev."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1007\/s00221-004-2137-1","article-title":"Joint angle variability in 3D bimanual pointing: Uncontrolled manifold analysis","volume":"163","author":"Domkin","year":"2005","journal-title":"Exp. Brain Res."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Glass, L., and Mackey, M. (1988). From Clocks to Chaos. The Rhythms of Life, Princeton University Press.","DOI":"10.1515\/9780691221793"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Tsonis, A.A. (1992). Chaos: From Theory to Applications, Plenum Press.","DOI":"10.1007\/978-1-4615-3360-3"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"882","DOI":"10.1038\/nm0898-882","article-title":"Self-organization, complexity and chaos: The new biology for medicine","volume":"4","author":"Coffey","year":"1998","journal-title":"Nat. Med."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"312","DOI":"10.1038\/nn.3616","article-title":"Temporal structure of motor variability is dynamically regulated and predicts motor learning ability","volume":"17","author":"Wu","year":"2014","journal-title":"Nat. Neurosci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"869","DOI":"10.1016\/j.humov.2011.06.002","article-title":"Human movement variability, nonlinear dynamics, and pathology: Is there a connection?","volume":"30","author":"Stergiou","year":"2011","journal-title":"Hum. Mov. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1080\/00222890009601366","article-title":"Variability and Noise in Continuous Force Production","volume":"32","author":"Slifkin","year":"2010","journal-title":"J. Mot. Behav."},{"key":"ref_20","unstructured":"Stergiou, N. (2004). Innovative Analyses of Human Movement, Human Kinetics."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1080\/00222890209601934","article-title":"Variability and determinism in motor behavior","volume":"34","author":"Riley","year":"2002","journal-title":"J. Mot. Behav."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1289","DOI":"10.1152\/jn.00426.2021","article-title":"Postural control strategies are revealed by the complexity of fractional components of COP","volume":"127","author":"Moreno","year":"2022","journal-title":"J. Neurophysiol."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Rhea, C.K., Silver, T.A., Hong, S.L., Ryu, J.H., Studenka, B.E., Hughes, C.M.L., and Haddad, J.M. (2011). Noise and Complexity in Human Postural Control: Interpreting the Different Estimations of Entropy. PLoS ONE, 6.","DOI":"10.1371\/journal.pone.0017696"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1109\/TNSRE.2007.897025","article-title":"Characterization of surface EMG signal based on fuzzy entropy","volume":"15","author":"Chen","year":"2007","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"82","DOI":"10.1063\/1.166141","article-title":"Quantification of scaling exponents and crossover phenomena in nonstationary heartbeat time series","volume":"5","author":"Peng","year":"1995","journal-title":"Chaos Interdiscip. J. Nonlinear Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"789","DOI":"10.1152\/ajpregu.00069.2002","article-title":"Sample entropy analysis of neonatal heart rate variability","volume":"283","author":"Lake","year":"2002","journal-title":"Am. J. Physiol.\u2014Regul. Integr. Comp. Physiol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2297","DOI":"10.1073\/pnas.88.6.2297","article-title":"Approximate entropy as a measure of system complexity","volume":"88","author":"Pincus","year":"1991","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"349","DOI":"10.1007\/s10439-012-0668-3","article-title":"The appropriate use of approximate entropy and sample entropy with short data sets","volume":"41","author":"Yentes","year":"2013","journal-title":"Ann. Biomed. Eng."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"256","DOI":"10.1007\/s00221-006-0441-7","article-title":"Dynamical structure of center-of-pressure trajectories in patients recovering from stroke","volume":"174","author":"Roerdink","year":"2006","journal-title":"Exp. Brain Res."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"200","DOI":"10.1097\/JES.0b013e3181877d71","article-title":"The structure of variability in human walking and running is speed-dependent","volume":"36","author":"Jordan","year":"2008","journal-title":"Exerc. Sport Sci."},{"key":"ref_31","first-page":"15","article-title":"Effect of nonstationarities on detrended fluctuation analysis","volume":"65","author":"Chen","year":"2002","journal-title":"Phys. Rev. E\u2014Stat. Phys. Plasmas Fluids Relat. Interdiscip. Top."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"245","DOI":"10.2165\/00007256-200333040-00001","article-title":"Movement systems as dynamical systems: The functional role of variability and its implications for sports medicine","volume":"33","author":"Davids","year":"2003","journal-title":"Sport. Med."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Zhou, J., Manor, B., Liu, D., Hu, K., Zhang, J., and Fang, J. (2013). The Complexity of Standing Postural Control in Older Adults: A Modified Detrended Fluctuation Analysis Based upon the Empirical Mode Decomposition Algorithm. PLoS ONE, 8.","DOI":"10.1371\/journal.pone.0062585"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"120","DOI":"10.1097\/01.NPT.0000281949.48193.d9","article-title":"Optimal movement variability: A new theoretical perspective for neurologic physical therapy","volume":"30","author":"Stergiou","year":"2006","journal-title":"J. Neurol. Phys. Ther."},{"key":"ref_35","first-page":"629","article-title":"Living in the Pink: Intentionality, Wellbeing, and Complexity","volume":"10","author":"Kloos","year":"2011","journal-title":"Philos. Complex Syst."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1007\/978-3-030-31605-1_32","article-title":"Constraints on Joint Degrees of Freedom Affect Human Postural Dynamics: A Pilot Study","volume":"Volume 11717","author":"Kodama","year":"2019","journal-title":"New Frontiers in Artificial Intelligence"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Urb\u00e1n, T., Caballero, C., Barbado, D., and Moreno, F.J. (2019). Do intentionality constraints shape the relationship between motor variability and performance?. PLoS ONE, 14.","DOI":"10.1371\/journal.pone.0214237"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1007\/s10339-015-0652-6","article-title":"Interaction between intention and environmental constraints on the fractal dynamics of human performance","volume":"16","author":"Washburn","year":"2015","journal-title":"Cogn. Process."},{"key":"ref_39","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":"Ashner","year":"1985","journal-title":"Behav. Brain Sci."},{"key":"ref_40","first-page":"61","article-title":"Non-linear tools and methodological concerns measuring human movement variability: An overview","volume":"32","author":"Caballero","year":"2014","journal-title":"Eur. J. Hum. Mov."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s00221-007-0905-4","article-title":"Regularity of center-of-pressure trajectories depends on the amount of attention invested in postural control","volume":"181","author":"Donker","year":"2007","journal-title":"Exp. Brain Res."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1215","DOI":"10.1007\/s00779-019-01268-3","article-title":"Grip strength forecast and rehabilitative guidance based on adaptive neural fuzzy inference system using sEMG","volume":"26","author":"Jiang","year":"2022","journal-title":"Pers. Ubiquitous Comput."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1349","DOI":"10.1080\/17461391.2019.1599450","article-title":"Fatigue reduces the complexity of knee extensor torque during fatiguing sustained isometric contractions","volume":"19","author":"Pethick","year":"2019","journal-title":"Eur. J. Sport Sci."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"109583","DOI":"10.1016\/j.jbiomech.2019.109583","article-title":"Hip extensor fatigue alters hip and knee coupling dynamics during single-limb step-downs: A randomized controlled trial","volume":"100","author":"Hollman","year":"2020","journal-title":"J. Biomech."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"573","DOI":"10.1007\/s00221-008-1326-8","article-title":"The effects of neuromuscular fatigue on task performance during repetitive goal-directed movements","volume":"187","author":"Gates","year":"2008","journal-title":"Exp. Brain Res."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"94","DOI":"10.1016\/j.jelekin.2017.02.003","article-title":"The effect of muscle fatigue and low back pain on lumbar movement variability and complexity","volume":"33","author":"Bauer","year":"2017","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"3939","DOI":"10.1007\/s00221-014-4020-z","article-title":"Effects of local and widespread muscle fatigue on movement timing","volume":"232","author":"Cowley","year":"2014","journal-title":"Exp. Brain Res."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1786","DOI":"10.1152\/japplphysiol.00390.2010","article-title":"Physiological complexity and system adaptability: Evidence from postural control dynamics of older adults","volume":"109","author":"Manor","year":"2010","journal-title":"J. Appl. Physiol."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"737","DOI":"10.1111\/sms.12181","article-title":"Neuromechanical coupling in the regulation of muscle tone and joint stiffness","volume":"24","author":"Needle","year":"2014","journal-title":"Scand. J. Med. Sci. Sport."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/4\/2256\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T18:39:05Z","timestamp":1760121545000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/4\/2256"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,2,17]]},"references-count":49,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2023,2]]}},"alternative-id":["s23042256"],"URL":"https:\/\/doi.org\/10.3390\/s23042256","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,2,17]]}}}