{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T05:06:03Z","timestamp":1787029563267,"version":"build-2736575974"},"reference-count":37,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2019,4,25]],"date-time":"2019-04-25T00:00:00Z","timestamp":1556150400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Lower leg muscle activity contributes to body control; thus, monitoring lower leg muscle activity is beneficial to understand the body condition and prevent accidents such as falls. Amplitude features such as the mean absolute values of electromyography (EMG) are used widely for monitoring muscle activity. Garment-type EMG measurement systems use electrodes and they enable us to monitor muscle activity in daily life without any specific knowledge and the installation for electrode placement. However, garment-type measurement systems require a high compression area around the electrodes to prevent electrode displacement. This makes it difficult for users to wear such measurement systems. A less restraining wearable system, wherein the electrodes are placed around the ankle, is realized for target muscles widely distributed around the shank. The signals obtained from around the ankle are propagated biosignals from several muscles, and are referred to as distal EMG signals. Our objective is to develop a sock-type wearable sensor for estimating lower leg muscle activity using distal EMG signals. We propose a signal processing method based on multiple bandpass filters from the perspectives of noise separation and feature augmentation. We conducted an experiment for designing the hardware configuration, and three other experiments for evaluating the estimation accuracy and dependability of muscle activity analysis. Compared to the baseline based on a 20-500 Hz bandpass filter, the results indicated that the proposed system estimates muscle activity with higher accuracy. Experimental results suggest that lower leg muscle activity can be estimated using distal EMG signals.<\/jats:p>","DOI":"10.3390\/s19081954","type":"journal-article","created":{"date-parts":[[2019,4,25]],"date-time":"2019-04-25T10:44:06Z","timestamp":1556189046000},"page":"1954","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":30,"title":["Sock-Type Wearable Sensor for Estimating Lower Leg Muscle Activity Using Distal EMG Signals"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4895-7333","authenticated-orcid":false,"given":"Takashi","family":"Isezaki","sequence":"first","affiliation":[{"name":"NTT Service Evolution Laboratories, Nippon Telegraph and Telephone Corporation, 1-1 Hikarinooka, Yokosuka, Kanagawa 239-0847, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hideki","family":"Kadone","sequence":"additional","affiliation":[{"name":"Center for Cybernics Research, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arinobu","family":"Niijima","sequence":"additional","affiliation":[{"name":"NTT Plala Inc., TOC Ariake East Tower 14F, 3-5-7 Ariake, Koto-ku, Tokyo 135-0063, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryosuke","family":"Aoki","sequence":"additional","affiliation":[{"name":"NTT Service Evolution Laboratories, Nippon Telegraph and Telephone Corporation, 1-1 Hikarinooka, Yokosuka, Kanagawa 239-0847, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tomoki","family":"Watanabe","sequence":"additional","affiliation":[{"name":"NTT Service Evolution Laboratories, Nippon Telegraph and Telephone Corporation, 1-1 Hikarinooka, Yokosuka, Kanagawa 239-0847, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Toshitaka","family":"Kimura","sequence":"additional","affiliation":[{"name":"NTT Communication Science Laboratories, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1736-5404","authenticated-orcid":false,"given":"Kenji","family":"Suzuki","sequence":"additional","affiliation":[{"name":"Faculty of Engineering, Information and Systems, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,4,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"278","DOI":"10.1080\/165019702760390374","article-title":"Ankle dorsiflexion delay can predict falls in the elderly","volume":"34","author":"Kemoun","year":"2002","journal-title":"J. Rehabil. Med."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Bounyong, S., Adachi, S., Ozawa, J., Yamada, Y., Kimura, M., Watanabe, Y., and Yokoyama, K. (2016, January 7\u201311). Fall risk estimation based on co-contraction of lower limb during walking. Proceedings of the 2016 IEEE International Conference on Consumer Electronics, Las Vegas, NV, USA.","DOI":"10.1109\/ICCE.2016.7430634"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Talbot, L.A., Musiol, R.J., Witham, E.K., and Metter, E.J. (2005). Falls in young, middle-aged and older community dwelling adults: Perceived cause, environmental factors and injury. BMC Public Health, 5.","DOI":"10.1186\/1471-2458-5-86"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/j.gaitpost.2004.11.009","article-title":"Mechanisms underlying age-related differences in ability to recover balance with the ankle strategy","volume":"23","author":"Mackey","year":"2006","journal-title":"Gait Posture"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1650","DOI":"10.1093\/brain\/awh189","article-title":"Electromyographic profiles of gait prior to onset of freezing episodes in patients with Parkinson\u2019s disease","volume":"127","author":"Nieuwboer","year":"2004","journal-title":"Brain"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1589\/jpts.27.139","article-title":"The effects of balance training and ankle training on the gait of elderly people who have fallen","volume":"27","author":"Choi","year":"2015","journal-title":"J. Phys. Ther. Sci."},{"key":"ref_7","unstructured":"Lieber, R.L. (1992). Skeletal Muscle Structure and Function: Implications for Rehabilitation and Sports Medicine, Williams & Wilkins."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Saponas, T.S., Tan, D.S., Morris, D., and Balakrishnan, R. (2008, January 5\u201310). Demonstrating the feasibility of using forearm electromyography for muscle-computer interfaces. Proceedings of the Twentysixth Annual CHI Conference on Human Factors in Computing Systems CHI 08, Florence, Italy.","DOI":"10.1145\/1357054.1357138"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Verikas, A., Vaiciukynas, E., Gelzinis, A., Parker, J., and Charlotte Olsson, M. (2016). Electromyographic patterns during golf swing: Activation sequence profiling and prediction of shot effectiveness. Sensors, 16.","DOI":"10.3390\/s16040592"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"608","DOI":"10.1109\/TNSRE.2016.2585962","article-title":"A Method for Locomotion Mode Identification Using Muscle Synergies","volume":"25","author":"Afzal","year":"2017","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Tsukada, S., Nakashima, H., and Torimitsu, K. (2012). Conductive polymer combined silk fiber bundle for bioelectrical signal recording. PLoS ONE, 7.","DOI":"10.1371\/journal.pone.0033689"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Myers, A., Du, L., Huang, H., and Zhu, Y. (2014, January 26\u201330). Novel wearable EMG sensors based on nanowire technology. Proceedings of the 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Chicago, IL, USA.","DOI":"10.1109\/EMBC.2014.6943928"},{"key":"ref_13","unstructured":"(2019, February 20). Conductive Fabric\u201412x13 Ripstop\u2014DEV-10056\u2014SparkFun Electronics. Available online: https:\/\/www.sparkfun.com\/products\/retired\/10055."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1016\/j.jneumeth.2003.10.014","article-title":"A method for positioning electrodes during surface EMG recordings in lower limb muscles","volume":"134","author":"Rainoldi","year":"2004","journal-title":"J. Neurosci. Methods"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"567","DOI":"10.1111\/j.1469-8986.1986.tb00676.x","article-title":"Guidelines for Human Electromyographic Research","volume":"23","author":"Fridlund","year":"1986","journal-title":"Psychophysiology"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1109\/TAFFC.2014.2313557","article-title":"Design of a wearable device for reading positive expressions from facial EMG signals","volume":"5","author":"Gruebler","year":"2014","journal-title":"IEEE Trans. Affect. Comput."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Takano, Y., and Suzuki, K. (2014, January 17\u201320). Affective communication aid using wearable devices based on biosignals. Proceedings of the 2014 Conference on Interaction Design and Children\u2014IDC \u201914, Aarhus, Denmark.","DOI":"10.1145\/2593968.2610455"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1016\/j.infbeh.2005.10.001","article-title":"Early changes in muscle activation patterns of toddlers during walking","volume":"29","author":"Chang","year":"2006","journal-title":"Infant Behav. Dev."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1016\/S0966-6362(03)00099-7","article-title":"Effect of gait cycle selection on EMG analysis during walking in adults and children with gait pathology","volume":"20","author":"Burridge","year":"2004","journal-title":"Gait Posture"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1123\/jab.13.2.135","article-title":"The use of surface electromyography in biomechanics","volume":"13","year":"1997","journal-title":"J. Appl. Biomech."},{"key":"ref_21","unstructured":"Kawamoto, H., Lee, S., Kanbe, S., and Sankai, Y. (2004, January 8). Power assist method for HAL-3 using EMG-based feedback controller. Proceedings of the SMC\u201903 Conference Proceedings, 2003 IEEE International Conference on Systems, Man and Cybernetics. Conference Theme\u2014System Security and Assurance (Cat. No.03CH37483), Washington, DC, USA."},{"key":"ref_22","unstructured":"Clancy, E., and Hogan, N. (November, January 30). Theoretic and experimental comparison of root-mean-square and mean-absolute-value electromyogram amplitude detectors. Proceedings of the 19th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, \u2018Magnificent Milestones and Emerging Opportunities in Medical Engineering\u2019 (Cat. No.97CH36136), Chicago, IL, USA."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1183","DOI":"10.1177\/0363546504274147","article-title":"Peroneus Longus Muscle Activation Pattern during Gait Cycle in Athletes Affected by Functional Ankle Instability","volume":"33","author":"Santilli","year":"2005","journal-title":"Am. J. Sports Med."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Isezaki, T., Watanabe, T., Yamada, T., Kadone, H., and Suzuki, K. (2017, January 11\u201315). Estimating the lower leg muscle activity from distal biosignals around the ankles. Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, Seogwipo, Korea.","DOI":"10.1109\/EMBC.2017.8037758"},{"key":"ref_25","unstructured":"Basmajian, J.V., and De Luca, C.J. (1985). Muscles Alive: Their Functions Revealed by Electromyography, Williams & Wilkins."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1016\/j.jelekin.2013.11.002","article-title":"Frequency analysis of lower extremity electromyography signals for the quantitative diagnosis of dystonia","volume":"24","author":"Go","year":"2014","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1573","DOI":"10.1016\/j.jbiomech.2010.01.027","article-title":"Filtering the surface EMG signal: Movement artifact and baseline noise contamination","volume":"43","author":"Kuznetsov","year":"2010","journal-title":"J. Biomech."},{"key":"ref_28","unstructured":"Bishop, C.M. (2006). Pattern Recognition and Machine Learning, Springer."},{"key":"ref_29","unstructured":"Garner, S.R. (1995, January 18\u201321). WEKA: The Waikato Environment for Knowledge Analysis. Proceedings of the New Zealand Computer Science Research Students Conference, Hamilton, New Zealand."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Hastie, T., Tibshirani, R., and Friedman, J. (2001). The Elements of Statistical Learning, Springer.","DOI":"10.1007\/978-0-387-21606-5"},{"key":"ref_31","unstructured":"Hewson, D., Duchene, J., and Hogrel, J.Y. (2001, January 25\u201328). Changes in impedance at the electrode-skin interface of surface EMG electrodes during long-term EMG recordings. Proceedings of the 2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Istanbul, Turkey."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Chen, T., and Guestrin, C. (2016). XGBoost: Reliable Large-scale Tree Boosting System. arXiv.","DOI":"10.1145\/2939672.2939785"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"384","DOI":"10.1016\/j.jelekin.2004.10.003","article-title":"Quantification of the dynamic properties of EMG patterns during gait","volume":"15","author":"Ricamato","year":"2005","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"857","DOI":"10.1016\/j.jelekin.2007.03.002","article-title":"Intra-session repeatability of lower limb muscles activation pattern during pedaling","volume":"18","author":"Dorel","year":"2008","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_35","first-page":"620","article-title":"Determination of an Optimal Threshold Value for Muscle Activity Detection in EMG Analysis","volume":"9","author":"Celik","year":"2010","journal-title":"J. Sports Sci. Med."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"46","DOI":"10.2186\/prp.3.46","article-title":"Determination of Electromyogram Biofeedback Threshold for Patients with Clenching Behavior","volume":"3","author":"Gohdo","year":"2004","journal-title":"Prosthodont. Res. Pract."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"98","DOI":"10.2174\/1874943701003010098","article-title":"Technical Aspects of Surface Electromyography for Clinicians","volume":"3","author":"Merlo","year":"2010","journal-title":"Open Rehabil. J."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/8\/1954\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:47:12Z","timestamp":1760186832000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/8\/1954"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,4,25]]},"references-count":37,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2019,4]]}},"alternative-id":["s19081954"],"URL":"https:\/\/doi.org\/10.3390\/s19081954","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,4,25]]}}}