{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,21]],"date-time":"2026-01-21T11:18:01Z","timestamp":1768994281286,"version":"3.49.0"},"reference-count":27,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T00:00:00Z","timestamp":1768867200000},"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>Background: Neuromuscular electrical stimulation (NMES) is an effective exogenous neuromuscular activation method widely used in sports training and rehabilitation. However, existing research primarily focuses on land-based sports or single-joint movements, with limited in-depth exploration of its intervention effects and underlying neuromuscular control mechanisms for complex, multi-joint coordinated aquatic activities like breaststroke swimming. This study aimed to investigate the effects of NMES combined with traditional resistance training on neuromuscular function during sport-specific technical movements in breaststroke athletes. Methods: A randomized controlled trial was conducted with 30 national-level or above breaststroke athletes assigned to either an experimental group (NMES combined with traditional squat resistance training) or a control group (traditional squat resistance training only) for an 8-week intervention. A specialized fully waterproof wireless electromyography (EMG) sensor system (Mini Wave Infinity Waterproof) was used to synchronously collect surface EMG signals from 10 lower limb and trunk muscles during actual swimming, combined with high-speed video for movement phase segmentation. Changes in lower limb explosive power were assessed using a force plate. Non-negative matrix factorization (NMF) muscle synergy analysis was employed to compare changes in muscle activation levels (iEMG, RMS) and synergy patterns (spatial structure, temporal activation coefficients) across different phases of the breaststroke kick before and after the intervention. Results: Compared to the control group, the experimental group demonstrated significantly greater improvements in single-leg jump height (\u0394 = 0.06 m vs. 0.03 m) and double-leg jump height (\u0394 = 0.07 m vs. 0.03 m). Time-domain EMG analysis revealed that the experimental group showed more significant increases in iEMG values for the adductor longus, adductor magnus, and gastrocnemius lateralis during the leg-retraction and leg-flipping phases (p &lt; 0.05). During the pedal-clamp phase, the experimental group exhibited significantly reduced activation of the tibialis anterior alongside enhanced activation of the gastrocnemius. Muscle synergy analysis indicated that post-intervention, the experimental group showed a significant increase in the weighting of the vastus medialis and biceps femoris within synergy module 4 (SYN4, related to propulsion and posture) (p &lt; 0.05), a significant increase in rectus abdominis weighting within synergy module 3 (SYN3, p = 0.033), and a significant shortening of the activation duration of synergy module 2 (SYN2, p = 0.007). Conclusions: NMES combined with traditional resistance training significantly enhances land-based explosive power in breaststroke athletes and specifically optimizes neuromuscular control strategies during the underwater breaststroke kick. This optimization is characterized by improved activation efficiency of key muscle groups, more economical coordination of antagonist muscles, and adaptive remodeling of inter-muscle synergy patterns in specific movement phases. This study provides novel evidence supporting the application of NMES in swimming-specific strength training, spanning from macroscopic performance to microscopic neural control.<\/jats:p>","DOI":"10.3390\/s26020671","type":"journal-article","created":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T08:36:33Z","timestamp":1768898193000},"page":"671","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Effects of NMES Combined with Resistance Training Using Underwater Surface EMG Sensors on Neuromuscular Activation of Breaststroke Technique in Breaststroke Athletes: Analysis of Non-Negative Matrix Muscle Synergy"],"prefix":"10.3390","volume":"26","author":[{"given":"Yaohao","family":"Guo","sequence":"first","affiliation":[{"name":"School of Mathematical Sciences, Fudan University, Shanghai 200433, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tingyan","family":"Gao","sequence":"additional","affiliation":[{"name":"Faculty of Physical Education, Fudan University, Shanghai 200433, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bin","family":"Kong","sequence":"additional","affiliation":[{"name":"Faculty of Physical Education, Fudan University, Shanghai 200433, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"103333","DOI":"10.1016\/j.iccn.2022.103333","article-title":"Effectiveness of physical exercise and neuromuscular electrical stimulation interventions for preventing and treating intensive care unit-acquired weakness: A systematic review of randomized controlled trials","volume":"74","year":"2023","journal-title":"Intensive Crit. Care Nurs."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1249\/MSS.0000000000001462","article-title":"Neuromuscular Electrical Stimulation Superimposed on Movement Early after ACL Surgery","volume":"50","author":"Labanca","year":"2018","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1011","DOI":"10.1016\/j.apmr.2017.12.019","article-title":"Effectiveness of Neuromuscular Electrical Stimulation on Lower Limbs of Patients With Hemiplegia After Chronic Stroke: A Systematic Review","volume":"99","author":"Hong","year":"2018","journal-title":"Arch. Phys. Med. Rehabil."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"512","DOI":"10.1136\/bjsports-2018-100310","article-title":"How should clinicians rehabilitate patients after ACL reconstruction? A systematic review of clinical practice guidelines (CPGs) with a focus on quality appraisal (AGREE II)","volume":"54","author":"Andrade","year":"2020","journal-title":"Br. J. Sports Med."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1940","DOI":"10.1080\/17461391.2022.2119434","article-title":"Ultrasound and surface electromyography analyses reveal an intensity dependent active stretch-shortening cycle of the vastus lateralis muscle during ergometer rowing","volume":"23","author":"Held","year":"2023","journal-title":"Eur. J. Sport Sci."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1080\/17461391.2015.1022605","article-title":"Influence of bench angle on upper extremity muscular activation during bench press exercise","volume":"16","author":"Lauver","year":"2016","journal-title":"Eur. J. Sport Sci."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Campanini, I., Merlo, A., Disselhorst-Klug, C., Mesin, L., Muceli, S., and Merletti, R. (2022). Fundamental Concepts of Bipolar and High-Density Surface EMG Understanding and Teaching for Clinical, Occupational, and Sport Applications: Origin, Detection, and Main Errors. Sensors, 22.","DOI":"10.3390\/s22114150"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Grzejszczak, T., Roksela, A., Po\u015bwiata, A., Siemianowicz, A., Kie\u0142bo\u0144, A., and Mikulski, M. (2024). Surface Electromyography Data Analysis for Evaluation of Physical Exercise Habits between Athletes and Non-Athletes during Indoor Rowing. Sensors, 24.","DOI":"10.3390\/s24061964"},{"key":"ref_9","first-page":"1","article-title":"Underwater Surface Electromyography for the Evaluation of Muscle Activity during Front Crawl Swimming: A Systematic Review","volume":"22","author":"Kwok","year":"2023","journal-title":"J. Sports Sci. Med."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Tse, D.H., Kwok, W.Y., and So, B.C. (2022). Investigation of Underwater Shoulder Muscle Activity during Manikin-Carrying in Young Elite Lifesaving Athletes. Sensors, 22.","DOI":"10.3390\/s22062143"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"30322","DOI":"10.1021\/acsnano.5c08540","article-title":"Robust Skin-Conformal Nano-Electrodes for Sustainable Health and Performance Monitoring","volume":"19","author":"Kim","year":"2025","journal-title":"ACS Nano"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Bongiorno, G., Sisti, G., Biancuzzi, H., Dal Mas, F., Minisini, F.G., and Miceli, L. (2024). Training in Roller Speed Skating: Proposal of Surface Electromyography and Kinematics Data for Educational Purposes in Junior and Senior Athletes. Sensors, 24.","DOI":"10.3390\/s24237617"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1186\/s12984-022-01061-z","article-title":"Fused ultrasound and electromyography-driven neuromuscular model to improve plantarflexion moment prediction across walking speeds","volume":"19","author":"Zhang","year":"2022","journal-title":"J. Neuroeng. Rehabil."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Casado-Hern\u00e1ndez, I., Becerro-de-Bengoa-Vallejo, R., Losa-Iglesias, M.E., Mart\u00ednez-Jim\u00e9nez, E.M., L\u00f3pez-L\u00f3pez, D., Mazoteras-Pardo, V., Romero-Morales, C., and Calvo-Lobo, C. (2020). Influence of Different Hardness Custom Foot Insoles in the Electromyography Activity Patterns of the Thigh and Hip Muscles during Motorcycling Sport: A Crossover Study. Sensors, 20.","DOI":"10.3390\/s20061551"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1023","DOI":"10.1038\/s41597-025-05391-0","article-title":"Comprehensive human locomotion and electromyography dataset: Gait120","volume":"12","author":"Boo","year":"2025","journal-title":"Sci. Data"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"046051","DOI":"10.1088\/1741-2552\/ac89b4","article-title":"Non-invasive dual attention TCN for electromyography and motion data fusion in lower limb ambulation prediction","volume":"19","author":"Zhou","year":"2022","journal-title":"J. Neural Eng."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1016\/j.humov.2018.04.003","article-title":"Magnitude and variability of gait characteristics when walking on an irregular surface at different speeds","volume":"59","author":"Blair","year":"2018","journal-title":"Hum. Mov. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"102830","DOI":"10.1016\/j.jelekin.2023.102830","article-title":"Trunk extensor muscle endurance and its relationship to action potential conduction velocity and spectral parameters estimated using high-density electromyography","volume":"73","author":"Brouwer","year":"2023","journal-title":"J. Electromyogr. Kinesiol. Off. J. Int. Soc. Electrophysiol. Kinesiol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1186\/s12984-025-01778-7","article-title":"Impact of Neural network-quantified musical groove on cyclists\u2019 joint coordination and muscle synergy: A repeated measures study","volume":"22","author":"Li","year":"2025","journal-title":"J. Neuroeng. Rehabil."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"6583","DOI":"10.1007\/s11357-025-01811-6","article-title":"Dual-channel mechanism of groove music fused with Tai Chi to improve cognitive-emotional abilities in older adults based on a coupled fNIRS-EMG analysis: A randomized controlled study","volume":"47","author":"Li","year":"2025","journal-title":"GeroScience"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1019","DOI":"10.55730\/1300-0144.5667","article-title":"Current developments in surface electromyography","volume":"53","author":"Alcan","year":"2023","journal-title":"Turk. J. Med. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1230","DOI":"10.1109\/TNSRE.2023.3242911","article-title":"Surface Electromyography-Based Analysis of the Lower Limb Muscle Network and Muscle Synergies at Various Gait Speeds","volume":"31","author":"Liang","year":"2023","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng. Publ. IEEE Eng. Med. Biol. Soc."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"056006","DOI":"10.1088\/1741-2552\/ad6fd5","article-title":"Characterizing upper limb motor dysfunction with temporal and spatial distribution of muscle synergy extracted from high-density surface electromyography","volume":"21","author":"Zhang","year":"2024","journal-title":"J. Neural Eng."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Geng, Y., Chen, Z., Zhao, Y., Cheung, V.C.K., and Li, G. (2022). Applying muscle synergy analysis to forearm high-density electromyography of healthy people. Front. Neurosci., 16.","DOI":"10.3389\/fnins.2022.1067925"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1062","DOI":"10.1109\/TBME.2022.3208381","article-title":"Joint Kinematics, Kinetics and Muscle Synergy Patterns During Transitions Between Locomotion Modes","volume":"70","author":"Liu","year":"2023","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Tajik, R., Dhahbi, W., Fadaei, H., and Mimar, R. (2025). Muscle synergy analysis during badminton forehand overhead smash: Integrating electromyography and musculoskeletal modeling. Front. Sports Act. Living, 7.","DOI":"10.3389\/fspor.2025.1596670"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"114","DOI":"10.1016\/j.gaitpost.2023.03.010","article-title":"Characteristics of muscle synergy and anticipatory synergy adjustments strategy when cutting in different angles","volume":"107","author":"Pan","year":"2024","journal-title":"Gait Posture"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/2\/671\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T08:39:31Z","timestamp":1768898371000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/2\/671"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,20]]},"references-count":27,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2026,1]]}},"alternative-id":["s26020671"],"URL":"https:\/\/doi.org\/10.3390\/s26020671","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,20]]}}}