{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T19:43:11Z","timestamp":1787773391420,"version":"build-2784847793"},"reference-count":43,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2021,3,3]],"date-time":"2021-03-03T00:00:00Z","timestamp":1614729600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>The goal of our study was to examine the muscle activity of the shoulder girdle after isokinetic fatigue, which may simulate muscle activities commonly occurring during specific sport-related activities in recreational overhead asymptomatic athletes. We hypothesized that exercise-induced fatigue, reported after isokinetic protocols, may cause a decrease in the median frequency (MF) of the upper trapezius (UT), infraspinatus (IS), and deltoid muscles. Twenty-four male overhead volleyball (n = 8), handball (n = 8), and tennis (n = 8) athletes participated in this study. All subjects were without shoulder injury history. The surface electromyography (SEMG) was collected on the right (dominant) side of the shoulder girdle muscles in the following order: UT, IS and anterior (DA), and posterior deltoideus (DP). The fatigue protocol consisted of three sets of 32 maximum isokinetic concentric contractions while performing shoulder internal and external rotation at an isokinetic speed of 120 o\/s. The resultant difference in median frequency (\u0394MF) values consistently dropped after the fatiguing tasks across all recorded muscles, in terms of the initial MF (MFINI = 65.1 \u00b1 1.1 Hz) and final MF (MFFIN = 57.9 \u00b1 0.9 Hz), and the main effect of time was significant (F(1,22) = 43.15, p &lt; 0.001). MF values decreased mostly for IS (\u0394MFIS = \u22129.9 \u00b1 1.6 Hz) and DP (\u0394MFPD = \u22129.5 \u00b1 1.9 Hz) muscles, while DA and UT showed smaller changes (\u0394MFDA = \u22126.9 \u00b1 1.5 Hz) and (\u0394MFUT = \u22123.2 \u00b1 1.3 Hz). The results of our study show a meaningful contribution in determining increased fatigue of the shoulder girdle muscles during repeated isokinetic internal-external rotation protocols. We have also demonstrated a significant decrease in MF in all examined muscles, especially IS and DA.<\/jats:p>","DOI":"10.3390\/ijerph18052516","type":"journal-article","created":{"date-parts":[[2021,3,3]],"date-time":"2021-03-03T20:33:57Z","timestamp":1614803637000},"page":"2516","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Electromyographic Evaluation of the Shoulder Muscle after a Fatiguing Isokinetic Protocol in Recreational Overhead Athletes"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8182-2975","authenticated-orcid":false,"given":"Sebastian","family":"Klich","sequence":"first","affiliation":[{"name":"Department of Paralympic Sport, University School of Physical Education in Wroc\u0142aw, 51-617 Wroc\u0142aw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7840-3799","authenticated-orcid":false,"given":"Adam","family":"Kawczy\u0144ski","sequence":"additional","affiliation":[{"name":"Department of Paralympic Sport, University School of Physical Education in Wroc\u0142aw, 51-617 Wroc\u0142aw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bogdan","family":"Pietraszewski","sequence":"additional","affiliation":[{"name":"Department of Biomechanics, University School of Physical Education in Wroc\u0142aw, 51-617 Wroc\u0142aw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matteo","family":"Zago","sequence":"additional","affiliation":[{"name":"Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1483-5028","authenticated-orcid":false,"given":"Aiguo","family":"Chen","sequence":"additional","affiliation":[{"name":"College of Physical Education, Yangzhou University, Yangzhou 225009, China"},{"name":"Chinese\u2014Polish Laboratory on Sport and Brain Science, Yangzhou University, Yangzhou 225009, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ma\u0142gorzata","family":"Smoter","sequence":"additional","affiliation":[{"name":"Gda\u0144sk Academy of Physical Education and Sport, 80-001 Gda\u0144sk, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hamidollah","family":"Hassanlouei","sequence":"additional","affiliation":[{"name":"Department of Cognitive and Behavioral Sciences and Technology in Sport, Shahid Beheshti University, Tehran 1983969411, Iran"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4115-0833","authenticated-orcid":false,"given":"Nicola","family":"Lovecchio","sequence":"additional","affiliation":[{"name":"Department of Public Health, Experimental and Forensic Medicine, University of Pavia, 27100 Pavia, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,3,3]]},"reference":[{"key":"ref_1","first-page":"74","article-title":"The effects of repetitive overhead throwing on shoulder rotator isokinetic work-fatigue","volume":"2","author":"Dale","year":"2007","journal-title":"N. Am. J. Sports Phys. Ther. NAJSPT"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1016\/j.jsams.2018.09.224","article-title":"Cluster analysis using physical performance and self-report measures to identify shoulder injury in overhead female athletes","volume":"22","author":"Gaudet","year":"2019","journal-title":"J. Sci. Med. Sport"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1047","DOI":"10.1123\/jsr.2019-0117","article-title":"Ultrasonographic and myotonometric evaluation of the shoulder girdle after an isokinetic muscle fatigue protocol","volume":"29","author":"Klich","year":"2019","journal-title":"J. Sport Rehabil."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2121","DOI":"10.1080\/02640414.2018.1440513","article-title":"Evolution of muscular fatigue in periscapular and rotator cuff muscles during isokinetic shoulder rotations","volume":"36","author":"Gaudet","year":"2018","journal-title":"J. Sports Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2417","DOI":"10.1007\/s00421-020-04464-9","article-title":"Shoulder muscle activation strategies differ when lifting or lowering a load","volume":"120","author":"Turpin","year":"2020","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"302","DOI":"10.3389\/fbioe.2020.00302","article-title":"Fatigue-induced scapular dyskinesis in healthy overhead athletes","volume":"8","author":"Zago","year":"2020","journal-title":"Front. Bioeng. Biotechnol."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Thigpen, C.A., Padua, D.A., Michener, L.A., Guskiewicz, K., Giuliani, C., Keener, J.D., and Stergiou, N. (2010). Head and shoulder posture affect scapular mechanics and muscle activity in overhead tasks. J. Electromyogr. Kinesiol., 20.","DOI":"10.1016\/j.jelekin.2009.12.003"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"40","DOI":"10.1016\/j.clinbiomech.2010.09.001","article-title":"The specificity of fatiguing protocols affect scapular orientation: Implications for subacromial impingement","volume":"26","author":"Chopp","year":"2011","journal-title":"Clin. Biomech."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1356","DOI":"10.1016\/j.jelekin.2013.08.007","article-title":"Scapular orientation following repetitive prone rowing: Implications for potential subacromial impingement mechanisms","volume":"23","author":"Noguchi","year":"2013","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"224","DOI":"10.1016\/j.jelekin.2005.06.015","article-title":"Effects of shoulder muscle fatigue caused by repetitive overhead activities on scapulothoracic and glenohumeral kinematics","volume":"16","author":"Ebaugh","year":"2006","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"557","DOI":"10.2519\/jospt.2006.2189","article-title":"Scapulothoracic and glenohumeral kinematics following an external rotation fatigue protocol","volume":"36","author":"Ebaugh","year":"2006","journal-title":"J. Orthop. Sports Phys. Ther."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1016\/j.jelekin.2006.01.008","article-title":"EMG analysis of shoulder muscle fatigue during resisted isometric shoulder elevation","volume":"17","author":"Minning","year":"2007","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1007\/s004210100454","article-title":"Static and dynamic myoelectric measures of shoulder muscle fatigue during intermittent dynamic exertions of low to moderate intensity","volume":"85","author":"Nussbaum","year":"2001","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1924","DOI":"10.1589\/jpts.28.1924","article-title":"Electromyographic analysis of an ergonomic risk factor: Overhead work","volume":"28","author":"Kinali","year":"2016","journal-title":"J. Phys. Ther. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"224","DOI":"10.1016\/j.jse.2009.07.006","article-title":"Voluntary activation of the infraspinatus muscle in nonfatigued and fatigued states","volume":"19","author":"Stackhouse","year":"2010","journal-title":"J. Shoulder Elbow Surg."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1351","DOI":"10.1007\/s00421-015-3114-z","article-title":"Functional connectivity between core and shoulder muscles increases during isometric endurance contractions in judo competitors","volume":"115","author":"Kawczynski","year":"2015","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_17","first-page":"21","article-title":"EMG frequency during isometric, submaximal activity: A statistical model for biceps brachii","volume":"12","author":"Solnik","year":"2010","journal-title":"Acta Bioeng. Biomech."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1016\/j.jelekin.2009.03.011","article-title":"EMG spectral indices and muscle power fatigue during dynamic contractions","volume":"20","author":"Malanda","year":"2010","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1446","DOI":"10.1152\/japplphysiol.00452.2005","article-title":"Fatigue and recovery of power and isometric torque following isotonic knee extensions","volume":"99","author":"Cheng","year":"2005","journal-title":"J. Appl. Physiol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"677","DOI":"10.1113\/jphysiol.1956.sp005558","article-title":"The relation between force and integrated electrical activity in fatigued muscle","volume":"132","author":"Edwards","year":"1956","journal-title":"J. Physiol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"321","DOI":"10.1007\/s00421-005-0014-7","article-title":"Relationship between perceived exertion and mean power frequency of the EMG signal from the upper trapezius muscle during isometric shoulder elevation","volume":"95","author":"Hummel","year":"2005","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1097\/00003677-200201000-00003","article-title":"Motor unit synchronization and neuromuscular performance","volume":"30","author":"Semmler","year":"2002","journal-title":"Exerc. Sport Sci. Rev."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"376","DOI":"10.1016\/j.jsams.2011.01.001","article-title":"The rotator cuff muscles have a direction specific recruitment pattern during shoulder flexion and extension exercises","volume":"14","author":"Wattanaprakornkul","year":"2011","journal-title":"J. Sci. Med. Sport"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"985","DOI":"10.1080\/02640414.2017.1347697","article-title":"Muscle recruitment patterns of the subscapularis, serratus anterior and other shoulder girdle muscles during isokinetic internal and external rotations","volume":"36","author":"Gaudet","year":"2018","journal-title":"J. Sports Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"541","DOI":"10.1016\/j.jsams.2011.05.002","article-title":"Isokinetic dynamometry applied to shoulder rotators\u2014velocity limitations in eccentric evaluations","volume":"14","author":"Zanca","year":"2011","journal-title":"J. Sci. Med. Sport"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"725","DOI":"10.1055\/s-2005-872870","article-title":"Concentric and eccentric muscle fatigue of the shoulder rotators","volume":"27","author":"Mullaney","year":"2006","journal-title":"Int. J. Sport Med."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/1758-2555-3-1","article-title":"Shoulder muscle endurance: The development of a standardized and reliable protocol","volume":"3","author":"Roy","year":"2011","journal-title":"Sports Med. Arthrosc. Rehabil. Ther. Technol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"e000279","DOI":"10.1136\/bmjsem-2017-000279","article-title":"Increased supraspinatus tendon thickness following fatigue loading in rotator cuff tendinopathy: Potential implications for exercise therapy","volume":"3","author":"McCreesh","year":"2017","journal-title":"BMJ Open Sport Exerc. Med."},{"key":"ref_29","first-page":"545","article-title":"Shoulder rotator isokinetic strength profile in young swimmers. Rev. Bras","volume":"14","author":"Batalha","year":"2012","journal-title":"Cineantropometria Desempenho Hum."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"325","DOI":"10.1007\/s00421-007-0589-2","article-title":"Time to task failure in shoulder elevation is associated to increase in amplitude and to spatial heterogeneity of upper trapezius mechanomyographic signals","volume":"102","author":"Madeleine","year":"2008","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1007\/s00420-002-0375-8","article-title":"The effects of neck-shoulder pain development on sensory-motor interactions among female workers in the poultry and fish industries. A prospective study","volume":"76","author":"Madeleine","year":"2003","journal-title":"Int. Arch. Occup. Environ. Health"},{"key":"ref_32","unstructured":"SENIAM (2007, March 27). Surface Electromyography for the Non-Invasive Assessment of Muscles; SENIAM Project: 2008. Available online: http:\/\/www.seniam.org\/."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1109\/MCSE.2007.53","article-title":"IPython: A system for interactive scientific computing","volume":"9","author":"Granger","year":"2007","journal-title":"Comput. Sci. Eng."},{"key":"ref_34","first-page":"65","article-title":"Teager\u2013Kaiser Operator improves the accuracy of EMG onset detection independent of signal-to-noise ratio","volume":"10","author":"Solnik","year":"2008","journal-title":"Acta Bioeng. Biomech."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"52","DOI":"10.1123\/jsr.2014-0260","article-title":"The effect of glenohumeral internal-rotation deficit on functional rotator-strength ratio in adolescent overhead athletes","volume":"25","author":"Guney","year":"2016","journal-title":"J. Sport Rehabil."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"S48","DOI":"10.1016\/j.jse.2007.08.007","article-title":"Scapular muscle recruitment patterns and isokinetic strength ratios of the shoulder rotator muscles in individuals with and without impingement syndrome","volume":"17","author":"Moraes","year":"2008","journal-title":"J. Shoulder Elbow Surg."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"542","DOI":"10.1177\/03635465030310041101","article-title":"Scapular muscle recruitment patterns: Trapezius muscle latency with and without impingement symptoms","volume":"31","author":"Cools","year":"2003","journal-title":"Am. J. Sports Med."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"236","DOI":"10.1002\/aja.1001890306","article-title":"Fiber type composition of the human male trapezius muscle: Enzyme-histochemical characteristics","volume":"189","author":"Lindman","year":"1990","journal-title":"Am. J. Anat."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"674","DOI":"10.2519\/jospt.2008.2878","article-title":"Fiber type composition of cadaveric human rotator cuff muscles","volume":"38","author":"Lovering","year":"2008","journal-title":"J. Orthop. Sports Phys. Ther."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"431","DOI":"10.1016\/j.jseint.2020.04.016","article-title":"Supraspinatus and deltoid muscle fiber composition in rotator cuff tear conditions","volume":"4","author":"Ravn","year":"2020","journal-title":"JSES Int."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1075","DOI":"10.1093\/ptj\/86.8.1075","article-title":"Shoulder function and 3-dimensional scapular kinematics in people with and without shoulder impingement syndrome","volume":"86","author":"McClure","year":"2006","journal-title":"Phys. Ther."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/j.jelekin.2015.08.001","article-title":"Fatigue-induced glenohumeral and scapulothoracic kinematic variability: Implications for subacromial space reduction","volume":"29","author":"McDonald","year":"2016","journal-title":"J. Electromyogr. Kinesiol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"154","DOI":"10.1589\/jpts.28.154","article-title":"Electromyographic analysis of the infraspinatus and scapular stabilizing muscles during isometric shoulder external rotation at various shoulder elevation angles","volume":"28","author":"Uga","year":"2016","journal-title":"J. Phys Ther. Sci."}],"container-title":["International Journal of Environmental Research and Public Health"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1660-4601\/18\/5\/2516\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:32:14Z","timestamp":1760160734000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1660-4601\/18\/5\/2516"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,3,3]]},"references-count":43,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2021,3]]}},"alternative-id":["ijerph18052516"],"URL":"https:\/\/doi.org\/10.3390\/ijerph18052516","relation":{},"ISSN":["1660-4601"],"issn-type":[{"value":"1660-4601","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,3,3]]}}}