{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,7]],"date-time":"2026-03-07T01:59:38Z","timestamp":1772848778733,"version":"3.50.1"},"reference-count":52,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2022,12,24]],"date-time":"2022-12-24T00:00:00Z","timestamp":1671840000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Foundation of Science and Technology (FCT Portugal)","doi-asserted-by":"publisher","award":["SFRH\/BD\/143608\/2019"],"award-info":[{"award-number":["SFRH\/BD\/143608\/2019"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Foundation of Science and Technology (FCT Portugal)","doi-asserted-by":"publisher","award":["PCIF\/SSO\/0063\/2018"],"award-info":[{"award-number":["PCIF\/SSO\/0063\/2018"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Physical fatigue is a serious threat to the health and safety of firefighters. Its effects include decreased cognitive abilities and a heightened risk of accidents. Subjective scales and, recently, on-body sensors have been used to monitor physical fatigue among firefighters and safety-sensitive professionals. Considering the capabilities (e.g., noninvasiveness and continuous monitoring) and limitations (e.g., assessed fatiguing tasks and models validation procedures) of current approaches, this study aimed to develop a physical fatigue prediction model combining cardiorespiratory and thermoregulatory measures and machine learning algorithms within a firefighters\u2019 sample. Sensory data from heart rate, breathing rate and core temperature were recorded from 24 participants during an incremental running protocol. Various supervised machine learning algorithms were examined using 21 features extracted from the physiological variables and participants\u2019 characteristics to estimate four physical fatigue conditions: low, moderate, heavy and severe. Results showed that the XGBoosted Trees algorithm achieved the best outcomes with an average accuracy of 82% and accuracies of 93% and 86% for recognising the low and severe levels. Furthermore, this study evaluated different methods to assess the models\u2019 performance, concluding that the group cross-validation method presents the most practical results. Overall, this study highlights the advantages of using multiple physiological measures for enhancing physical fatigue modelling. It proposes a promising health and safety management tool and lays the foundation for future studies in field conditions.<\/jats:p>","DOI":"10.3390\/s23010194","type":"journal-article","created":{"date-parts":[[2022,12,27]],"date-time":"2022-12-27T03:03:31Z","timestamp":1672110211000},"page":"194","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["Machine Learning Approach to Model Physical Fatigue during Incremental Exercise among Firefighters"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4942-7625","authenticated-orcid":false,"given":"Denisse","family":"Bustos","sequence":"first","affiliation":[{"name":"Associated Laboratory for Energy, Transports and Aeronautics, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7829-5222","authenticated-orcid":false,"given":"Filipa","family":"Cardoso","sequence":"additional","affiliation":[{"name":"Centre of Research, Education, Innovation and Intervention in Sport, CIFI2D, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"},{"name":"Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3574-6692","authenticated-orcid":false,"given":"Manoel","family":"Rios","sequence":"additional","affiliation":[{"name":"Centre of Research, Education, Innovation and Intervention in Sport, CIFI2D, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"},{"name":"Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6347-9608","authenticated-orcid":false,"given":"M\u00e1rio","family":"Vaz","sequence":"additional","affiliation":[{"name":"Associated Laboratory for Energy, Transports and Aeronautics, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"},{"name":"Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2367-2187","authenticated-orcid":false,"given":"Joana","family":"Guedes","sequence":"additional","affiliation":[{"name":"Associated Laboratory for Energy, Transports and Aeronautics, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"}]},{"given":"Jos\u00e9","family":"Torres Costa","sequence":"additional","affiliation":[{"name":"Associated Laboratory for Energy, Transports and Aeronautics, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8524-5503","authenticated-orcid":false,"given":"Jo\u00e3o","family":"Santos Baptista","sequence":"additional","affiliation":[{"name":"Associated Laboratory for Energy, Transports and Aeronautics, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal"},{"name":"Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5811-0443","authenticated-orcid":false,"given":"Ricardo J.","family":"Fernandes","sequence":"additional","affiliation":[{"name":"Centre of Research, Education, Innovation and Intervention in Sport, CIFI2D, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"},{"name":"Porto Biomechanics Laboratory, Faculty of Sport, University of Porto, 4200-450 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,12,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"519","DOI":"10.1016\/0020-7489(96)00004-1","article-title":"Fatigue: A concept analysis","volume":"33","author":"Ream","year":"1996","journal-title":"Int. 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