{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,7]],"date-time":"2026-05-07T13:44:08Z","timestamp":1778161448278,"version":"3.51.4"},"reference-count":72,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2023,6,12]],"date-time":"2023-06-12T00:00:00Z","timestamp":1686528000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"FCT\u2014Portuguese Foundation for Science and Technology","award":["UID\/04045\/2021"],"award-info":[{"award-number":["UID\/04045\/2021"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Background: Loneliness in older people seems to have emerged as an increasingly prevalent social problem. Objective: To apply a machine learning (ML) algorithm to the task of understanding the influence of sociodemographic variables, physical fitness, physical activity levels (PAL), and sedentary behavior (SB) on the loneliness feelings of physically trained older people. Materials and Methods: The UCLA loneliness scale was used to evaluate loneliness, the Functional Fitness Test Battery was used to evaluate the correlation of sociodemographic variables, physical fitness, PAL, and SB in the loneliness feelings scores of 23 trained older people (19 women and 4 men). For this purpose, a naive Bayes ML algorithm was applied. Results: After analysis, we inferred that aerobic fitness (AF), hand grip strength (HG), and upper limb strength (ULS) comprised the most relevant variables panel to cause high participant loneliness with 100% accuracy and F-1 score. Conclusions: The naive Bayes algorithm with leave-one-out cross-validation (LOOCV) predicted loneliness in trained older with a high precision. In addition, AF was the most potent variable in reducing loneliness risk.<\/jats:p>","DOI":"10.3390\/life13061374","type":"journal-article","created":{"date-parts":[[2023,6,13]],"date-time":"2023-06-13T01:35:30Z","timestamp":1686620130000},"page":"1374","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Aerobic Fitness as an Important Moderator Risk Factor for Loneliness in Physically Trained Older People: An Explanatory Case Study Using Machine Learning"],"prefix":"10.3390","volume":"13","author":[{"given":"Samuel","family":"Encarna\u00e7\u00e3o","sequence":"first","affiliation":[{"name":"Department of Sport Sciences, Instituto Polit\u00e9cnico de Bragan\u00e7a (IPB), 5300-253 Bragan\u00e7a, Portugal"},{"name":"Research Centre in Basic Education (CIEB), Instituto Polit\u00e9cnico de Bragan\u00e7a (IPB), 5300-253 Bragan\u00e7a, Portugal"},{"name":"Department of Physical Activity and Sport Sciences, Universidad Aut\u00f3noma de Madrid (UAM), Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7678-6781","authenticated-orcid":false,"given":"Paula","family":"Vaz","sequence":"additional","affiliation":[{"name":"Research Centre in Basic Education (CIEB), Instituto Polit\u00e9cnico de Bragan\u00e7a (IPB), 5300-253 Bragan\u00e7a, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"\u00c1lvaro","family":"Fortunato","sequence":"additional","affiliation":[{"name":"Department of Sport Sciences, Instituto Polit\u00e9cnico de Bragan\u00e7a (IPB), 5300-253 Bragan\u00e7a, Portugal"},{"name":"Research Centre in Sports Sciences, Health Sciences and Human Development (CIDESD), 5001-801 Vila Real, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0184-6780","authenticated-orcid":false,"given":"Pedro","family":"Forte","sequence":"additional","affiliation":[{"name":"Department of Sport Sciences, Instituto Polit\u00e9cnico de Bragan\u00e7a (IPB), 5300-253 Bragan\u00e7a, Portugal"},{"name":"Research Centre in Sports Sciences, Health Sciences and Human Development (CIDESD), 5001-801 Vila Real, Portugal"},{"name":"CI-ISCE, Higher Institute of Educational Sciences of the Douro (ISCE Douro), 4560-708 Penafiel, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5771-7510","authenticated-orcid":false,"given":"C\u00e1tia","family":"Vaz","sequence":"additional","affiliation":[{"name":"CI-ISCE, Higher Institute of Educational Sciences of the Douro (ISCE Douro), 4560-708 Penafiel, Portugal"},{"name":"Department of Education and Supervision, Instituto Polit\u00e9cnico de Bragan\u00e7a (IPB), 5300-253 Bragan\u00e7a, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4467-1722","authenticated-orcid":false,"given":"Ant\u00f3nio","family":"Monteiro","sequence":"additional","affiliation":[{"name":"Department of Sport Sciences, Instituto Polit\u00e9cnico de Bragan\u00e7a (IPB), 5300-253 Bragan\u00e7a, Portugal"},{"name":"Department of Physical Activity and Sport Sciences, Universidad Aut\u00f3noma de Madrid (UAM), Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Rodrigues, F., Jacinto, M., Figueiredo, N., Monteiro, A.M., and Forte, P. 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