{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,7]],"date-time":"2026-05-07T04:02:28Z","timestamp":1778126548985,"version":"3.51.4"},"reference-count":27,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2021,9,3]],"date-time":"2021-09-03T00:00:00Z","timestamp":1630627200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Horizon 2020","award":["824984"],"award-info":[{"award-number":["824984"]}]},{"DOI":"10.13039\/501100004329","name":"Javna Agencija za Raziskovalno Dejavnost RS","doi-asserted-by":"publisher","award":["J5-9350"],"award-info":[{"award-number":["J5-9350"]}],"id":[{"id":"10.13039\/501100004329","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004329","name":"Javna Agencija za Raziskovalno Dejavnost RS","doi-asserted-by":"publisher","award":["P5-0147"],"award-info":[{"award-number":["P5-0147"]}],"id":[{"id":"10.13039\/501100004329","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Monitoring core body temperature (Tc) during training and competitions, especially in a hot environment, can help enhance an athlete\u2019s performance, as well as lower the risk for heat stroke. Accordingly, a noninvasive sensor that allows reliable monitoring of Tc would be highly beneficial in this context. One such novel non-invasive sensor was recently introduced onto the market (CORE, greenTEG, R\u00fcmlang, Switzerland), but, to our knowledge, a validation study of this device has not yet been reported. Therefore, the purpose of this study was to evaluate the validity and reliability of the CORE sensor. In Study I, 12 males were subjected to a low-to-moderate heat load by performing, on two separate occasions several days apart, two identical 60-min bouts of steady-state cycling in the laboratory at 19 \u00b0C and 30% relative humidity. In Study II, 13 males were subjected to moderate-to-high heat load by performing 90 min of cycling in the laboratory at 31 \u00b0C and 39% relative humidity. In both cases the core body temperatures indicated by the CORE sensor were compared to the corresponding values obtained using a rectal sensor (Trec). The first major finding was that the reliability of the CORE sensor is acceptable, since the mean bias between the two identical trials of exercise (0.02 \u00b0C) was not statistically significant. However, under both levels of heat load, the body temperature indicated by the CORE sensor did not agree well with Trec, with approximately 50% of all paired measurements differing by more than the predefined threshold for validity of \u22640.3 \u00b0C. In conclusion, the results obtained do not support the manufacturer\u2019s claim that the CORE sensor provides a valid measure of core body temperature.<\/jats:p>","DOI":"10.3390\/s21175932","type":"journal-article","created":{"date-parts":[[2021,9,6]],"date-time":"2021-09-06T13:18:26Z","timestamp":1630934306000},"page":"5932","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":66,"title":["Reliability and Validity of the CORE Sensor to Assess Core Body Temperature during Cycling Exercise"],"prefix":"10.3390","volume":"21","author":[{"given":"Nina","family":"Verdel","sequence":"first","affiliation":[{"name":"Swedish Winter Sports Research Centre, Mid Sweden University, 83125 \u00d6stersund, Sweden"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0142-4457","authenticated-orcid":false,"given":"Tim","family":"Podlogar","sequence":"additional","affiliation":[{"name":"Faculty of Health Sciences, University of Primorska, 6310 Izola, Slovenia"},{"name":"Department of Automation, Biocybernetics, and Robotics, Jozef Stefan Institute, 1000 Ljubljana, Slovenia"},{"name":"Human Performance Centre, 1000 Ljubljana, Slovenia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8382-7449","authenticated-orcid":false,"given":"Ur\u0161a","family":"Ciuha","sequence":"additional","affiliation":[{"name":"Department of Automation, Biocybernetics, and Robotics, Jozef Stefan Institute, 1000 Ljubljana, Slovenia"}]},{"given":"Hans-Christer","family":"Holmberg","sequence":"additional","affiliation":[{"name":"Department of Health, Medicine, and Rehabilitation, Lule\u00e5 University of Technology, 97187 Lule\u00e5, Sweden"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7053-3978","authenticated-orcid":false,"given":"Tadej","family":"Debevec","sequence":"additional","affiliation":[{"name":"Department of Automation, Biocybernetics, and Robotics, Jozef Stefan Institute, 1000 Ljubljana, Slovenia"},{"name":"Faculty of Sport, University of Ljubljana, 1000 Ljubljana, Slovenia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7231-7002","authenticated-orcid":false,"given":"Matej","family":"Supej","sequence":"additional","affiliation":[{"name":"Swedish Winter Sports Research Centre, Mid Sweden University, 83125 \u00d6stersund, Sweden"},{"name":"Faculty of Sport, University of Ljubljana, 1000 Ljubljana, Slovenia"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1111\/j.1600-0838.2010.01206.x","article-title":"Exercise in a Hot Environment: The Skin Circulation","volume":"20","author":"Johnson","year":"2010","journal-title":"Scand. J. Med. Sci. Sports"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"861","DOI":"10.1519\/JSC.0b013e3182aa5dd0","article-title":"Reliability of Intestinal Temperature Using an Ingestible Telemetry Pill System during Exercise in a Hot Environment","volume":"28","author":"Ruddock","year":"2014","journal-title":"J. Strength Cond. Res."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"American College of Sports Medicine, Armstrong, L.E.,  Casa, D.J.,  Millard-Stafford, M.,  Moran, D.S., Pyne, S.W., and Roberts, W.O. (2007). American College of Sports Medicine Position Stand. Exertional Heat Illness during Training and Competition. Med. Sci. Sports Exerc., 39, 556\u2013572.","DOI":"10.1249\/MSS.0b013e31802fa199"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"841","DOI":"10.1001\/archinte.1974.00320170117011","article-title":"Environmental Heat Illness: An Eclectic Review","volume":"133","author":"Knochel","year":"1974","journal-title":"Arch. Intern. Med."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"38","DOI":"10.3389\/fspor.2019.00038","article-title":"The Use of Technology to Protect the Health of Athletes During Sporting Competitions in the Heat","volume":"1","author":"Sutehall","year":"2019","journal-title":"Front. Sports Act. Living"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1113\/jphysiol.2004.063289","article-title":"Sustained and Generalized Extracellular Fluid Expansion Following Heat Acclimation","volume":"559","author":"Patterson","year":"2004","journal-title":"J. Physiol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"659","DOI":"10.1007\/s00421-009-1182-7","article-title":"Induction and Decay of Short-Term Heat Acclimation","volume":"107","author":"Garrett","year":"2009","journal-title":"Eur. J. Appl. Physiol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1016\/j.jtherbio.2014.10.006","article-title":"Considerations for the Measurement of Core, Skin and Mean Body Temperatures","volume":"46","author":"Taylor","year":"2014","journal-title":"J. Therm. Biol."},{"key":"ref_9","first-page":"333","article-title":"Validity of Devices That Assess Body Temperature during Outdoor Exercise in the Heat","volume":"42","author":"Casa","year":"2007","journal-title":"J. Athl. Train."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"259","DOI":"10.1088\/0967-3334\/36\/2\/259","article-title":"Intestinal Temperature Does Not Reflect Rectal Temperature during Prolonged, Intense Running with Cold Fluid Ingestion","volume":"36","author":"Savoie","year":"2015","journal-title":"Physiol. Meas."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"848","DOI":"10.1080\/110241500447218","article-title":"Accuracy of Digital Tympanic, Oral, Axillary, and Rectal Thermometers Compared with Standard Rectal Mercury Thermometers","volume":"166","author":"Jensen","year":"2000","journal-title":"Eur. J. Surg."},{"key":"ref_12","first-page":"939","article-title":"Core Temperature Measurement during Supine Exercise: Esophageal, Rectal, and Intestinal Temperatures","volume":"71","author":"Lee","year":"2000","journal-title":"Aviat. Space Environ. Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"879","DOI":"10.2165\/00007256-200232140-00001","article-title":"Core Temperature Measurement: Methods and Current Insights","volume":"32","author":"Moran","year":"2002","journal-title":"Sports Med."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1080\/00913847.1994.11947680","article-title":"Assessing Core Temperature in Collapsed Athletes","volume":"22","author":"Roberts","year":"1994","journal-title":"Phys. Sportsmed."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1016\/j.jtherbio.2019.05.010","article-title":"Wireless Measurement of Rectal Temperature during Exercise: Comparing an Ingestible Thermometric Telemetric Pill Used as a Suppository against a Conventional Rectal Probe","volume":"83","author":"Gosselin","year":"2019","journal-title":"J. Therm. Biol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1926","DOI":"10.1249\/01.mss.0000233800.69776.ef","article-title":"The Validity and Reliability of Intestinal Temperature during Intermittent Running","volume":"38","author":"Gant","year":"2006","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"124","DOI":"10.4085\/1062-6050-44.2.124","article-title":"Validity and Reliability of Devices That Assess Body Temperature during Indoor Exercise in the Heat","volume":"44","author":"Ganio","year":"2009","journal-title":"J. Athl. Train."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1016\/j.autneu.2016.01.001","article-title":"Thermoregulatory Disorders and Illness Related to Heat and Cold Stress","volume":"196","author":"Cheshire","year":"2016","journal-title":"Auton. Neurosci."},{"key":"ref_19","unstructured":"(2021, August 15). Core Body Temperature Monitoring CORE Body Temperature Monitoring Device Launches in 2020. Available online: https:\/\/twitter.com\/corebodytemp\/status\/1258035688991309826."},{"key":"ref_20","first-page":"e9341","article-title":"Recommendations for Assessment of the Reliability, Sensitivity, and Validity of Data Provided by Wearable Sensors Designed for Monitoring Physical Activity","volume":"6","author":"Fuss","year":"2018","journal-title":"JMIR Mhealth Uhealth"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1240","DOI":"10.1136\/bjsports-2016-097295","article-title":"Wearable, Yes, but Able?: It Is Time for Evidence-Based Marketing Claims!","volume":"51","author":"Sperlich","year":"2017","journal-title":"Br. J. Sports Med."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2011","DOI":"10.1249\/MSS.0000000000002343","article-title":"A \u201cStep-Ramp-Step\u201d Protocol to Identify the Maximal Metabolic Steady State","volume":"52","author":"Iannetta","year":"2020","journal-title":"Med. Sci. Sports Exerc."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1177\/096228029900800204","article-title":"Measuring Agreement in Method Comparison Studies","volume":"8","author":"Bland","year":"1999","journal-title":"Stat. Methods Med. Res."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"986","DOI":"10.4085\/1062-6050-50.9.07","article-title":"National Athletic Trainers\u2019 Association Position Statement: Exertional Heat Illnesses","volume":"50","author":"Casa","year":"2015","journal-title":"J. Athl. Train."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1134","DOI":"10.1016\/j.jsams.2020.05.014","article-title":"Menstrual Cycle and Thermoregulation during Exercise in the Heat: A Systematic Review and Meta-Analysis","volume":"23","author":"Giersch","year":"2020","journal-title":"J. Sci. Med. Sport"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"126","DOI":"10.1136\/bjsm.2006.026344","article-title":"The Ingestible Telemetric Body Core Temperature Sensor: A Review of Validity and Exercise Applications","volume":"41","author":"Byrne","year":"2007","journal-title":"Br. J. Sports Med."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"915","DOI":"10.1088\/0967-3334\/33\/6\/915","article-title":"Telemetry Pill versus Rectal and Esophageal Temperature during Extreme Rates of Exercise-Induced Core Temperature Change","volume":"33","author":"Teunissen","year":"2012","journal-title":"Physiol. Meas."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/17\/5932\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:55:56Z","timestamp":1760165756000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/17\/5932"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,9,3]]},"references-count":27,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2021,9]]}},"alternative-id":["s21175932"],"URL":"https:\/\/doi.org\/10.3390\/s21175932","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,9,3]]}}}