{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T20:24:09Z","timestamp":1786652649245,"version":"build-2736575974"},"reference-count":22,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2024,12,17]],"date-time":"2024-12-17T00:00:00Z","timestamp":1734393600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JFMK"],"abstract":"<jats:p>Background: The Apple Watch provides promising health data that could aid in increasing exercise adherence; regular exercise can help individuals manage and prevent diseases such as obesity and cardiovascular disease. However, the impact of skin pigmentation on the accuracy of the Apple Watch Series 9 for measures of energy expenditure (EE) and heart rate (HR) is unknown. Purpose: The purpose of this study was to determine the accuracy of the Apple Watch Series 9 on various skin pigmentations for measures of EE and HR. Methods: Thirty young, healthy individuals were assigned to one of three groups based on their scores on the Fitzpatrick skin survey. Participants completed a 10 min treadmill protocol with varying speeds and inclines while wearing an Apple Watch Series 9, a two-way non-rebreathing mouthpiece connected to a Parvo Medics metabolic cart, and a Polar H7 chest strap to measure EE and HR. Results: Overall, EE was found to be inconsistent for all skin pigmentation groups. However, for HR, the Apple Watch Series 9 was more variable (i.e., less accurate) for darker skin pigmentations compared to lighter skin pigmentations. Conclusions: The Apple Watch Series 9 was found to vary in both EE and HR measures from criterion across intensity and skin pigmentation, with greater discrepancies for individuals in Group 3 for measures of HR. Further investigation might aim to study the impact of skin pigmentations and wrist subcutaneous fat on the accuracy of the latest Apple Watch Series 9 for measures of EE and HR.<\/jats:p>","DOI":"10.3390\/jfmk9040275","type":"journal-article","created":{"date-parts":[[2024,12,17]],"date-time":"2024-12-17T06:26:12Z","timestamp":1734416772000},"page":"275","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Accuracy of the Apple Watch Series 9 for Measures of Energy Expenditure and Heart Rate at Rest and During Exercise: Impact of Skin Pigmentation"],"prefix":"10.3390","volume":"9","author":[{"given":"Sydney E.","family":"Chase","sequence":"first","affiliation":[{"name":"Health & Human Physiological Sciences, Skidmore College, Saratoga Springs, NY 12866, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rebecca G.","family":"Liddell","sequence":"additional","affiliation":[{"name":"Health & Human Physiological Sciences, Skidmore College, Saratoga Springs, NY 12866, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chloe L.","family":"McGonagle","sequence":"additional","affiliation":[{"name":"Health & Human Physiological Sciences, Skidmore College, Saratoga Springs, NY 12866, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7722-8818","authenticated-orcid":false,"given":"Stephen J.","family":"Ives","sequence":"additional","affiliation":[{"name":"Health & Human Physiological Sciences, Skidmore College, Saratoga Springs, NY 12866, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,12,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1152\/advan.00136.2013","article-title":"The history of \u201cExercise Is Medicine\u201d in ancient civilizations","volume":"38","author":"Tipton","year":"2014","journal-title":"Adv. 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