{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,21]],"date-time":"2026-07-21T22:26:41Z","timestamp":1784672801782,"version":"3.55.0"},"reference-count":46,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T00:00:00Z","timestamp":1783382400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Digit. Health"],"abstract":"\n Introduction<\/jats:title>\n Cardiovascular age is a powerful risk-communication tool that translates complex physiological data into an intuitive number, yet traditional estimates require clinical testing. Consumer wearables now estimate cardiorespiratory fitness age from photoplethysmography-derived heart rate data, enabling continuous, passive health monitoring, but whether such estimates capture substantive lifestyle variation has not been examined.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n We characterized Cardio Age, a wearable-derived cardiorespiratory fitness age estimate, in 442 Ultrahuman Ring users across a 12-month window ending February 2026 (retrospective observational cohort), separating independent lifestyle correlates from direct or indirect algorithmic inputs. Analyses used cross-sectional Spearman rank correlations, extreme-group comparisons between the youngest and oldest cardiovascular ages, and within-person longitudinal trajectories.<\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n The mean Cardio Age gap (CA gap; mean Cardio Age minus chronological age) was \u22121.84\u2009\u00b1\u20092.97 years, with 82.6% of participants exhibiting younger estimated cardiovascular ages. Independent lifestyle metrics with no algorithmic link to Cardio Age showed significant associations: sleep efficiency (\n r<\/jats:italic>\n \u2009=\u2009\u22120.194,\n p<\/jats:italic>\n \u2009&lt;\u20090.001), rapid eye movement (REM) sleep (\n r<\/jats:italic>\n \u2009=\u2009\u22120.203,\n p<\/jats:italic>\n \u2009&lt;\u20090.001), sleep duration (\n r<\/jats:italic>\n \u2009=\u2009\u22120.200,\n p<\/jats:italic>\n \u2009&lt;\u20090.001), and daily steps (\n r<\/jats:italic>\n \u2009=\u2009\u22120.145,\n p<\/jats:italic>\n \u2009=\u20090.003). A monotonic body mass index (BMI) dose-response was observed, with underweight participants showing a mean CA gap of \u22123.73 years versus \u22120.52 for obese participants. Extreme-group comparisons revealed that users with the youngest cardiovascular ages slept 37 minutes longer, achieved 22 more minutes of REM sleep, and had 1.8% higher sleep efficiency than those with the oldest cardiovascular ages (all\n p<\/jats:italic>\n \u2009&lt;\u20090.05). Sustained improvers over 12 months showed a mean CA reduction of 3.24 years; across the broader longitudinal improver and worsener groups, improving trajectories were accompanied by decreased resting heart rate (\u22120.8 bpm,\n p<\/jats:italic>\n \u2009&lt;\u20090.001) and increased estimated VO\n 2<\/jats:sub>\n max (+1.3 mL\/kg\/min,\n p<\/jats:italic>\n \u2009&lt;\u20090.001).\n <\/jats:p>\n <\/jats:sec>\n \n Discussion<\/jats:title>\n \n These independent lifestyle associations indicate that Cardio Age reflects physiological and behavioral variation beyond its algorithmic inputs. The within-person concordance with decreased resting heart rate and increased estimated VO\n 2<\/jats:sub>\n max, both direct algorithm inputs, is consistent with sensitivity to physiological change over time, supporting Cardio Age as a continuous, intuitive cardiovascular-fitness indicator.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fdgth.2026.1842633","type":"journal-article","created":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T05:47:34Z","timestamp":1783403254000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Wearable-derived cardiovascular fitness age and its lifestyle correlates in 442 adults"],"prefix":"10.3389","volume":"8","author":[{"given":"Aditi","family":"Shanmugam","sequence":"first","affiliation":[{"name":"Ultrahuman Healthcare Pvt Ltd.","place":["Bangalore, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kanika","family":"Gupta","sequence":"additional","affiliation":[{"name":"Ultrahuman Healthcare Pvt Ltd.","place":["Bangalore, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nihav","family":"Dhawale","sequence":"additional","affiliation":[{"name":"Ultrahuman Healthcare Pvt Ltd.","place":["Bangalore, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vatsal","family":"Singhal","sequence":"additional","affiliation":[{"name":"Ultrahuman Healthcare Pvt Ltd.","place":["Bangalore, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohit","family":"Kumar","sequence":"additional","affiliation":[{"name":"Ultrahuman Healthcare Pvt Ltd.","place":["Bangalore, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bhuvan","family":"Srinivasan","sequence":"additional","affiliation":[{"name":"Ultrahuman Healthcare Pvt Ltd.","place":["Bangalore, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vinayak","family":"Narasimhan","sequence":"additional","affiliation":[{"name":"Ultrahuman Healthcare Pvt Ltd.","place":["Bangalore, India"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,7]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"743","DOI":"10.1161\/CIRCULATIONAHA.107.699579","article-title":"General cardiovascular risk profile for use in primary care: the Framingham heart study","volume":"117","author":"D\u2019Agostino","year":"2008","journal-title":"Circulation"},{"key":"B2","doi-asserted-by":"publisher","first-page":"243","DOI":"10.1016\/j.rec.2015.10.019","article-title":"Vascular age versus cardiovascular risk: clarifying concepts","volume":"69","author":"Cuende","year":"2016","journal-title":"Rev Esp 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