Association of Smartwatch-Based Heart Rate and Physical Activity With Cardiorespiratory Fitness Measures in the Community: Cohort Study.
Yuankai Zhang, Xuzhi Wang, Chathurangi H Pathiravasan, Nicole L Spartano, Honghuang Lin, Belinda Borrelli, Emelia J Benjamin, David D McManus, Martin G Larson, Ramachandran S Vasan, Ravi V Shah, Gregory D Lewis, Chunyu Liu, Joanne M Murabito, Matthew Nayor
Author Information
Yuankai Zhang: Department of Biostatistics, School of Public Health, Boston University, Boston, MA, United States. ORCID
Xuzhi Wang: Department of Biostatistics, School of Public Health, Boston University, Boston, MA, United States. ORCID
Chathurangi H Pathiravasan: Department of Biostatistics, School of Public Health, Boston University, Boston, MA, United States. ORCID
Nicole L Spartano: Section of Endocrinology, Diabetes, Nutrition, and Weight Management, Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, United States. ORCID
Honghuang Lin: Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States. ORCID
Belinda Borrelli: Center for Behavioral Science Research, Department of Health Policy & Health Services Research, Boston University, Henry M. Goldman School of Dental Medicine, Boston, MA, United States. ORCID
Emelia J Benjamin: Boston University's and National Heart, Lung, and Blood Institute's Framingham Heart Study, Framingham, MA, United States. ORCID
David D McManus: Cardiology Division, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States. ORCID
Martin G Larson: Department of Biostatistics, School of Public Health, Boston University, Boston, MA, United States. ORCID
Ramachandran S Vasan: Boston University's and National Heart, Lung, and Blood Institute's Framingham Heart Study, Framingham, MA, United States. ORCID
Ravi V Shah: Cardiology Division, Vanderbilt Translational and Clinical Research Center, Vanderbilt University Medical Center, Nashville, TN, United States. ORCID
Gregory D Lewis: Cardiology Division, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States. ORCID
Chunyu Liu: Department of Biostatistics, School of Public Health, Boston University, Boston, MA, United States. ORCID
Joanne M Murabito: Boston University's and National Heart, Lung, and Blood Institute's Framingham Heart Study, Framingham, MA, United States. ORCID
Matthew Nayor: Sections of Cardiology and Preventive Medicine and Epidemiology, Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, United States. ORCID
BACKGROUND: Resting heart rate (HR) and routine physical activity are associated with cardiorespiratory fitness levels. Commercial smartwatches permit remote HR monitoring and step count recording in real-world settings over long periods of time, but the relationship between smartwatch-measured HR and daily steps to cardiorespiratory fitness remains incompletely characterized in the community. OBJECTIVE: This study aimed to examine the association of nonactive HR and daily steps measured by a smartwatch with a multidimensional fitness assessment via cardiopulmonary exercise testing (CPET) among participants in the electronic Framingham Heart Study. METHODS: Electronic Framingham Heart Study participants were enrolled in a research examination (2016-2019) and provided with a study smartwatch that collected longitudinal HR and physical activity data for up to 3 years. At the same examination, the participants underwent CPET on a cycle ergometer. Multivariable linear models were used to test the association of CPET indices with nonactive HR and daily steps from the smartwatch. RESULTS: We included 662 participants (mean age 53, SD 9 years; n=391, 59% women, n=599, 91% White; mean nonactive HR 73, SD 6 beats per minute) with a median of 1836 (IQR 889-3559) HR records and a median of 128 (IQR 65-227) watch-wearing days for each individual. In multivariable-adjusted models, lower nonactive HR and higher daily steps were associated with higher peak oxygen uptake (VO), % predicted peak VO, and VO at the ventilatory anaerobic threshold, with false discovery rate (FDR)-adjusted P values <.001 for all. Reductions of 2.4 beats per minute in nonactive HR, or increases of nearly 1000 daily steps, corresponded to a 1.3 mL/kg/min higher peak VO. In addition, ventilatory efficiency (V/VCO; FDR-adjusted P=.009), % predicted maximum HR (FDR-adjusted P<.001), and systolic blood pressure-to-workload slope (FDR-adjusted P=.01) were associated with nonactive HR but not associated with daily steps. CONCLUSIONS: Our findings suggest that smartwatch-based assessments are associated with a broad array of cardiorespiratory fitness responses in the community, including measures of global fitness (peak VO), ventilatory efficiency, and blood pressure response to exercise. Metrics captured by wearable devices offer a valuable opportunity to use extensive data on health factors and behaviors to provide a window into individual cardiovascular fitness levels.
