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Original Investigation
January 2016

Association of Fitness in Young Adulthood With Survival and Cardiovascular RiskThe Coronary Artery Risk Development in Young Adults (CARDIA) Study

Author Affiliations
  • 1Cardiovascular Division, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
  • 2Cardiovascular Medicine Division, Department of Medicine, University of Michigan, Ann Arbor
  • 3Nuclear Medicine Division, Department of Radiology, University of Michigan, Ann Arbor
  • 4Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
  • 5Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, Bethesda, Maryland
  • 6Department of Medicine and Cardiology, Heart and Vascular Institute, Johns Hopkins Medical Institutions, The Johns Hopkins University, Baltimore, Maryland
  • 7Division of Cardiology, Department of Internal Medicine, Rhode Island Hospital, Brown University, Providence, Rhode Island
  • 8Department of Epidemiology, Colorado School of Public Health, Aurora
  • 9Department of Epidemiology, Vanderbilt University, Nashville, Tennessee
  • 10Department of Cardiology, Kaiser Permanente Northern California, Oakland
  • 11Department of Medicine, University of California, San Francisco
  • 12Human Genomics Laboratory, Pennington Biomedical Research Center, Baton Rouge, Louisiana
  • 13Department of Medicine, Massachusetts General Hospital, Boston
  • 14Noninvasive Cardiovascular Imaging Section, Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts
  • 15Department of Radiology, Brigham and Women’s Hospital, Boston, Massachusetts
  • 16Division of Preventative Medicine, Department of Medicine, University of Alabama at Birmingham
  • 17Department of Preventative Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
JAMA Intern Med. 2016;176(1):87-95. doi:10.1001/jamainternmed.2015.6309

Importance  Although cardiorespiratory fitness (CRF) is prognostic in older adults, the effect of CRF during early adulthood on long-term cardiovascular structure, function, and prognosis is less clear.

Objective  To examine whether CRF in young adults is associated with long-term clinical outcome and subclinical cardiovascular disease (CVD).

Design, Setting, and Participants  Prospective study of 4872 US adults aged 18 to 30 years who underwent treadmill exercise testing at a baseline study visit from March 25, 1985, to June 7, 1986, and 2472 individuals who underwent a second treadmill test 7 years later. Median follow-up was 26.9 years, with assessment of obesity, left ventricular mass and strain, coronary artery calcification (CAC), and vital status and incident CVD. Follow-up was complete on August 31, 2011, and data were analyzed from recruitment through the end of follow-up.

Main Outcomes and Measures  The presence of CAC was assessed by computed tomography at years 15 (2000-2001), 20 (2005-2006), and 25 (2010-2011), and left ventricular mass was assessed at years 5 (1990-1991) and 25 (with global longitudinal strain). Incident CVD and all-cause mortality were adjudicated.

Results  Of the 4872 individuals, 273 (5.6%) died and 193 (4.0%) experienced CVD events during follow-up. After comprehensive adjustment, each additional minute of baseline exercise test duration was associated with a 15% lower hazard of death (hazard ratio [HR], 0.85; 95% CI, 0.80-0.91; P < .001) and a 12% lower hazard of CVD (HR, 0.88; 95% CI, 0.81-0.96; P = .002). Higher levels of baseline CRF were associated with significantly lower left ventricular mass index (β = −0.24; 95% CI, −0.45 to −0.03; P = .02) and significantly better lobal longitudinal strain (β = −0.09; 95% CI, −0.14 to −0.05; P < .001) at year 25. Fitness was not associated with CAC. A 1-minute reduction in fitness by year 7 was associated with 21% and 20% increased hazards of death (HR, 1.21; 95% CI, 1.07-1.37; P = .002) and CVD (HR, 1.20; 95% CI, 1.06-1.37; P = .006), respectively, along with a more impaired strain (β = 0.15; 95% CI, 0.08-0.23; P < .001). No association between change in fitness and CAC was found.

Conclusions and Relevance  Higher levels of fitness at baseline and improvement in fitness early in adulthood are favorably associated with lower risks for CVD and mortality. Fitness and changes in fitness are associated with myocardial hypertrophy and dysfunction but not CAC. Regular efforts to ascertain and improve CRF in young adulthood may play a critical role in promoting cardiovascular health and interrupting early CVD pathogenesis.