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Prognostic Relevance of Cardiorespiratory Fitness as Assessed by Submaximal Exercise Testing for All-Cause Mortality: A UK Biobank Prospective Study



      To investigate whether the inverse associations of cardiorespiratory fitness (CRF) with all-cause and cardiovascular mortality in the general population vary among individuals who are at different levels of pretest risk.

      Patients and Methods

      Cardiorespiratory fitness was assessed through submaximal bicycle tests in 58,892 participants aged 40 to 69 years who completed baseline questionnaires between January 1, 2006, and December 31, 2010, in the UK Biobank Prospective Study. Participants were categorized into risk categories, which determined allocation to an individualized bicycle protocol. The groups at minimal risk (category 1), small risk (category 2), and medium risk (category 3) were tested at 50%, 35% of the predicted maximal workload, and constant level, respectively. We investigated associations of CRF with mortality across different levels of pretest risk and determined whether CRF improves risk prediction.


      During a median follow-up of 5.8 years, 936 deaths occurred. Cardiorespiratory fitness was linearly associated with mortality risk. Comparing extreme fifths of CRF, the multivariable-adjusted hazard ratios (95% CIs) for mortality were 0.63 (0.52-0.77), 0.54 (0.36-0.82), 0.81 (0.46-1.43), and 0.58 (0.48-0.69) in categories 1, 2, and 3 and overall population, respectively. The addition of CRF to a 5-year mortality risk score containing established risk factors was associated with a C-index change (0.0012; P=.49), integrated discrimination improvement (0.0005; P<.001), net reclassification improvement (+0.0361; P=.005), and improved goodness of fit (likelihood ratio test, P<.001). Differences in 5-year survival were more pronounced across levels of age, smoking status, and sex.


      Cardiorespiratory fitness, assessed by submaximal exercise testing, improves mortality risk prediction beyond conventional risk factors and its prognostic relevance varies across cardiovascular risk levels.

      Abbreviations and Acronyms:

      CPX (cardiopulmonary exercise testing), CRF (cardiorespiratory fitness), CVD (cardiovascular disease), ECG (electrocardiography), HR (hazard ratio), IDI (integrated discrimination improvement), IQR (interquartile range), MET (metabolic equivalent), NHS (National Health Service), SBP (systolic blood pressure)
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      Linked Article

      • Correction
        Mayo Clinic ProceedingsVol. 95Issue 10
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          Correction to ‘Prognostic Relevance of Cardiorespiratory Fitness as Assessed by Submaximal Exercise Testing for All-Cause Mortality: A UK Biobank Prospective Study’ [Mayo Clinic Proceedings 95 (2020) 867–878/2729]
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      • UK Biobank Contributes to Aerobic and Muscle Fitness Research
        Mayo Clinic ProceedingsVol. 95Issue 5
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          Considerable evidence indicates a substantial lack of physical activity (PA) and exercise training (ET) and a very high prevalence of sedentary behavior throughout most of the world.1-5 This often leads to low levels of cardiorespiratory fitness (CRF), which is perhaps one of the strongest predictors of cardiovascular disease (CVD) as well as CVD and all-cause mortality.1,3,4,6,7 In addition, recent evidence suggests that resistance exercise and muscular fitness also contribute to CVD risk factors,8,9 including diabetes mellitus risk,10 and to CVD and all-cause mortality.
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