Cardiorespiratory Fitness and Classification of Risk of Cardiovascular Disease Mortality

University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9047, USA.
Circulation (Impact Factor: 14.43). 03/2011; 123(13):1377-83. DOI: 10.1161/CIRCULATIONAHA.110.003236
Source: PubMed


Cardiorespiratory fitness (fitness) is associated with cardiovascular disease (CVD) mortality. However, the extent to which fitness improves risk classification when added to traditional risk factors is unclear.
Fitness was measured by the Balke protocol in 66 371 subjects without prior CVD enrolled in the Cooper Center Longitudinal Study between 1970 and 2006; follow-up was extended through 2006. Cox proportional hazards models were used to estimate the risk of CVD mortality with a traditional risk factor model (age, sex, systolic blood pressure, diabetes mellitus, total cholesterol, and smoking) with and without the addition of fitness. The net reclassification improvement and integrated discrimination improvement were calculated at 10 and 25 years. Ten-year risk estimates for CVD mortality were categorized as <1%, 1% to <5%, and ≥5%, and 25-year risk estimates were categorized as <8%, 8% to 30%, and ≥30%. During a median follow-up period of 16 years, there were 1621 CVD deaths. The addition of fitness to the traditional risk factor model resulted in reclassification of 10.7% of the men, with significant net reclassification improvement at both 10 years (net reclassification improvement=0.121) and 25 years (net reclassification improvement=0.041) (P<0.001 for both). The integrated discrimination improvement was 0.010 at 10 years (P<0.001), and the relative integrated discrimination improvement was 29%. Similar findings were observed for women at 25 years.
A single measurement of fitness significantly improves classification of both short-term (10-year) and long-term (25-year) risk for CVD mortality when added to traditional risk factors.

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    • "To estimate cardiorespiratory fitness , a component of physical fitness , we used a maximal continuous graded exercise test performed on a cycle ergometer until voluntary exhaustion . With such a protocol , there is a high correlation between exercise time and directly measured maximal oxygen uptake , allowing for an estimation of fitness ( Gupta et al . , 2011 ) ."
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    ABSTRACT: The current study examined the effects of cardiorespiratory fitness, identified with a continuous graded cycle ergometry, and aerobic exercise on cognitive functioning and entropy of the electroencephalogram (EEG) in 30 adolescents between the ages of 13 and 14 years. Higher and lower fit participants performed an executive function task after a bout of acute exercise and after rest while watching a film. EEG entropy, using the sample entropy measure, was repeatedly measured during the 1500 ms post-stimulus interval to evaluate changes in entropy over time. Analysis of the behavioral data for lower and higher fit groups revealed an interaction between fitness levels and acute physical exercise. Notably, lower fit, but not higher fit, participants had higher error rates (ER) for No Go relative to Go trials in the rest condition, whereas in the acute exercise condition there were no differences in ER between groups; higher fit participants also had significantly faster reaction times in the exercise condition in comparison with the rest condition. Analysis of EEG data revealed that higher fit participants demonstrated lower entropy post-stimulus than lower fit participants in the left frontal hemisphere, possibly indicating increased efficiency of early stage stimulus processing and more efficient allocation of cognitive resources to the task demands. The results suggest that EEG entropy is sensitive to stimulus processing demands and varies as a function of physical fitness levels, but not acute exercise. Physical fitness, in turn, may enhance cognition in adolescence by facilitating higher functionality of the attentional system in the context of lower levels of frontal EEG entropy.
    Frontiers in Human Neuroscience 11/2015; 9:538. DOI:10.3389/fnhum.2015.00538 · 3.63 Impact Factor
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    • "Numerous studies have emphasized the importance of CRF for future risks of mortality and CVD events, including a meta-analysis of 33 studies where researchers observed that each 1-MET increase in CRF was equivalent to a 13% reduction in all-cause mortality and a 15% reduction in CVD and CHD events (1,19). A study by Lee et al. (20) also demonstrated that for every 1-MET CRF increase, all-cause and CVD morality decreased by 15 and 19%, respectively, independently of BMI (21). "
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    ABSTRACT: OBJECTIVE Low cardiorespiratory fitness (CRF) is an independent risk factor for cardiovascular disease (CVD), especially in individuals with type 2 diabetes. Age-predicted, sex-stratified, and maximal MET cut points have been developed to determine the risk of CVD events and mortality in low CRF categories. We examined the proportion of Health Benefits of Aerobic and Resistance Training in Individuals With Type 2 Diabetes (HART-D) participants above these cut points before and after 9 months of aerobic training (AT), resistance training (RT), or a combination of both (ATRT).RESEARCH DESIGN AND METHODS Participants from the HART-D study (n = 196) who were randomly assigned to exercise training (AT, RT, or ATRT) or to a nonexercise control group between April 2007 and August 2009 were used in this ancillary study. Cut points were previously established for age-predicted METs (>100% and >85%, mean and increased CVD risk, respectively), age- and sex-stratified METs (Aerobic Center Longitudinal Study), and clinically discernible METs (men >8.0, women >6.5).RESULTSBaseline prevalence of participants above these cut points was similar for all intervention groups (P > 0.50) and ranged from 11.9% (>100% age predicted) to 55.1% (>85% age predicted). Baseline prevalence and age-, sex-, and race/ethnic group-adjusted percentage of participants above each cut point increased significantly after AT and ATRT (P < 0.05 for all).CONCLUSIONS Structured exercise training, especially the AT component, was associated with a greater number of participants moving above established cut points indicative of low CRF. These results have public health and clinical implications for the growing number of patients with type 2 diabetes at high risk for CVD.
    Diabetes care 07/2013; 36(10). DOI:10.2337/dc12-2194 · 8.42 Impact Factor
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    • "Increased physical fitness has been found to associate with reduced risk of cardiovascular mortality [6,7] and all-cause mortality [8]. By contributing to weight reduction and maintenance, physical activity also reduces morbidity and mortality risk indirectly. "
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    ABSTRACT: Objective Body mass index (BMI) is more commonly used than waist circumference as a measure of adiposity in clinical and research settings. The purpose of this study was to compare the associations of BMI and waist circumference with cardiorespiratory fitness. Methods In a cross-sectional study of 403 healthy men and women aged 50 ± 8.8 years, BMI and waist circumference were measured. Cardiorespiratory fitness was assessed from estimated maximal O2 uptake (VO2max), as calculated from a maximal fitness test. Results Mean BMI (kg/m2) was 27.8 ± 3.7 and 25.5 ± 4.6; and mean waist circumference (cm) 94.1 ± 9.7 and 84.3 ± 10.4 for men and women, respectively. Both men and women reported an average of 2.5 hours of weekly sports related physical activity, and 18% were current smokers. Correlation coefficients between both BMI and waist circumference, and VO2max were statistically significant in men (r = −0.280 and r = −0.377, respectively, p > 0.05 for both) and in women (r = −0.514 and r = −0.491, respectively, p > 0.05 for both). In women, the contribution of BMI to the level of VO2max in a regression model was greater, while in men waist circumference contributed more to the final model. In these models, age, hours of training per week, and weekly caloric expenditure in sport activity, significantly associated with VO2max, while smoking did not. Conclusion The differences observed between the sexes in the associations of BMI and waist circumference with VO2max support the clinical use of both obesity measures for assessment of cardiorespiratory fitness.
    Nutrition Journal 01/2013; 12(1):12. DOI:10.1186/1475-2891-12-12 · 2.60 Impact Factor
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