Use of functional aerobic capacity based on stress testing to predict outcomes in normal, overweight, and obese patients

Cardiac Effects of Obesity: PATHOPHYSIOLOGIC, CLINICAL, AND PROGNOSTIC CONSEQUENCES-A REVIEW

Obesity produces various hemodynamic alterations and changes in cardiac morphology that predispose to ventricular dysfunction and heart failure (HF). Obesity may serve as a risk factor for or the primary cause of HF. Obesity is also associated with impairment of cardiorespiratory fitness. An obesity paradox exists with respect to mortality in those with HF wherein overweight and mildly to moderately obese individuals have a better prognosis than underweight or normal weight persons. Cardiorespiratory fitness is an important determinant of the prognosis in obesity. Many of the alterations in cardiac structure and function as well as the clinical manifestations of HF are reversible with substantial weight loss in moderately to severely obese individuals.

The Exercise Rehabilitation Paradox: Less May Be More?

BACKGROUND

Debatably, the most commonly prescribed lifestyle modification for cardiovascular health involves daily exercise training (ET) and physical activity. Exercise has numerous known health benefits on blood pressure, lipid profile, weight loss, and glucose metabolism. However, controversy exists regarding the link between excessive endurance ET and harmful cardiac effects.

METHODS

We review the current literature and discuss the numerous known adverse effects of endurance ET on cardiac function.

RESULTS

Excessive endurance ET may negatively affect cardiac anatomy, play a role in osteoarthritis and coronary artery disease development, and increase the risks of cardiac arrhythmia and sudden cardiac death.

CONCLUSION

More ET may not always be better when it comes to endurance ET, and optimal ET dosing regimens are clearly needed.

Effects of Running on Chronic Diseases and Cardiovascular and All-Cause Mortality

Considerable evidence has established the link between high levels of physical activity (PA) and all-cause and cardiovascular disease (CVD)-specific mortality. Running is a popular form of vigorous PA that has been associated with better overall survival, but there is debate about the dose-response relationship between running and CVD and all-cause survival. In this review, we specifically reviewed studies published in PubMed since 2000 that included at least 500 runners and 5-year follow-up so as to analyze the relationship between vigorous aerobic PA, specifically running, and major health consequences, especially CVD and all-cause mortality. We also made recommendations on the optimal dose of running associated with protection against CVD and premature mortality, as well as briefly discuss the potential cardiotoxicity of a high dose of aerobic exercise, including running (eg, marathons).

Association of Cardiorespiratory Fitness With Coronary Heart Disease in Asymptomatic Men

OBJECTIVE

To examine the association of cardiorespiratory fitness (CRF) with risk of coronary heart disease (CHD) while controlling for an individual's Framingham Risk Score (FRS)-predicted CHD risk.

PATIENTS AND METHODS

The study included 29,854 men from the Aerobics Center Longitudinal Study, who received a baseline examination from January 1, 1979, to December 31, 2002. Coronary heart disease events included self-reported myocardial infarction or revascularization or CHD death. Multivariable survival analysis investigated the association between CRF, FRS, and CHD. Cardiorespiratory fitness was analyzed as both a continuous and a categorical variable. The population was stratified by "low" and "moderate or high" risk of CHD to test for differences in the FRS stratified by CRF.

RESULTS

Compared with men without incident CHD, men with incident CHD were older (mean age, 51.6 years vs 44.6 years), had lower average maximally achieved fitness (10.9 metabolic equivalent of tasks vs 12.0 metabolic equivalent of tasks [METs]), and were more likely to have moderate or high 10-year CHD risk (P<.001). Cardiorespiratory fitness, defined as maximal METs, exhibited a 20% lower risk of CHD (hazard ratio, 0.80; 95% CI, 0.77-0.83) for each 1-unit MET increase. Among men in the low CRF strata, individuals with moderate or high 10-year CHD risk, according to the FRS, had a higher CHD risk (hazard ratio, 6.55; 95% CI, 3.64-11.82) than men with low CHD risk according to the FRS.

CONCLUSION

Clinicians should promote physical activity to improve CRF so as to reduce CHD risk, even to patients with otherwise low CHD risk.

Cardiorespiratory fitness and the paradoxical BMI-mortality risk association in male veterans

OBJECTIVE

To assess the effect of fitness status on the paradoxical body mass index (BMI)-mortality risk association.

PATIENTS AND METHODS

From February 1, 1986, through December 30, 2011, we assessed fitness and BMI in 18,033 male veterans (mean age, 58.4 ± 11.4 years) in 2 Veterans Affairs Medical centers. We established 3 fitness categories on the basis of peak metabolic equivalents achieved during an exercise test as well as 5 BMI categories. The primary outcome was all-cause mortality.

RESULTS

During the follow-up period (median, 10.8 years, comprising a total of 207,168 person-years), 5070 participants (28%) died. After adjusting for age, risk factors, muscle-wasting diseases, medications, and year of entry, mortality risk was higher for individuals with a BMI of 20.1 to 23.9 kg/m(2) (hazard ratio [HR], 1.21; 95% CI, 1.12-1.30) and 18.5 to 20.0 kg/m(2) (HR, 1.56; 95% CI, 1.37-1.77) than for those with a BMI of 24.0 to 27.9 kg/m(2); mortality risk was not increased for those with a BMI of 28.0 kg/m(2) or greater. When stratified by fitness, the trend was similar for low-fit and moderate-fit individuals. However, mortality risk was not increased for high-fit individuals across BMI categories. When fitness status was considered within each BMI category, mortality risk increased progressively with decreased fitness and was more pronounced for moderate-fit (HR, 2.52; 95% CI, 2.06-3.08) and low-fit (HR, 2.48; 95% CI, 2.0-3.06) individuals with a BMI of 18.5-20.0 kg/m(2). Mortality risk was not significantly increased for high-fit individuals (HR, 1.17; 95% CI, 0.78-1.78; P=.45).

CONCLUSION

A high mortality risk associated with low BMI levels was observed only in moderate-fit and low-fit individuals, and not in high-fit individuals. Thus, fitness greatly affects the paradoxical BMI-mortality risk association. Furthermore, our findings indicate that lower BMI levels do not increase the risk for premature death as long as they are associated with high fitness. Thus, the paradoxically higher mortality risk observed with lower body weight as represented by lower BMI is likely the result of unhealthy reduction in body weight and, perhaps most importantly, considerable loss of lean body mass.