Duck-chul Lee

Long-Term Effects of Changes in Cardiorespiratory Fitness and Body Mass Index on All-Cause and Cardiovascular Disease Mortality in Men The Aerobics Center Longitudinal Study

Background— The combined associations of changes in cardiorespiratory fitness and body mass index (BMI) with mortality remain controversial and uncertain. Methods and Results— We examined the independent and combined associations of changes in fitness and BMI with all-cause and cardiovascular disease (CVD) mortality in 14 345 men (mean age 44 years) with at least 2 medical examinations. Fitness, in metabolic equivalents (METs), was estimated from a maximal treadmill test. BMI was calculated using measured weight and height. Changes in fitness and BMI between the baseline and last examinations over 6.3 years were classified into loss, stable, or gain groups. During 11.4 years of follow-up after the last examination, 914 all-cause and 300 CVD deaths occurred. The hazard ratios (95% confidence intervals) of all-cause and CVD mortality were 0.70 (0.59–0.83) and 0.73 (0.54–0.98) for stable fitness, and 0.61 (0.51–0.73) and 0.58 (0.42–0.80) for fitness gain, respectively, compared with fitness loss in multivariable analyses including BMI change. Every 1-MET improvement was associated with 15% and 19% lower risk of all-cause and CVD mortality, respectively. BMI change was not associated with all-cause or CVD mortality after adjusting for possible confounders and fitness change. In the combined analyses, men who lost fitness had higher all-cause and CVD mortality risks regardless of BMI change. Conclusions— Maintaining or improving fitness is associated with a lower risk of all-cause and CVD mortality in men. Preventing age-associated fitness loss is important for longevity regardless of BMI change.

Mortality trends in the general population: the importance of cardiorespiratory fitness

Cardiorespiratory fitness (CRF) is not only an objective measure of habitual physical activity, but also a useful diagnostic and prognostic health indicator for patients in clinical settings. Although compelling evidence has shown that CRF is a strong and independent predictor of all-cause and cardiovascular disease mortality, the importance of CRF is often overlooked from a clinical perspective compared with other risk factors such as hypertension, diabetes, smoking, or obesity. Several prospective studies indicate that CRF is at least as important as the traditional risk factors, and is often more strongly associated with mortality. In addition, previous studies report that CRF appears to attenuate the increased risk of death associated with obesity. Most individuals can improve their CRF through regular physical activity. Several biological mechanisms suggest that CRF improves insulin sensitivity, blood lipid profile, body composition, inflammation, and blood pressure. Based on the evidence, health professionals should encourage their patients to improve CRF through regular physical activity.

The intriguing metabolically healthy but obese phenotype: cardiovascular prognosis and role of fitness

AIMS Current knowledge on the prognosis of metabolically healthy but obese phenotype is limited due to the exclusive use of the body mass index to define obesity and the lack of information on cardiorespiratory fitness. We aimed to test the following hypotheses: (i) metabolically healthy but obese individuals have a higher fitness level than their metabolically abnormal and obese peers; (ii) after accounting for fitness, metabolically healthy but obese phenotype is a benign condition, in terms of cardiovascular disease and mortality. METHODS AND RESULTS Fitness was assessed by a maximal exercise test on a treadmill and body fat per cent (BF%) by hydrostatic weighing or skinfolds (obesity = BF% ≥ 25 or ≥ 30%, men or women, respectively) in 43 265 adults (24.3% women). Metabolically healthy was considered if meeting 0 or 1 of the criteria for metabolic syndrome. Metabolically healthy but obese participants (46% of the obese subsample) had a better fitness than metabolically abnormal obese participants (P < 0.001). When adjusting for fitness and other confounders, metabolically healthy but obese individuals had lower risk (30-50%, estimated by hazard ratios) of all-cause mortality, non-fatal and fatal cardiovascular disease, and cancer mortality than their metabolically unhealthy obese peers; while no significant differences were observed between metabolically healthy but obese and metabolically healthy normal-fat participants. CONCLUSIONS (i) Higher fitness should be considered a characteristic of metabolically healthy but obese phenotype. (ii) Once fitness is accounted for, the metabolically healthy but obese phenotype is a benign condition, with a better prognosis for mortality and morbidity than metabolically abnormal obese individuals.

Leisure-Time Running Reduces All-Cause and Cardiovascular Mortality Risk

BACKGROUND Although running is a popular leisure-time physical activity, little is known about the long-term effects of running on mortality. The dose-response relations between running, as well as the change in running behaviors over time, and mortality remain uncertain. OBJECTIVES We examined the associations of running with all-cause and cardiovascular mortality risks in 55,137 adults, 18 to 100 years of age (mean age 44 years). METHODS Running was assessed on a medical history questionnaire by leisure-time activity. RESULTS During a mean follow-up of 15 years, 3,413 all-cause and 1,217 cardiovascular deaths occurred. Approximately 24% of adults participated in running in this population. Compared with nonrunners, runners had 30% and 45% lower adjusted risks of all-cause and cardiovascular mortality, respectively, with a 3-year life expectancy benefit. In dose-response analyses, the mortality benefits in runners were similar across quintiles of running time, distance, frequency, amount, and speed, compared with nonrunners. Weekly running even <51 min, <6 miles, 1 to 2 times, <506 metabolic equivalent-minutes, or <6 miles/h was sufficient to reduce risk of mortality, compared with not running. In the analyses of change in running behaviors and mortality, persistent runners had the most significant benefits, with 29% and 50% lower risks of all-cause and cardiovascular mortality, respectively, compared with never-runners. CONCLUSIONS Running, even 5 to 10 min/day and at slow speeds <6 miles/h, is associated with markedly reduced risks of death from all causes and cardiovascular disease. This study may motivate healthy but sedentary individuals to begin and continue running for substantial and attainable mortality benefits.

Comparisons of leisure-time physical activity and cardiorespiratory fitness as predictors of all-cause mortality in men and women

Objective To examine the combined associations and relative contributions of leisure-time physical activity (PA) and cardiorespiratory fitness (CRF) with all-cause mortality. Design Prospective cohort study. Setting Aerobics centre longitudinal study. Participants 31 818 men and 10 555 women who received a medical examination during 1978–2002. Assessment of risk factors Leisure-time PA assessed by self-reported questionnaire; CRF assessed by maximal treadmill test. Main outcome measures All-cause mortality until 31 December 2003. Results There were 1492 (469 per 10 000) and 230 (218 per 10 000) deaths in men and women, respectively. PA and CRF were positively correlated in men (r=0.49) and women (r=0.47) controlling for age (p<0.001 for both). PA was inversely associated with mortality in multivariable Cox regression analysis among men, but the association was eliminated after further adjustment for CRF. No significant association of PA with mortality was observed in women. CRF was inversely associated with mortality in men and women, and the associations remained significant after further adjustment for PA. In the PA and CRF combined analysis, compared with the reference group “not meeting the recommended PA (<500 metabolic equivalent-minute/week) and unfit”, the relative risks (95% CIs) of mortality were 0.62 (0.54 to 0.72) and 0.61 (0.44 to 0.86) in men and women “not meeting the recommended PA and fit”, 0.96 (0.61 to 1.53) and 0.93 (0.33 to 2.58) in men and women “meeting the recommended PA and unfit” and 0.60 (0.51 to 0.70) and 0.56 (0.37 to 0.85) in men and women “meeting the recommended PA and fit”, respectively. Conclusions CRF was more strongly associated with all-cause mortality than PA; therefore, improving CRF should be encouraged in unfit individuals to reduce risk of mortality and considered in the development of future PA guidelines.

Exercise and the Cardiovascular System: Clinical Science and Cardiovascular Outcomes

Substantial evidence has established the value of high levels of physical activity, exercise training (ET), and overall cardiorespiratory fitness in the prevention and treatment of cardiovascular diseases. This article reviews some basics of exercise physiology and the acute and chronic responses of ET, as well as the effect of physical activity and cardiorespiratory fitness on cardiovascular diseases. This review also surveys data from epidemiological and ET studies in the primary and secondary prevention of cardiovascular diseases, particularly coronary heart disease and heart failure. These data strongly support the routine prescription of ET to all patients and referrals for patients with cardiovascular diseases, especially coronary heart disease and heart failure, to specific cardiac rehabilitation and ET programs.

The obesity paradox, cardiorespiratory fitness, and coronary heart disease.

OBJECTIVE To investigate associations of cardiorespiratory fitness (CRF) and different measures of adiposity with cardiovascular disease (CVD) and all-cause mortality in men with known or suspected coronary heart disease (CHD). PATIENTS AND METHODS We analyzed data from 9563 men (mean age, 47.4 years) with documented or suspected CHD in the Aerobics Center Longitudinal Study (August 13, 1977, to December 30, 2002) using baseline body mass index (BMI) and CRF (quantified as the duration of a symptom-limited maximal treadmill exercise test). Waist circumference (WC) and percent body fat (BF) were measured using standard procedures. RESULTS There were 733 deaths (348 of CVD) during a mean follow-up of 13.4 years. After adjustment for age, examination year, and multiple baseline risk factors, men with low fitness had a higher risk of all-cause mortality in the BMI categories of normal weight (hazard ratio [HR], 1.60; 95% confidence interval [CI], 1.24-2.05), obese class I (HR, 1.38; 95% CI, 1.04-1.82), and obese class II/III (HR, 2.43; 95% CI, 1.55-3.80) but not overweight (HR, 1.09; 95% CI, 0.88-1.36) compared with the normal-weight and high-fitness reference group. We observed a similar pattern for WC and percent BF tertiles and for CVD mortality. Among men with high fitness, there were no significant differences in CVD and all-cause mortality risk across BMI, WC, and percent BF categories. CONCLUSION In men with documented or suspected CHD, CRF greatly modifies the relation of adiposity to mortality. Using adiposity to assess mortality risk in patients with CHD may be misleading unless fitness is considered.

Effects of Muscular Strength on Cardiovascular Risk Factors and Prognosis

Physical fitness is one of the strongest predictors of individual future health status. Together with cardiorespiratory fitness (CRF), muscular strength has been increasingly recognized in the pathogenesis and prevention of chronic disease. We review the most recent literature on the effect of muscular strength in the development of cardiovascular disease, with special interest in elucidating its specific benefits beyond those from CRF and body composition. Muscular strength has shown an independent protective effect on all-cause and cancer mortality in healthy middle-aged men, as well as in men with hypertension and patients with heart failure. It has also been inversely associated with age-related weight and adiposity gains, risk of hypertension, and prevalence and incidence of the metabolic syndrome. In children and adolescents, higher levels of muscular fitness have been inversely associated with insulin resistance, clustered cardiometabolic risk, and inflammatory proteins. Generally, the influence of muscular fitness was weakened but remained protective after considering CRF. Also, interestingly, higher levels of muscular fitness seems to some extent counteract the adverse cardiovascular profile of overweight and obese individuals. As many of the investigations have been conducted with non-Hispanic white men, it is important to examine how race/ethnicity and gender may affect these relationships. To conclude, most important effects of resistance training are also summarized, to better understand how higher levels of muscular fitness may result in a better cardiovascular prognosis and survival.

Changes in Fitness and Fatness on the Development of Cardiovascular Disease Risk Factors: Hypertension, Metabolic Syndrome, and Hypercholesterolemia

OBJECTIVES This study sought examine the independent and combined associations of changes in fitness and fatness with the subsequent incidence of the cardiovascular disease (CVD) risk factors of hypertension, metabolic syndrome, and hypercholesterolemia. BACKGROUND The relative and combined contributions of fitness and fatness to health are controversial, and few studies are available on the associations of changes in fitness and fatness with the development of CVD risk factors. METHODS We followed up 3,148 healthy adults who received at least 3 medical examinations. Fitness was determined by using a maximal treadmill test. Fatness was expressed by percent body fat and body mass index. Changes in fitness and fatness between the first and second examinations were categorized into loss, stable, or gain groups. RESULTS During the 6-year follow-up after the second examination, 752, 426, and 597 adults developed hypertension, metabolic syndrome, and hypercholesterolemia, respectively. Maintaining or improving fitness was associated with lower risk of developing each outcome, whereas increasing fatness was associated with higher risk of developing each outcome, after adjusting for possible confounders and fatness or fitness for each other (all p for trend <0.05). In the joint analyses, the increased risks associated with fat gain appeared to be attenuated, although not completely eliminated, when fitness was maintained or improved. In addition, the increased risks associated with fitness loss were also somewhat attenuated when fatness was reduced. CONCLUSIONS Both maintaining or improving fitness and preventing fat gain are important to reduce the risk of developing CVD risk factors in healthy adults.

. A prospective study of muscular strength and all-cause mortality in men with hypertension.

OBJECTIVES This study sought to assess the impact of muscular strength on mortality in men with hypertension. BACKGROUND Muscular strength is inversely associated with mortality in healthy men, but this association has not been examined in men with hypertension. METHODS We followed 1,506 hypertensive men age 40 years and older enrolled in the Aerobics Center Longitudinal Study from 1980 to 2003. Participants received an extensive medical examination at baseline. Muscular strength was quantified by combining 1 repetition maximum (1-RM) measures for leg and bench press and cardiorespiratory fitness assessed by maximum exercise test on a treadmill. RESULTS During an average follow-up of 18.3 years, 183 deaths occurred. Age-adjusted death rates per 10,000 person-years across incremental thirds of muscular strength were 81.8, 65.5, and 52.0 (p < 0.05 for linear trend). Multivariable Cox regression hazard ratios were 1.0 (reference), 0.81 (95% confidence interval [CI]: 0.57 to 1.14), and 0.59 (95% CI: 0.40 to 0.86) across incremental thirds of muscular strength. After further adjustment for cardiorespiratory fitness, those participants in the upper third of muscular strength still had a lower risk of death (hazard ratio [HR]: 0.66; 95% CI: 0.45 to 0.98). In the muscular strength and CRF combined analysis, men simultaneously in the upper third of muscular strength and high fitness group had the lowest mortality risk among all combination groups (HR: 0.49; 95% CI: 0.30 to 0.82), with men in the lower third of muscular strength and low fitness group as reference. CONCLUSIONS High levels of muscular strength appear to protect hypertensive men against all-cause mortality, and this is in addition to the benefit provided by cardiorespiratory fitness.