Fitness Important for Cardiovascular Health
News Author: Laurie Barclay, MD
CME Author: Désirée Lie, MD, MSEd
Authors and Disclosures
Release Date: December 16, 2003; Valid for credit through December 16, 2004
Dec. 16, 2003 — Fitness plays an important, independent protective role in cardiovascular health, according to the results of a longitudinal population cohort study published in the Dec. 17 issue of The Journal of the American Medical Association.
, 百拇医药
"Numerous risk factors for cardiovascular disease (CVD), including hypertension, diabetes, and hypercholesterolemia..., are suspected to be influenced by fitness, and these factors may mediate the association between low fitness and mortality," write Mercedes R. Carnethon, PhD, from Northwestern University Feinberg School of Medicine in Chicago, Illinois, and colleagues. "Previous work has demonstrated that engaging in a regular exercise program can improve fitness."
, 百拇医药
The Coronary Artery Risk Development in Young Adults (CARDIA) study recruited 5,115 subjects aged 18 to 30 years from Birmingham, Alabama; Chicago; Minneapolis, Minnesota; and Oakland, California. Of the subjects who completed a treadmill examination at baseline and were followed from 1985-1986 to 2000-2001, 2,478 subjects repeated the exercise test in 1992-1993.
Compared with subjects at or above the 60th percentile on the exercise treadmill test, subjects below the 20th percentile were three- to six-fold more likely to develop diabetes, hypertension, and metabolic syndrome, after adjustment for age, race, sex, smoking, and family history of diabetes, hypertension, or premature myocardial infarction (P < .001 for all). Adjusting for baseline body mass (BMI) index reduced these risks to two-fold (P < .001).
, 百拇医药
Although improved fitness over seven years was associated with decreased risk of developing diabetes (P < .04) and metabolic syndrome (P < .001), adjusting for changes in weight reduced the strength and significance of these associations.
Study limitations include use of treadmill test duration as an estimate of fitness, possible practice effect on treadmill testing, and failure to account for genetic contributions to fitness.
, 百拇医药 "Our findings demonstrate the importance of low cardiorespiratory fitness in young adulthood as a risk factor for developing cardiovascular comorbidities in middle age," the authors write. "If the association between fitness and CVD risk factor development is causal, and if all unfit young adults had been fit, there may have been 21% to 28% fewer cases of hypertension, diabetes, and metabolic syndrome. Given the current obesity epidemic and observations of a decline in daily energy expenditure in the population, improving cardiorespiratory fitness in young men and women and developing public health policies that encourage physical activity should be important health policy goals."
, http://www.100md.com
The National Institutes of Health partially supported this study. The National Heart, Lung, and Blood Institute helped support Dr. Carnethon through a career development award.
JAMA. 2003;290:3092-3100
Learning Objectives
Upon completion of this activity, participants will be able to:
Describe the role of fitness in the determination of CVD risk factors.
, 百拇医药
Identify the link between fitness and obesity in the development of these risk factors.
Clinical Context
Fitness and body mass have been implicated in the development of CVD risk factors such as hypertension, diabetes, metabolic syndrome, and hypercholesterolemia. One study by Petrella and colleagues, published in the May 2003 issue of the American Journal of Preventive Medicine, has demonstrated that engaging in regular exercise can improve fitness. An association between mortality and fitness has been shown in a study by Wei and colleagues, published in the Oct. 27, 1999, issue of JAMA. But the association between body mass and fitness and the attenuating effect of obesity on fitness as an independent variable have not previously been fully examined.
, 百拇医药
Physical fitness can promote muscle insulin sensitivity, transport of glucose, autonomic function, lower heart rate, and leaner body mass, all contributing to lower incidence of CVD risk factors. Promoting fitness in the general population is thus of public health importance for the prevention of CVD mortality and morbidity.
This population-based, longitudinal cohort study of healthy adults aged 18 to 30 years in the CARDIA study examined the effect of physical fitness and improvement in physical fitness over seven years on the incidence of CVD risk factors. The association between fitness and obesity on these risk factors was also examined.
, 百拇医药
Study Highlights
1. Of 5,112 participants recruited from 4 geographic areas between 1985 and 1986, those who successfully completed treadmill stress testing were followed at years 2, 5, 7, 10, and 15. A subset of 2,478 participants had repeat treadmill testing at 7 years.
2. Exclusion criteria were inability to complete treadmill testing, pregnancy, those with existing CVD or risk factors for CVD and those using beta-blockers.
, http://www.100md.com
3. Fitness was defined as duration of the treadmill test using the modified Balke protocol. Subjects were classified by quintiles into a "low fitness" (< 20th percentile) to high fitness (>/= 60th percentile) categories.
4. At baseline and follow-up, participants provided a medical history of CVD risk factors; blood pressure, BMI, and waist circumference measurements; fasting glucose levels; and complete lipid panels.
5. Change in fitness was calculated as the difference in treadmill test duration between baseline and year 7.
, 百拇医药
6. Incidence of each CVD risk factor was identified as a diagnosis of any of the conditions at follow-up. Diabetes was defined as a fasting glucose of 126 mg/dL; obesity as a BMI of 30 kg/m2; hypertension a blood pressure of 140/90 mm Hg, and hypercholesterolemia and metabolic syndrome by the criteria of the National Cholesterol Education Program/Adult Treatment Panel III.
7. Incidence rates were calculated using Poisson regression, and Cox proportional hazards regression was used to evaluate risk factor by fitness category. The hazards ratio (HR) for CVD morbidity and population attributable to low fitness were calculated.
, 百拇医药
8. Adjustments were made for age, sex, race, smoking, and family history of CVD in the analysis.
9. At baseline, less-fit women were slightly older, had lower education, and less favorable CVD risk factors than moderate- and high-fitness groups, with similar associations seen in men.
10. The incidence of diabetes, hypertension, metabolic syndrome, and hypercholesterolemia were 2.8, 13.0, 10.2, and 11.7 per 1,000 person-years, respectively.
, 百拇医药
11. The distribution of fitness varied by obesity status. Only 13% of nonobese participants were in the low-fitness category compared with 68% of obese participants.
12. Obesity emerged as an effect modifier for the association between fitness and the development of diabetes and metabolic syndrome, with evidence of a dose response.
13. The low-fitness subjects were 3- to 6-fold more likely to develop diabetes, hypertension, and metabolic syndrome than the high-fitness subjects (P < .001). Adjusting for baseline BMI diminished the strength of the association 2-fold (P < .001).
, 百拇医药
14. Low-fitness level was only weakly associated with hypercholesterolemia (HR, 1.4; 95% confidence interval [CI], 1.1 - 1.7; P = .02), and this association decreased to marginal significance after adjustment for BMI (P = .13).
15. Participants who repeated the treadmill test gained an average of 7 kg at 7 years and 12.7 kg at 15 years.
16. Improved fitness over 7 years was associated with reduced risk of developing diabetes (HR, 0.4; 95% CI, 0.2 - 1.0; P = .04) and metabolic syndrome (HR, 0.5; 95% CI, 0.3 - 0.7; P < .001), but the strength of this association was also reduced after accounting for changes in weight.
, 百拇医药
17. Improved fitness over 7 years did not reduce the incidence of hypertension or hypercholesterolemia.
18. The rate of developing hypertension, diabetes, and metabolic syndrome remained double among participants in the low-fitness category whose fitness level remained unchanged at 7 years compared with participants in the high-fitness category.
Pearls for Practice
1. The protective effect of fitness on CVD risk factors is partially linked to body mass and weight maintenance.
2. Improving fitness over seven years modifies the risk for diabetes and metabolic syndrome but not for hypertension or hypercholesterolemia., http://www.100md.com
CME Author: Désirée Lie, MD, MSEd
Authors and Disclosures
Release Date: December 16, 2003; Valid for credit through December 16, 2004
Dec. 16, 2003 — Fitness plays an important, independent protective role in cardiovascular health, according to the results of a longitudinal population cohort study published in the Dec. 17 issue of The Journal of the American Medical Association.
, 百拇医药
"Numerous risk factors for cardiovascular disease (CVD), including hypertension, diabetes, and hypercholesterolemia..., are suspected to be influenced by fitness, and these factors may mediate the association between low fitness and mortality," write Mercedes R. Carnethon, PhD, from Northwestern University Feinberg School of Medicine in Chicago, Illinois, and colleagues. "Previous work has demonstrated that engaging in a regular exercise program can improve fitness."
, 百拇医药
The Coronary Artery Risk Development in Young Adults (CARDIA) study recruited 5,115 subjects aged 18 to 30 years from Birmingham, Alabama; Chicago; Minneapolis, Minnesota; and Oakland, California. Of the subjects who completed a treadmill examination at baseline and were followed from 1985-1986 to 2000-2001, 2,478 subjects repeated the exercise test in 1992-1993.
Compared with subjects at or above the 60th percentile on the exercise treadmill test, subjects below the 20th percentile were three- to six-fold more likely to develop diabetes, hypertension, and metabolic syndrome, after adjustment for age, race, sex, smoking, and family history of diabetes, hypertension, or premature myocardial infarction (P < .001 for all). Adjusting for baseline body mass (BMI) index reduced these risks to two-fold (P < .001).
, 百拇医药
Although improved fitness over seven years was associated with decreased risk of developing diabetes (P < .04) and metabolic syndrome (P < .001), adjusting for changes in weight reduced the strength and significance of these associations.
Study limitations include use of treadmill test duration as an estimate of fitness, possible practice effect on treadmill testing, and failure to account for genetic contributions to fitness.
, 百拇医药 "Our findings demonstrate the importance of low cardiorespiratory fitness in young adulthood as a risk factor for developing cardiovascular comorbidities in middle age," the authors write. "If the association between fitness and CVD risk factor development is causal, and if all unfit young adults had been fit, there may have been 21% to 28% fewer cases of hypertension, diabetes, and metabolic syndrome. Given the current obesity epidemic and observations of a decline in daily energy expenditure in the population, improving cardiorespiratory fitness in young men and women and developing public health policies that encourage physical activity should be important health policy goals."
, http://www.100md.com
The National Institutes of Health partially supported this study. The National Heart, Lung, and Blood Institute helped support Dr. Carnethon through a career development award.
JAMA. 2003;290:3092-3100
Learning Objectives
Upon completion of this activity, participants will be able to:
Describe the role of fitness in the determination of CVD risk factors.
, 百拇医药
Identify the link between fitness and obesity in the development of these risk factors.
Clinical Context
Fitness and body mass have been implicated in the development of CVD risk factors such as hypertension, diabetes, metabolic syndrome, and hypercholesterolemia. One study by Petrella and colleagues, published in the May 2003 issue of the American Journal of Preventive Medicine, has demonstrated that engaging in regular exercise can improve fitness. An association between mortality and fitness has been shown in a study by Wei and colleagues, published in the Oct. 27, 1999, issue of JAMA. But the association between body mass and fitness and the attenuating effect of obesity on fitness as an independent variable have not previously been fully examined.
, 百拇医药
Physical fitness can promote muscle insulin sensitivity, transport of glucose, autonomic function, lower heart rate, and leaner body mass, all contributing to lower incidence of CVD risk factors. Promoting fitness in the general population is thus of public health importance for the prevention of CVD mortality and morbidity.
This population-based, longitudinal cohort study of healthy adults aged 18 to 30 years in the CARDIA study examined the effect of physical fitness and improvement in physical fitness over seven years on the incidence of CVD risk factors. The association between fitness and obesity on these risk factors was also examined.
, 百拇医药
Study Highlights
1. Of 5,112 participants recruited from 4 geographic areas between 1985 and 1986, those who successfully completed treadmill stress testing were followed at years 2, 5, 7, 10, and 15. A subset of 2,478 participants had repeat treadmill testing at 7 years.
2. Exclusion criteria were inability to complete treadmill testing, pregnancy, those with existing CVD or risk factors for CVD and those using beta-blockers.
, http://www.100md.com
3. Fitness was defined as duration of the treadmill test using the modified Balke protocol. Subjects were classified by quintiles into a "low fitness" (< 20th percentile) to high fitness (>/= 60th percentile) categories.
4. At baseline and follow-up, participants provided a medical history of CVD risk factors; blood pressure, BMI, and waist circumference measurements; fasting glucose levels; and complete lipid panels.
5. Change in fitness was calculated as the difference in treadmill test duration between baseline and year 7.
, 百拇医药
6. Incidence of each CVD risk factor was identified as a diagnosis of any of the conditions at follow-up. Diabetes was defined as a fasting glucose of 126 mg/dL; obesity as a BMI of 30 kg/m2; hypertension a blood pressure of 140/90 mm Hg, and hypercholesterolemia and metabolic syndrome by the criteria of the National Cholesterol Education Program/Adult Treatment Panel III.
7. Incidence rates were calculated using Poisson regression, and Cox proportional hazards regression was used to evaluate risk factor by fitness category. The hazards ratio (HR) for CVD morbidity and population attributable to low fitness were calculated.
, 百拇医药
8. Adjustments were made for age, sex, race, smoking, and family history of CVD in the analysis.
9. At baseline, less-fit women were slightly older, had lower education, and less favorable CVD risk factors than moderate- and high-fitness groups, with similar associations seen in men.
10. The incidence of diabetes, hypertension, metabolic syndrome, and hypercholesterolemia were 2.8, 13.0, 10.2, and 11.7 per 1,000 person-years, respectively.
, 百拇医药
11. The distribution of fitness varied by obesity status. Only 13% of nonobese participants were in the low-fitness category compared with 68% of obese participants.
12. Obesity emerged as an effect modifier for the association between fitness and the development of diabetes and metabolic syndrome, with evidence of a dose response.
13. The low-fitness subjects were 3- to 6-fold more likely to develop diabetes, hypertension, and metabolic syndrome than the high-fitness subjects (P < .001). Adjusting for baseline BMI diminished the strength of the association 2-fold (P < .001).
, 百拇医药
14. Low-fitness level was only weakly associated with hypercholesterolemia (HR, 1.4; 95% confidence interval [CI], 1.1 - 1.7; P = .02), and this association decreased to marginal significance after adjustment for BMI (P = .13).
15. Participants who repeated the treadmill test gained an average of 7 kg at 7 years and 12.7 kg at 15 years.
16. Improved fitness over 7 years was associated with reduced risk of developing diabetes (HR, 0.4; 95% CI, 0.2 - 1.0; P = .04) and metabolic syndrome (HR, 0.5; 95% CI, 0.3 - 0.7; P < .001), but the strength of this association was also reduced after accounting for changes in weight.
, 百拇医药
17. Improved fitness over 7 years did not reduce the incidence of hypertension or hypercholesterolemia.
18. The rate of developing hypertension, diabetes, and metabolic syndrome remained double among participants in the low-fitness category whose fitness level remained unchanged at 7 years compared with participants in the high-fitness category.
Pearls for Practice
1. The protective effect of fitness on CVD risk factors is partially linked to body mass and weight maintenance.
2. Improving fitness over seven years modifies the risk for diabetes and metabolic syndrome but not for hypertension or hypercholesterolemia., http://www.100md.com