Cardiorespiratory fitness and coronary heart disease risk factor association in women

Association between Leisure Time Physical Activity and HDL-C in the Elsa-Brasil Study Participants: Are There Any Gender Differences in the Dose-Response Effect?

BACKGROUND

High levels of high-density lipoprotein (HDL-C) are known for their protective effect against cardiovascular diseases and the regular practice of leisure time physical activity (LTPA) may be associated with their increase.

OBJECTIVE

To verify the existence of differences between genders in the dose-response effect regarding the association between LTPA and HDL-C in the ELSA-Brasil study cohort.

METHODS

Cross-sectional study with data from wave 2 of 13,931 participants of both genders (7,607 women) from the Longitudinal Study of Adult Health ELSA-Brasil. The LTPA was measured using the International Physical Activity Questionnaire (IPAQ) and classified into four categories: sedentary, low active, active and very active. The discriminatory power of LTPA at different intensities analyzed for high HDL-C was tested using ROC curves. Associations, adjusted for confounders between LTPA and HDL-C were analyzed by logistic regression. A 95% confidence interval was used.

RESULTS

A positive association, with a dose-response effect, was observed between LTPA and HDL-C in both men and women. With regard to intensity, only vigorous physical activity discriminated high HDL-C in men, while both walking and moderate and vigorous physical activity discriminated high HDL-C in women.

CONCLUSIONS

LTPA shows a positive association with gradient dose-response and HDL-C, but in men, the association is not observed for those classified as physically unfit. In women, both walking intensity and moderate or vigorous physical activity can discriminate high HDL-C levels, whereas only vigorous intensity-exercise discriminate elevated HDL-C levels in men, demonstrating that males need to do more physical activity for this benefit to be observed.

Cardiorespiratory Fitness and Mortality in Healthy Men and Women

BACKGROUND

There is a well-established inverse relationship between cardiorespiratory fitness (CRF) and mortality. However, this relationship has almost exclusively been studied using estimated CRF.

OBJECTIVES

This study aimed to assess the association of directly measured CRF, obtained using cardiopulmonary exercise (CPX) testing with all-cause, cardiovascular disease (CVD), and cancer mortality in apparently healthy men and women.

METHODS

Participants included 4,137 self-referred apparently healthy adults (2,326 men, 1,811 women; mean age: 42.8 ± 12.2 years) who underwent CPX testing to determine baseline CRF. Participants were followed for 24.2 ± 11.7 years (1.1 to 49.3 years) for mortality. Cox-proportional hazard models were performed to determine the relationship of CRF (ml·kg^-1·min^-1) and CRF level (low, moderate, and high) with mortality outcomes.

RESULTS

During follow-up, 727 participants died (524 men, 203 women). CPX-derived CRF was inversely related to all-cause, CVD, and cancer mortality. Low CRF was associated with higher risk for all-cause (hazard ratio [HR]: 1.73; 95% confidence interval [CI]: 1.20 to 3.50), CVD (HR: 2.27; 95% CI: 1.20 to 3.49), and cancer (HR: 2.07; 95% CI: 1.18 to 3.36) mortality compared with high CRF. Further, each metabolic equivalent increment increase in CRF was associated with a 11.6%, 16.1%, and 14.0% reductions in all-cause, CVD, and cancer mortality, respectively.

CONCLUSIONS

Given the prognostic ability of CPX-derived CRF for all-cause and disease-specific mortality outcomes, its use should be highly considered for apparently healthy populations as it may help to improve the efficacy of the individualized patient risk assessment and guide clinical decisions.

Primary Prevention of Atherosclerotic Cardiovascular Disease in Women

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of morbidity and mortality among women. Despite improvements in cardiovascular disease prevention efforts, there remain gaps in cardiovascular disease awareness among women, as well as age and racial disparities in ASCVD outcomes for women. Disparity also exists in the impact the traditional risk factors confer on ASCVD risk between women and men, with smoking and diabetes both resulting in stronger relative risks in women compared to men. Additionally there are risk factors that are unique to women (such as pregnancy-related factors) or that disproportionally affect women (such as auto-immune disease) where preventive efforts should be targeted. Risk assessment and management must also be sex-specific to effectively reduce cardiovascular disease and improve outcomes among women. Evidence supports the use of statin therapy for primary prevention in women at higher ASCVD risk. However, some pause should be given to prescribing aspirin therapy in women without known ASCVD, with most evidence supporting the use of aspirin for women≥65 years not at increased risk for bleeding. This review article will summarize (1) traditional and non-traditional assessments of ASCVD risk and (2) lifestyle and pharmacologic therapies for the primary prevention of ASCVD in women.

Guidelines for the primary prevention of stroke: a statement for healthcare professionals from the American Heart Association/American Stroke Association

The aim of this updated statement is to provide comprehensive and timely evidence-based recommendations on the prevention of stroke among individuals who have not previously experienced a stroke or transient ischemic attack. Evidence-based recommendations are included for the control of risk factors, interventional approaches to atherosclerotic disease of the cervicocephalic circulation, and antithrombotic treatments for preventing thrombotic and thromboembolic stroke. Further recommendations are provided for genetic and pharmacogenetic testing and for the prevention of stroke in a variety of other specific circumstances, including sickle cell disease and patent foramen ovale.

Associations of cardiorespiratory fitness with cardiovascular disease risk factors in middle-aged Chinese women: a cross-sectional study

Background

High levels of physical activity (PA) and cardiorespiratory fitness (CRF) are each associated with a favorable cardiovascular disease (CVD) risk profile. However, the relationship between CRF and obesity is still inconsistent across studies, and there has been no thorough exploration of the independent contribution of CRF to different CVD risk factors in Chinese women. This study investigated the relationship between CRF and CVD risk factors in 40–49 year old women in Beijing.

Methods

The study included 231 urban-dwelling asymptomatic 40–49 year old women. Body mass index (BMI), body fat percentage (BF%), blood glucose, blood lipids, blood pressure, and pulse wave velocity (PWV) were measured at rest. Cycle ergometer exercise tests were conducted to assess CRF as indicated by maximal oxygen uptake (VO_2max). Participants were categorized into three CRF levels (low, moderate and high).

Results

High CRF level was associated with significantly less BF%, lower PWV, and higher weekly physical activity compared with low and moderate CRF (P < 0.05). Compared to high CRF, the odds ratios for having ≥3 main CVD risk factors (overweight, hypertension, and dyslipidemia) in low and moderate CRF were 2.09 (95% CI: 1.48-2.94) and 1.84 (95% CI: 1.29-2.62), respectively. The proportion of participants with clinical ST segment depression and prolonged QTC interval during cycle ergometer testing was significantly higher in women with low CRF.

Conclusions

Overall, Chinese middle-aged women demonstrated a moderate level of CRF. CRF was independently associated with CVD risk factors, including overweight, hypertension, dyslipidemia, arterial stiffness, and abnormal ECG during exercise, with the least fit women exhibiting the highest number of CVD risk factors.

Physical activity, health benefits, and mortality risk

A plethora of epidemiologic evidence from large studies supports unequivocally an inverse, independent, and graded association between volume of physical activity, health, and cardiovascular and overall mortality. This association is evident in apparently healthy individuals, patients with hypertension, type 2 diabetes mellitus, and cardiovascular disease, regardless of body weight. Moreover, the degree of risk associated with physical inactivity is similar to, and in some cases even stronger than, the more traditional cardiovascular risk factors. The exercise-induced health benefits are in part related to favorable modulations of cardiovascular risk factors observed by increased physical activity or structured exercise programs. Although the independent contribution of the exercise components, intensity, duration, and frequency to the reduction of mortality risk is not clear, it is well accepted that an exercise volume threshold defined at caloric expenditure of approximately 1,000 Kcal per week appears to be necessary for significant reduction in mortality risk. Further reductions in risk are observed with higher volumes of energy expenditure. Physical exertion is also associated with a relatively low and transient increase in risk for cardiac events. This risk is significantly higher for older and sedentary individuals. Therefore, such individuals should consult their physician prior to engaging in exercise.

“Walking is man’s best medicine”

Hippocrates

A study on how a 6-month aerobic exercise program can modify coronary risk factors depending on their severity in middle-aged sedentary women

It is well known that physical exercise can reduce coronary risk factors. But how an aerobic exercise modifies coronary risk factors in relation to severity and physical fitness is still controversial.Fifty-four middle-aged women (mean age, 55 years) completed a 6-month on-site and home-based anaerobic threshold-level exercise program. The changes in coronary risk factor profiles were observed during the pre-intervention and intervention periods. Before the intervention (during control period), most coronary risk factors showed a rather unfavorable trend. After the program, their mean body weight decreased from 56.7 to 55.7 kg (p>0.05) and the proportion of body fat from 30.9 to 27.9% (p>0.05) without any reduction in lean body mass. Systolic blood pressure (SBP) decreased from 129.0 to 125.0 mm Hg (p>0.05) and diastolic blood pressure from 79.5 to 76.6 mm Hg (p>0.05). Fasting plasma glucose (FPG) declined from 109.6 to 103.4 mg/dl (p>0.05). Changes in SBP and FPG were most remarkable in their respective worst tertile. Serum lipids improved only modestly. Maximum oxygen uptake increased from 23.6 to 26.1 ml/kg/min (p>0.01). However, no significant correlations were found between changes in coronary risk factors and those in physical fitness. We conclude that the 6-month aerobic exercise program would modify women's coronary risk factors depending on their initial values, probably independently of the changes in physical fitness.

Physical inactivity and mortality risk

In recent years a plethora of epidemiologic evidence accumulated supports a strong, independent and inverse, association between physical activity and the fitness status of an individual and mortality in apparently healthy individuals and diseased populations. These health benefits are realized at relatively low fitness levels and increase with higher physical activity patterns or fitness status in a dose-response fashion. The risk reduction is at least in part attributed to the favorable effect of exercise or physical activity on the cardiovascular risk factors, namely, blood pressure, diabetes mellitus and obesity. In this review, we examine evidence from epidemiologic and interventional studies in support of the association between exercise and physical activity and health. In addition, we present the exercise effects on the aforementioned risk factors. Finally, we include select dietary approaches and their impact on risk factors and overall mortality risk.

Guidelines for the primary prevention of stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association

BACKGROUND AND PURPOSE

This guideline provides an overview of the evidence on established and emerging risk factors for stroke to provide evidence-based recommendations for the reduction of risk of a first stroke.

METHODS

Writing group members were nominated by the committee chair on the basis of their previous work in relevant topic areas and were approved by the American Heart Association (AHA) Stroke Council Scientific Statement Oversight Committee and the AHA Manuscript Oversight Committee. The writing group used systematic literature reviews (covering the time since the last review was published in 2006 up to April 2009), reference to previously published guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulate recommendations using standard AHA criteria (Tables 1 and 2). All members of the writing group had the opportunity to comment on the recommendations and approved the final version of this document. The guideline underwent extensive peer review by the Stroke Council leadership and the AHA scientific statements oversight committees before consideration and approval by the AHA Science Advisory and Coordinating Committee.

RESULTS

Schemes for assessing a person's risk of a first stroke were evaluated. Risk factors or risk markers for a first stroke were classified according to potential for modification (nonmodifiable, modifiable, or potentially modifiable) and strength of evidence (well documented or less well documented). Nonmodifiable risk factors include age, sex, low birth weight, race/ethnicity, and genetic predisposition. Well-documented and modifiable risk factors include hypertension, exposure to cigarette smoke, diabetes, atrial fibrillation and certain other cardiac conditions, dyslipidemia, carotid artery stenosis, sickle cell disease, postmenopausal hormone therapy, poor diet, physical inactivity, and obesity and body fat distribution. Less well-documented or potentially modifiable risk factors include the metabolic syndrome, excessive alcohol consumption, drug abuse, use of oral contraceptives, sleep-disordered breathing, migraine, hyperhomocysteinemia, elevated lipoprotein(a), hypercoagulability, inflammation, and infection. Data on the use of aspirin for primary stroke prevention are reviewed.

CONCLUSIONS

Extensive evidence identifies a variety of specific factors that increase the risk of a first stroke and that provide strategies for reducing that risk.

Lifestyle Modifications for Its Prevention and Management

Therapeutic lifestyle changes (TLC) are important for the prevention and management of, as well as adjuncts to, pharmacotherapy of hypertension. This article reviews relevant TLC and their effects on blood pressure (BP) levels, with emphasis on exercise and dietary habits. Regular, moderate-intensity (40%-70% of heart rate reserve) aerobic exercise training for 30 to 60 minutes, 3 to 5 times per week, can lower systolic and diastolic BP levels, with a greater reduction observed in patients with hypertension compared with those with normal BP levels. A diet rich in fruits, vegetables, and whole grains, with a moderate intake of fat-free or low-fat dairy products, and low in saturated and total fat, sodium, and alcohol, such as the Dietary Approaches to Stop Hypertension eating pattern, also significantly reduces BP levels. A TLC program including regular exercise and dietary modifications along with weight management appears to result in a greater BP reduction than either intervention alone. TLC can also significantly reduce other risk factors for cardiovascular disease commonly accompanying hypertension. Multiple mechanisms appear to contribute to BP reduction by dietary intervention (reduced weight, sodium, and alcohol and increased calcium, potassium, and magnesium). For exercise, these include improvements in arterial endothelial function and compliance, left ventricular structure and function, and perhaps vascular blood supply with increased cardiorespiratory endurance. The available evidence is robust in support of TLC for management of elevated BP and for the primary prevention of hypertension, supporting the recommendations by the Joint National Committee Seventh Report on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure.

Primary Prevention of Ischemic Stroke

Background and Purpose— This guideline provides an overview of the evidence on various established and potential stroke risk factors and provides recommendations for the reduction of stroke risk.

Methods— Writing group members were nominated by the committee chair on the basis of each writer’s previous work in relevant topic areas and were approved by the American Heart Association Stroke Council’s Scientific Statement Oversight Committee. The writers used systematic literature reviews (covering the time period since the last review published in 2001 up to January 2005), reference to previously published guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulate recommendations based on standard American Heart Association criteria. All members of the writing group had numerous opportunities to comment in writing on the recommendations and approved the final version of this document. The guideline underwent extensive peer review before consideration and approval by the AHA Science Advisory and Coordinating Committee.

Results— Schemes for assessing a person’s risk of a first stroke were evaluated. Risk factors or risk markers for a first stroke were classified according to their potential for modification (nonmodifiable, modifiable, or potentially modifiable) and strength of evidence (well documented or less well documented). Nonmodifiable risk factors include age, sex, low birth weight, race/ethnicity, and genetic factors. Well-documented and modifiable risk factors include hypertension, exposure to cigarette smoke, diabetes, atrial fibrillation and certain other cardiac conditions, dyslipidemia, carotid artery stenosis, sickle cell disease, postmenopausal hormone therapy, poor diet, physical inactivity, and obesity and body fat distribution. Less well-documented or potentially modifiable risk factors include the metabolic syndrome, alcohol abuse, drug abuse, oral contraceptive use, sleep-disordered breathing, migraine headache, hyperhomocysteinemia, elevated lipoprotein(a), elevated lipoprotein-associated phospholipase, hypercoagulability, inflammation, and infection. Data on the use of aspirin for primary stroke prevention are reviewed.

Conclusion— Extensive evidence is available identifying a variety of specific factors that increase the risk of a first stroke and providing strategies for reducing that risk.

The beneficial effect of regular endurance exercise training on blood pressure and quality of life in patients with hypertension

Regular aerobic exercise can reduce blood pressure and is recommended as part of the lifestyle modification to reduce high blood pressure and cardiovascular risk. Hypertension itself, or/and pharmacological treatment for hypertension is associated with adverse effects on some aspects of quality of life. This study was performed to evaluate the effects of regular endurance exercise training on quality of life and blood pressure. Patients with mild to moderate hypertension (systolic blood pressure 140-180 or diastolic blood pressure 90-110 mm Hg) were randomized to a moderate-intensity aerobic exercise group training for 3 sessions/week over 10 weeks or to a non-exercising control group. Health-related quality of life was assessed with the Short Form 36-item Health Survey (SF-36) at baseline and after 6 and 10 weeks. In the 102 subjects (47 male, mean age 47 years) who completed the study, reductions in blood pressure in the exercise group at 10 weeks (-13.1/-6.3 mm Hg) were significant (P < 0.001) compared to baseline and to the control group (-1.5/+6.0 mm Hg). Unlike the control group, the exercise group showed an increase in exercise capacity from 8.2 +/- 1.6 to 10.8 +/- 2.2 METS (P < 0.01) and showed higher scores on 7 out of 8 subscales (P < 0.05) of the SF-36. Improvement in bodily pain and general health sub-scores correlated with reduction in systolic blood pressure. Regular endurance training improves both blood pressure and quality of life in hypertensive patients and should be encouraged more widely.

Self-reported leisure-time physical activity during pregnancy and relationship to psychological well-being

The psychological benefits of physical exercise have been reported in numerous populations. While studies have found elevated stress and depressed mood during pregnancy and no adverse birth effects associated with low to moderate intensity exercise, few have examined exercise in relation to psychosocial outcomes during pregnancy. The present study examined leisure-time physical activity (LTPA) patterns during pregnancy and its association to psychological well-being. In each trimester of pregnancy 180 women self-reported on frequency, form and duration of LTPA through structured interviews. Beginning in the third month of pregnancy, data was collected monthly on depressed mood (Lubin depression adjective checklist), state-anxiety, pregnancy-specific stress (pregnancy experiences questionnaire) and Hassles Scale. Independent samples t-tests comparing exercisers and non-exercisers in each trimester showed exercisers reported significantly less depressed mood, daily hassles, state-anxiety and pregnancy-specific stress in the first and second trimester. Women who exercised in the third trimester reported less state-anxiety in that trimester compared to non-exercisers. The results indicate a consistent association between enhanced psychological well-being, as measured by a variety of psychosocial inventories, and LTPA participation particularly during the first and second trimesters of pregnancy. In healthy pregnant women, even low-intensity regular exercise may be a potentially effective low-cost method of enhancing psychological well-being.

Antihypertensive effects of aerobic exercise in middle-aged normotensive men with exaggerated blood pressure response to exercise

An exaggerated blood pressure (BP) response to physical exertion among normotensive subjects is considered a significant risk factor for future hypertension. The purpose of this study was to examine whether regular aerobic exercise can lead to a reduction in hypertensive risks in patients with such a high-risk profile. Thirty-five sedentary men (46 +/- 2 years old) with normal BP at rest but an exaggerated BP response during exercise were randomly assigned to an exercise or control group for 12 weeks followed by an 8-week washout period. The subjects were then crossed over to the alternate group for an additional 12-week period. The exercise training consisted of 3 days per week of stationary bicycling for 45 min at 50-60% of the heart rate reserve. The treatment effects were evaluated using the method of Hills and Armitage. The training-induced reduction in resting BP was not statistically significant. In ambulatory BP monitoring, the averages of 24-h and daytime systolic and diastolic BP were significantly lower, but nighttime BP remained unchanged after training. During ergometric exercise, significant decreases were observed in systolic and diastolic BP and plasma norepinephrine concentration measured at the submaximal workloads. M-mode echocardiographic and Doppler-derived left ventricular variables were not significantly affected by training. These findings suggest that regular aerobic exercise attenuates BP elevations during physical exertion and daytime activities mainly as a result of the reduction in enhanced sympathetic nervous tonus, which may in turn play a role in lowering the risk for hypertension in normotensive subjects with an exaggerated BP response to exercise.

Blood lipid and lipoprotein adaptations to exercise: a quantitative analysis

Dose-response relationships between exercise training volume and blood lipid changes suggest that exercise can favourably alter blood lipids at low training volumes, although the effects may not be observable until certain exercise thresholds are met. The thresholds established from cross-sectional literature occur at training volumes of 24 to 32 km (15 to 20 miles) per week of brisk walking or jogging and elicit between 1200 to 2200 kcal/wk. This range of weekly energy expenditure is associated with 2 to 3 mg/dl increases in high-density lipoprotein-cholesterol (HDL-C) and triglyceride (TG) reductions of 8 to 20 mg/dl. Evidence from cross-sectional studies indicates that greater changes in HDL-C levels can be expected with additional increases in exercise training volume. HDL-C and TG changes are often observed after training regimens requiring energy expenditures similar to those characterised from cross-sectional data. Training programmes that elicit 1200 to 2200 kcal/wk in exercise are often effective at elevating HDL-C levels from 2 to 8 mg/dl, and lowering TG levels by 5 to 38 mg/dl. Exercise training seldom alters total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C). However, this range of weekly exercise energy expenditure is also associated with TC and LDL-C reductions when they are reported. The frequency and extent to which most of these lipid changes are reported are similar in both genders, with the exception of TG. Thus, for most individuals, the positive effects of regular exercise are exerted on blood lipids at low training volumes and accrue so that noticeable differences frequently occur with weekly energy expenditures of 1200 to 2200 kcal/wk. It appears that weekly exercise caloric expenditures that meet or exceed the higher end of this range are more likely to produce the desired lipid changes. This amount of physical activity, performed at moderate intensities, is reasonable and attainable for most individuals and is within the American College of Sports Medicine's currently recommended range for healthy adults.

Exercise as hypertension therapy

In conclusion, the findings of most recent studies show that moderate-intensity aerobic exercise training can lower BP in patients with stage 1 and 2 essential hypertension. The average reduction in BP is 10.5 mm Hg for systolic and 7.6 mm Hg for diastolic BP. The reductions do not appear to be gender- or age-specific. Significant reductions in BP and LVH regression in patients with stage 3 hypertension have also been reported following aerobic exercise training. Resistance training exercise has not consistently shown to significantly lower BP and is not recommended as the only form of exercise for hypertensive patients. The exercise training program for optimal benefits should consist of 3 to 5 times per week, 30 to 60 minutes per session, at 50% to 80% of PMHR. However, exercise programs should be individualized to meet the patient's needs and abilities. Exercise intensity and duration should be manipulated to promote a safe and effective antihypertensive program. Initially, the exercise intensity should be low and the duration short. Both intensity and duration should progressive increase over a period of weeks until the desired goal, is achieved. The rate of progression must be tailored to meet individual patient needs and abilities. The exercise program for overweight or obese hypertensive patients should aim to promote a caloric expenditure of 300 to 500 Kcal per day and 1000 to 2000 Kcal per week. Such an approach, combined with a prudent diet, is likely to reduce body weight. The mechanisms mediating exercise-induced BP reduction are poorly understood. BP reductions appear to be independent of changes in body weight or body composition. There are also no indications of age- or gender-related differences in BP response to exercise. The use of ambulatory blood pressure measuring devices in exercise studies is not extensive. The few studies available indicate a more moderate reduction in BP than that reported by casual observations.

Obesity, body fat distribution, and coronary artery disease

Obesity is an independent risk factor for the development of coronary artery disease (CAD). Obesity also increases risk for CAD indirectly through its association with insulin resistance, hyperlipidemia, and hypertension. An increased accumulation of fat in the intraabdominal cavity, termed visceral adiposity, is highly correlated with an adverse coronary risk profile. In patients at risk for coronary artery disease, the treatment of obesity results in an improved coronary risk profile. The prevalence of obesity is extremely high in coronary populations, yet the effect of weight loss on cardiovascular outcomes in CAD patients has received relatively little attention. Observational studies in the cardiac rehabilitation setting showed that patients who lose weight and exercise show an improvement in coronary risk profile. Further research is needed to better define the clinical effectiveness of weight loss programs and their benefits in coronary patients.

Exercise and hypertension

Randomized, well-controlled exercise intervention studies have shown consistently that regularly performed aerobic exercise significantly lowers blood pressure in patients with essential hypertension. Mild to moderate intensity exercise may be more effective in lowering blood pressure than higher intensity exercises. Such exercise is also safe and effective in lowering blood pressure in treated patients with severe hypertension and left ventricular hypertrophy. A significant reduction in blood pressure and regression of left ventricular hypertrophy may be achieved in these patients even after substantial reductions in antihypertensive medication. Recent findings have also shown that exercise training attenuates exaggerated blood pressure response during physical exertion. The safety and efficacy of mild to moderate exercise has significant and positive clinical implications for all hypertensive patients. Exercise-induced reductions in resting blood pressure and prevention of abnormal increases in blood pressure during physical exertion can lead to fewer cardiovascular events. They may also reduce antihypertensive medication requirements, cost, and medication-related side-effects, and improve quality of life.

Physical activity and high density lipoprotein cholesterol levels: what is the relationship?

High density lipoprotein cholesterol (HDL-C) levels are strongly, inversely and independently associated with coronary heart disease (CHD). Increased physical activity is associated with reduced CHD mortality. This protection against CHD may partially be explained by the increase in HDL-C levels observed following aerobic exercise training. Many also agree that an exercise threshold needs to be met before such favourable changes in HDL-C metabolism can occur. Most likely, the exercise-induced changes in HDL-C are the result of the interaction amongst exercise intensity, frequency, duration of each exercise session and length of the exercise training period. Although a relative contribution of each exercise component (intensity, duration and frequency) is also likely, it has not been established. There is also substantial support for a dose-response relationship. Favourable changes in HDL-C appear to occur incrementally and reach statistical significance at approximately 7-10 miles per week or 1200 to 1600kcal. Exercise-induced changes in HDL-C may also be gender dependent. The volume of exercise required to increase HDL-C levels appears to be substantially more for women than men. This perhaps is due to higher HDL-C levels in women at baseline compared with men. However, the many other health benefits derived from increased physical activity should encourage women to participate in regular exercise regardless of the exercise effects on HDL-C levels. A practical approach in prescribing exercise for patients is to use moderate intensity exercises (70 to 80% of predicted maximal heart rate), 3 to 5 times per week, for a total of 7 to 14 miles per week. This is equivalent to approximately 1200 to 1600kcal per week. Moderate to low intensity exercise should be preferred because such exercise carries a lower risk for cardiac complications. In addition, patients are more likely to participate and sustain a lower than higher intensity exercise programme. It is also important to recognise that other modes of physical activity can also be encouraged for patients. Such activities should be associated with similar increases in HDL-C levels as long as they meet or exceed the caloric expenditure of 1200 to 1600kcal (7 to 14 miles per week of jogging).

Screening for cardiovascular disease. Concepts, conflicts, and consensus

CVD in the United States is prevalent, costly, and disabling. Wherever in the arterial tree atherosclerosis occurs, the process appears to begin in youth, to develop under the influence of the same risk factors, and to be amenable to the same interventions. The relationship between CVD and its associated risk factors is continuous, is graded, and extends below thresholds previously defined as normal. This observation, in turn, is based on an appreciation that in our society, the gap between normal and optimal can be considerable. CVD is a multifactorial process, often related to modifiable lifestyle choices; we focus on any single risk factor to the exclusion of others puts patients in danger. Because risk factors rarely occur in isolation, risk assessment must be as multifactorial as the underlying disease process. By understanding differences between risk factors in terms of the impact of their modification on the underlying disease, targeted interventions become possible that are tailored to the likelihood of an individual patient acquiring CVD. To change the overall prevalence of an epidemic disease such as CVD, however, such a high-risk approach must be applied in concert with a population strategy that seeks to effect smaller degrees of change in the large segment of society that may be at only moderate risk but--because of their great numbers--bears most of the morbidity and mortality of CVD. Finally, despite the remarkable progress that has been made in our understanding of the pathophysiology of CVD and the effectiveness of risk factor modification, significant gaps remain between knowledge and behavior. Fewer than 50% of diabetics are even aware that they have the disease. Only a third of those whose lipid levels qualify them for treatment receive intervention of any kind, including dietary advice. Only 27% of hypertensives have their blood pressure adequately controlled. The potential impact of more vigorous screening practices in the primary care setting on the health of individuals and communities cannot be overstated.

Women's physical activity patterns: nursing implications

OBJECTIVE

To develop a method of categorizing patterns of physical activity by describing the frequency, intensity, and duration of women's activities.

DESIGN

A 24-cell quota sample stratified by four occupations, two races, and three age groups.

SETTING

Ten employment sites.

PARTICIPANTS

One hundred seventy-six women, ages 35-65 years, who worked 20 or more hours per week at their job, were not currently using hormone replacement therapy, not pregnant, and did not have a hysterectomy before the age of 53.

MAIN OUTCOME MEASURES

An interviewer and self-administered, retrospective occupational, household, and leisure physical activity questionnaire covering the previous 12 months and lifelong activity.

RESULTS

Five patterns of household and leisure physical activity were identified: vigorous, continuous, cumulative, occasional, and inactive. Participation in the vigorous pattern was low, but 34% followed a continuous pattern of leisure activity and 75% followed a continuous pattern of household activity. The number of weekly work hours did not affect the household or leisure pattern.

CONCLUSION

Women may be able to obtain the recommended levels of physical activity from a combination of occupational, household, and leisure activities. Nursing recommendations should guide women to increase their regular leisure physical activity and/or accumulate sessions of moderate-intensity activity by aerobically enhancing daily activities in which they already participate.

Physical activity and women in the United States: an overview of health benefits, prevalence, and intervention opportunities

Despite decades of physical activity research and interventions conducted on men, very little is known about the patterns of physical activity among US women. Rates from several national surveys show much lower rates of physical activity for women than for men. Among women, rates may vary by socioeconomic status. Studies relating physical activity and experience with heart disease, cancer, osteoporosis, and mental health are discussed. Interventions in the workplace and the community may increase the level of physical activity among US women. A history of not participating in exercise and lack of time for this activity appear to be important constraints for many women. The Surgeon General's Report on physical activity sanctioned future research on specific groups, such as women. Applied research coupled with community and workplace policies that support women's efforts to be more physically active may decrease the rates of some chronic diseases in this population.

Exercise and rehabilitation in women. Indications and outcomes

Women have been shown to improve their cardiovascular risk profiles with increasing levels of physical activity and physical fitness. All-cause mortality is lower among more fit women, but reductions in cardiovascular death rates have not been established, owing to the limited number and size of existing studies. Because older women are at greater risk for cardiac events and are the least likely to engage in regular physical activity, concerted effort should be made to increase the proportion of older women who participate in regular physical activity. Attention to concerns raised by older, sedentary women and development of personalized programs that proceed gradually in intensity and duration and avoid high-impact activities should improve the likelihood of initiation and continuation of greater activity levels. Cardiac rehabilitation programs are under-used by women. Personal and social barriers have been identified as well as the potential for referral bias. Reduction in cardiovascular risk levels and improvements in exercise capacity have been demonstrated for women who do participate. Approaches that meet the needs of older women may require considerable alteration from the standard program established for middle-aged men. Yet women may have the most to gain from participation in multidisciplinary, personalized rehabilitation programs.

Cardiovascular function before, during, and after the first and subsequent pregnancies

This study was designed to test the hypothesis that the vascular remodeling of pregnancy begins early, persists for at least 1 year after delivery, and is accentuated by a second pregnancy. Serial estimates of heart rate, arterial pressure, left ventricular volumes, cardiac output, and calculated peripheral resistance were obtained before pregnancy, every 8 weeks during pregnancy, and 12, 24, and 52 weeks postpartum in 15 nulliparous and 15 parous women using electrocardiography, automated manometry, and M-mode ultrasound. During pregnancy, body weight increased 14.5 +/- 1.8 kg and returned to prepregnancy values 1 year postpartum. Heart rate peaked at term 15 +/- 1 beat/min above prepregnancy levels (57 +/- 1 beat/min). Mean arterial pressure reached its nadir (-6 +/- 1 mm Hg) at 16 weeks, returning to baseline at term. The increases in left ventricular volumes and cardiac output (2.2 +/- 0.2 L/min) peaked at 24 weeks as did the 500 +/- 29 dynes x cm x s(-5) decrease in peripheral resistance, and their magnitude was significantly greater in the parous women. Postpartum they gradually returned toward baseline but remained significantly different from prepregnancy values in both groups at 1 year. We conclude that cardiovascular adaptations to the initial pregnancy begin early, persist postpartum, and appear to be enhanced by a subsequent pregnancy. We speculate that persistence of these changes may lower cardiovascular risk in later life.

Effect of a high or a low fat diet on cardiovascular risk factors in male and female runners

Dietary fat may be associated with coronary heart disease (CHD). Studies suggest that restricting fat intake may compromise endurance performance and that increasing fat intake may improve endurance performance. We studied the effects of varying dietary fat intake on CHD risk factors in runners. Twelve male and 13 female runners increased fat from 16% to 30% of daily calories (4 wk each). Of this group, six males and six females increased fat to 42% of daily calories (4 wk). Physiological and lipoprotein risk factors were measured after each diet. Results were analyzed by repeated measures ANOVA. Increasing dietary fat from 16% to 42% of daily calories did not change adiposity, weight, heart rate, blood pressure, serum triglycerides, total cholesterol, LDL cholesterol. Apolipoprotein B, or the Apo A1/Apo B ratio. Compared with those eating higher fat, subjects eating 16% fat had lower HDL cholesterol (50 +/- 3 vs 62 +/- 3 mg.dl-1, P < 0.0001) and Apolipoprotein A1 (111 +/- 6 v. 134 +/- 6 mg/dl, P < 0.0005) and a higher TC/HDL-C ratio (4.05 +/- 0.27 vs 3.42 +/- 0.24, P < 0.0005). Runners who increased fat intake to 42% further raised HDL cholesterol (64 +/- 6 to 69 +/- 5 mg.dl-1, P < 0.04) without adversely affecting other lipoproteins. In conclusion, a 42% fat diet maintained favorable CHD risk factors in female and male runners whereas a 16% fat diet lowered Apo A1 and HDL-C and raised the TC/HDL-C ratio.