Osteoporosis is a disease characterized by low bone mass and microarchitectural deterioration of bone tissue leading to enhanced bone fragility and a consequent increase in fracture risk. Both men and women are at risk for osteoporotic fractures. However, as osteoporosis is more common in females and more exercise-related research has been directed at reducing the risk of osteoporotic fractures in women, this Position Stand applies specifically to women. Factors that influence fracture risk include skeletal fragility, frequency and severity of falls, and tissue mass surrounding the skeleton. Prevention of osteoporotic fractures, therefore, is focused on the preservation or enhancement of the material and structural properties of bone, the prevention of falls, and the overall improvement of lean tissue mass. The load-bearing capacity of bone reflects both its material properties, such as density and modulus, and the spatial distribution of bone tissue. These features of bone strength are all developed and maintained in part by forces applied to bone during daily activities and exercise. Functional loading through physical activity exerts a positive influence on bone mass in humans. The extent of this influence and the types of programs that induce the most effective osteogenic stimulus are still uncertain. While it is well-established that a marked decrease in physical activity, as in bedrest for example, results in a profound decline in bone mass, improvements in bone mass resulting from increased physical activity are less conclusive. Results vary according to age, hormonal status, nutrition, and exercise prescription. An apparent positive effect of activity on bone is more marked in cross-sectional studies than in prospective studies. Whether this is an example of selection bias or differences in the intensity and duration of the training programs is uncertain at this time. It has long been recognized that changes in bone mass occur more rapidly with unloading than with increased loading. Habitual inactivity results in a downward spiral in all physiologic functions. As women age, the loss of strength, flexibility, and cardiovascular fitness leads to a further decrease in activity. Eventually older individuals may find it impossible to continue the types of activities that provide an adequate load-bearing stimulus to maintain bone mass. Fortunately, it appears that strength and overall fitness can be improved at any age through a carefullly planned exercise program. Unless the ability of the underlying physiologic systems essential for load-bearing activity are restored, it may be difficult for many older women to maintain a level of activity essential for protecting the skeleton from further bone loss. (ABSTRACT TRUNCATED)
Details: PMID-7791573
Thursday, April 9, 2009
Injuries in recreational adult fitness activities.
Center for Sports Medicine, Saint Francis Memorial Hospital, San Francisco, California.
Volunteers (986) from fitness clubs and studios were recruited and followed for a 3-month period to document the injury consequences of adult recreational fitness participation. Participants were telephoned each week and their activities as well as any injuries that occurred were recorded. Of the 525 injuries and complaints reported during 60,629 hours of activity, 475 occurred as a result of sports participation for an overall rate of 7.83 per 1000 hours of participation. Seventy-six percent of these episodes caused the patient to alter or miss 1 or more activities, while 9.5% involved a physician visit. The rate for time-loss injuries was less than 2 per person per year (1.76 per 298 hours) or 5.92 per 1000 hours. Running had a higher risk of injury compared with most other individual sports. Cardiovascular fitness activities had low to medium rates, as did weight work; competitive sports were higher. For 6 of the most commonly injured areas, the reinjury rate was about twice that reported for those with no history of previous injury. The risks of injury from most recreational fitness activities were relatively modest, particularly if the activities were not competitive. Physicians might help patients reduce their risks of injury by encouraging suitable activities and by reducing the risks of reinjury by implementing appropriate rehabilitation programs.
Details: PMID-8346764
Volunteers (986) from fitness clubs and studios were recruited and followed for a 3-month period to document the injury consequences of adult recreational fitness participation. Participants were telephoned each week and their activities as well as any injuries that occurred were recorded. Of the 525 injuries and complaints reported during 60,629 hours of activity, 475 occurred as a result of sports participation for an overall rate of 7.83 per 1000 hours of participation. Seventy-six percent of these episodes caused the patient to alter or miss 1 or more activities, while 9.5% involved a physician visit. The rate for time-loss injuries was less than 2 per person per year (1.76 per 298 hours) or 5.92 per 1000 hours. Running had a higher risk of injury compared with most other individual sports. Cardiovascular fitness activities had low to medium rates, as did weight work; competitive sports were higher. For 6 of the most commonly injured areas, the reinjury rate was about twice that reported for those with no history of previous injury. The risks of injury from most recreational fitness activities were relatively modest, particularly if the activities were not competitive. Physicians might help patients reduce their risks of injury by encouraging suitable activities and by reducing the risks of reinjury by implementing appropriate rehabilitation programs.
Details: PMID-8346764
Influences of cardiorespiratory fitness levels and other predictors on cardiovascular disease mortality in men.
Cooper Institute for Aerobics Research, Dallas, TX 75230, USA.
PURPOSE: This investigation quantifies the relation between cardiorespiratory fitness levels and cardiovascular disease (CVD) mortality within strata of other CVD predictors. METHODS: Participants included 25,341 male Cooper Clinic patients who underwent a maximal graded exercise test. CVD death rates were determined for low (least fit one-fifth), moderate (next two-fifths), and high (top two-fifths) cardiorespiratory fitness categories by strata of smoking habit, blood cholesterol level, resting blood pressure, and health status. There were 226 cardiovascular deaths during 211,996 man-years of follow-up. RESULTS: For individuals with none of the major CVD predictors (smoking, elevated resting systolic blood pressure, elevated blood cholesterol), there was a strong inverse relation (P = 0.001) between fitness level and CVD mortality. An inverse relation between CVD mortality and fitness level was seen within strata of cholesterol levels and health status. No evidence of a trend (P = 0.60) for decreased mortality was seen across fitness levels for individuals with elevated systolic blood pressure; however, a strong inverse gradient (P < 0.001) was seen across fitness levels for individuals with normal systolic blood pressure. There was a tendency for association between high levels of fitness and decreased CVD mortality in smokers compared with low and moderately fit smokers (P < 0.076). There was no significant association between level of fitness and CVD mortality for individuals with multiple (two or more) predictors (P = 0.325). Approximately 20% of the 226 CVD deaths in the population studied were attributed to low fitness level. CONCLUSIONS: Moderate and high levels of cardiorespiratory fitness seem to provide some protection from CVD mortality, even in the presence of well established CVD predictors.
Details: PMID-9624649
PURPOSE: This investigation quantifies the relation between cardiorespiratory fitness levels and cardiovascular disease (CVD) mortality within strata of other CVD predictors. METHODS: Participants included 25,341 male Cooper Clinic patients who underwent a maximal graded exercise test. CVD death rates were determined for low (least fit one-fifth), moderate (next two-fifths), and high (top two-fifths) cardiorespiratory fitness categories by strata of smoking habit, blood cholesterol level, resting blood pressure, and health status. There were 226 cardiovascular deaths during 211,996 man-years of follow-up. RESULTS: For individuals with none of the major CVD predictors (smoking, elevated resting systolic blood pressure, elevated blood cholesterol), there was a strong inverse relation (P = 0.001) between fitness level and CVD mortality. An inverse relation between CVD mortality and fitness level was seen within strata of cholesterol levels and health status. No evidence of a trend (P = 0.60) for decreased mortality was seen across fitness levels for individuals with elevated systolic blood pressure; however, a strong inverse gradient (P < 0.001) was seen across fitness levels for individuals with normal systolic blood pressure. There was a tendency for association between high levels of fitness and decreased CVD mortality in smokers compared with low and moderately fit smokers (P < 0.076). There was no significant association between level of fitness and CVD mortality for individuals with multiple (two or more) predictors (P = 0.325). Approximately 20% of the 226 CVD deaths in the population studied were attributed to low fitness level. CONCLUSIONS: Moderate and high levels of cardiorespiratory fitness seem to provide some protection from CVD mortality, even in the presence of well established CVD predictors.
Details: PMID-9624649
Effects of exercise on lipoprotein(a).
Department of Human Movement Studies, University of Queensland, Brisbane, Australia. laurel@hms.uq.edu.au
Lipoprotein(a) [Lp(a)] is a unique lipoprotein complex in the blood. At high levels (> 30 mg/dl), Lp(a) is considered an independent risk factor for cardiovascular diseases. Serum Lp(a) levels are largely genetically determined, remain relatively constant within a given individual, and do not appear to be altered by factors known to influence other lipoproteins (e.g. lipid-lowering drugs, dietary modification and change in body mass). Since regular exercise is associated with favourable changes in lipoproteins in the blood, recent attention has focused on whether serum Lp(a) levels are also influenced by physical activity. Population and cross-sectional studies consistently show a lack of association between serum Lp(a) levels and regular moderate physical activity. Moreover, exercise intervention studies extending from 12 weeks to 4 years indicate that serum Lp(a) levels do not change in response to moderate exercise training, despite improvements in fitness level and other lipoprotein levels in the blood. However, recent studies suggest the possibility that serum Lp(a) levels may increase in response to intense load-bearing exercise training, such as distance running or weight lifting, over several months to years. Cross-sectional studies have reported abnormally high serum Lp(a) levels in experienced distance runners and body builders who train for 2 to 3 hours each day. However, the possible confounding influence of racial or ethnic factors in these studies cannot be discounted. Recent intervention studies also suggest that 9 to 12 months of intense exercise training may elevate serum Lp(a) levels. However, these changes are generally modest (10 to 15%) and, in most individuals, serum Lp(a) levels remain within the recommended range. It is unclear whether increased serum Lp(a) levels after intense exercise training are of clinical relevance, and whether certain Lp(a) isoforms are more sensitive to the effects of exercise training. Since elevation of both low density lipoprotein cholesterol (LDL-C) and Lp(a) levels in the blood exerts a synergistic effect on cardiovascular disease risk, attention should focus on changing lifestyle factors to decrease LDL-C (e.g. dietary intervention) and increase high density lipoprotein cholesterol (e.g. exercise) levels in the blood.
Details: PMID-10461709
Lipoprotein(a) [Lp(a)] is a unique lipoprotein complex in the blood. At high levels (> 30 mg/dl), Lp(a) is considered an independent risk factor for cardiovascular diseases. Serum Lp(a) levels are largely genetically determined, remain relatively constant within a given individual, and do not appear to be altered by factors known to influence other lipoproteins (e.g. lipid-lowering drugs, dietary modification and change in body mass). Since regular exercise is associated with favourable changes in lipoproteins in the blood, recent attention has focused on whether serum Lp(a) levels are also influenced by physical activity. Population and cross-sectional studies consistently show a lack of association between serum Lp(a) levels and regular moderate physical activity. Moreover, exercise intervention studies extending from 12 weeks to 4 years indicate that serum Lp(a) levels do not change in response to moderate exercise training, despite improvements in fitness level and other lipoprotein levels in the blood. However, recent studies suggest the possibility that serum Lp(a) levels may increase in response to intense load-bearing exercise training, such as distance running or weight lifting, over several months to years. Cross-sectional studies have reported abnormally high serum Lp(a) levels in experienced distance runners and body builders who train for 2 to 3 hours each day. However, the possible confounding influence of racial or ethnic factors in these studies cannot be discounted. Recent intervention studies also suggest that 9 to 12 months of intense exercise training may elevate serum Lp(a) levels. However, these changes are generally modest (10 to 15%) and, in most individuals, serum Lp(a) levels remain within the recommended range. It is unclear whether increased serum Lp(a) levels after intense exercise training are of clinical relevance, and whether certain Lp(a) isoforms are more sensitive to the effects of exercise training. Since elevation of both low density lipoprotein cholesterol (LDL-C) and Lp(a) levels in the blood exerts a synergistic effect on cardiovascular disease risk, attention should focus on changing lifestyle factors to decrease LDL-C (e.g. dietary intervention) and increase high density lipoprotein cholesterol (e.g. exercise) levels in the blood.
Details: PMID-10461709
Maximal exercise test as a predictor of risk for mortality from coronary heart disease in asymptomatic men.
Cooper Clinic and the Cooper Institute for Aerobics Research, Dallas, Texas, USA.
Exercise testing in asymptomatic persons has been criticized for failing to accurately predict those at risk for coronary heart disease (CHD). Previous studies on asymptomatic subjects, however, may not have been large enough or long enough to provide reliable outcome measures. This study examines the ability of a maximal exercise test to predict death from CHD and death from any cause in a population of asymptomatic men. This is a prospective longitudinal study performed between 1970 and 1989, with an average follow-up of 8.4 years. The subjects are 25,927 healthy men, 20 to 82 years of age at baseline (mean 42.9 years) who were free of cardiovascular disease and who were evaluated in a preventive medicine clinic. The main outcome measures are CHD mortality and all-cause mortality. During follow-up there were 612 deaths from all causes and 158 deaths from CHD. The sensitivity of an abnormal exercise test to predict coronary death was 61%. The age-adjusted relative risk of an abnormal exercise test for CHD death was 21 (6.9 to 63.3) in those with no risk factors, 27 (10.7 to 68.8) in those with 1 risk factor, 54 (21.5 to 133.7) in those with 2 risk factors, and 80 (30.0 to 212. 5) in those with >/=3 factors. A maximal exercise test performed in asymptomatic men free of cardiovascular disease does appear to be a worthwhile tool in predicting future risk of CHD death. An abnormal exercise test is a more powerful predictor of risk in those with than without conventional risk factors.
Details: PMID-10867092
Exercise testing in asymptomatic persons has been criticized for failing to accurately predict those at risk for coronary heart disease (CHD). Previous studies on asymptomatic subjects, however, may not have been large enough or long enough to provide reliable outcome measures. This study examines the ability of a maximal exercise test to predict death from CHD and death from any cause in a population of asymptomatic men. This is a prospective longitudinal study performed between 1970 and 1989, with an average follow-up of 8.4 years. The subjects are 25,927 healthy men, 20 to 82 years of age at baseline (mean 42.9 years) who were free of cardiovascular disease and who were evaluated in a preventive medicine clinic. The main outcome measures are CHD mortality and all-cause mortality. During follow-up there were 612 deaths from all causes and 158 deaths from CHD. The sensitivity of an abnormal exercise test to predict coronary death was 61%. The age-adjusted relative risk of an abnormal exercise test for CHD death was 21 (6.9 to 63.3) in those with no risk factors, 27 (10.7 to 68.8) in those with 1 risk factor, 54 (21.5 to 133.7) in those with 2 risk factors, and 80 (30.0 to 212. 5) in those with >/=3 factors. A maximal exercise test performed in asymptomatic men free of cardiovascular disease does appear to be a worthwhile tool in predicting future risk of CHD death. An abnormal exercise test is a more powerful predictor of risk in those with than without conventional risk factors.
Details: PMID-10867092
Is physical activity or physical fitness more important in defining health benefits?
The Cooper Institute, Dallas, TX 75230, USA. sblair@cooperinst.org
PURPOSE: We addressed three questions: 1) Is there a dose-response relation between physical activity and health? 2) Is there a dose-response relation between cardiorespiratory fitness and health? 3) If both activity and fitness have a dose-response relation to health, is it possible to determine which exposure is more important? METHODS: We identified articles by PubMed search (restricted from 1/1/90 to 8/25/00) using keywords related to physical activity, physical fitness, and health. An author scanned titles and abstracts of 9831 identified articles. We included for thorough review articles that included three or more categories of activity or fitness and a health outcome and excluded articles on clinical trials, review papers, comments, letters, case reports, and nonhuman studies. We used an evidence-based approach to evaluate the quality of the published data. RESULTS: We summarized results from 67 articles meeting final selection criteria. There is good consensus across studies with most showing an inverse dose-response gradient across both activity and fitness categories for morbidity from coronary heart disease (CHD), stroke, cardiovascular disease (CVD), or cancer; and for CVD, cancer, or all-cause mortality. CONCLUSIONS: All studies reviewed were prospective observational investigations; thus, conclusions are based on Evidence Category C. 1) There is a consistent gradient across activity groups indicating greater longevity and reduced risk of CHD, CVD, stroke, and colon cancer in more active individuals. 2) Studies are compelling in the consistency and steepness of the gradient across fitness groups. Most show a curvilinear gradient, with a steep slope at low levels of fitness and an asymptote in the upper part of the fitness distribution. 3) It is not possible to conclude whether activity or fitness is more important for health. Future studies should define more precisely the shape of the dose-response gradient across activity or fitness groups, evaluate the role of musculoskeletal fitness, and investigate additional health outcomes.
Details: PMID-11427763
PURPOSE: We addressed three questions: 1) Is there a dose-response relation between physical activity and health? 2) Is there a dose-response relation between cardiorespiratory fitness and health? 3) If both activity and fitness have a dose-response relation to health, is it possible to determine which exposure is more important? METHODS: We identified articles by PubMed search (restricted from 1/1/90 to 8/25/00) using keywords related to physical activity, physical fitness, and health. An author scanned titles and abstracts of 9831 identified articles. We included for thorough review articles that included three or more categories of activity or fitness and a health outcome and excluded articles on clinical trials, review papers, comments, letters, case reports, and nonhuman studies. We used an evidence-based approach to evaluate the quality of the published data. RESULTS: We summarized results from 67 articles meeting final selection criteria. There is good consensus across studies with most showing an inverse dose-response gradient across both activity and fitness categories for morbidity from coronary heart disease (CHD), stroke, cardiovascular disease (CVD), or cancer; and for CVD, cancer, or all-cause mortality. CONCLUSIONS: All studies reviewed were prospective observational investigations; thus, conclusions are based on Evidence Category C. 1) There is a consistent gradient across activity groups indicating greater longevity and reduced risk of CHD, CVD, stroke, and colon cancer in more active individuals. 2) Studies are compelling in the consistency and steepness of the gradient across fitness groups. Most show a curvilinear gradient, with a steep slope at low levels of fitness and an asymptote in the upper part of the fitness distribution. 3) It is not possible to conclude whether activity or fitness is more important for health. Future studies should define more precisely the shape of the dose-response gradient across activity or fitness groups, evaluate the role of musculoskeletal fitness, and investigate additional health outcomes.
Details: PMID-11427763
Walking compared with vigorous exercise for the prevention of cardiovascular events in women.
Division of Preventive Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston 02215, USA. jmanson@rics.bwh.harvard.edu
BACKGROUND: The role of walking, as compared with vigorous exercise, in the prevention of cardiovascular disease remains controversial. Data for women who are members of minority racial or ethnic groups are particularly sparse. METHODS: We prospectively examined the total physical-activity score, walking, vigorous exercise, and hours spent sitting as predictors of the incidence of coronary events and total cardiovascular events among 73,743 postmenopausal women 50 to 79 years of age in the Women's Health Initiative Observational Study. At base line, participants were free of diagnosed cardiovascular disease and cancer, and all participants completed detailed questionnaires about physical activity. We documented 345 newly diagnosed cases of coronary heart disease and 1551 total cardiovascular events. RESULTS: An increasing physical-activity score had a strong, graded, inverse association with the risk of both coronary events and total cardiovascular events. There were similar findings among white women and black women. Women in increasing quintiles of energy expenditure measured in metabolic equivalents (the MET score) had age-adjusted relative risks of coronary events of 1.00, 0.73, 0.69, 0.68, and 0.47, respectively (P for trend, <0.001). In multivariate analyses, the inverse gradient between the total MET score and the risk of cardiovascular events remained strong (adjusted relative risks for increasing quintiles, 1.00, 0.89, 0.81, 0.78, and 0.72, respectively; P for trend <0.001). Walking and vigorous exercise were associated with similar risk reductions, and the results did not vary substantially according to race, age, or body-mass index. A brisker walking pace and fewer hours spent sitting daily also predicted lower risk. CONCLUSIONS: These prospective data indicate that both walking and vigorous exercise are associated with substantial reductions in the incidence of cardiovascular events among postmenopausal women, irrespective of race or ethnic group, age, and body-mass index. Prolonged sitting predicts increased cardiovascular risk. Copyright 2002 Massachusetts Medical Society
Details: PMID-12213942
BACKGROUND: The role of walking, as compared with vigorous exercise, in the prevention of cardiovascular disease remains controversial. Data for women who are members of minority racial or ethnic groups are particularly sparse. METHODS: We prospectively examined the total physical-activity score, walking, vigorous exercise, and hours spent sitting as predictors of the incidence of coronary events and total cardiovascular events among 73,743 postmenopausal women 50 to 79 years of age in the Women's Health Initiative Observational Study. At base line, participants were free of diagnosed cardiovascular disease and cancer, and all participants completed detailed questionnaires about physical activity. We documented 345 newly diagnosed cases of coronary heart disease and 1551 total cardiovascular events. RESULTS: An increasing physical-activity score had a strong, graded, inverse association with the risk of both coronary events and total cardiovascular events. There were similar findings among white women and black women. Women in increasing quintiles of energy expenditure measured in metabolic equivalents (the MET score) had age-adjusted relative risks of coronary events of 1.00, 0.73, 0.69, 0.68, and 0.47, respectively (P for trend, <0.001). In multivariate analyses, the inverse gradient between the total MET score and the risk of cardiovascular events remained strong (adjusted relative risks for increasing quintiles, 1.00, 0.89, 0.81, 0.78, and 0.72, respectively; P for trend <0.001). Walking and vigorous exercise were associated with similar risk reductions, and the results did not vary substantially according to race, age, or body-mass index. A brisker walking pace and fewer hours spent sitting daily also predicted lower risk. CONCLUSIONS: These prospective data indicate that both walking and vigorous exercise are associated with substantial reductions in the incidence of cardiovascular events among postmenopausal women, irrespective of race or ethnic group, age, and body-mass index. Prolonged sitting predicts increased cardiovascular risk. Copyright 2002 Massachusetts Medical Society
Details: PMID-12213942
A ketogenic diet favorably affects serum biomarkers for cardiovascular disease in normal-weight men.
Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs 06269-1110, USA.
Very low-carbohydrate (ketogenic) diets are popular yet little is known regarding the effects on serum biomarkers for cardiovascular disease (CVD). This study examined the effects of a 6-wk ketogenic diet on fasting and postprandial serum biomarkers in 20 normal-weight, normolipidemic men. Twelve men switched from their habitual diet (17% protein, 47% carbohydrate and 32% fat) to a ketogenic diet (30% protein, 8% carbohydrate and 61% fat) and eight control subjects consumed their habitual diet for 6 wk. Fasting blood lipids, insulin, LDL particle size, oxidized LDL and postprandial triacylglycerol (TAG) and insulin responses to a fat-rich meal were determined before and after treatment. There were significant decreases in fasting serum TAG (-33%), postprandial lipemia after a fat-rich meal (-29%), and fasting serum insulin concentrations (-34%) after men consumed the ketogenic diet. Fasting serum total and LDL cholesterol and oxidized LDL were unaffected and HDL cholesterol tended to increase with the ketogenic diet (+11.5%; P = 0.066). In subjects with a predominance of small LDL particles pattern B, there were significant increases in mean and peak LDL particle diameter and the percentage of LDL-1 after the ketogenic diet. There were no significant changes in blood lipids in the control group. To our knowledge this is the first study to document the effects of a ketogenic diet on fasting and postprandial CVD biomarkers independent of weight loss. The results suggest that a short-term ketogenic diet does not have a deleterious effect on CVD risk profile and may improve the lipid disorders characteristic of atherogenic dyslipidemia.
Details: PMID-12097663
Very low-carbohydrate (ketogenic) diets are popular yet little is known regarding the effects on serum biomarkers for cardiovascular disease (CVD). This study examined the effects of a 6-wk ketogenic diet on fasting and postprandial serum biomarkers in 20 normal-weight, normolipidemic men. Twelve men switched from their habitual diet (17% protein, 47% carbohydrate and 32% fat) to a ketogenic diet (30% protein, 8% carbohydrate and 61% fat) and eight control subjects consumed their habitual diet for 6 wk. Fasting blood lipids, insulin, LDL particle size, oxidized LDL and postprandial triacylglycerol (TAG) and insulin responses to a fat-rich meal were determined before and after treatment. There were significant decreases in fasting serum TAG (-33%), postprandial lipemia after a fat-rich meal (-29%), and fasting serum insulin concentrations (-34%) after men consumed the ketogenic diet. Fasting serum total and LDL cholesterol and oxidized LDL were unaffected and HDL cholesterol tended to increase with the ketogenic diet (+11.5%; P = 0.066). In subjects with a predominance of small LDL particles pattern B, there were significant increases in mean and peak LDL particle diameter and the percentage of LDL-1 after the ketogenic diet. There were no significant changes in blood lipids in the control group. To our knowledge this is the first study to document the effects of a ketogenic diet on fasting and postprandial CVD biomarkers independent of weight loss. The results suggest that a short-term ketogenic diet does not have a deleterious effect on CVD risk profile and may improve the lipid disorders characteristic of atherogenic dyslipidemia.
Details: PMID-12097663
Heart rate reserve as a predictor of cardiovascular and all-cause mortality in men.
The Cooper Institute, 12330 Preston Road, Dallas, TX 75230, USA. ycheng@cooperinst.org
This study examined the relationship of heart rate reserve (HRR: maximal heart rate - resting heart rate) and cardiovascular disease mortality (CVD) or all-cause mortality among healthy men. METHODS: Subjects were 27,459 healthy men, age 20-59 yr, who completed a maximal treadmill exercise test and answered a health questionnaire at the baseline examination. We followed study participants from the baseline visit to the date of death or December 31, 1996, for survivors. RESULTS: Over an average follow-up of 13.0 +/- 6.2 yr, there were 724 deaths, 205 (28.3%) from CVD. For analyses, the men were stratified into two age groups: younger (20-39 yr) and older (40-59 yr). Cox regression analysis was used to adjust for age, resting heart rate, cardiorespiratory fitness (CRF), resting systolic blood pressure (SBP), SBP difference, cholesterol, triglycerides, body mass index (BMI), smoking, and alcohol consumption. Among younger men, HRR was the only factor associated with CVD mortality (instantaneous relative risk (RR) and 95% confidence interval for HRR = 0.6, 0.5-0.9 for CVD mortality by 10 beats.min(-1) increment), whereas only CRF and BMI were associated with all-cause mortality. Among older men, HRR was inversely associated with CVD and all-cause mortality, as were several other known risk factors, including CRF (RR(per 2 METs), and 95% CI for HRR = 0.7, 0.5-0.9 for CVD mortality and 0.8, 0.7-0.9 for all-cause mortality). CONCLUSIONS HRR, independent from CRF, was inversely associated with CVD mortality among men in this study. HRR may be an important exercise test parameter to predict CVD mortality in younger men, whereas CRF and other established risk factors are better predictors of CVD and all-cause mortality in older men.
Details: PMID-12471290
This study examined the relationship of heart rate reserve (HRR: maximal heart rate - resting heart rate) and cardiovascular disease mortality (CVD) or all-cause mortality among healthy men. METHODS: Subjects were 27,459 healthy men, age 20-59 yr, who completed a maximal treadmill exercise test and answered a health questionnaire at the baseline examination. We followed study participants from the baseline visit to the date of death or December 31, 1996, for survivors. RESULTS: Over an average follow-up of 13.0 +/- 6.2 yr, there were 724 deaths, 205 (28.3%) from CVD. For analyses, the men were stratified into two age groups: younger (20-39 yr) and older (40-59 yr). Cox regression analysis was used to adjust for age, resting heart rate, cardiorespiratory fitness (CRF), resting systolic blood pressure (SBP), SBP difference, cholesterol, triglycerides, body mass index (BMI), smoking, and alcohol consumption. Among younger men, HRR was the only factor associated with CVD mortality (instantaneous relative risk (RR) and 95% confidence interval for HRR = 0.6, 0.5-0.9 for CVD mortality by 10 beats.min(-1) increment), whereas only CRF and BMI were associated with all-cause mortality. Among older men, HRR was inversely associated with CVD and all-cause mortality, as were several other known risk factors, including CRF (RR(per 2 METs), and 95% CI for HRR = 0.7, 0.5-0.9 for CVD mortality and 0.8, 0.7-0.9 for all-cause mortality). CONCLUSIONS HRR, independent from CRF, was inversely associated with CVD mortality among men in this study. HRR may be an important exercise test parameter to predict CVD mortality in younger men, whereas CRF and other established risk factors are better predictors of CVD and all-cause mortality in older men.
Details: PMID-12471290
Larger thigh and hip circumferences are associated with better glucose tolerance: the Hoorn study.
Institute for Research in Extramural Medicine, VU University Medical Center, Amsterdam, The Netherlands. mb.snijder.emgo@med.vu.nl
OBJECTIVE: A higher waist-to-hip ratio, which can be due to a higher waist circumference, a lower hip circumference, or both, is associated with higher glucose levels and incident diabetes. A lower hip circumference could reflect either lower fat mass or lower muscle mass. Muscle mass might be better reflected by thigh circumference. The aim of this study was to investigate the contributions of thigh and hip circumferences, independent of waist circumference, to measures of glucose metabolism. RESEARCH METHODS AND PROCEDURES: For this cross-sectional study we used baseline data from the Hoorn Study, a population-based cohort study of glucose tolerance among 2484 men and women aged 50 to 75. Glucose tolerance was assessed by a 75-g oral glucose tolerance test; hemoglobin A(1c) and fasting insulin were also measured. Anthropometric measurements included body mass index (BMI) and waist, hip, and thigh circumferences. RESULTS: Stratified analyses and multiple linear regression showed that after adjustment for age, BMI, and waist circumference, thigh circumference was negatively associated with markers of glucose metabolism in women, but not in men. Standardized beta values in women were -0.164 for fasting, -0.206 for post-load glucose, -0.190 for hemoglobin A(1c) (all p < 0.001), and -0.065 for natural log insulin levels (p = 0.061). Hip circumference was negatively associated with markers of glucose metabolism in both sexes (standardized betas ranging from -0.093 to -0.296, p < 0.05) except for insulin in men. Waist circumference was positively associated with glucose metabolism. DISCUSSION: Thigh circumference in women and hip circumference in both sexes are negatively associated with markers of glucose metabolism independently of the waist circumference, BMI, and age. Both fat and muscle tissues may contribute to these associations.
Details: PMID-12529492
OBJECTIVE: A higher waist-to-hip ratio, which can be due to a higher waist circumference, a lower hip circumference, or both, is associated with higher glucose levels and incident diabetes. A lower hip circumference could reflect either lower fat mass or lower muscle mass. Muscle mass might be better reflected by thigh circumference. The aim of this study was to investigate the contributions of thigh and hip circumferences, independent of waist circumference, to measures of glucose metabolism. RESEARCH METHODS AND PROCEDURES: For this cross-sectional study we used baseline data from the Hoorn Study, a population-based cohort study of glucose tolerance among 2484 men and women aged 50 to 75. Glucose tolerance was assessed by a 75-g oral glucose tolerance test; hemoglobin A(1c) and fasting insulin were also measured. Anthropometric measurements included body mass index (BMI) and waist, hip, and thigh circumferences. RESULTS: Stratified analyses and multiple linear regression showed that after adjustment for age, BMI, and waist circumference, thigh circumference was negatively associated with markers of glucose metabolism in women, but not in men. Standardized beta values in women were -0.164 for fasting, -0.206 for post-load glucose, -0.190 for hemoglobin A(1c) (all p < 0.001), and -0.065 for natural log insulin levels (p = 0.061). Hip circumference was negatively associated with markers of glucose metabolism in both sexes (standardized betas ranging from -0.093 to -0.296, p < 0.05) except for insulin in men. Waist circumference was positively associated with glucose metabolism. DISCUSSION: Thigh circumference in women and hip circumference in both sexes are negatively associated with markers of glucose metabolism independently of the waist circumference, BMI, and age. Both fat and muscle tissues may contribute to these associations.
Details: PMID-12529492
Waist–hip ratio is the dominant risk factor predicting cardiovascular death in Australia
Objective:To evaluate clinical measures of obesity for their ability to predict death from cardiovascular disease (CVD) and coronary heart disease (CHD), in parallel with conventional cardiovascular risk factors.
Design, participants and setting:Cross-sectional analysis of an age- and sex-stratified sample of 9206 adults aged 20–69 years from Australian capital cities (1989 Australian Risk Factor Prevalence Survey). Blood pressure, fasting serum lipid levels, smoking, history of heart disease or diabetes, and obesity as measured by body mass index (BMI), waist circumference and waist–hip ratio were recorded. These data were linked with the National Death Index to determine causes of death of the 473 survey subjects who had died to 31 December 2000.
Main outcome measures:Hazard ratios for the risk factors predicting CVD mortality and CHD mortality.
Results:Of the modifiable risk factors, obesity, as measured by waist–hip ratio, is a dominant, independent, predictive variable for CVD and CHD deaths in Australian men and women. Self-reported angina/myocardial infarction in both sexes, and cigarette smoking in women, are also independent risk factors.
Conclusions:Obesity assessed by waist–hip ratio is a better predictor of CVD and CHD mortality than waist circumference, which, in turn, is a better predictor than BMI. The recognition of central obesity is clinically important, as lifestyle intervention is likely to provide significant health benefits.
Details: eMJA
Design, participants and setting:Cross-sectional analysis of an age- and sex-stratified sample of 9206 adults aged 20–69 years from Australian capital cities (1989 Australian Risk Factor Prevalence Survey). Blood pressure, fasting serum lipid levels, smoking, history of heart disease or diabetes, and obesity as measured by body mass index (BMI), waist circumference and waist–hip ratio were recorded. These data were linked with the National Death Index to determine causes of death of the 473 survey subjects who had died to 31 December 2000.
Main outcome measures:Hazard ratios for the risk factors predicting CVD mortality and CHD mortality.
Results:Of the modifiable risk factors, obesity, as measured by waist–hip ratio, is a dominant, independent, predictive variable for CVD and CHD deaths in Australian men and women. Self-reported angina/myocardial infarction in both sexes, and cigarette smoking in women, are also independent risk factors.
Conclusions:Obesity assessed by waist–hip ratio is a better predictor of CVD and CHD mortality than waist circumference, which, in turn, is a better predictor than BMI. The recognition of central obesity is clinically important, as lifestyle intervention is likely to provide significant health benefits.
Details: eMJA
Prospective study of abdominal adiposity and gallstone disease in US men1,2,3
Chung-Jyi Tsai, Michael F Leitzmann, Walter C Willett and Edward L Giovannucci
1 From the Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women’s Hospital, Boston, and the Department of Nutrition, Harvard School of Public Health, Boston.
Background: Obesity is an established risk factor for gallstones, but whether abdominal adiposity contributes independently to the risk, particularly in men, remains unclear.
Objective: The purpose of the study was to examine the associations of abdominal circumference and waist-to-hip ratio, as measures of abdominal adiposity, with the risk of symptomatic gallstone disease in men.
Design: We prospectively studied measures of abdominal obesity in relation to the incidence of symptomatic gallstone disease in a cohort of 29 847 men who were free of prior gallstone disease and who provided complete data on waist and hip circumferences. Data on weight, height, and waist and hip circumferences were collected in 1986 and in 1987 through self-administered questionnaires. As part of the Health Professionals Follow-Up Study, men reported newly diagnosed symptomatic gallstone disease on questionnaires mailed to them every 2 y.
Results: We documented 1117 new cases of symptomatic gallstone disease during 264 185 person-years of follow-up. After adjustment for body mass index and other known or suspected risk factors for gallstones, men with a height-adjusted waist circumference 102.6 cm (40.4 in) had a relative risk of 2.29 (95% CI: 1.69, 3.11; P for trend < 0.001) compared with men with a height-adjusted waist circumference < 86.4 cm (34 in). Men with a waist-to-hip ratio 0.99 had a multivariate relative risk of 1.78 (1.38, 2.28; P for trend < 0.001) compared with men with a waist-to-hip ratio < 0.89.
Conclusions: Our data suggest the presence of a significant association between abdominal adiposity and the incidence of symptomatic gallstone disease. As measures of abdominal adiposity, abdominal circumference and waist-to-hip ratio predict the risk of developing gallstones independently of body mass index.
Details: AJCN
1 From the Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women’s Hospital, Boston, and the Department of Nutrition, Harvard School of Public Health, Boston.
Background: Obesity is an established risk factor for gallstones, but whether abdominal adiposity contributes independently to the risk, particularly in men, remains unclear.
Objective: The purpose of the study was to examine the associations of abdominal circumference and waist-to-hip ratio, as measures of abdominal adiposity, with the risk of symptomatic gallstone disease in men.
Design: We prospectively studied measures of abdominal obesity in relation to the incidence of symptomatic gallstone disease in a cohort of 29 847 men who were free of prior gallstone disease and who provided complete data on waist and hip circumferences. Data on weight, height, and waist and hip circumferences were collected in 1986 and in 1987 through self-administered questionnaires. As part of the Health Professionals Follow-Up Study, men reported newly diagnosed symptomatic gallstone disease on questionnaires mailed to them every 2 y.
Results: We documented 1117 new cases of symptomatic gallstone disease during 264 185 person-years of follow-up. After adjustment for body mass index and other known or suspected risk factors for gallstones, men with a height-adjusted waist circumference 102.6 cm (40.4 in) had a relative risk of 2.29 (95% CI: 1.69, 3.11; P for trend < 0.001) compared with men with a height-adjusted waist circumference < 86.4 cm (34 in). Men with a waist-to-hip ratio 0.99 had a multivariate relative risk of 1.78 (1.38, 2.28; P for trend < 0.001) compared with men with a waist-to-hip ratio < 0.89.
Conclusions: Our data suggest the presence of a significant association between abdominal adiposity and the incidence of symptomatic gallstone disease. As measures of abdominal adiposity, abdominal circumference and waist-to-hip ratio predict the risk of developing gallstones independently of body mass index.
Details: AJCN
Home-based resistance training is not sufficient to maintain improved glycemic control following supervised training in older individuals with type 2
International Diabetes Institute, Melbourne, Victoria, Australia. ddunstan@idi.org.au
OBJECTIVE: To examine whether improvements in glycemic control and body composition resulting from 6 months of supervised high-intensity progressive resistance training could be maintained after an additional 6 months of home-based resistance training. RESEARCH DESIGN AND METHODS: We performed a 12-month randomized controlled trial in 36 sedentary, overweight men and women with type 2 diabetes (aged 60-80 years) who were randomly assigned to moderate weight loss plus high-intensity progressive resistance training (RT&WL group) or moderate weight loss plus a control program (WL group). Supervised gymnasium-based training for 6 months was followed by an additional 6 months of home-based training. Glycemic control (HbA1c), body composition, muscle strength, and metabolic syndrome abnormalities were assessed at 0, 3, 6, 9, and 12 months. RESULTS: Compared with the WL group, HbA1c decreased significantly more in the RT&WL group (-0.8%) during 6 months of supervised gymnasium-based training; however, this effect was not maintained after an additional 6 months of home-based training. In contrast, the greater increase in lean body mass (LBM) observed in the RT&WL group compared with the WL group (0.9 kg, P < 0.05) after the gymnasium-based training tended to be maintained after the home-based training (0.8 kg, P = 0.08). Similarly, the gymnasium-based increases in upper body and lower body muscle strength in the RT&WL group were maintained over the 12 months (P < 0.001). There were no between-group differences for changes in body weight, fat mass, fasting glucose, or insulin at 6 or 12 months. CONCLUSIONS: In older adults with type 2 diabetes, home-based progressive resistance training was effective for maintaining the gymnasium-based improvements in muscle strength and LBM but not glycemic control. Reductions in adherence and exercise training volume and intensity seem to impede the effectiveness of home-based training for maintaining improved glycemic control.
Details: PMID-15616225
OBJECTIVE: To examine whether improvements in glycemic control and body composition resulting from 6 months of supervised high-intensity progressive resistance training could be maintained after an additional 6 months of home-based resistance training. RESEARCH DESIGN AND METHODS: We performed a 12-month randomized controlled trial in 36 sedentary, overweight men and women with type 2 diabetes (aged 60-80 years) who were randomly assigned to moderate weight loss plus high-intensity progressive resistance training (RT&WL group) or moderate weight loss plus a control program (WL group). Supervised gymnasium-based training for 6 months was followed by an additional 6 months of home-based training. Glycemic control (HbA1c), body composition, muscle strength, and metabolic syndrome abnormalities were assessed at 0, 3, 6, 9, and 12 months. RESULTS: Compared with the WL group, HbA1c decreased significantly more in the RT&WL group (-0.8%) during 6 months of supervised gymnasium-based training; however, this effect was not maintained after an additional 6 months of home-based training. In contrast, the greater increase in lean body mass (LBM) observed in the RT&WL group compared with the WL group (0.9 kg, P < 0.05) after the gymnasium-based training tended to be maintained after the home-based training (0.8 kg, P = 0.08). Similarly, the gymnasium-based increases in upper body and lower body muscle strength in the RT&WL group were maintained over the 12 months (P < 0.001). There were no between-group differences for changes in body weight, fat mass, fasting glucose, or insulin at 6 or 12 months. CONCLUSIONS: In older adults with type 2 diabetes, home-based progressive resistance training was effective for maintaining the gymnasium-based improvements in muscle strength and LBM but not glycemic control. Reductions in adherence and exercise training volume and intensity seem to impede the effectiveness of home-based training for maintaining improved glycemic control.
Details: PMID-15616225
Acute and reversible cardiomyopathy provoked by stress in women from the United States.
Minneapolis Heart Institute Foundation, Minneapolis, Minn 55407, USA.
BACKGROUND: A clinical entity characterized by acute but rapidly reversible left ventricular (LV) systolic dysfunction and triggered by psychological stress is emerging, with reports largely confined to Japan. METHODS AND RESULTS: Over a 32-month period, 22 consecutive patients with this novel cardiomyopathy were prospectively identified within a community-based practice in the Minneapolis-St. Paul, Minn, area. All patients were women aged 32 to 89 years old (mean 65+/-13 years); 21 (96%) were > or =50 years of age. The syndrome is characterized by (1) acute substernal chest pain with ST-segment elevation and/or T-wave inversion; (2) absence of significant coronary arterial narrowing by angiography; (3) systolic dysfunction (ejection fraction 29+/-9%), with abnormal wall motion of the mid and distal LV, ie, "apical ballooning"; and (4) profound psychological stress (eg, death of relatives, domestic abuse, arguments, catastrophic medical diagnoses, devastating financial or gambling losses) immediately preceding and triggering the cardiac events. A significant proportion of patients (37%) had hemodynamic compromise and required vasopressor agents and intra-aortic balloon counterpulsation. Each patient survived with normalized ejection fraction (63+/-6%; P<0.001) and rapid restoration to previous functional cardiovascular status within 6+/-3 days. In 95%, MRI identified diffusely distributed segmental wall-motion abnormalities that encompassed LV myocardium in multiple coronary arterial vascular territories. CONCLUSIONS: A reversible cardiomyopathy triggered by psychologically stressful events occurs in older women and may mimic evolving acute myocardial infarction or coronary syndrome. This condition is characterized by a distinctive form of systolic dysfunction that predominantly affects the distal LV chamber and a favorable outcome with appropriate medical therapy.
Details: PMID-15687136
BACKGROUND: A clinical entity characterized by acute but rapidly reversible left ventricular (LV) systolic dysfunction and triggered by psychological stress is emerging, with reports largely confined to Japan. METHODS AND RESULTS: Over a 32-month period, 22 consecutive patients with this novel cardiomyopathy were prospectively identified within a community-based practice in the Minneapolis-St. Paul, Minn, area. All patients were women aged 32 to 89 years old (mean 65+/-13 years); 21 (96%) were > or =50 years of age. The syndrome is characterized by (1) acute substernal chest pain with ST-segment elevation and/or T-wave inversion; (2) absence of significant coronary arterial narrowing by angiography; (3) systolic dysfunction (ejection fraction 29+/-9%), with abnormal wall motion of the mid and distal LV, ie, "apical ballooning"; and (4) profound psychological stress (eg, death of relatives, domestic abuse, arguments, catastrophic medical diagnoses, devastating financial or gambling losses) immediately preceding and triggering the cardiac events. A significant proportion of patients (37%) had hemodynamic compromise and required vasopressor agents and intra-aortic balloon counterpulsation. Each patient survived with normalized ejection fraction (63+/-6%; P<0.001) and rapid restoration to previous functional cardiovascular status within 6+/-3 days. In 95%, MRI identified diffusely distributed segmental wall-motion abnormalities that encompassed LV myocardium in multiple coronary arterial vascular territories. CONCLUSIONS: A reversible cardiomyopathy triggered by psychologically stressful events occurs in older women and may mimic evolving acute myocardial infarction or coronary syndrome. This condition is characterized by a distinctive form of systolic dysfunction that predominantly affects the distal LV chamber and a favorable outcome with appropriate medical therapy.
Details: PMID-15687136
Neurohumoral features of myocardial stunning due to sudden emotional stress.
Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, USA. iwittste@jhmi.edu
BACKGROUND: Reversible left ventricular dysfunction precipitated by emotional stress has been reported, but the mechanism remains unknown. METHODS: We evaluated 19 patients who presented with left ventricular dysfunction after sudden emotional stress. All patients underwent coronary angiography and serial echocardiography; five underwent endomyocardial biopsy. Plasma catecholamine levels in 13 patients with stress-related myocardial dysfunction were compared with those in 7 patients with Killip class III myocardial infarction. RESULTS: The median age of patients with stress-induced cardiomyopathy was 63 years, and 95 percent were women. Clinical presentations included chest pain, pulmonary edema, and cardiogenic shock. Diffuse T-wave inversion and a prolonged QT interval occurred in most patients. Seventeen patients had mildly elevated serum troponin I levels, but only 1 of 19 had angiographic evidence of clinically significant coronary disease. Severe left ventricular dysfunction was present on admission (median ejection fraction, 0.20; interquartile range, 0.15 to 0.30) and rapidly resolved in all patients (ejection fraction at two to four weeks, 0.60; interquartile range, 0.55 to 0.65; P<0.001). Endomyocardial biopsy showed mononuclear infiltrates and contraction-band necrosis. Plasma catecholamine levels at presentation were markedly higher among patients with stress-induced cardiomyopathy than among those with Killip class III myocardial infarction (median epinephrine level, 1264 pg per milliliter [interquartile range, 916 to 1374] vs. 376 pg per milliliter [interquartile range, 275 to 476]; norepinephrine level, 2284 pg per milliliter [interquartile range, 1709 to 2910] vs. 1100 pg per milliliter [interquartile range, 914 to 1320]; and dopamine level, 111 pg per milliliter [interquartile range, 106 to 146] vs. 61 pg per milliliter [interquartile range, 46 to 77]; P<0.005 for all comparisons). CONCLUSIONS: Emotional stress can precipitate severe, reversible left ventricular dysfunction in patients without coronary disease. Exaggerated sympathetic stimulation is probably central to the cause of this syndrome. Copyright 2005 Massachusetts Medical Society.
Details: PMID-15703419
BACKGROUND: Reversible left ventricular dysfunction precipitated by emotional stress has been reported, but the mechanism remains unknown. METHODS: We evaluated 19 patients who presented with left ventricular dysfunction after sudden emotional stress. All patients underwent coronary angiography and serial echocardiography; five underwent endomyocardial biopsy. Plasma catecholamine levels in 13 patients with stress-related myocardial dysfunction were compared with those in 7 patients with Killip class III myocardial infarction. RESULTS: The median age of patients with stress-induced cardiomyopathy was 63 years, and 95 percent were women. Clinical presentations included chest pain, pulmonary edema, and cardiogenic shock. Diffuse T-wave inversion and a prolonged QT interval occurred in most patients. Seventeen patients had mildly elevated serum troponin I levels, but only 1 of 19 had angiographic evidence of clinically significant coronary disease. Severe left ventricular dysfunction was present on admission (median ejection fraction, 0.20; interquartile range, 0.15 to 0.30) and rapidly resolved in all patients (ejection fraction at two to four weeks, 0.60; interquartile range, 0.55 to 0.65; P<0.001). Endomyocardial biopsy showed mononuclear infiltrates and contraction-band necrosis. Plasma catecholamine levels at presentation were markedly higher among patients with stress-induced cardiomyopathy than among those with Killip class III myocardial infarction (median epinephrine level, 1264 pg per milliliter [interquartile range, 916 to 1374] vs. 376 pg per milliliter [interquartile range, 275 to 476]; norepinephrine level, 2284 pg per milliliter [interquartile range, 1709 to 2910] vs. 1100 pg per milliliter [interquartile range, 914 to 1320]; and dopamine level, 111 pg per milliliter [interquartile range, 106 to 146] vs. 61 pg per milliliter [interquartile range, 46 to 77]; P<0.005 for all comparisons). CONCLUSIONS: Emotional stress can precipitate severe, reversible left ventricular dysfunction in patients without coronary disease. Exaggerated sympathetic stimulation is probably central to the cause of this syndrome. Copyright 2005 Massachusetts Medical Society.
Details: PMID-15703419
Psychologic functioning and physical health: a paradigm of flexibility.
Division of Cardiology, St. Luke's-Roosevelt Hospital Center, 1111 Amsterdam Ave, New York, NY 10025, USA. AR77@columbia.edu
Recent evidence suggests that positive psychologic factors may be protective against coronary artery disease (CAD). We consider this possibility through a paradigm that explores three interrelated factors that may promote healthy psychologic functioning: vitality, emotional flexibility, and coping flexibility. Vitality is a positive and restorative emotional state that is associated with a sense of enthusiasm and energy. Flexibility is related both to the ability to regulate emotions effectively and cope effectively with challenging daily experiences. A variety of factors may diminish vitality, including chronic stress and negative emotions. Pathophysiologically, chronic stress and negative emotional states can both invoke a "chronic stress response" characterized by increased stimulation of the sympathetic nervous system and hypothalamic-pituitary-adrenal axis, with resultant peripheral effects, including augmented heart rate and blood pressure responsiveness and delayed recovery to stressful stimuli. Research indicates a wide array of stressful conditions--associated with either elements of relative inflexibility in psychologic functioning and/or relatively unabated stressful stimulation--that are associated with this type of exhausting hyperarousal. Conversely, new data suggest that positive psychologic factors, including positive emotions, optimism, and social support, may diminish physiological hyperresponsiveness and/or reduce adverse clinical event rates. Still other positive factors such as gratitude and altruistic behavior have been linked to a heightened sense of well-being but have not yet been tested for beneficial physiological effects. Pending further study, these observations could serve as the basis for expanding the potential behavioral interventions that may be used to assist patients with psychosocial risk factors for CAD.
Details: PMID-15953801
Recent evidence suggests that positive psychologic factors may be protective against coronary artery disease (CAD). We consider this possibility through a paradigm that explores three interrelated factors that may promote healthy psychologic functioning: vitality, emotional flexibility, and coping flexibility. Vitality is a positive and restorative emotional state that is associated with a sense of enthusiasm and energy. Flexibility is related both to the ability to regulate emotions effectively and cope effectively with challenging daily experiences. A variety of factors may diminish vitality, including chronic stress and negative emotions. Pathophysiologically, chronic stress and negative emotional states can both invoke a "chronic stress response" characterized by increased stimulation of the sympathetic nervous system and hypothalamic-pituitary-adrenal axis, with resultant peripheral effects, including augmented heart rate and blood pressure responsiveness and delayed recovery to stressful stimuli. Research indicates a wide array of stressful conditions--associated with either elements of relative inflexibility in psychologic functioning and/or relatively unabated stressful stimulation--that are associated with this type of exhausting hyperarousal. Conversely, new data suggest that positive psychologic factors, including positive emotions, optimism, and social support, may diminish physiological hyperresponsiveness and/or reduce adverse clinical event rates. Still other positive factors such as gratitude and altruistic behavior have been linked to a heightened sense of well-being but have not yet been tested for beneficial physiological effects. Pending further study, these observations could serve as the basis for expanding the potential behavioral interventions that may be used to assist patients with psychosocial risk factors for CAD.
Details: PMID-15953801
An elevation of triglycerides reflecting decreased triglyceride clearance may not be pathogenic -- relevance to high-carbohydrate diets
Pantox Laboratories, 4622 Santa Fe St., San Diego, CA 92109, USA. mmccarty@nai-online.com
The fact that carbohydrate-rich diets often increase plasma triglycerides has led some to question the wisdom of such diets. This increase is primarily attributable to a decrease in the efficiency of triglyceride clearance -- whereas the elevation of triglycerides observed in insulin-resistant subjects stems mainly from increased hepatic production of VLDL particles. There is growing reason to suspect that the increased coronary risk associated with elevated triglycerides in Western epidemiology reflects the fact that high triglycerides are a marker for insulin resistance syndrome, rather than any inherent pathogenic role of triglycerides per se. Thus, endothelial dysfunction is seen only in those hypertriglyceridemic subjects who are insulin resistant, and is absent in patients whose markedly elevated triglycerides reflect genetically defective lipoprotein lipase activity. Triglyceride levels are relatively high in certain Third World societies which are virtually immune to coronary disease so long as they persist in their traditional very-low-fat diets; in Ornish's celebrated study, a moderate rise in triglycerides coincided with a marked reduction in coronary events. Although the particle size of both LDL and HDL tends to decrease when triglyceride levels are high, it is questionable whether this effect has a major pathogenic impact. The one clear drawback of high-carbohydrate diets is a decrease in HDL particle number, resulting from decreased hepatic production of apoA-I; this effect is seen whether or not triglycerides increase. The very favorable effects of very-low-fat, whole food, quasi-vegan diets on LDL cholesterol, insulin sensitivity, and body weight appear to more than compensate for this decrease in HDL; it is notable that HDL levels tend to be quite low in Third World cultures at minimal risk for coronary disease. On the other hand, this decrease in HDL may be of more significance in the context of omnivore diets only moderately low in fat, as suggested by the fact that diets higher in unsaturated fats emerge as more protective in Western prospective epidemiology. The tendency of high-carbohydrate diets to boost triglycerides can be minimized by exercise training, supplemental fish oil, an emphasis on fiber-rich, low-glycemic-index whole foods, and the "spontaneous" weight loss often seen with ad libitum consumption of such diets -- measures which are highly recommendable whether or not triglycerides are a concern.
More details: PMID-15504577
The fact that carbohydrate-rich diets often increase plasma triglycerides has led some to question the wisdom of such diets. This increase is primarily attributable to a decrease in the efficiency of triglyceride clearance -- whereas the elevation of triglycerides observed in insulin-resistant subjects stems mainly from increased hepatic production of VLDL particles. There is growing reason to suspect that the increased coronary risk associated with elevated triglycerides in Western epidemiology reflects the fact that high triglycerides are a marker for insulin resistance syndrome, rather than any inherent pathogenic role of triglycerides per se. Thus, endothelial dysfunction is seen only in those hypertriglyceridemic subjects who are insulin resistant, and is absent in patients whose markedly elevated triglycerides reflect genetically defective lipoprotein lipase activity. Triglyceride levels are relatively high in certain Third World societies which are virtually immune to coronary disease so long as they persist in their traditional very-low-fat diets; in Ornish's celebrated study, a moderate rise in triglycerides coincided with a marked reduction in coronary events. Although the particle size of both LDL and HDL tends to decrease when triglyceride levels are high, it is questionable whether this effect has a major pathogenic impact. The one clear drawback of high-carbohydrate diets is a decrease in HDL particle number, resulting from decreased hepatic production of apoA-I; this effect is seen whether or not triglycerides increase. The very favorable effects of very-low-fat, whole food, quasi-vegan diets on LDL cholesterol, insulin sensitivity, and body weight appear to more than compensate for this decrease in HDL; it is notable that HDL levels tend to be quite low in Third World cultures at minimal risk for coronary disease. On the other hand, this decrease in HDL may be of more significance in the context of omnivore diets only moderately low in fat, as suggested by the fact that diets higher in unsaturated fats emerge as more protective in Western prospective epidemiology. The tendency of high-carbohydrate diets to boost triglycerides can be minimized by exercise training, supplemental fish oil, an emphasis on fiber-rich, low-glycemic-index whole foods, and the "spontaneous" weight loss often seen with ad libitum consumption of such diets -- measures which are highly recommendable whether or not triglycerides are a concern.
More details: PMID-15504577
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