Changes in plasma lipids and lipoproteins in overweight men during weight loss through dieting as compared with exercise

Exercise as a coronary protective factor

Exercise has multiple beneficial actions, both in normal subjects and in patients with coronary artery disease, which can be cardioprotective. Apart from reducing known risk factors and protecting against their deleterious effects, exercise also reduces the risk of coronary artery disease by increasing cardiovascular fitness. The exact contribution of each of these mechanisms in reducing coronary artery disease morbidity and mortality is unclear. Although fitness may be desirable, much of the cardioprotection can be achieved through increased leisure time and recreational physical activity. The risk-benefit ratio is very much in favor of moderate intensity exercise. Even in the absence of a controlled trial, the available evidence suggests that efforts to encourage physical activity are justified.

The effects on plasma lipoproteins of a prudent weight-reducing diet, with or without exercise, in overweight men and women

BACKGROUND

The National Cholesterol Education Program (NCEP) recommends a low-saturated-fat, low-cholesterol diet, with weight loss if indicated, to correct elevated plasma cholesterol levels. Weight loss accomplished by simple caloric restriction or increased exercise typically increases the level of high-density lipoprotein (HDL) cholesterol. Little is known about the effects on plasma lipoproteins of a hypocaloric NCEP diet with or without exercise in overweight people.

METHODS

We tested the hypothesis that exercise (walking or jogging) will increase HDL cholesterol levels in moderately overweight, sedentary people who adopt a hypocaloric NCEP diet. We randomly assigned 132 men and 132 women 25 to 49 years old to one of three groups: control, hypocaloric NCEP diet, or hypocaloric NCEP diet with exercise. One hundred nineteen of the men and 112 of the women returned for testing after one year.

RESULTS

After one year, the subjects in both intervention groups had reached or closely approached NCEP Step 1 dietary goals and reduced their mean body fat significantly (range of reduction in mean fat weight, 4.0 to 7.8 kg). Weight loss on the NCEP diet alone did not significantly change HDL cholesterol levels in either the men or the women as compared with the subjects in the control group. Plasma levels of HDL cholesterol increased significantly more in the men who exercised and dieted (mean [+/- SE] change, +13 +/- 3 percent) than in the men who only dieted (+2 +/- 3 percent, P less than 0.01) or the men who acted as controls (-4 +/- 2 percent, P less than 0.001). HDL cholesterol levels remained about the same in the women who exercised and dieted (+1 +/- 2 percent); they were higher than in the women who only dieted (-10 +/- 3 percent, P less than 0.01), but not higher than in the controls (-3 +/- 3 percent).

CONCLUSIONS

Regular exercise in overweight men and women enhances the improvement in plasma lipoprotein levels that results from the adoption of a low-saturated-fat, low-cholesterol diet.

Loss of abdominal fat and metabolic response to exercise training in obese women

Numerous studies have shown that a high accumulation of abdominal fat is associated with metabolic complications and with an increased risk of coronary heart disease. The present study examined the effects of changes in body fatness and in the level of abdominal fat on metabolic variables in a sample of 13 obese premenopausal women, aged 38.8 +/- 5.3 (SD) yr. Women exercised for 90 min at approximately 55% of maximal aerobic power (VO2 max) four to five times a week for a period of 14 mo. The training program induced a significant increase in VO2 max and a mean reduction in body fat mass of 4.6 kg (P less than 0.01), with no change in fat-free mass. Measurement of adipose tissue areas by computed tomography indicated a greater loss of abdominal fat compared with midthigh adipose tissue (P less than 0.05). The training program also produced significant reductions in the insulinogenic index measured during an oral glucose tolerance test and in plasma cholesterol (Chol), low-density lipoprotein (LDL)-Chol, and apolipoprotein (apo) B levels (P less than 0.05). Training also significantly increased plasma high-density lipoprotein (HDL)-apo A-I and HDL2-Chol levels and decreased plasma HDL3-Chol concentration (P less than 0.05). Whereas no change in postheparin plasma lipoprotein lipase activity was noted, a significant decrease in postheparin plasma hepatic triglyceride lipase activity was observed after training (P less than 0.005). Metabolic responses were not correlated with changes in VO2 max but were significantly correlated with the reduction in body fat mass and/or with the loss of deep abdominal fat.(ABSTRACT TRUNCATED AT 250 WORDS)

Health benefits of aerobic exercise

Regular aerobic exercise has significant cardiovascular benefits, including a reduction in incidence of and mortality from coronary artery disease--probably because of positive effects on blood lipid levels and blood pressure. Aerobic exercise can also be an important adjunct to a weight-loss program. Many persons who continue an exercise program do so because of its positive mental benefits, including reduction in anxiety and depression and modulation of stress levels. Aerobic exercise has a place in the management of diabetes, pregnancy, and aging. The problems associated with aerobic exercise are minimal compared with its benefits.

Effects of physical conditioning on fibrinolytic variables and fibrinogen in young and old healthy adults

BACKGROUND

The effects of 6 months of intensive endurance exercise training on resting tissue-type plasminogen activator (t-PA) activity, plasminogen activator inhibitor type 1 (PAI-1) activity, t-PA antigen, and fibrinogen were studied in 10 young (24-30 years) and in 13 old male subjects (60-82 years).

METHODS AND RESULTS

After training, maximum oxygen consumption was increased in the young group by 18% (44.9 +/- 5.0 to 52.9 +/- 6.6 ml/kg/min, p less than 0.001), whereas it was increased in the old group by 22% (29.0 +/- 4.2 to 35.5 +/- 3.6 ml/kg/min, p less than 0.001). The young group had no significant changes in any of the measured variables, whereas the old group had a 39% increase in t-PA activity (0.82 +/- 0.47 to 1.14 +/- 0.42 IU/ml, p less than 0.03), a 141% increase in the percentage of t-PA in the active form (11.1 +/- 7.7 to 26.8 +/- 15.1%, p less than 0.01), a 58% decrease in PAI-1 activity (8.4 +/- 4.9 to 3.5 +/- 1.7 AU/ml, p less than 0.01), and a 13% decrease in fibrinogen (3.57 +/- 0.79 to 3.11 +/- 0.52 g/l, p less than 0.01).

CONCLUSIONS

We conclude that intensive exercise training enhances resting t-PA activity and reduces fibrinogen and PAI-1 activity in older men. These effects are potential mechanisms by which habitual physical activity might reduce the risk of cardiovascular disease.

The role of exercise in weight regulation in nonathletes

Obesity is an extremely prevalent condition that is associated with a range of deleterious health effects. While traditionally considered a disorder primarily of energy intake, accumulating evidence underscores the importance of energy expenditure in the development and treatment of obesity. As the most variable component of energy expenditure, physical activity can influence the development of obesity as well as success in achieving both initial and long term weight loss. Among the types of exercise-related physiological and behavioural factors most likely to be involved in the development of obesity are reductions in the amount of physical activity actually performed, differences in the effect of physical activity on diet-induced thermogenesis, and modeling of deleterious dietary and exercise patterns on the part of the family and other facets of the environment. In contrast, there is relatively little evidence supporting the common belief that obese individuals have a significantly greater energy intake than nonobese individuals. With respect to weight reduction in the already obese, while increased physical activity levels often augment caloric restriction programmes in aiding initial weight loss, evidence suggests that physical activity may be particularly important in helping to sustain initial losses through increased total energy output, preservation of lean body mass, and changes in substrate utilisation. The psychological benefits received from regular participation in a physical activity programme may serve as an additional impetus for engaging in such activities over the long run. Developing programmes to aid in long term adherence to physical activity regimens remains the most critical challenge. Recent results suggest the utility of regular, brief contacts in aiding sustained physical activity participation in individuals attempting to control their weight.

Randomized clinical trials of weight reduction in nonhypertensive persons

Since 1987, four randomized controlled clinical trials with 872 nonhypertensive subjects have produced results on weight-reducing interventions, involving decreased caloric intake and/or increased expenditure, for effects on blood pressure (BP). The Hypertension Prevention Trial maintained a 3.5-kg net weight loss through 36 months with intake reduction alone. This program decreased BP by 2.4/1.8 mm Hg (systolic/diastolic) compared to controls, but both weight loss and blood pressure changes were smaller when combined with decreased sodium intake. A Stanford University trial achieved weight losses of 7.4 and 5.1 kg over 12 months with diet and exercise, respectively. Effects on clinic BP were in the range of 1.5 to 3.0 mm Hg and did not differ by intervention approach. The sole trial in children, conducted at University of Michigan, found similar weight loss (about 7 kg) and BP effects from limiting caloric intake over 20 weeks, regardless of inclusion of an exercise program; the latter did, however, result in greater reductions in percent body fat, heart rate, and serum insulin levels. The Primary Prevention of Hypertension trial tested a multifactor intervention including reductions in weight (mean, 2.7 kg), sodium and alcohol intake, and increased physical activity. During a 5-year period, clinic BP was reduced by 2.0/1.9 mm Hg, and the incidence of hypertension, by 52%. It is concluded that weight loss, however achieved, lowers BP in overweight nonhypertensive persons, and probably can contribute substantially to reducing the incidence of hypertension. Whether there are independent effects additive to weight loss from increasing physical activity and reducing sodium intake remains unknown.

Effect of physical training on lipids, lipoproteins, apolipoproteins, lipases, and endogenous sex hormones in men with premature myocardial infarction

In 17 men, aged 27 to 54 years, with myocardial infarction 2 to 10 months before the current exercise study, we aimed to determine whether 3 months of exercise training, at a level designed to elevate high-density lipoprotein cholesterol (HDLC), would be associated with changes in endogenous sex steroid hormones and postheparin lipoprotein and hepatic lipases, and whether the changes in sex hormones, lipids, lipoproteins, apolipoproteins, and physical activity were interrelated. Supervised bicycle ergometry, 30 minutes, 3 days per week, eliciting 75% of maximum heart rate, produced a significant training effect, with a 26% increase in the duration of the exercise test at a standardized, submaximal workload (P less than or equal to .001), and a reduction in heart rate measured at a standardized submaximal workload, P = .08. After 3 months' training, mean HDLC increased 23% (30 to 37 mg/dL), P less than or equal to .001, mean apo A2 increased 19% (43 to 51 mg/dL), P less than or equal to .001, and the ratio of total cholesterol (TC) to HDLC decreased 26% (P less than or equal to .01), while estradiol (E2) levels decreased 45% (50.1 to 27.8 pg/mL), P less than or equal to .0001. After 1 and 2 months' exercise, TC (12% [P less than or equal to .001], 11% [P less than or equal to .01]), and low-density lipoprotein cholesterol (LDLC) (13% [P less than or equal to .01], 12% [P less than or equal to .01]) were reduced. Hepatic lipase decreased 16% (P less than or equal to .01) and 16% (P less than or equal to .05) after 1 and 3 months' exercise. There were no significant changes in apo A1, lipoprotein lipase, testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), or weight. By stepwise regression analysis, after 3 months' training, 66% (P = .0025) of the variance for the increase in HDLC from baseline to day 90 was accounted for independently by a decrease in triglyceride (F = 13.2, P = .003), by reduced heart rate on a fixed submaximal load (F = 12.7, P = .0035), and by a decrease in hepatic lipase (F = 5.5, P = .036). A modest, achievable exercise program can have significant cardiovascular benefit for men after myocardial infarction by ameliorating their hyperestrogenemia, reducing TC and LDLC, improving the TC to HDLC ratio, and elevating HDLC and apo A2. The increment in HDLC was related independently to improved capacity to sustain submaximal exercise and to exercise-induced reductions in triglyceride and postheparin hepatic lipase.

The epidemiology of endometrial cancer

The descriptive and analytical epidemiology of endometrial cancer is reviewed. Over the last few decades, age-standardized incidence rates have been rising in several countries. The rise has been even greater in terms of absolute numbers of cases, and hence public health implications, due to the aging of the population. Although endometrial cancer rates were found to be higher in richer countries and urban populations, there is now evidence of some changes in the socioeconomic determinants of the disease in developed countries. In etiological terms, any factor that increases exposure to unopposed estrogens (such as menopausal replacement treatment, obesity, and irregular menstrual cycles) tends to increase the risk of the disease, while factors that decrease exposure to estrogens or increase progesterone levels (such as oral contraceptives or smoking) tend to be protective. Less well defined, or more difficult to explain in biological terms, is the role of other factors, such as births, miscarriages, or diabetes and hypertension, and only suggestive evidence is available on diet from analytical epidemiology. The data reviewed herein are discussed in terms of models of carcinogenesis, as well as attributable risks and public health implications.

Lifestyle determinants of HDL2- and HDL3-cholesterol levels in a hypercholesterolemic male population

In this cross-sectional study we investigated the role of lifestyle and other factors in determining serum HDL2- and HDL3-cholesterol levels among 82 dyslipidemic (total cholesterol minus HDL-cholesterol greater than or equal to 5.2 mmol/l) middle-aged participants of the Helsinki Heart Study. Alcohol consumption correlated positively with both subfractions of HDL-cholesterol, while leisure time physical activity had a significant correlation with the HDL3-subfraction only. HDL levels were lower in smokers than in non-smokers but the differences were not statistically significant. Using the multiple linear regression model, alcohol consumption emerged as the only significant factor influencing both HDL cholesterol subfraction levels. Leisure time physical activity had an independent contribution to HDL3-level, but lifestyle variables other than alcohol consumption did not contribute significantly to HDL2-cholesterol level. The model incorporating alcohol consumption, physical activity, smoking and relative body weight explained 13.4% of the variation in HDL2 and 17.5% in HDL3-cholesterol.

Cardiovascular risk factors and the effects of intervention

Cardiovascular risk factors can be substantially modified by changes in life-style such as diet, exercise, smoking cessation, and moderation of alcohol consumption. In turn, these can reduce blood pressure, heart rate at rest, and blood lipid concentrations. Epidemiologic evidence shows that for every 1% change in serum cholesterol levels, there is a 3% change in the likelihood of developing coronary heart disease. In addition, a long-term (5-year) change of 5 to 6 mm Hg in diastolic blood pressure can reduce the chances of stroke by 35 to 40% and of coronary heart disease by 20 to 25%. The full impact of this broad range of interventions on population health has still to be fully realized in many countries, including the United Kingdom, however it is likely to be considerable. Some of the recent evidence in support of such cardiovascular risk factor modification is selectively reviewed.

Managing the whole patient with hypertension: practical applications in a clinical setting

Physicians are aware of the value of treating hypertension. Complications such as stroke and congestive heart failure are less likely to occur in the well-controlled patient. In our quest to add coronary heart disease to this list, we must go beyond simple reduction of blood pressure. We must consider other risk factors such as hypercholesterolemia, cigarette smoking, diabetes mellitus, and family history. The presence of one or more of these may indicate a more aggressive treatment approach. Similarly the presence of left ventricular hypertrophy, coronary disease, or renal disease may indicate specific pharmacotherapy. On the other hand, the low-risk patient with no other problems or conditions may be treated with only nonpharmacologic therapy such as weight loss, dietary sodium reduction, and/or alcohol restriction. Every patient has a different constellation of findings. Every patient should be treated individually. It is no longer sufficient just to lower blood pressure; we need to manage the whole patient with hypertension; keeping in mind that most antihypertensive agents are equally effective, the side effect profile is often the decisive factor in choosing an antihypertensive agent.

Management of the patient with a low HDL-cholesterol

While there is epidemiologic evidence linking a low high-density lipoprotein (HDL) cholesterol level with coronary disease events, and interventions that raise HDL while lowering low-density lipoprotein (LDL) cholesterol levels have been shown to reduce subsequent coronary events, there are no studies showing benefit from raising HDL when a low HDL level is the sole lipid abnormality. HDL is thought to play a key role in reverse cholesterol transport, removing lipids from peripheral cells, but the precise role of HDL in cholesterol metabolism is not understood. The measurement of HDL levels has not been well standardized. Reliance on ratios relating HDL to LDL or to total cholesterol may be misleading in the management of patients. It has not been shown that measuring HDL subfractions or apolipoprotein levels is superior to measuring total HDL levels in predicting coronary risk. HDL levels may be raised by hygienic measures such as smoking cessation and exercise, but a considerable amount of exercise over a long period of time is required. Alcohol consumption and weight loss through dieting inconsistently raise HDL. Estrogen therapy raises and progestational agents lower HDL. Certain beta-blocking drugs lower HDL levels. For the patient with an isolated low HDL level the hygienic measures may be advised, but drug therapy such as nicotinic acid or gem-fibrozil should be prescribed only when low HDL is accompanied by elevated LDL levels that are unresponsive to diet and hygienic measures.

Failure of family history to predict high blood cholesterol among hispanic preschool children

Recommendations for screening children for high blood cholesterol remain controversial. The American Academy of Pediatrics, the American Heart Association, and the National Institutes of Health (NIH) Consensus Conference have recommended targeted screening of children with positive family history. We examined data from a sample of 108 Hispanic preschool children and their families to test targeted screening strategies. Thirty-seven children (34.3%) had total cholesterol levels of greater than or equal to 4.40 mmole/liter (170 mg/dl). Using the American Academy of Pediatrics definition of family history, sensitivity (proportion of those with high blood cholesterol with positive family history) was 0.57 (95% confidence interval, 0.40 to 0.73) and accuracy (overall proportion correctly classified) was 0.58 (0.48 to 0.68). Using the American Heart Association and NIH Consensus Conference definition of family history, sensitivity was 0.46 (0.30 to 0.63) and accuracy was 0.62 (0.52 to 0.71). Classification of children based on the mother's total cholesterol level of greater than or equal to 5.17 mmole/liter (200 mg/dl), the mother's low-density lipoprotein cholesterol level of greater than or equal to 4.14 mmole/liter (160 mg/dl), the mother's low-density lipoprotein cholesterol level of greater than or equal to 3.36 mmole/liter (130 mg/dl), or the child's own body mass index greater than or equal to 75th percentile was less sensitive and no more accurate. These findings indicate that current recommendations as well as other potential strategies for targeted cholesterol screening in young children have serious shortcomings and lend support to universal cholesterol screening in childhood.

Interrelations between carbohydrates, lipids, and the hemostatic system in relation to the risk of thrombotic and cardiovascular disease

Metabolic diseases, such as obesity, impaired glucose tolerance, type I and type II diabetes, hypercholesterolemia, and hypertriglyceridemia, are among the main risk factors for the development of atherothrombosis. Various abnormalities of the hemostatic system (platelet hyperaggregability, hypercoagulability, and hypofibrinolysis) have been described in all these situations. The individual effect of each of these disease on the hemostatic system is difficult to evaluate because these states are often associated in the same patient and the treatment of one can benefit the others. Therefore it may be queried if a common abnormality of these pathologic states might explain their impact on the cardiovascular system. We have been interested by hyperinsulinemia, which is observed in obesity, impaired glucose tolerance, type II diabetes, and hypertriglyceridemia, and we have shown a very strong correlation between plasma insulin, body mass index, triglyceride levels, and one of the main inhibitors of the fibrinolytic system, plasminogen activator inhibitor-1. Partial correlation analysis showed that only the correlation between insulin and plasminogen activator inhibitor-1 was independent. Therefore a high plasma insulin level could be responsible for elevated levels of plasminogen activator inhibitor-1, which by inducing an hypofibrinolysis, could play a role in the deposition of fibrin and the development of atherothrombosis. The description of some interrelations between metabolic diseases and hemostasis is satisfactory but does not exclude specific effects of these diseases on hemostasis, such as glycation of the coagulation and fibrinolytic factors in diabetes or toxic action of lipoprotein on endothelial cells in hyperlipoproteinemia.

Plasma lipid and lipoprotein levels in obese post-menopausal women: effects of a short-term low-protein diet and exercise

Obesity is associated with an increased prevalence of cardiovascular and cerebrovascular disease, probably mediated by the induction of an atherogenic lipid profile. Since few data are available concerning plasma lipid levels and the effects of short-term dieting on these parameters in obese postmenopausal women, we studied plasma lipid and lipoprotein levels in such women and also the effects on these levels of a short-term hypocaloric low-fat diet combined with a moderately intense physical exercise programme. Plasma triglycerides and low-density-lipoprotein cholesterol (LDL-C) levels were significantly higher, whereas high-density-lipoprotein cholesterol (HDL-C) and apoprotein A1 (ApoA1) levels, as well as the HDL-C/LDL-C and ApoA1/ApoB ratios, were significantly lower in moderately to severely obese women (Body Mass Index greater than 30, n = 26) than in non-obese post-menopausal controls. A short-term (4 week) protein-sparing modified fast diet, providing 400 calories (1675 J), resulted in a mean weight loss of 7.7 +/- 2.8 (S.D.) kg. While plasma cholesterol, LDL-C and ApoB levels decreased by approximately 25% and reached the levels recorded in normal controls, ApoA2 decreased by 20%. HDL-C and HDL2-C levels remained unchanged and as a consequence the HDL-C/LDL-C and the ApoA1/Apob ratios increased, indicating a shift towards a less atherogenic lipid profile. No correlation was observed between weight loss and changes in lipid or lipoprotein levels. It was concluded that a hypocaloric, low-fat diet combined with our physical exercise programme, resulted in the normalization of plasma lipids within 4 weeks.

Weight set-point theory and the high-density lipoprotein concentrations of long-distance runners

Long-distance runners have higher high-density lipoprotein (HDL)-cholesterol concentrations and lower adiposity than sedentary men. Most cross-sectional studies claim that the runners' elevated HDL-cholesterol is not due to the runners' leanness. However, when cross-sectional studies use analysis of covariance (ANCOVA) to adjust for adiposity, or when they compare runners with lean sedentary men, they make an incorrect tacit assumption. They assume that the relationship between change in adiposity and change in HDL-cholesterol in men who have lost fat by running is the same as the cross-sectional difference in HDL-cholesterol between naturally fat and lean sedentary men. Regression slopes for HDL-cholesterol versus adiposity during and at the end of 1 year of running in 35 initially sedentary men suggest this assumption is incorrect; the increase in HDL-cholesterol that accompanies weight loss (-4.28 +/- 1.01 mg/100 mL per kg/m2) is considerably greater than the increase in HDL-cholesterol that is associated with lower adiposity cross-sectionally (-0.78 +/- 0.46 mg/100 mL per kg/m2). These results suggest the following theory: long-distance runners have the HDL metabolism of men who are below their sedentary set-point weight rather than the HDL metabolism of men who are naturally lean without exercising or dieting. This theory was applied to data from 23 published comparisons between long-distance runners and sedentary men.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid profile in trained subjects undergoing complete food deprivation combined with prolonged intermittent exercise

Sixteen male subjects [18-21 years, maximal oxygen consumption (VO2max) = 59.2 ml.kg-1.min-1 +/- SEM 5.6] participated in a study to evaluate the effect of prolonged, complete food deprivation combined with physical effort, on plasma lipoprotein concentrations. The subjects were deprived of food for 81 h but were supplied with water: they walked for 10 h a day at 40% of VO2max, covering a total of 105 km. During this period the subjects' average mass decreased significantly (P less than 0.05) reflecting a marked catabolic process. Plasma concentration of low density lipoprotein-cholesterol [( LDL-C]) and triglycerides were significantly lower (P less than 0.05) and total cholesterol, high-density lipoprotein-cholesterol [( HDL-C]), and free fatty acid levels were significantly higher (P less than 0.05) at the end of the experimental period compared to the start. The ratio between plasma [HDL-C] to plasma [LDL-C] increased from 0.51 to 0.89 at the end of the exercise period, reflecting a marked anti-atherogenic effect. All changes were transient and reversible within 12 days of recovery.

Changes in lipoprotein subfractions during diet-induced and exercise-induced weight loss in moderately overweight men

We studied separately the effects of weight loss by calorie restriction (dieting) and by calorie expenditure (primarily, running) on lipoprotein subfraction concentrations in sedentary, moderately overweight men assigned at random into three groups as follows: exercise without calorie restriction (n = 46), calorie restriction without exercise (n = 42), and control (n = 42). Plasma lipoprotein mass concentrations were measured by analytic ultracentrifugation for flotation rates (F0(1.20), S0f) within high density lipoprotein (HDL) (F0(1.20) 0-9), low density lipoprotein (LDL) (S0f 0-12), intermediate density lipoprotein (IDL) (S0f 12-20), and very low density lipoprotein (VLDL) (S0f 20-400) particle distributions. Particle diameter and flotation rate of the most abundant LDL species were determined by nondenaturing polyacrylamide gradient gel electrophoresis and analytic ultracentrifugation, respectively. During the 1-year trial, the exercisers ran (mean +/- SD) 15.6 +/- 9.1 km/wk, and the dieters ate 340 +/- 71 fewer kilocalories per day than at baseline. Total body weight was reduced significantly more in dieters (-7.2 +/- 4.1 kg) and exercisers (-4.0 +/- 3.9 kg) than controls (0.6 +/- 3.7 kg). As compared with mean changes in controls, the exercisers and dieters significantly increased HDL2 mass (48.6% and 47.1%, respectively), decreased VLDL mass (-23.9% and -25.5%), and increased LDL peak particle diameter (2.4 and 3.2 A). When adjusted to an equivalent change in body mass index by analysis of covariance, 1) exercise-induced and diet-induced weight loss produced comparable mean changes in the mass of small LDL and VLDL, and in LDL peak particle diameter; 2) the exercisers versus control group difference in HDL2 was attributed to the exercisers' reduced body mass index; and 3) HDL2 increased significantly less in dieters than in exercisers. In dieters, low calorie intake might mitigate the effects of weight loss on HDL2.

A prospective study of obesity and risk of coronary heart disease in women

We examined the incidence of nonfatal and fatal coronary heart disease in relation to obesity in a prospective cohort study of 115,886 U.S. women who were 30 to 55 years of age in 1976 and free of diagnosed coronary disease, stroke, and cancer. During eight years of follow-up (775,430 person-years), we identified 605 first coronary events, including 306 nonfatal myocardial infarctions, 83 deaths due to coronary heart disease, and 216 cases of confirmed angina pectoris. A higher Quetelet index (weight in kilograms divided by the square of the height in meters) was positively associated with the occurrence of each category of coronary heart disease. For increasing levels of current Quetelet index (less than 21, 21 to less than 23, 23 to less than 25, 25 to less than 29, and greater than or equal to 29), the relative risks of nonfatal myocardial infarction and fatal coronary heart disease combined, as adjusted for age and cigarette smoking, were 1.0, 1.3, 1.3, 1.8, and 3.3 (Mantel-extension chi for trend = 7.29; P less than 0.00001). As expected, control for a history of hypertension, diabetes mellitus, and hypercholesterolemia--conditions known to be biologic effects of obesity--attenuated the strength of the association. The current Quetelet index was a more important determinant of coronary risk than that at the age of 18; an intervening weight gain increased risk substantially. These prospective data emphasize the importance of obesity as a determinant of coronary heart disease in women. After control for cigarette smoking, which is essential to assess the true effects of obesity, even mild-to-moderate overweight increased the risk of coronary disease in middle-aged women.

Effects of long-term, self-monitored exercise on the serum lipoprotein and apolipoprotein profile in middle-aged men

To study the effects of long-term, self-monitored exercise on the serum lipid profile and body composition of middle-aged non-smoking males, a controlled study was conducted in 61 sedentary, middle-class Swiss men. Thirty-nine men were randomly allocated to jog 2 h/wk for 4 months on an individually prescribed, heart rate-controlled basis, whereas 22 men served as controls. Despite varying adherence to the exercise regimen, the following 4-month net changes (effect in exercise group minus effect in control group) in lipids were seen: HDL cholesterol (C) +0.12 mmol/l (95% CI 0.02, 0.22; P = 0.028), LDL-C +0.08 mmol/l (ns), VLDL-C -0.26 mmol/l (-0.45, -0.07; P = 0.009), total triglycerides (TT) -0.21 mmol/l (ns), HDL-C/total C +0.02 (0.001, 0.05; P = 0.047). The net changes in endurance capacity and resting heart rate in favour of exercisers were significant as well, whereas no significant changes in apolipoprotein levels were seen. Exploratory analyses revealed, for example, associations of the increase in total physical activity with an increase in the HDL-C/total C ratio (r = 0.46; P less than 0.001), and of the change in estimated body fat content with an opposed change in the HDL-C/total C ratio (r = -0.40; P less than 0.001), or an inverse relationship of the change in subcutaneous fat with a change in the HDL2-C level (r = -0.39; P less than 0.001). Multivariable regression analysis suggested that much of the effect of jogging on HDL-C was apparently mediated through a decrease in body fat content. A change in the waist/hip ratio was unrelated to lipoprotein changes but was related to the change of TT level (r = 0.22; P less than 0.05). This study confirms that individually prescribed, unsupervised jogging can increase HDL-C levels and improve the serum lipoprotein profile in self-selected nonsmoking males. Although the effect is modest, it may be relevant to preventive cardiology, given the evidence for a reduction in cardiovascular risk even after apparently small decreases in risk factor levels.

Association between risk factors for coronary heart disease in schoolboys and adult mortality rates in the same localities

Risk factors for coronary heart disease were compared in fifth year boys (15-16 years old) from two schools that were chosen from localities with a fourfold difference in adult mortality from coronary heart disease. One school was in an underprivileged urban locality in the area of increased incidence of heart disease ('high risk') and the other in a semi-rural affluent locality with an incidence of heart disease similar to the national average ('low risk'). Smoking, hypertension, hypercholesterolaemia, obesity, physical fitness, and inactivity were evaluated as risk factors for coronary heart disease. Smoking, increased body fat, poor diet, and physical inactivity were found increased among pupils from the school in the high risk area compared with those in the low risk area. Lipids, maximum oxygen uptake, and hypertension were similar in both schools. The risk of coronary heart disease seems to reflect the adult mortality rates in the area. To reduce the overall incidence of coronary heart disease, health education should be directed towards prevention of smoking, improving diets, and increasing amounts of activity among school children, with special attention directed toward children in regions where there is a high mortality from coronary heart disease among adults.

Effects of body composition and exercise capacity on glucose tolerance, insulin, and lipoprotein lipids in healthy older men: a cross-sectional and longitudinal intervention study

The relationships of age, body composition, and physical conditioning status to glucose tolerance, insulin, and lipoprotein levels were examined in 77 healthy, nonsmoking white male volunteers, aged 46 to 73 years with no evidence of coronary artery or endocrine-metabolic disease. The men had a wide range of body fat (13% to 39%), indexed as waist-to-hip ratio (WHR, 0.84 to 1.08), and maximal aerobic capacity (VO2max, 17 to 48 mL/kg.min). Multiple regression analysis with age, VO2max, WHR, and percent body fat as independent variables demonstrated that fasting plasma insulin, triglyceride (TG), and high density lipoprotein cholesterol (HDL-C) levels were independently related to both percent body fat and WHR. In contrast, fasting plasma glucose levels and insulin responses during oral glucose tolerance tests (OGTT) correlated independently with percent body fat, and glucose responses to OGTT correlated only with WHR. Although fasting plasma TG and HDL-C correlated with glucose and insulin levels, in multiple regression analyses only percent body fat and WHR were the significant independent variables. Fasting total and low density lipoprotein cholesterol values were not related to these variables. To test the effects of weight loss and exercise training on these relationships, 20 obese men of comparable age, percent body fat, WHR, and VO2max were randomly assigned to weight loss or aerobic exercise training programs. A 12% +/- 3% loss in body weight (P less than .01, mean +/- SD) resulted in a 19% +/- 9% decline in body fat (P less than .01) with no change in fat free mass, WHR, or VO2max.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutritional management of plasma lipid disorders

Prevention of vascular disease and acute pancreatitis is the goal of hyperlipidemia treatment. The risk of coronary heart disease (CHD) increases with increasing plasma cholesterol levels because low-density lipoprotein (LDL), the major carrier of cholesterol in the plasma, is atherogenic. High-density lipoprotein (HDL), especially the HDL2 subfraction, protects against CHD. Hypertriglyceridemia, although not an independent risk factor for CHD, is generally accompanied by low HDL cholesterol (HDLch), which may predispose to CHD. Reducing plasma LDL and raising HDL levels are thus goals in preventing CHD. Serum LDL levels may be lowered by reducing saturated fat and cholesterol intake; weight loss may decrease LDL but is more effective in lowering plasma triglycerides and raising HDLch. The percent of total calories from polyunsaturated, monounsaturated, and saturated fats should be less than 10%, up to 10-15%, and less than 10%, respectively. High cholesterol intake increases the flux of cholesterol, which may be harmful to arterial walls, but beyond a certain point does not increase plasma cholesterol levels. Some diets change the composition rather than the level of LDL and apoproteins. Weight reduction and maintenance are the most effective dietary measures to lower plasma triglycerides; omega-3 fatty acids (fish oils) have shown promise in reducing triglyceride but not cholesterol levels. Substitution of starch for sugar lowered triglyceride levels toward normal in hypertriglyceridemia patients. Fasting triglyceride levels rise in all individuals fed high-carbohydrate diets, but the high levels persist in hypertriglyceridemia patients. Weight loss, cessation of cigarette smoking, increased physical activity, good control of diabetes, and moderate alcohol use all raise HDLch levels. Vitamin E deficiency causes neurological sequelae in children with severe malabsorption problems due to abetalipoproteinemia or cholestatic liver disease.

The clinical significance of serum high density lipoproteins

Serum high density lipoproteins (HDL) are a protective factor against atherosclerosis. Many epidemiological studies show a strong inverse relationship between serum HDL-cholesterol (HDL-C) and the likelihood of developing coronary artery disease (CAD). HDL-C levels appear to be a stronger predictive factor for CAD than serum total or low density lipoprotein cholesterol (LDL-C) levels. In the presence of high HDL-C levels, the development of CAD is unlikely even in persons with increased total or LDL-C. Conversely, subjects with low serum levels of HDL-C are at increased risk even if their total and LDL-C is within the "desirable" range. A number of studies have also shown that increasing HDL-C levels is associated with both primary and secondary prevention of atherosclerosis. HDL-C levels should be estimated in individuals with family and/or personal history of premature atherosclerosis, even if they have normal total cholesterol. Only the current problems with the accuracy and precision of the serum HDL-C assay prevent it from being the single most important test for assessment of the lipid risk factors for CAD. The most frequent causes of low HDL-C are smoking, obesity, and hypertriglyceridemia. Treatment of low HDL-C includes removal of these factors, and if this is ineffective, use of drugs. Gemfibrozil and niacin are most effective in raising serum HDL-C, although a number of other medications can markedly improve the total:HDL-C ratio.

Drug therapy and the prevention of atherosclerosis in humans

The results of the World Health Organization Cooperative Trial, the Coronary Drug Project, the Coronary Primary Prevention Trial and the Helsinki Heart Study indicate that clinical expression of coronary artery disease can be delayed with pharmacologic modification of plasma lipoproteins. Change in coronary artery disease can be semiquantitated by repeat arteriograms. Three randomized clinical trials indicate that rate of progression of atherosclerosis, as defined by arteriography, can be reduced, and existing lumen obstruction decreased. Tendon xanthomas occur in hypercholesterolemia, and reduction in xanthoma size with drug therapy suggests an improved atherosclerotic disease state. The clinician has a variety of pharmacologic therapies available. The role of bile acid-binding resins, fibric acid derivatives, hydroxymethylglutaryl coenzyme A reductase inhibitors, nicotinic acid and antioxidants is each unique. Understanding the role of lipoproteins in atherosclerosis will help in selecting the most appropriate therapy for each individual patient. Medications not designed for their lipoprotein effects can significantly alter lipoproteins. Medications, such as nonselective beta blockers, can alter low-density lipoprotein (LDL) subclass distribution with no change in LDL cholesterol content. Such changes may eradicate part of the beneficial cardiovascular effect of beta blockade therapy. In the future, therapeutic choices may depend in part on lipoprotein abnormalities such as lipoprotein (a), apolipoprotein E isoforms, hyperapobetalipoproteinemia, LDL.

Management of blood lipid abnormalities in coronary heart disease patients

Information obtained from clinical and laboratory research strongly supports a causal relationship between hyperlipidemia (dyslipidemia) and coronary heart disease (CHD), and provides an impetus to develop strategy for control of dyslipidemia. Some recent developments in the field may include the use of: (1) colestipol-niacin to control hypercholesterolemia and induce regression of coronary atherosclerosis; (2) limited amounts of foods rich in stearic or oleic fatty acids to enhance the appeal of cholesterol-lowering regimen; (3) gemfibrozil or lovastatin to inhibit cholesterol synthetic activity; and (4) gemfibrozil to raise atherosclerosis-protective plasma high-density lipoprotein levels. These and other newer developments will stimulate interest in research on dyslipidemia and its control to facilitate primary and secondary prevention of CHD.

Physical exercise conditioning in the absence of weight loss reduces fasting and postprandial triglyceride-rich lipoprotein levels

The effect of physical exercise conditioning on fasting and postprandial lipoprotein levels was studied in six normolipidemic subjects. The study consisted of two phases: a baseline stabilization phase in which subjects maintained their regular physical activity and an exercise conditioning phase in which subjects had 29 exercise sessions during a 7-week period. Each of these sessions consisted of jogging on a treadmill for 30 minutes. The subjects averaged 15.2 miles/wk. To control for possible confounding factors, such as changes in diet composition and weight loss, we placed the subjects on a metabolic diet and increased their daily caloric intake during the exercise phase. At the end of each phase of the study, a vitamin A-fat loading test was done to specifically label and follow postprandial lipoprotein levels, and a maximum oxygen consumption test was done to evaluate the subjects' physical fitness. The exercise conditioning phase significantly increased the subjects' aerobic capacity and postheparin lipoprotein lipase activity, and the phase decreased fasting triglyceride levels. Physical exercise also significantly decreased chylomicron (Sf greater than 1,000) levels by 37%. In summary, this study suggests that physical exercise conditioning reduces fasting and postprandial lipoprotein levels by increasing the catabolism of triglyceride-rich particles. Because these particles may have a role in atherogenesis, this could be a major mechanism by which exercise prevents coronary heart disease.

Dietary prevention of coronary artery disease. How to help patients modify eating habits and reduce cholesterol

The prevalence of high serum cholesterol levels and the associated epidemic of coronary artery disease in our society are largely the by-products of a maladaptive diet. Dietary modification is the logical and effective approach to this problem for most patients. In general, dietary therapy consists of a reduction in the intake of saturated fatty acids, cholesterol, and excess calories. Many specific dietary modifications, including increased intake of omega-9 and omega-3 fatty acids and soluble fiber, may also help reduce cholesterol levels and prevent coronary artery disease.

Reemphasizing the Role of Exercise in Preventing Heart Disease

New studies suggest that high-density lipoprotein cholesterol (HDL-C) may be a better predictor of heart disease than is total cholesterol. Physicians evaluating that evidence stress that even moderate amounts of aerobic exercise can raise HDL-C-and lower the risk of coronary artery disease.

A review of combined hyperlipidaemia and its treatment with fenofibrate

Approximately 15% of myocardial infarction survivors less than 60 years of age have a plasma lipid abnormality defined as combined hyperlipidaemia. Patients with this condition are at substantial risk for future cardiovascular events. Combined hyperlipidaemia involves elevations in both plasma triglycerides and low-density lipoprotein (LDL) cholesterol and may share similarities with hyperapolipoproteinaemia, LDL-pattern B and the small LDL-pattern. Treatment is directed at reduction of LDL-cholesterol and plasma triglyceride values. Nicotinic acid and the fibric acid derivatives are useful therapeutic agents. Fenofibrate is a fibric acid derivative that lowers both triglycerides and LDL-cholesterol in combined hyperlipidaemia. In combined hyperlipidaemia, fenofibrate has been shown to reduce significantly plasma triglycerides by approximately 40%, LDL-cholesterol by 6%, and to increase high-density lipoprotein cholesterol by 15%. Apoproteins are favourably altered with increases in apoprotein-A, decreases in apoprotein-E and inconsistent decreases in apoprotein-B. Fenofibrate is well tolerated with primarily dermatological side-effects.

Exercise, cardiovascular disease and blood pressure

The "chronic" effect of exercise on blood pressure has been controversial and the debate has been confused by a large number of studies with inadequate methodology. Recent consistent findings in epidemiological, experimental and longitudinal intervention studies have suggested that a true antihypertensive effect which is independent of confounding effects of sodium intake, weight, etc. is more likely than not. Unlike some other measures of lowering blood pressure such as sodium restriction, alcohol moderation and some drugs, regular exercise is associated with beneficial effects on several risk factors and probably has an independent effect on cardiovascular mortality. The magnitude of the effect in previously sedentary subjects is greater than that of dietary measures which lower blood pressure except for weight reduction in the obese. Long-term effects on blood pressure are supported by evidence of a favourable influence on left ventricular hypertrophy. The mechanisms involved in the antihypertensive effect of exercise are unclear, but sympathetic withdrawal is one factor involved. Present evidence appears sufficient to include regular exercise amongst the useful therapies for hypertension.