Modest changes in high-density lipoprotein concentration and metabolism with prolonged exercise training

The Effect of Gender on Triple Heart Valve Surgery Outcomes; Reinforcing Women's Health

Female gender is a risk factor in several cardiac surgery risk stratification systems. This study explored the differences in the outcomes following triple heart valve surgery in men vs women. The study included 250 patients (males n = 101; females n = 149) who underwent triple valve surgery from 2009 to 2020. BMI (body mass index) was higher in females (29.6 vs 26.5 kg/m2, P < .001), and diabetes was more common in males (44 vs 42%, P = .012). The ejection fraction was higher in females (55 vs 50%, P < .001). The severity of mitral valve stenosis and tricuspid valve regurgitation was significantly greater in females (33.11 vs 27.72%, P = .003 and 44.30 vs 19.8%, P < .001, respectively). Mitral valve replacement was more common in females (P < .001), and they had lower concomitant coronary artery bypass grafting (P = .001). Bleeding and renal failure were lower in females (P = .021 and <0.001, respectively). Hospital mortality, readmission, and reintervention were not significantly different between genders. By multivariable analysis, male gender was a risk factor for lower survival [HR (hazard ratio): 2.18; P = .024]. Triple valve surgery can be performed safely in both genders, with better long-term survival in females. Female gender was not a risk factor in patients undergoing triple valve surgery.

Seasonal Factors Are Associated with Activities of Enzymes Involved in High-Density Lipoprotein Metabolism among Pregnant Females in Ghana

Background

Small-quantity lipid-based nutrient supplements (SQ-LNS) during pregnancy and postnatally were previously shown to improve high-density lipoprotein (HDL) cholesterol efflux capacity (CEC) and length in the children of supplemented mothers at 18 mo of age in the International Lipid-Based Nutrient Supplements (iLiNS) DYAD trial in Ghana. However, the effects of SQ-LNS on maternal HDL functionality during pregnancy are unknown.

Objective

The goal of this cross-sectional, secondary outcome analysis was to compare HDL function in mothers supplemented with SQ-LNS vs. iron and folic acid (IFA) during gestation.

Methods

HDL CEC and the activities of 3 HDL-associated enzymes were analyzed in archived plasma samples (N = 197) from a subsample of females at 36 weeks of gestation enrolled in the iLiNS-DYAD trial in Ghana. Correlations between HDL function and birth outcomes, inflammatory markers C-reactive protein (CRP) and alpha-1-acid glycoprotein (AGP), and the effects of season were explored to determine the influence of these factors on HDL function in this cohort of pregnant females.

Results

There were no statistically significant differences in HDL CEC, plasma lecithin-cholesterol acyltransferase (LCAT) activity, cholesteryl ester transfer protein (CETP) activity, or phospholipid transfer protein (PLTP) activity between mothers supplemented with SQ-LNS compared with IFA control, and no statistically significant relationships between maternal HDL function and childbirth outcomes. LCAT activity was negatively correlated with plasma AGP (R = -0.19, P = 0.007) and CRP (R = -0.28, P < 0.001), CETP and LCAT activity were higher during the dry season compared to the wet season, and PLTP activity was higher in the wet season compared to the dry season.

Conclusions

Mothers in Ghana supplemented with SQ-LNS compared with IFA during gestation did not have measurable differences in HDL functionality, and maternal HDL function was not associated with childbirth outcomes. However, seasonal factors and markers of inflammation were associated with HDL function, indicating that these factors had a stronger influence on HDL functionality than SQ-LNS supplementation during pregnancy.

Clinical Trial Registry number

The study was registered as NCT00970866. https://clinicaltrials.gov/study/NCT00970866.

The effect of 10 days of energy-deficit diet and high-intensity exercise training on the plasma high-density-lipoprotein (HDL) level among healthy collegiate males

ABSTRACTAn energy-deficit (ED) diet increases lipid mobilisation, while endurance exercise improves lipid profile by promoting formation of high-density lipoproteins (HDLs) among moderately active population. However, it is not clear whether ED with high-intensity exercise training can improve lipid profiles. Therefore, 20 recreationally active males (20.3 ± 2.7 years old with peak oxygen consumption (V˙O₂peak) of 2.8 ± 0.2 L min^-1) with HDL concentration of 1.44 ± 0.32 mmol L^-1, were evenly allocated to either an ED group (1590 ± 79 kcal day^-1: 40% of total caloric omitted at lunchtime) or a control (CON) group (2570 ± 139 kcal day^-1). Participants in both groups performed high-intensity cycling at 90% V˙O₂peak at a constant workload for 8 min, 2 h after breakfast on day D₀, D₂, D₄, D₆, D₈ and D₁₀ (D_n is day number), after which blood samples were collected. In ED, compared to D₀, triglycerides (TG) decreased on D_6-10 (p < .01) while total low-density lipoprotein (LDL), total cholesterol (TC) increased on D_2-10, while HDL progressively increased on D_6-10 (p = .01) with a final value of 1.67 ± 0.24 mmol L^-1. In CON, there were no changes in TG, TC and HDL while LDL was reduced on D_8-10 (p = .01). Moreover, the proportions of TC/HDL and LDL/HDL increased in ED on D_2-10 and D_2-8 (p = .05), respectively, while LDL/HDL in CON was reduced on D_8-10 (p = .01). In brief, 10 days of ED and a series of high-intensity exercise sessions show progressive elevation of HDL which suggest longer period is required to observe changes in lipid ratios.

Site-Specific Glycoprofiles of HDL-Associated ApoE are Correlated with HDL Functional Capacity and Unaffected by Short-Term Diet

Since high-density lipoprotein (HDL) glycoprofiles are associated with HDL functional capacity, we set out to determine whether diet can alter the glycoprofiles of key HDL-associated proteins, including ApoE, a potent driver of chronic disease risk. Ten healthy subjects consumed a fast food (FF) and a Mediterranean (Med) diet for 4 days in randomized order, with a 4-day wash-out between treatments. A multiple reaction monitoring method was used to characterize the site-specific glycoprofiles of HDL proteins, and HDL functional capacity was analyzed. We describe for the first time that ApoE has 7 mucin-type O-glycosylation sites, which were not affected by short-term diet. The glycoprofiles of other HDL-associated proteins were also unaffected, except that a disialylated ApoC-III glycan was enriched after Med diet, and a nonsialylated ApoC-III glycan was enriched after FF diet. Twenty-five individual glycopeptides were significantly correlated with cholesterol efflux capacity and 21 glycopeptides were correlated with immunomodulatory capacity. Results from this study indicate that the glycoprofiles of HDL-associated proteins including ApoE are correlated with HDL functional capacity but generally unaffected by diet in the short term, except ApoC-III sialylation. These results suggest that HDL protein glycoprofiles are affected by both acute and long-term factors and may be useful for biomarker discovery.

The HDL lipidome is widely remodeled by fast food versus Mediterranean diet in 4 days

INTRODUCTION

HDL is associated with increased longevity and protection from multiple chronic diseases. The major HDL protein ApoA-I has a half-life of about 4 days, however, the effects of diet on the composition of HDL particles at this time scale have not been studied.

OBJECTIVES

The objective of this study is to investigate the short term dietary effect on HDL lipidomic composition.

METHODS

In this randomized order cross-over study, ten healthy subjects consumed a Mediterranean (Med) and a fast food (FF) diet for 4 days, with a 4-day wash-out between treatments. Lipidomic composition was analyzed in isolated HDL fractions by an untargeted LC-MS method with 15 internal standards.

RESULTS

HDL phosphatidylethanolamine (PE) content was increased by FF diet, and 41 out of 170 lipid species were differentially affected by diet. Saturated fatty acids (FAs) and odd chain FA were enriched after FF diet, while very-long chain FA and unsaturated FA were enriched after Med diet. The composition of phosphatidylcholine (PC), triacylglycerol (TG) and cholesteryl ester (CE) were significantly altered to reflect the FA composition of the diet whereas the composition of sphingomyelin (SM) and ceramides were generally unaffected.

CONCLUSION

Results from this study indicate that the HDL lipidome is widely remodeled within 4 days of diet change and that certain lipid classes are more sensitive markers of diet whereas other lipid classes are better indicators of non-dietary factors.

Therapeutic Lifestyle Changes Improve HDL Function by Inhibiting Myeloperoxidase-Mediated Oxidation in Patients With Metabolic Syndrome

OBJECTIVE

Phagocyte-derived myeloperoxidase (MPO) and proinflammatory HDL are associated with metabolic syndrome (MetS) and increased cardiovascular disease risk. Therapeutic lifestyle changes (TLCs), such as a Mediterranean diet and exercise, decrease this risk. However, the link among TLCs, HDL, and MPO-mediated oxidative stress remains unclear.

RESEARCH DESIGN AND METHODS

In this study, we characterized changes in cholesterol efflux capacity (CEC), a metric of HDL function; MPO-mediated oxidation; and the HDL proteomic profile in 25 patients with MetS who underwent 12 weeks of TLCs.

RESULTS

After 12 weeks, before significant changes to HDL levels, most MetS components improved as a result of the TLCs. CEC was significantly increased, and HDL MPO oxidation products, 3-chlorotyrosine and 3-nitrotyrosine, were decreased with TLCs. The changes in CEC were inversely related to the unit changes in 3-chlorotyrosine after we controlled for changes in the other MetS components. TLCs did not remodel the HDL proteome.

CONCLUSIONS

In summary, TLCs improved HDL function by inhibiting MPO-mediated oxidative stress even before appreciable changes in HDL levels.

Effect of concurrent resistance and sprint training on body composition and cardiometabolic health indicators in masters cyclists

In older previously sedentary individuals endurance training imposes a more effective stimulus to enhance cardiometabolic health compared with resistance or sprint training. We examined the effect of replacing a portion of endurance training with combined resistance and/or sprint training and how this influences cardiometabolic health indicators in masters endurance cyclists. Twenty-seven well-trained male road cyclists (53.7±8.2 years) were allocated to a resistance and track sprint-cycling training group (RTC, n=10), an endurance and track sprint-cycling group (ETC, n=7) or a control endurance group (CTRL, n=10). Both the RTC and ETC groups completed a 12-week intervention of specific training while the CTRL group maintained their endurance training load. Lower limb lean mass (LLM), trunk fat mass (TFM), fasting blood glucose (FBG), total cholesterol (TC), triglycerides (TG), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured before and after the intervention period. TFM decreased for all groups (P<0.05) while LLM significantly increased for RTC and ETC groups (P<0.05). No significant between group or time effects were observed for FBG, TC, TG, SBP, or DBP. The results suggest that replacing a portion of endurance training with 12 weeks of ETC or RTC training favourably affects body composition by lowering TFM and increasing LLM without negatively affecting cardiometabolic health indicators in well-trained masters endurance cyclists.

Arginine-directed glycation and decreased HDL plasma concentration and functionality

BACKGROUND/OBJECTIVES

Decreased plasma concentration of high-density lipoprotein cholesterol (HDL-C) is a risk factor linked to increased risk of cardiovascular disease (CVD). Decreased anti-atherogenic properties of HDL are also implicated in increased CVD risk. The cause is unknown but has been linked to impaired glucose tolerance. The aim of this study was to quantify the modification of HDL by methylglyoxal and related dicarbonyls in healthy people and patients with type 2 diabetes characterise structural, functional and physiological consequences of the modification and predict the importance in high CVD risk groups.

SUBJECTS/METHODS

Major fractions of HDL, HDL2 and HDL3 were isolated from healthy human subjects and patients with type 2 diabetes and fractions modified by methylglyoxal and related dicarbonyl metabolites quantified. HDL2 and HDL3 were glycated by methylglyoxal to minimum extent in vitro and molecular, functional and physiological characteristics were determined. A one-compartment model of HDL plasma clearance was produced including formation and clearance of dicarbonyl-modified HDL.

RESULTS

HDL modified by methylglyoxal and related dicarbonyl metabolites accounted for 2.6% HDL and increased to 4.5% in patients with type 2 diabetes mellitus (T2DM). HDL2 and HDL3 were modified by methylglyoxal to similar extents in vitro. Methylglyoxal modification induced re-structuring of the HDL particles, decreasing stability and plasma half-life in vivo. It occurred at sites of apolipoprotein A-1 in HDL linked to membrane fusion, intramolecular bonding and ligand binding. Kinetic modelling of methylglyoxal modification of HDL predicted a negative correlation of plasma HDL-C with methylglyoxal-modified HDL. This was validated clinically. It also predicted that dicarbonyl modification produces 2-6% decrease in total plasma HDL and 5-13% decrease in functional HDL clinically.

CONCLUSIONS

These results suggest that methylglyoxal modification of HDL accelerates its degradation and impairs its functionality in vivo, likely contributing to increased risk of CVD-particularly in high CVD risk groups.

Impact of surgical menopause on lipid and bone metabolism

OBJECTIVE

To clarify the effects of ovariectomy on lipid and bone metabolism.

METHODS

This study was a prospective study with a longitudinal design within 1 year after surgery. Sixty-two premenopausal women were recruited and divided into two groups: group M (preservation of ovary, n=27) and group BSO (bilateral ovariectomy, n=35). Serum lipid levels, urinary N-telopeptide of type I collagen (NTx) and bone mineral density (BMD) were measured. We also examined the number of postoperative episodes requiring pharmacological intervention.

RESULTS

There was a significant elevation in the level of low density lipoprotein cholesterol in group BSO from 6 to 12 months compared with the baseline level; the level did not change in group M. The NTx level significantly increased from 6 to 12 months, and the BMD was significantly decreased by as much as 6.7% at 12 months in group BSO; these variables did not change in group M. The effect of lipid and bone metabolism in group BSO was observed when the ages of the two groups were matched. Carbohydrate metabolism and arterial stiffness, measured by pulse wave velocity, did not change throughout the study period in either group. No subjects in group M required medication expect for two patients whose ovarian function was diminished by postoperative radiation and by natural menopause. Eleven women received medication in group BSO: nine for climacteric disorders using hormone therapy (25.7%), and two for dyslipidemia using statins (5.7%).

CONCLUSIONS

Bilateral ovariectomy seems to cause dyslipidemia and serious loss of bone mineral density within only 1 year, and patients who lose ovarian function may require careful medical care.

Plasma triglyceride concentrations are rapidly reduced following individual bouts of endurance exercise in women

It is known that chronic endurance training leads to improvements in the lipoprotein profile, but less is known about changes that occur during postexercise recovery acutely. We analyzed triglyceride (TG), cholesterol classes and apolipoproteins in samples collected before, during and after individual moderate- and hard-intensity exercise sessions in men and women that were isoenergetic between intensities. Young healthy men (n = 9) and young healthy women (n = 9) were studied under three different conditions with diet unchanged between trials: (1) before, during and 3 h after 90 min of exercise at 45% VO₂peak (E45); (2) before, during and 3 h after 60 min of exercise at 65% VO₂peak (E65), and (3) in a time-matched sedentary control trial (C). At baseline, high-density lipoprotein cholesterol (HDL-C) was higher in women than men (P < 0.05). In men and in women, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), HDL-C, apolipoprotein A-I (apoA-I), apolipoprotein B (apoB), and LDL peak particle size were unaltered by exercise either during exertion or after 3 h of recovery. In women, but not in men, average plasma TG was significantly reduced below C at 3 h postexercise by approximately 15% in E45 and 25% in E65 (P < 0.05) with no significant difference between exercise intensities. In summary, plasma TG concentration rapidly declines following exercise in women, but not in men. These results demonstrate an important mechanism by which each individual exercise session may incrementally reduce the risk for cardiovascular disease (CVD) in women.

Effect of motorized scooters on quality of life and cardiovascular risk

Physical inactivity increases cardiovascular risk. The possible adverse effects of regular motorized scooter use, recently popularized for patients with physical limitations, has not been previously examined. We performed a single-center, retrospective cohort study of 102 consecutive patients who had obtained medical approval for, and subsequently received, a motorized scooter during a 6-year period. The clinical data were collected for the 12 months before and after the intervention. Surveys assessing 11 different facets of health-related quality of life were returned by 28% of patients. The patients receiving a scooter were 68 +/- 19 years old, and 55% were women. The medical indications for scooter use, by decreasing frequency, were disabling arthritis, chronic lung disease, neurologic disorders, and heart failure. Patients returning the surveys estimated scooter use at a median of 4 hours/day, with walking confined to 30 min/day. Despite significant physical and psychological improvements in all quality-of-life categories (p <0.001), the fasting blood glucose increased from 119 +/- 39 to 133 +/- 49 mg/dl (p = 0.009), hemoglobin A1c increased from 6.3 +/- 0.8 to 6.8 +/- 1.2 (p = 0.019), and 18.7% of patients developed diabetes during the follow-up period. No significant changes in blood pressure were noted, although 20% of patients required additional antihypertensive medication. Despite improvements in total and low-density lipoprotein cholesterol over time, 50% of dyslipidemic patients required either an increase medication dose or additional medications during follow-up. In conclusion, interventions, such as scooters, that improve self-perceived quality of life, can have detrimental long-term effects by increasing cardiovascular risk, particularly insulin resistance. Physicians should carefully weigh such risks before approving their use, as well as ensure healthy levels of activity afterward.

Exercise training, lipid regulation, and insulin action: a tangled web of cause and effect

Lipids are a strong mediator of coronary artery disease and cardiovascular risk. Although the effects of exercise to improve high-density lipoprotein (HDL) cholesterol and serum triglycerides (TGs) have been known for some time, the effects of different amounts and intensities of exercise on fasting and postprandial serum lipids are little understood. Normal lipid physiology is perturbed in insulin resistant states, where inhibition of lipolysis is impaired, particularly in the postprandial period when excursions in insulin and serum TGs are particularly high. In our STRRIDE (Studies of a Targeted Risk Reduction Intervention through Defined Exercise) study, three important metabolic cardiovascular risk-related variables were improved more by moderate intensity than vigorous-intensity exercise. Moderate-intensity exercise was significantly more effective at lowering TGs and improving insulin sensitivity than was vigorous exercise. Additionally, a composite score for metabolic syndrome improved significantly with low-amount/moderate, but did not with low-amount/vigorous-intensity exercise. That all three of these strong, independent, cardiovascular risk factors were significantly affected by moderate-intensity exercise suggests that regular walking exercise might be as effective, if not more so, than more vigorous exercise in favorably modifying cardiovascular risk. Despite the impressive effects of regular exercise on fasting lipids and atherogenic dyslipidemia, they are more impressive when compared with the trajectory of changes that occur in individuals that remain inactive, without regular exposure to regular exercise. A scientific priority for future investigations should be to study the independent and combined effects of exercise intensity and amount on exercise responses through a direct comparison between two groups matched on amount but differing in intensity.

Physical Activity, Blood Lipids, and Lipoproteins

Dyslipidemia is a major modifiable cardiovascular disease (CVD) risk factor. While pharmacological treatment has been a focal point of dyslipidemia management for several years, increasing physical activity is a safe, cost-effective treatment option that should also be recommended by health care practitioners. Moderate aerobic exercise consistently increases high-density lipoprotein cholesterol (HDL-C) and reduces triglycerides (TG), independent of changes in body weight. However, reductions in total and low-density lipoprotein cholesterol are reported less often following aerobic exercise. Therefore, clinicians should understand that aerobic exercise is not likely to be an effective treatment option for their management. Recent empirical evidence also indicates that aerobic exercise may be of benefit for treating emerging lipid and lipoprotein risk factors such as lipoprotein particle size and number and triglyceride-rich lipoproteins. Further work is needed to clarify the impact of aerobic exercise on apolipoproteins. Based on current evidence, prescribing aerobic exercise as a means of increasing HDL-C and lowering TG is usually an efficacious strategy for treating these aspects of dyslipidemia. These effects are likely to be accompanied by changes in emerging lipid and lipoprotein risk factors.

Brisk walking offsets the increase in postprandial TAG concentrations found when changing to a diet with increased carbohydrate

We tested the hypothesis that 30 min of brisk walking daily would offset the increase in plasma TAG concentrations associated with substituting dietary fat for carbohydrate. Fourteen subjects (six males) aged 57 (sd 5) years underwent three 4 d trials in a counterbalanced order: (i) 4 d on a typical UK diet (40 % energy from fat, 45 % carbohydrate and 15 % protein); (ii) 4 d on an isoenergetic diet but substituting fat for carbohydrate in line with the present recommendations (30 % fat, 55 % carbohydrate and 15 % protein); (iii) 4 d on the same recommended diet with 30 min of brisk walking each day. The food provided for the first 3 d of each trial was isoenergetic with each volunteer's previously determined daily energy intake. On day 4, the subjects consumed breakfast, lunch and an early evening meal, equivalent in total to 90 % of their daily energy intake. Blood samples were collected and substrate utilisation and energy expenditure were determined in the fasted state and for 9 h postprandially. Substrate utilisation differed significantly among trials (P = 0.003); RER was higher on the recommended diet trial than during either of the other two trials (P = 0.012 and 0.021 for the UK diet and recommended diet with walking, respectively). The rise in plasma TAG concentrations over the day was steeper on the recommended diet trial than on the other two trials (trial x time interaction, P = 0.040). The increase in postprandial TAG concentrations associated with substituting dietary fat for carbohydrate was offset by 30 min of brisk walking daily.

Habitual consumption of eggs does not alter the beneficial effects of endurance training on plasma lipids and lipoprotein metabolism in untrained men and women

Changes in plasma lipid and apolipoprotein profiles were evaluated in 12 healthy, unfit subjects (VO(2peak) 39.1+/-2.8 ml.kg(-1).min(-1); 5 women, 7 men) at baseline and following endurance exercise training. The exercise protocol consisted of a 6-week endurance exercise training program (4-5 days week(-1); 60 min.session(-1); > or =65% HR(max)). Subjects were randomly assigned to consume an egg- (n=6; 12 eggs.week(-1)) or no-egg (n=6; 0 eggs.week(-1))-based, eucaloric, standardized diet for 8 weeks. Both diets were macronutrient balanced [60% carbohydrate, 30% fat, 10% protein (0.8 g.kg(-1).day(-1))] and individually designed for weight maintenance. Plasma lipids were measured twice within the same week at baseline and following exercise training. At baseline, subjects were normolipidemic with values of 163.9+/-41.8, 84.8+/-36.7, 60.6+/-15.4 and 93.1+/-52 mg dl(-1) for total cholesterol, LDL cholesterol and HDL cholesterol and triglyceride concentrations, respectively. A two-way ANOVA was used to analyze diet and exercise effects and interactions. In both groups, endurance exercise training resulted in a significant 10% increase in HDL-C (P<.05), a 19% decrease in Apo B concentrations (P<.05) and reductions in plasma CETP activity (P<.05). Plasma LDL-C decreased by 21% (P=.06). No main effects of diet or interactions with plasma lipids or Apo B concentrations were observed. These data demonstrate that endurance training improved the plasma lipid profiles of previously unfit, normolipidemic subjects independent of dietary cholesterol intake from eggs.

Effect of obesity on high-density lipoprotein metabolism

Reduced levels of high-density lipoproteins (HDL) in non-obese and obese states are associated with increased risk for the development of coronary artery disease. Therefore, it is imperative to determine the mechanisms responsible for reduced HDL in obese states and, conversely, to examine therapies aimed at increasing HDL levels in these individuals. This paper examines the multiple causes for reduced HDL in obese states and the effect of exercise and diet--two non-pharmacologic therapies--on HDL metabolism in humans. In general, the concentration of HDL-cholesterol is adversely altered in obesity, with HDL-cholesterol levels associated with both the degree and distribution of obesity. More specifically, intra-abdominal visceral fat deposition is an important negative correlate of HDL-cholesterol. The specific subfractions of HDL that are altered in obese states include the HDL2, apolipoprotein A-I, and pre-beta1 subfractions. Decreased HDL levels in obesity have been attributed to both an enhancement in the uptake of HDL2 by adipocytes and an increase in the catabolism of apolipoprotein A-I on HDL particles. In addition, there is a decrease in the conversion of the pre-beta1 subfraction, the initial acceptor of cholesterol from peripheral cells, to pre-beta2 particles. Conversely, as a means of reversing the decrease in HDL levels in obesity, sustained weight loss is an effective method. More specifically, weight loss achieved through exercise is more effective at raising HDL levels than dieting. Exercise mediates positive effects on HDL levels at least partly through changes in enzymes of HDL metabolism. Increased lipid transfer to HDL by lipoprotein lipase and reduced HDL clearance by hepatic triglyceride lipase as a result of endurance training are two important mechanisms for increases in HDL observed from exercise.

Physical activity, C-reactive protein levels and the risk of future coronary artery disease in apparently healthy men and women: the EPIC-Norfolk prospective population study

BACKGROUND

Physical activity is inversely associated with the risk of future coronary artery disease. Whether this relationship is in part mediated by lower levels of systemic inflammation, as indicated by C-reactive protein concentrations, is unknown.

METHODS

We performed a nested case-control study among apparently healthy men and women enrolled in the European Prospective Investigation into Cancer and Nutrition-Norfolk prospective population study, to investigate the relationship among habitual (work-related and leisure time) physical activity, cardiovascular risk factors and the risk of future coronary artery disease.

RESULTS

Among men, those with an active lifestyle had a significantly lower risk of future coronary artery disease than those with an inactive lifestyle [odds ratio (OR) 0.65; 95% confidence interval (CI) 0.47-0.90; P for linearity, 0.008], after adjustment for smoking, systolic blood pressure, diabetes, body mass index and low-density lipoprotein and high-density lipoprotein cholesterol. Additional adjustment for C-reactive protein levels attenuated this relationship only slightly (OR 0.68; 95%CI 0.49-0.93; P for linearity, 0.02). Similarly, active women had an adjusted odds ratio of 0.48 (0.28-0.82; P for linearity <0.001) for future coronary artery disease compared with inactive women. Additional adjustment for C-reactive protein levels attenuated this relationship slightly (OR 0.51; 0.30-0.87; P for linearity, 0.003).

CONCLUSIONS

We observed that people with an active lifestyle had a substantially lower risk of future coronary artery disease than people with an inactive lifestyle, and that this relationship was partly mediated through lower levels of established cardiovascular risk factors and in addition, C-reactive protein. This observation suggests that reduced systemic inflammation may be one of the mechanisms through which physical activity leads to reduced cardiovascular risk.

Work and leisure time physical activity assessed using a simple, pragmatic, validated questionnaire and incident cardiovascular disease and all-cause mortality in men and women: The European Prospective Investigation into Cancer in Norfolk prospective population study

BACKGROUND

The health benefits of physical activity are well established, but the overall amount of physical activity associated with cardiovascular and other health outcomes, and whether the relationships are similar in men and women and at different ages is still debated. This may be partly related to different methods for assessing physical activity. Most studies have focused on leisure time physical activity.

METHODS

We examined the prospective relationship between usual physical activity, taking into account both leisure and work activity, using a simple, pragmatic, four-point rating scale validated against heart rate monitoring, and cardiovascular disease incidence and total mortality after an average 8 years follow-up in 22,191 community living men and women aged 45-79 years with no known cardiovascular disease or cancer at baseline.

RESULTS

The relative risks (95% confidence interval) for all-cause mortality (1,553 deaths) for men and women who were moderately inactive, moderately active, and active compared with those who were inactive were 0.83 (0.73-0.95), 0.68 (0.58-0.80), and 0.68 (0.57-0.81), respectively, after adjusting for age, sex, systolic blood pressure, blood cholesterol, cigarette smoking, alcohol intake, diabetes, body mass index, and social class. The relationships were also consistent for cardiovascular disease incidence (3,079 events), in subgroups stratified by age, sex, body mass index, smoking status and social class, and after excluding deaths in the first 2 years. The combined scale was more consistently associated with mortality than the individual work and leisure time components separately.

CONCLUSIONS

When both work and leisure time physical activity patterns are taken into account, using a simple, pragmatic, validated questionnaire feasible for use in clinical and public health practice, even very moderate levels of usual physical activity are associated with significantly reduced risk of mortality and cardiovascular disease in men and women in the general population and potential population attributable impact of 14% for inactive compared with active levels. These findings may encourage efforts to increase physical activity levels not only in leisure time but also in usual daily working life.

Blood lipid responses to plant stanol ester supplementation and aerobic exercise training

The purpose of this study was to determine the independent and combined effects of plant stanol ester (PSE) margarine and aerobic exercise on blood lipid concentrations and related intravascular enzymes in 26 healthy sedentary, middle-aged men and postmenopausal women (age, 53 +/- 8 years; body mass index, 27 +/- 1.0, % fat, 28.5 +/- 2). In a stratified double-blind manner, participants were randomly assigned to either a PSE (n = 17) or a placebo (CON, n = 9) margarine group. Participants supplemented their daily diets with 42 g of margarine spread (PSE = 3 g; CON, PSE = 0 g, of approximately equal energy content) for 9 weeks. During the last 4 weeks of margarine supplementation (MS), participants expended 400 kcal on a treadmill 5 d/wk at 65% of VO(2) reserve (2000 kcal/wk). Fasting blood samples were obtained before initiating and after 4 weeks of MS and after exercise training. All blood samples were analyzed for total cholesterol, low-density lipoprotein cholesterol, triglyceride, high-density lipoprotein cholesterol (HDL-C), hepatic lipase, lipoprotein lipase, and cholesterol ester transfer protein activities. Total cholesterol (-10%), low-density lipoprotein cholesterol (-13%), and triglyceride (-18%) concentrations decreased after 4 weeks of MS in the PSE group, but not in the CON group (P < .05 for all). Four weeks of aerobic exercise increased HDL-C by 21% in the CON group (P < .05) and by 4% in the PSE group (P > .05). Total cholesterol-HDL-C ratio decreased significantly (P < .05) in the PSE group, but not in the CON group. No other significant alterations were observed with either PSE or exercise. Our findings suggest that PSE is effective in reducing blood cholesterol concentrations and that exercise can increase HDL-C in middle-aged men and postmenopausal women. Our findings also suggest that PSE supplementation may attenuate the exercise-induced increase in HDL-C.

Prescribing Aerobic Exercise for the Regulation of Postprandial Lipid Metabolism

Prolonged presence of elevated plasma triglycerides (TGs) during the postprandial period has been suggested to increase the risk for coronary artery disease. Aerobic exercise attenuates postprandial lipaemia and this has generally been described as a short-term effect of the exercise. Effects of exercise on postprandial lipaemia have mostly been investigated, and documented, with large exercise-induced energy expenditures (i.e. 1000 kcal). The exact mechanisms involved in the attenuation of postprandial lipaemia with exercise are not completely understood, but it appears that at least two mechanisms are involved: a decrease in TG secretion by the liver and an increase in plasma TG clearance by the muscle. Changes in the metabolism of other lipids, such as those in high-density lipoprotein cholesterol, have been documented only when the exercise is performed some hours before the fat meal. Although factors such as the physical fitness and percentage body fat of an individual are likely to also be involved, the most important factors determining the magnitude of the attenuation in postprandial lipaemia appear to be the magnitude of the exercise-induced energy expenditure and the intensity of exercise. To date, the evidence suggests that healthy individuals can generally induce favourable changes in postprandial lipaemia with aerobic exercise that: (i) is completed during the period extending from 16 hours before a meal through 1.5 hours after a meal; (ii) is of moderate intensity; and (iii) results in an energy expenditure of approximately 500 kcal (or more).

Generic, Simple Risk Stratification Model for Heart Valve Surgery

Background— Heart valve surgery has an associated in-hospital mortality rate of 4% to 8%. This study aims to develop a simple risk model to predict the risk of in-hospital mortality for patients undergoing heart valve surgery to provide information to patients and clinicians and to facilitate institutional comparisons.

Methods and Results— Data on 32 839 patients were obtained from the Society of Cardiothoracic Surgeons of Great Britain and Ireland on patients who underwent heart valve surgery between April 1995 and March 2003. Data from the first 5 years (n=16 679) were used to develop the model; its performance was evaluated on the remaining data (n=16 160). The risk model presented here is based on the combined data. The overall in-hospital mortality was 6.4%. The risk model included, in order of importance (all P <0.01), operative priority, age, renal failure, operation sequence, ejection fraction, concomitant tricuspid valve surgery, type of valve operation, concomitant CABG surgery, body mass index, preoperative arrhythmias, diabetes, gender, and hypertension. The risk model exhibited good predictive ability (Hosmer-Lemeshow test, P =0.78) and discriminated between high- and low-risk patients reasonably well (receiver-operating characteristics curve area, 0.77).

Conclusions— This is the first risk model that predicts in-hospital mortality for aortic and/or mitral heart valve patients with or without concomitant CABG. Based on a large national database of heart valve patients, this model has been evaluated successfully on patients who had valve surgery during a subsequent time period. It is simple to use, includes routinely collected variables, and provides a useful tool for patient advice and institutional comparisons.

Apolipoprotein C-III SstI genotypes modulate exercise-induced hypotriglyceridemia

PURPOSE

To investigate whether the efficacy of exercise as an antitriglyceridemic treatment was dependent on the apolipoprotein (apo) C-III SstI gene polymorphism.

METHODS

A subgroup of 100 Korean men, who were prescreened by genotypes (S1S1 = 40, S1S2 = 40, S2S2 = 20), participated in a 6-d moderate-exercise intervention using either a motor-driven treadmill or a cycle ergometer. Height and weight for body mass index and waist circumference were measured. Fasting total cholesterol, triglycerides (TG), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, glucose, and insulin were measured. Univariate analysis of variance and ANCOVA followed by Bonferroni post hoc tests were used to compare the preintervention values and the pre- to postexercise change (delta) scores in the measured variables across the genotypes, respectively. Multivariate linear regressions were carried out with age, smoking, waist circumference, body mass index, and genotype as independent variables and lipids, glucose, and insulin as dependent variables.

RESULTS

Subjects with the S2S2 genotype had a significantly higher preintervention TG concentration than subjects with the S1S1 genotype (P = 0.022). Waist circumference and genotype were the only significant predictors for the preintervention TG (P < 0.001). With respect to the delta scores, the subjects with the S2S2 genotype had a greater reduction in TG than the subjects with the S1S1 genotype, adjusted for the preintervention difference (P = 0.047).

CONCLUSION

This study suggests that the apo C-III SstI gene polymorphism might be useful for determining who is most susceptible to intervention by exercise in lowering fasting TG concentration.

Physical activity and its effects on lipids

Physical activity is an important component of weight control, and is widely recommended to prevent and treat obesity-related complications such as diabetes and coronary heart disease (CHD). Although the cardiovascular benefits of increased physical activity are likely multifactorial, much of the attention has been focused on the known high-density lipoprotein (HDL) cholesterol-raising properties of regular physical activity. Physical activity, however, can also reliably lower triglycerides and favorably affect both low-density lipoprotein (LDL) and HDL particle sizes. Limited data on resistance exercise suggest that this type of physical activity may reduce LDL cholesterol. Although these lipid effects are modest and variable, they are likely to be particularly important in reducing the morbidity and mortality from CHD on a population level, and may be especially important in patients with atherogenic dyslipidemia.

Dose-response relationship of the cardiovascular adaptation to endurance training in healthy adults: how much training for what benefit?

Occupational or recreational exercise reduces mortality from cardiovascular disease. The potential mechanisms for this reduction may include changes in blood pressure (BP) and autonomic control of the circulation. Therefore, we conducted the present long-term longitudinal study to quantify the dose-response relationship between the volume and intensity of exercise training, and regulation of heart rate (HR) and BP. We measured steady-state hemodynamics and analyzed dynamic cardiovascular regulation by spectral and transfer function analysis of cardiovascular variability in 11 initially sedentary subjects during 1 yr of progressive endurance training sufficient to allow them to complete a marathon. From this, we found that 1) moderate exercise training for 3 mo decreased BP, HR, and total peripheral resistance, and increased cardiovascular variability and arterial baroreflex sensitivity; 2) more prolonged and intense training did not augment these changes further; and 3) most of these changes returned to control values at 12 mo despite markedly increased training duration and intensity equivalent to that routinely observed in competitive athletes. In conclusion, increases in R-wave-R-wave interval and cardiovascular variability indexes are consistent with an augmentation of vagal modulation of HR after exercise training. It appears that moderate doses of training for 3 mo are sufficient to achieve this response as well as a modest hypotensive effect from decreasing vascular resistance. However, more prolonged and intense training does not necessarily lead to greater enhancement of circulatory control and, therefore, may not provide an added protective benefit via autonomic mechanisms against death by cardiovascular disease.

The effect of physical exercise on reverse cholesterol transport

High-density lipoproteins (HDL) are recognized for their role in coronary artery disease (CAD) risk reduction. Plasma HDL plays a pivotal role in the reverse cholesterol transport (RCT) process. Physical exercise is well recognized as a modality that affects HDL metabolism. The purpose of this discussion is to describe the effects of physical exercise on RCT.

The effects of physical exercise on plasma prebeta-1 high-density lipoprotein

The impact of physical exercise on high-density lipoprotein (HDL) metabolism is recognized as a major mechanism of coronary artery disease (CAD) risk reduction. Prebeta-1 HDL subparticle species play a pivotal role in initiating reverse cholesterol transport (RCT). We examined the effect of acute physical exercise on plasma prebeta-1 HDL levels. Nineteen nonsmoking, healthy men (n = 11) and women (n = 8) not receiving lipid-altering medications completed dietary surveys, and had percent body fat determinations, and fasting blood drawn for measurements of plasma lipids, lipoproteins, apolipoprotein A-I (Apo A-I), and absolute and percent prebeta-1 HDL. Each subject completed cardiopulmonary exercise stress testing to Vo(2max) followed by a 4-km course of run-jogging. Laboratory measurements were repeated from blood drawn immediately after exercise. Mean +/- SD values were determined for age, percent body fat, dietary calories, dietary cholesterol, dietary fat, and plasma lipids, lipoproteins, Apo A-I, and absolute and percent prebeta-1 HDL using 1-way analysis of variance (ANOVA). One-way ANOVA comparisons were made for measurements of plasma lipids, lipoproteins, Apo A-I, and absolute and percent prebeta HDL measurements taken before and after exercise for all subjects combined. Entry characteristics showed the following (mean +/-SD): age, 24 +/- 5.8 years; body mass index (BMI), 22.4 +/- 2.6; percent body fat, 13 +/- 5.7; and Vo(2max), 49.1 +/- 7.9 mL O(2)/kg/min. Exercise significantly increased absolute plasma prebeta HDL (0.10 +/- 0.05 to 0.130 +/- 0.07 microg/mL, P =.039) and decreased plasma HDL-triglycerides (23.3 +/- 10.8 to 12.5 +/- 5.6 mg/dL, P =.012). Our findings indicate that prebeta-1 HDL and HDL-triglyceride metabolism are significant components of the effect of acute exercise on RCT. These findings have important relevance for studies pertaining to exercise-related effects on HDL metabolism as pertains to CAD risk reduction.

Exercise training, without weight loss, increases insulin sensitivity and postheparin plasma lipase activity in previously sedentary adults

OBJECTIVE

To determine the effects of exercise, without weight loss, on insulin sensitivity (S(I)), postheparin plasma lipase activity (PHPL), intravenous fat clearance rate (K(2)), and fasting lipids in sedentary adults.

RESEARCH DESIGN AND METHODS

At baseline and after 6 months of walk training (intensity 45-55 or 65-75% heart rate reserve, frequency 3-4 or 5-7 days/week, duration 30 min/session), anthropometric indexes, S(I), PHPL, K(2), and fasting lipids were measured in 18 sedentary adults (12 women, 6 men; 51.9 +/- 5.8 years of age, BMI 28.9 +/- 4.6 kg/m(2)).

RESULTS

Exercise increased S(I) (2.54 +/- 2.74 vs. 4.41 +/- 3.30 microU ml(-1) x min(-1), P < 0.005) and both lipoprotein lipase (LPL) (1890 +/- 1380 vs. 4926 +/- 1858 nEq free fatty acid [FFA]. ml(-1). h(-1)) and hepatic lipase (HL) activities (3326 +/- 1605 vs. 4636 +/- 1636 nEq FFA. ml(-1) x h(-1)) (both P < 0.001), without altering BMI, waist circumference, K(2), or fasting lipids. Correlations between changes in LPL and the total:HDL cholesterol ratio (r = -0.54) and changes in the LPL:HL ratio and waist circumference (r = -0.50) were significant (P < 0.05).

CONCLUSIONS

Exercise, without weight loss, increases S(I) and PHPL activity in previously sedentary adults, without changing K(2) or fasting lipid levels. Furthermore, increased LPL is associated with a decreased total:HDL ratio, and an increased LPL:HL ratio is associated with a decreased waist circumference. Therefore, even modest amounts of exercise in the absence of weight loss positively affect markers of glucose and fat metabolism in previously sedentary, middle-aged adults.

Exercise and postprandial lipid metabolism: an update on potential mechanisms and interactions with high-carbohydrate diets (review)

Endurance trained people exhibit low levels of postprandial lipemia. However, this favorable situation is rapidly reversed with de-training and it is likely that the triglyceride (TG) lowering effects of exercise are mainly the result of acute metabolic responses to recent exercise rather than long-term training adaptations. A large body of evidence suggests that postprandial lipemia can be attenuated following an individual exercise session, with the energy expended during exercise being an important determinant of the extent of TG lowering. Increased lipoprotein lipase-mediated TG clearance and reduced hepatic TG secretion are both likely to contribute to the exercise-induced TG reductions. These changes may occur in response to post-exercise substrate deficits in skeletal muscle and/or the liver. In addition, regular exercise can oppose the hypertriglyceridaemia sometimes seen with low-fat, high-carbohydrate diets. Levels of physical activity should therefore be taken into account when considering nutritional strategies for reducing the risk of cardiovascular disease.

Lipids, lipoproteins, and exercise

PURPOSE

Dose-response relationships between exercise training volume and blood lipid changes suggest that exercise can favorably alter blood lipids at low training volumes, although the effects may not be observable until certain exercise thresholds are met.

METHODS AND RESULTS

Plasma triglyceride reductions are often observed after exercise training regimens requiring energy expenditures similar to those characterized to increase high-density lipoprotein cholesterol (HDL-C). Thresholds established from cross-sectional and longitudinal exercise training studies indicate that 15 to 20 miles/week of brisk walking or jogging, which elicit between 1,200 to 2,200 kcals of energy expenditure per week, is associated with triglyceride reductions of 5 to 38 mg/dL and HDL-C increases of 2 to 8 mg/dL. Exercise training seldom alters total cholesterol and low-density lipoprotein cholesterol (LDL-C) unless dietary fat intake is reduced and body weight loss is associated with the exercise training program, or both. Thus, for most individuals, the positive effects of regular exercise are exerted on blood lipids at low training volumes and accrue so that noticeable differences frequently occur with energy expenditures of 1,200 to 2,200 kcals/week.

CONCLUSIONS

It appears that weekly exercise caloric expenditures that meet or exceed the higher end of this range are more likely to produce the desired lipid changes. Regarding hyperlipidemic disorders, the primary means for intervention is pharmacologic, whereas diet modification, weight loss, and exercise, although important, are viewed as adjunctive therapies. Because much is known about the exercise training-induced plasma lipid and lipoprotein modifications as well as the mechanisms responsible for these changes, rehabilitation professionals can better develop a comprehensive medical management plan that optimizes pharmacologic, reduced dietary fat intake, weight loss, and exercise interventions.

Comparing the benefits of diet and exercise in the treatment of dyslipidemia

BACKGROUND

Lifestyle changes are advocated as a first line of treatment for dyslipidemia. However, few studies have directly compared various combinations of diets and exercise.

METHODS

In a randomized controlled pilot study, we compared the standard lifestyle recommendations (NCEP step I diet with regular exercise) and more intense interventions including the NCEP step I diet with a supervised aerobic exercise program and the step II diet with and without a supervised aerobic exercise program. We measured risk factors, dietary intake, time on treadmill, and health-related quality of life at baseline and after 3 months.

RESULTS

Out of 198 eligible subjects, 47 (24%) were willing to participate and 41 completed the study. No significant change were observed with standard lifestyle recommendations. In contrast, participants in the more intense interventions lost weight (-1.7 to -3.7 kg) and reduced their total cholesterol (-4% to -6%), low-density lipoprotein cholesterol (-6%), and systolic blood pressure (-7.3 to -8.8 mmHg). Participants in the exercise program significantly increased their exercise capacity (1.6 to 1.9 METS). Overall, each 10% reduction in body weight was associated with a 7.6% reduction in low-density lipoprotein cholesterol.

CONCLUSION

Standard lifestyle recommendations had little effect on blood lipid levels but more intense lifestyle interventions may be effective at improving blood lipids, other risk factors, and quality of life.

Blood lipid and lipoprotein adaptations to exercise: a quantitative analysis

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

Exercise and heart disease

Atherosclerotic coronary artery disease (CAD) is a leading cause of death in the United States. It accounts for myocardial infarction in approximately 1.5 million Americans annually and results in approximately 500,000 deaths yearly. Half of these deaths occur prior to patients being admitted to a hospital. A dramatic reduction in mortality related to atherosclerotic CAD has occurred in the last decade. This reduction has resulted from significant advances in both the medical and surgical management of this disease as well as from increased efforts to modify risk factors known to increase the likelihood of developing CAD. Modifiable risk factors include cigarette smoking, hypercholesterolemia, and hypertension. More recently, physical inactivity has been found to be a significant modifiable risk factor that can influence the development of CAD. This article reviews some of the observational data that support these conclusions, discusses the role of exercise in the prevention of CAD in select groups, and reviews some of the mechanisms by which exercise may modify the development of CAD.

Physical activity and cardiovascular risk factors in a developing population

PURPOSE

Noncommunicable diseases are emerging in developing countries. However, few studies have been conducted in those countries to evaluate the role of physical activity in the development of cardiovascular diseases. This study investigated physical activity and its relationship to risk factors for cardiovascular disease in a large population (N = 799) of civil servants from Benin City, Nigeria.

METHODS

Physical activity levels were estimated by an interviewer-administered questionnaire, which determined the average hours per week over the past year spent in occupational and leisure activities. Time spent walking or biking to work was assessed as well. Other major measures included body mass index (BMI), waist-hip ratio (WHR), blood pressures, plasma insulin level, lipid profiles, and diet.

RESULTS

More of the physical activity was attributed to occupational than to leisure activities. Compared with women, men had a higher activity level. No significant trend was observed across age groups. Male senior staff (a marker of higher socioeconomic status) had a lower physical activity level than male junior staff. Physical activity, especially time walking or biking to work, was inversely correlated with weight, BMI, WHR, blood pressures, insulin, total cholesterol, LDL and HDL cholesterol, and triglycerides in men, while such correlations were not consistent in women. In multivariate analysis in men, blood pressure and insulin were independently associated with BMI but not with walking, while an independent inverse association was seen between walking and BMI.

CONCLUSION

Lack of physical activity was associated with adverse risk profiles for cardiovascular disease in this developing population.

Exercise prevents the augmentation of postprandial lipaemia attributable to a low-fat high-carbohydrate diet

There is concern that replacement of dietary fat with carbohydrate may not reduce the overall risk of CHD because this replacement strategy elevates postprandial plasma triacylglycerol (TAG) concentrations. The present study was designed to test the hypothesis that daily exercise can offset the augmented postprandial lipaemia associated with a short-term high-carbohydrate diet. Nine healthy, normolipidaemic men aged 33 (sd 4) years consumed a test meal (g/kg body mass; 1.2 fat, 1.1 carbohydrate, 0.2 protein) on three occasions: after 3 d on a typical Western diet (46, 38 and 16 % energy from carbohydrate, fat and protein respectively); after 3 d on an isoenergetic high-carbohydrate diet (corresponding values: 70, 15 and 15 % energy); after 3 d on the same high-carbohydrate diet with 30 min moderate exercise daily. Fasting plasma TAG concentration was higher after the high-carbohydrate diet (1.15 (se 0.16) mmol/l) than after the Western diet (0.83 (se 0.10) mmol/l; ). Similarly, postprandial lipaemia (6 h total area under plasma TAG concentration v. time curve) was higher after the high-carbohydrate diet (12.54 (se 2.07) mmol/l.h) than after the Western diet (9.30 (se 1.30) mmol/l.h; ). The addition of exercise to the high-carbohydrate diet significantly reduced postprandial lipaemia (9.95 (se 1.94) mmol/l.h; when compared with the high-carbohydrate diet) but not fasting TAG concentration (1.02 (se 0.24) mmol/l). In conclusion, daily exercise prevented the augmentation of postprandial lipaemia attributable to the short-term high-carbohydrate diet and, thus, exercise may be a powerful adjunct to dietary change.

Exercise in the treatment of lipid disorders

As a result of scientific evaluation, we know that exercise has a positive impact on the lipid and lipoprotein profile, and we have a greater understanding for the necessary amount of exercise needed to cause these changes. In the case of hyperlipidemic disorders, we know the primary means for intervention is pharmacological, and that diet, weight loss, and exercise are viewed as adjunctive therapies. Because much is known about the exercise training-induced plasma lipid and lipoprotein modifications as well as the lipoprotein enzyme changes, future research should continue to focus on the molecular basis for these changes. For example by knowing a person's apo E genotype, we gain better comprehension as to why some individuals respond to exercise, while others do not. Another area for further investigation is the assessment of drug and exercise interaction. Presently, little is known regarding the use of lipid-lowering drugs and the impact of exercise. Finally, these investigations could provide new insights for better understanding the exercise CAD protective effects. The future challenge is to better understand the impact that regular exercise participation has in optimizing the lipid and lipoprotein profile with individuals with special lipid disorders.

Effect of exercise intensity and frequency on lipid levels in men with coronary heart disease: Training Level Comparison Trial

The objective of the Training Level Comparison Trial was to determine whether a more intense exercise program versus a less intensive program has additional favorable effects on blood lipids in men with coronary heart disease (CHD) over a 12-month period. The study-a randomized, controlled trial conducted at 2 clinical centers-enrolled 185 patients with documented CHD. A simple randomization procedure led to unequal numbers of patients in the 2 interventions: 82 in the low-intensity and 103 in the high-intensity group. Target heart rate during exercise corresponded to 50% of maximum oxygen uptake (VO(2 max)) +/- 5 beats/min in the low-intensity group and 85% +/- 5 beats/min in the high-intensity group. The intensity of exercise made little difference on lipid improvements. However, the attendance rates for the 6- and 12-month periods (percentage of total exercise sessions attended) were significantly related to increased high-density lipoprotein (HDL) cholesterol (r(s) [Spearman rank correlation coefficient 0.20 to 0.26, p <0.05]), and decreases in the ratios of low-density lipoprotein (LDL)-to-HDL cholesterol (LDL:HDL, r(s) = -0.24 to -0.28, p < 0.01) and total-to-HDL cholesterol (total:HDL, r(s) = -0.25 to -0.29, p < 0.01) at 6 and 12 months. The relation of the attendance rate to LDL:HDL and total:HDL ratios remained significant in repeated-measures regression analysis. Exercise frequency may be more important than intensity in improving HDL cholesterol and LDL:HDL and total:HDL ratios in men with CHD.

Differentiation of populations with different physiologic profiles by plasma Fourier-transform infrared spectra classification

The pathologic condition of a patient presenting a metabolic disease can change rapidly, and a variety of pathologic conditions are possible. Plasma Fourier-transform infrared (FT-IR) spectra were used to differentiate patients with type 1 diabetes, healthy subjects, and endurance-trained rowers. Analytic and classification methods that use the same plasma FT-IR spectra are described. Complete spectra (4000 to 500 cm(-1)) classifications led to a differentiation between most patients with type 1 diabetes and other subjects but not between control and trained subjects. Classification of defined absorption regions of spectra allowed different metabolic distinctions between populations. These were performed on the amide I and II absorption regions of proteins (1720 to 1480 cm(-1)); on the nu=CH, nu(as)CH(2), and nu(as)CH(3) absorption regions of lipids (3020 to 2880 cm(-1)); and on the nuC-O absorption region of saccharides (1300 to 900 cm(-1)). A classification that uses a combination of four absorption regions-nu=CH (3020 to 3000 cm(-1)), nu(as)CH(3) (3000 to 2950 cm(-1)), nuC-O (amide I: 1720 to 1600 cm(-1)), and nuC-O (carbonyle: 1300 to 900 cm(-1))-led to the formation of three exclusive clusters that comprised the defined populations. FT-IR spectroscopy is an exciting technique that allows a versatile approach to biologic samples from which analytic and statistical methods might be used for metabolic profile characterization and evaluation.

Coronary risk factors: influences on the lipid profile

Risk factors for cardiovascular disease have been defined by various groups and experts for decades. Unfortunately, the lack of consensus among these groups and the periodic changes in risk factor listings have led to confusion among health care professionals. Because so many risk factors inter-relate, it is difficult to isolate the effect of a specific risk factor on the lipid profile. In an effort to eliminate some of the confusion, this article describes the known effects of physical inactivity, obesity, cigarette smoking, age, hypertension, and diabetes mellitus on lipids and lipoproteins. A summary of the known results is displayed in a table. Because of the complexity of the atherosclerotic disease process and the multifactorial influences on lipid metabolism, this remains an exciting and challenging area for research.

Differential effect of resistance training on the body composition and lipoprotein-lipid profile in older men and women

The effects of a 12-week resistance exercise training (RT) program on body composition and serum lipid concentrations were assessed in weight-stable, moderately overweight older men (n = 18) and women (n = 17) aged 54 to 71 years with a body mass index (BMI) of 26 to 36 kg/m2. Following RT, the men had a significant increase in fat-free mass (FFM) and a decrease in percent body fat (%BF) and fat mass (FM), whereas the women demonstrated no change, resulting in significant time-by-sex interactions for FFM (P = .002), %BF (P = .006), and FM (P = .005). There were no changes in total cholesterol (Chol), low-density lipoprotein cholesterol (LDL-C), or triacylglycerol (Tg) due to RT. However, following RT, high-density lipoprotein cholesterol (HDL-C) increased (0.06+/-0.02 mmol/L) in the men and decreased (0.09+/-0.03 mmol/L) in the women (time-by-sex interaction, P = .0004). The Chol/HDL-C ratio decreased (0.36+/-0.11) in the men and increased (0.29+/-0.10) in the women (time-by-sex interaction, P = .0001). For all subjects combined, the changes in HDL-C and the Chol/HDL-C ratio were not related to any changes in body fat stores (ie, %BF or FM), suggesting that RT may potentially alter the lipoprotein-lipid profile in older weight-stable men and women. In conclusion, although the changes in the lipoprotein-lipid profile were small, the men had a significantly increased HDL-C level and decreased Chol/HDL-C ratio, while the women demonstrated opposite changes.

Interaction of physical activity and diet: implications for lipoprotein metabolism

OBJECTIVE

To consider how physical activity interacts with diet to modify lipoprotein metabolism and comment on implications for human health.

DESIGN

An overview of lipoprotein metabolism is followed by a summary of the main effects of physical activity on lipoprotein metabolism. Interactions with dietary practice and the disposition of dietary lipid are reviewed, with comment on links with body fatness.

SETTING

Literature is reviewed in relation to the risk of atherosclerotic disease.

SUBJECTS

Although some data are presented on athletic groups, evidence relating to individuals with normal physical activity habits is mainly discussed.

RESULTS

Physical inactivity is a risk factor for cardiovascular disease and one mechanism may involve changes to lipoprotein metabolism. The consensus is that aerobic activity involving an expenditure of > or = 8 MJ week(-1) results in an increase in HDL cholesterol and probably decreases in fasting triacylglycerol. These changes Occur despite the spontaneous increase in the proportion of dietary energy from carbohydrate which accompanies increased exercise. For this reason, exercise may be a means of reducing the hypertriglyceridaemic and HDL-lowering effects of low fat (high carbohydrate) diets. Decreases in total and low density lipoprotein cholesterol are sometimes, but not always, reported in sedentary individuals beginning exercise. One mechanism linking all these changes may be alterations to the dynamics of triacylglycerol-rich particles, particularly in the fed state.

CONCLUSION

The expenditure of considerable amounts of energy through regular, frequent physical activity increases the turnover of lipid substrates, with effects on their transport and disposition which may reduce the progression of atherosclerosis.