Single session exercise stimulates formation of pre beta 1-HDL in leg muscle

Metabolic plasticity and obesity-associated changes in diurnal postexercise metabolism in mice

BACKGROUND

Circadian disruption is widespread and increases the risk of obesity. Timing of therapeutic interventions may promote coherent and efficient gating of metabolic processes and restore energy homeostasis.

AIM

To characterize the diurnal postexercise metabolic state in mice and to identify the influence of diet-induced obesity on identified outcomes.

METHODS

C57BL6/NTac male mice (6 wks of age) were fed a standard chow or high-fat diet for 5 weeks. At week 5, mice were subjected to a 60-min (16 m/min, 5 % incline) running bout (or sham) during the early rest (day) or early active (night) phase. Tissue and serum samples were collected immediately post-exercise (n = 6/group). In vivo glucose oxidation was measured after oral administration of 13C-glucose via 13CO2 exhalation analysis in metabolic cages. Basal and isoproterenol-stimulated adipose tissue lipolysis was assessed ex vivo for 1 h following exercise.

RESULTS

Lean mice displayed exercise-timing-specific plasticity in metabolic outcomes, including phase-specificity in systemic glucose metabolism and adipose-tissue-autonomous lipolytic activity depending on time of day. Conversely, obesity impaired temporal postexercise differences in whole-body glucose oxidation, as well as the phase- and exercise-mediated induction of lipolysis in isolated adipose tissue. This obesity-induced alteration in diurnal metabolism, as well as the indistinct response to exercise, was observed concomitant with disruption of core clock gene expression in peripheral tissues.

CONCLUSIONS

Overall, high-fat fed obese mice exhibit metabolic inflexibility, which is also evident in the diurnal exercise response. Our study provides physiological insight into exercise timing-dependent aspects in the dynamic regulation of metabolism and the influence of obesity on this biology.

Beyond Statins: Emerging Evidence for HDL-Increasing Therapies and Diet in Treating Cardiovascular Disease

Coronary heart disease continues to be the leading cause of death in the United States. Current attempts to treat atherosclerosis and coronary artery disease often involve pharmaceutical and surgical treatments. While these treatments are successful in managing the pain from coronary heart disease, they do little to prevent or stop it. There are a number of clinical strategies that are currently being researched to treat atherosclerosis through HDL-increasing therapies. These clinical studies have shown positive effects through nutritional intervention, exercise, stress reduction, and tobacco and alcohol cessation. These treatment options are explored in greater detail, including their potential to halt and even reverse atherosclerosis. The results from these recent studies and how they relate to the mechanism of reverse cholesterol transport are also critically examined. Reverse cholesterol transport is a multistep process resulting in the net movement of cholesterol from peripheral tissues back to the liver via the plasma. The mechanism of reverse cholesterol transport is also further explored in this review.

Exercise Training Favorably Modulates Gene and Protein Expression That Regulate Arterial Cholesterol Content in CETP Transgenic Mice

Aerobic exercise training (AET) improves the reverse cholesterol transport (RCT) in cholesteryl ester transfer protein-transgenic (CETP-tg) mice. We aimed at investigating the role of AET in the expression of genes and proteins involved in lipid flux in the aorta and macrophages of CETP-tg mice. Three-month-old male mice were randomly divided into trained (T; treadmill 15 m/min; 30 min/day) and sedentary (S) groups. After 6 weeks, peritoneal macrophages and the aortic arch were obtained immediately (0 h) or 48 h after the last exercise session. mRNA was determined by RT-qPCR, protein levels by immunoblot and ¹⁴C-cholesterol efflux determined in macrophages. AET did not change body weight, plasma cholesterol, triglycerides, glucose and CETP activity. In macrophages, at time 0 h, a higher expression of genes that encode PPAR gamma, ABCA-1 and a lower expression of MCP-1 and IL-10, was observed in T as compared to S. After 48 h, lower expressions of MCP-1 and PPAR gamma genes were observed in T mice. Increase in ABCA-1, SR-BI and IL-6 and decrease of LOX-1, MCP-1, TNF and IL-10 gene expression was observed in the aorta of T compared to S mice (0 h) and LOX-1 and MCP-1 remained diminished after 48 h. The protein level of MCP-1 and SR-BI in the aortic arch was unchanged in T animals after 48 h as compared to S, but LOX-1 was reduced confirming data of gene expression. The apo A-I and the HDL₂ mediated-cholesterol efflux (8 and 24 h) were not different between T and S animals. In the presence of CETP, AET positively influences gene expression in the arterial wall and macrophages of CETP-tg mice contributing to the RCT and prevention of atherosclerosis. These changes were perceptible immediately after the exercise session and were influenced by the presence of CETP although independent of changes in its activity. Reductions in gene and protein expression of LOX-1 were parallel and reflect the ability of exercise training in reducing the uptake of modified LDL by the arterial wall macrophages.

High-density lipoprotein maintains skeletal muscle function by modulating cellular respiration in mice

BACKGROUND

Abnormal glucose metabolism is a central feature of disorders with increased rates of cardiovascular disease. Low levels of high-density lipoprotein (HDL) are a key predictor for cardiovascular disease. We used genetic mouse models with increased HDL levels (apolipoprotein A-I transgenic [apoA-I tg]) and reduced HDL levels (apoA-I-deficient [apoA-I ko]) to investigate whether HDL modulates mitochondrial bioenergetics in skeletal muscle.

METHODS AND RESULTS

ApoA-I ko mice exhibited fasting hyperglycemia and impaired glucose tolerance test compared with wild-type mice. Mitochondria isolated from gastrocnemius muscle of apoA-I ko mice displayed markedly blunted ATP synthesis. Endurance capacity during exercise exhaustion test was impaired in apoA-I ko mice. HDL directly enhanced glucose oxidation by increasing glycolysis and mitochondrial respiration rate in C2C12 muscle cells. ApoA-I tg mice exhibited lower fasting glucose levels, improved glucose tolerance test, increased lactate levels, reduced fat mass, associated with protection against age-induced decline of endurance capacity compared with wild-type mice. Circulating levels of fibroblast growth factor 21, a novel biomarker for mitochondrial respiratory chain deficiencies and inhibitor of white adipose lipolysis, were significantly reduced in apoA-I tg mice. Consistent with an increase in glucose utilization of skeletal muscle, genetically increased HDL and apoA-I levels in mice prevented high-fat diet-induced impairment of glucose homeostasis.

CONCLUSIONS

In view of impaired mitochondrial function and decreased HDL levels in type 2 diabetes mellitus, our findings indicate that HDL-raising therapies may preserve muscle mitochondrial function and address key aspects of type 2 diabetes mellitus beyond cardiovascular disease.

Voluntary exercise increases cholesterol efflux but not macrophage reverse cholesterol transport in vivo in mice

Physical exercise beneficially impacts on the plasma lipoprotein profile as well as on the incidence of cardiovascular events and is therefore recommended in primary and secondary prevention strategies against atherosclerotic cardiovascular disease. However, the underlying mechanisms of the protective effect of exercise remain largely unknown. Therefore, the present study tested the hypothesis that voluntary exercise in mice impacts on cholesterol efflux and in vivo reverse cholesterol transport (RCT). After two weeks of voluntary wheel running (average 10.1 ± 1.4 km/day) plasma triglycerides were lower (p < 0.05), while otherwise lipid and lipoprotein levels did not change. Macrophage cholesterol efflux towards plasma was significantly increased in running (n = 8) compared to sedentary (n = 6) mice (14.93 ± 1.40 vs. 12.33 ± 2.60%, p < 0.05). In addition, fecal excretion of bile acids (3.86 ± 0.50 vs. 2.90 ± 0.51 nmol/d, p = 0.001) and neutral sterols (2.75 ± 0.43 vs. 1.94 ± 0.22 nmol/d, p < 0.01) was significantly higher in running mice. However, RCT from macrophages to feces remained essentially unchanged in running mice compared with sedentary controls (bile acids: 3.2 ± 1.0 vs. 2.9 ± 1.1 % of injected dose, n.s.; neutral sterols: 1.4 ± 0.7 vs. 1.1 ± 0.5 % injected dose, n.s.). Judged by the plasma lathosterol to cholesterol ratio, endogenous cholesterol synthesis was increased in exercising mice (0.15 ± 0.03 vs. 0.11 ± 0.02, p < 0.05), while the hepatic mRNA expression of key transporters for biliary cholesterol (Abcg5/g8, Sr-bI) as well as bile acid (Abcb11) and phospholipd (Abcb4) excretion did not change. These data indicate that the beneficial effects of exercise on cardiovascular health include increased cholesterol efflux, but do not extend to other components of RCT. The increased fecal cholesterol excretion observed in running mice is likely explained by higher endogenous cholesterol synthesis, however, it does not reflect increased RCT in the face of unchanged expression of key transporters for biliary sterol secretion.

Endurance training enhances ABCA1 expression in rat small intestine

The purpose of this study was to investigate liver and intestinal ABCA1 expression and plasma HDL-C level in response to treadmill-running training in rats. Twenty adult Wistar male rats (17-18 weeks old, 300-322 g) were divided into control (n = 10) and Training (n = 10) groups. Training group trained at 25 m/min (0% grade) for 60 min/day, 5 days/week for 12 weeks. Rats were killed 48 h after the last session of training. The intestinal and liver ABCA1 mRNA expression was found to be significantly higher in trained compared to control group (P < 0.006 and P < 0.024, respectively). Intestine and liver ATP concentrations remained unchanged. Plasma HDL-C, HDL2-C, Apo A-1, pre-beta HDL-C concentration, LCAT activity, TC/HDL-C and LDL-C/HDL-C ratio significantly increased in trained group (P < 0.01, P < 0.006, P < 0.001, P < 0.001 P < 0.067, P < 0.02, and P < 0.03, respectively). However, other lipoprotein concentrations were unchanged. In conclusion, we found that endurance training induced significant elevation in plasma HDL-C and HDL2-C concentrations, accompanied by higher plasma Apo A-1, pre-beta HDL-C concentrations, LCAT activity and ABCA1 mRNA expressions in rat intestine, and liver.

HDL atheroprotection by aerobic exercise training in type 2 diabetes mellitus

PURPOSE

In this study we analyzed the role played by aerobic exercise training in the plasma lipoprotein profile, prebeta 1-HDL concentration, and in the in vitro HDL3 ability to remove cholesterol from macrophages and inhibit LDL oxidation in type 2 diabetes mellitus (DM) patients and control subjects, in the fasting and postprandial states.

METHODS

Healthy controls (HTC, N = 11; 1 M/10 F) and subjects with type 2 diabetes mellitus (DMT, N = 11; 3M/8F) were engaged in a 4-month aerobic training program, and compared with a group of sedentary subjects with type 2 diabetes mellitus (DMS, N = 10; 4 M/6 F). All groups were submitted to an oral fat load test to analyze all parameters, both at the beginning of the investigation protocol (basal) and at the end of the study period (final).

RESULTS

Exercising did not modify body weight, BMI, plasma concentrations of total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides (TG), glucose, insulin, or HOMA-IR, but it reduced the waist circumference. The HDL3 composition did not change, and its ability to remove cell cholesterol was unaltered by aerobic training. In DMT but not in HTC, aerobic training improved 15% the HDL3 protective effect against LDL maximal oxidation rate in the fasting state, and reduced 24% the plasma prebeta 1-HDL concentration in the postprandial state, suggesting an enhanced prebeta 1-HDL conversion into larger, more mature HDL particles. In this regard, regular aerobic exercise enriched HDL2 with TG in the fasting and postprandial states in HTC and in the fasting phase in DMT.

CONCLUSION

Our results show that aerobic exercise training in diabetes mellitus improves the HDL efficiency against LDL oxidation and favors HDL maturation. These findings were independent of changes in insulin resistance and of the rise of plasma HDL cholesterol concentration.

High density lipoprotein cholesterol: an evolving target of therapy in the management of cardiovascular disease

Since the pioneering work of John Gofman in the 1950s, our understanding of high density lipoprotein cholesterol (HDL-C) and its relationship to coronary heart disease (CHD) has grown substantially. Numerous clinical trials since the Framingham Study in 1977 have demonstrated an inverse relationship between HDL-C and one’s risk of developing CHD. Over the past two decades, preclinical research has gained further insight into the nature of HDL-C metabolism, specifically regarding the ability of HDL-C to promote reverse cholesterol transport (RCT). Recent attempts to harness HDL’s ability to enhance RCT have revealed the complexity of HDL-C metabolism. This review provides a detailed update on HDL-C as an evolving therapeutic target in the management of cardiovascular disease.

Treadmill exercise enhances ABCA1 expression in rat liver

ATP-binding cassette transporters (ABCs) belong to a large family and include 49 mammalian transmembrane transporters that transfer a variety of substrates across the lipid bilayers in an energy-dependent manner. ABCA1 is a member of this family which plays a crucial role in plasma HDL-C remodeling. The purpose of this study was to investigate liver ABCA1 expression and plasma HDL level in response to treadmill running program in rats. Ten adult Wistar male rats (12-14weeks old, 200-220g) were used for this study. Animals were divided into control (Con, n=5) and Training (TR, n=5) groups. Training group was given exercise on a motor-driven treadmill at 25m/min (0% grade) for 90min/day, 5 days/week for 6 weeks. Rats were sacrificed 24h after the last session of exercise portion of the liver was excised, immediately washed in ice-cold saline, and frozen in liquid nitrogen for extraction of ABCA1 mRNA. Plasma was collected for HDL-C, LDL, TC, TG, and VLDL-C measurements. Liver ABCA1 mRNA expression was significantly (P<0.001) higher in trained rats compared to control rats. Plasma HDL-C, LCAT, pre-beta-HDL concentrations were significantly higher (P<0.01, P<0.001, P<0.028, respectively) in trained rats at the end of treadmill exercise. However, plasma lipids, other lipoproteins and TC/HDL and LDL/HDL ratio were unchanged. In conclusion, a treadmill running-induced elevated plasma HDL-C concentration was accompanied with a higher liver ABCA1 mRNA expression and increased in LCAT and pre-beta-HDL levels.

ABCA1 expression in humans is associated with physical activity and alcohol consumption

Genetic variation in ABCA1 significantly affects HDL levels and atherosclerotic risk. The aim of this study was to examine lifestyle factors influencing ABCA1 expression in human leukocytes and skeletal muscle. A fasting venous blood sample and a vastus lateralis muscle biopsy were taken from 30 volunteers (53+/-1 years; mean+/-S.E.M.). Levels of ABCA1 mRNA were measured in blood leukocytes and muscle biopsies. Plasma-induced cholesterol efflux from THP-1 human macrophages as well as plasma lipids and lipid-related parameters were also measured. The amount of alcohol consumed per week correlated strongly with both muscle ABCA1 expression (r(2)=+0.37, p<0.001) and cholesterol efflux (r(2)=+0.41, p<0.001). Higher levels of physical exercise were associated with higher leukocyte ABCA1 expression (p<0.005), and higher concentrations of plasma apoA-I (p<0.05) and pre beta(1)-HDL (p<0.001). All these relationships were independent of diabetic status on multivariate analysis. ABCA1 expression in leukocytes and skeletal muscle was not related, suggesting different regulatory mechanisms. In conclusion, ABCA1 expression in human leukocytes and muscle is associated with physical activity and alcohol consumption, respectively.

Recent studies of lipoprotein kinetics in the metabolic syndrome and related disorders

PURPOSE OF REVIEW

Dyslipoproteinemia is a cardinal feature of the metabolic syndrome that accelerates atherosclerosis. Recent in-vivo kinetic studies of dyslipidemia in the metabolic syndrome are reviewed here.

RECENT FINDINGS

The dysregulation of lipoprotein metabolism may be caused by a combination of overproduction of VLDL apolipoprotein B-100, decreased catabolism of apolipoprotein B-containing particles, and increased catabolism of HDL apolipoprotein A-I particles. Nutritional modifications and increased physical exercise may favourably alter lipoprotein transport by collectively decreasing the hepatic secretion of VLDL apolipoprotein B and the catabolism of HDL apolipoprotein A-I, as well as by increasing the clearance of LDL apolipoprotein B. Conventional and new pharmacological treatments, such as statins, fibrates and cholesteryl ester transfer protein inhibitors, can also correct dyslipidemia by several mechanisms, including decreased secretion and increased catabolism of apolipoprotein B, as well as increased secretion and decreased catabolism of apolipoprotein A-I.

SUMMARY

Kinetic studies provide a mechanistic insight into the dysregulation and therapy of lipid and lipoprotein disorders. Future research mandates the development of new tracer methodologies with practicable in-vivo protocols for investigating fatty acid turnover, macrophage reverse cholesterol transport, cholesterol transport in plasma, corporeal cholesterol balance, and the turnover of several subpopulations of HDL particles.

Elevated HDL Cholesterol is Functionally Ineffective in Cardiac Transplant Recipients: Evidence for Impaired Reverse Cholesterol Transport

BACKGROUND

Cardiac transplant recipients frequently have high plasma HDL levels but it is unclear whether these promote a cardioprotective profile.

METHODS

Parameters of reverse cholesterol transport and endothelial function were compared in 25 cardiac transplant recipients with low (<1.4 mmol/L; n=11) or high (>1.4 mmol/L; n=14) plasma levels of HDL and in a reference healthy group.

RESULTS

Patients with high HDL had lower levels of triglyceride and prebeta1-HDL and a higher proportion of large HDL particles. When normalized to apoA-I content, non-ABCA1-dependent cholesterol efflux from RAW 264.7 macrophage cells to plasma from high HDL patients was 33% lower when compared to plasma from patients with low HDL, whereas ABCA1-dependent cholesterol efflux was not impaired. Forearm vascular responses to acetylcholine and sodium nitroprusside were not influenced by HDL levels in these patients. Compared to a reference healthy group (n=26), cardiac transplant recipients had higher levels of triglyceride, lower levels of prebeta1-HDL and LCAT, and lower activities of cholesteryl ester transfer protein and phospholipid transfer protein.

CONCLUSIONS

Hyperalphalipoproteinaemia in cardiac transplant recipients is associated with the formation of partially dysfunctional HDL. We conclude that high levels of HDL may not confer cardioprotection in this group of patients.

Apolipoprotein A1 genotype affects the change in high density lipoprotein cholesterol subfractions with exercise training

High density lipoprotein cholesterol (HDL-C) is a primary risk factor for cardiovascular disease. Apolipoprotein A-1 (apoA1) is the major HDL-associated apolipoprotein. The -75G/A single nucleotide polymorphism (SNP) in the apolipoprotein A1 gene (APOA1) promoter has been reported to be associated with HDL-C concentrations as well as HDL-C response to dietary changes in polyunsaturated fat intake. We examined the effect of this APOA1 SNP on exercise-induced changes in HDL subfraction distribution. From a cohort of healthy normolipidemic adults who volunteered for 6 months of supervised aerobic exercise, 75 subjects were genotyped for the -75G/A SNP. Of these, 53 subjects were G homozygotes (G/G) and 22 were A carriers (A/G and A/A). HDL subfractions were measured by nuclear magnetic resonance (NMR) spectroscopy by adding categories HDL-C 1+2 for the small subfraction, and HDL-C 3+4+5 for the large. The change in total HDL-C after exercise was 0.8+/-7.2 mg/dL (+1.7%), and was not statistically significant. HDL subfraction amounts also did not significantly change with exercise training in the total cohort or in G homozygotes or A carriers. The amount of the large HDL subfraction increased in the G homozygotes and decreased in the A carriers (mean+/-S.E.M., 1.8+/-6.6 mg/dL versus -6.1+/-2.3 mg/dL, p<0.0005). In contrast, the amount of the small HDL subfraction decreased in G homozygotes and increased in A carriers (-1.3+/-6.6 mg/dL versus 4.7+/-1.2 mg/dL, p<0.005). These results show that genetic variation at the APOA1 gene promoter is associated with HDL subfraction redistribution resulting from exercise training.

Molecular Mechanism of Reverse Cholesterol Transport: Reaction of Pre-β-Migrating High-Density Lipoprotein with Plasma Lecithin/Cholesterol Acyltransferase

A 70-75 kDa high-density lipoprotein (HDL) particle with pre-beta-electrophoretic migration (pre-beta(1)-HDL) has been identified in several studies as an early acceptor of cell-derived cholesterol. However, the further metabolism of this complex has not been determined. Here we sought to identify the mechanism by which cell-derived cholesterol was esterified and converted to mature HDL as part of reverse cholesterol transport (RCT). Human plasma selectively immunodepleted of pre-beta(1)-HDL was used to study factors regulating pre-beta(1)-HDL production. A major role for phospholipid transfer protein (PLTP) in the recycling of pre-beta(1)-HDL was identified. Cholesterol binding, esterification by lecithin/cholesterol acyltransferase (LCAT) and transfer by cholesteryl ester transfer protein (CETP) were measured using (3)H-cholesterol-labeled cell monolayers. LCAT bound to (3)H-free cholesterol (FC)-labeled pre-beta(1)-HDL generated cholesteryl esters at a rate much greater than the rest of HDL. The cholesteryl ester produced in pre-beta(1)-HDL in turn became the preferred substrate of CETP. Selective LCAT-mediated reactivity with pre-beta(1)-HDL represents a novel mechanism increasing the efficiency of RCT.

Physical Fitness and Reverse Cholesterol Transport

BACKGROUND

Physical exercise is associated with a decreased risk of cardiovascular disease, which may be partly caused by the effect of exercise on the lipoprotein profile. The most consistent effect of exercise on lipoprotein metabolism is an increase in high-density lipoprotein (HDL).

METHODS AND RESULTS

Parameters of reverse cholesterol transport (RCT) in 25 endurance-trained male athletes were compared with 33 age-matched males enjoying an active lifestyle. VO2max was higher in athletes than in controls (53.4+/-1.2 versus 38.8+/-1.0 mL/min per kg; P<0.01). The following differences in parameters of RCT were found: (1) plasma HDL cholesterol and apoA-I levels were higher in athletes compared with controls (1.7+/-0.1 versus 1.4+/-0.1 mmol/L; P<0.001; and 145+/-2 versus 128+/-3 mg/dL; P<0.001, respectively). Both correlated with VO2max up to the value of 51 mL/min per kg; (2) prebeta1-HDL was higher in athletes than in controls (54+/-4 versus 37+/-3 microg/mL; P<0.001) and correlated positively with VO2max; (3) lecithin cholesterol: acyltransferase activity was higher in athletes (29.8+/-1.2 versus 24.2+/-1.4 nmol/microL per hour; P<0.005); and (4) the capacity of plasma to promote cholesterol efflux from macrophages was higher in athletes (18.8%+/-0.8% versus 16.2%+/-0.3%; P<0.03).

CONCLUSIONS

The likely reason for higher HDL concentration in physically fit people is increased formation of HDL from apoA-I and cellular lipids.

Lifestyle determinants of high-density lipoprotein cholesterol: the National Heart, Lung, and Blood Institute Family Heart Study

BACKGROUND

While genetic factors are major determinants of high-density lipoprotein cholesterol (HDL-C), environmental factors also play a role. The latter include 3 modifiable lifestyle factors: alcohol consumption, physical activity, and smoking.

METHODS

We compared the relative effects of alcohol, physical activity, and smoking on HDL-C levels, using data from 2309 subjects (1226 women and 1083 men), aged 25 to 91 years, from randomly selected families participating in the National Heart, Lung, and Blood Institute Family Heart Study.

RESULTS

Alcohol consumption was associated with the largest increment in HDL-C (an increase of 9.0-13.1 mg/dL from nondrinker to highest categories); physical activity with a more modest increment (an increase of 3.0-3.3 mg/dL from lowest to highest categories); and cigarette smoking with a large decrement in women (a decrease of 9.9 mg/dL) and a modest one in men (a decrease of 2.6 mg/dL) between nonsmoker and > or =20 cigarettes per day categories. The 3 lifestyle behaviors plus age, body mass index, education, and current estrogen use explained 22.4% and 18.2% of the total variance of HDL-C for women and men, respectively. Alcohol accounted for 28.6% of this variance among women and 50.1% among men; smoking accounted for 6.7% and 3.3%, respectively, and physical activity for 2.7% and 3.6%, respectively, among women and men. Age, body mass index, education, and current estrogen use explained the remaining 62.0% and 43.0%, respectively, of the variance attributed to environmental factors.

CONCLUSIONS

This study suggests that, among lifestyle behaviors, alcohol consumption is the more important correlate of HDL-cholesterol.

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.