Cardiovascular fitness, body composition, and lipoprotein lipid metabolism in older men

The Influence of Menopause and Cardiorespiratory Fitness on Lipoprotein Particles in Midlife Women

Lipoprotein particles may provide better information about cardiovascular risk than standard cholesterol measures for women. Whether lipoprotein subclasses change with menopausal stage is unclear. Given the high prevalence of low cardiorespiratory fitness in midlife women and benefit to cardiovascular risk, it is also important to understand the effect of fitness on lipoprotein profiles.

PURPOSE

To evaluate the influence of menopausal status and fitness on lipoprotein particles in healthy midlife women.

METHODS

Lipoprotein particles were measured in high-(HIGH,n=25) and low-fit(LOW,n=13) perimenopausal and late postmenopausal women, and in HIGH premenopausal(n=10), perimenopausal(n=12), and late postmenopausal women(n=13).

RESULTS

There were larger low-density lipoprotein particles(LDL-P, 21.7±0.06vs.21.3±0.1nm, p=0.002), more large LDL-P(623.1±32.8vs.500.2±52.6nmol/L, p=0.045), and fewer small LDL-P(145.5±31.4vs. 311.5±44.7nmol/L, p=0.001) in HIGH vs. LOW. High-density lipoprotein particles(HDL-P) were larger(10.1±0.1vs.9.7±0.1nm, p=0.002) in HIGH, with more large(14.8±0.7vs.11.0±0.9μmol/L, p=0.002), medium(12.9±0.8vs. 8.4±0.9μmol/L, p=0.002), and fewer small HDL-P(10.2±1.1vs.15.4±1.6μmol/L, p=0.009) compared to LOW. HIGH postmenopausal women had more large LDL-P(662.9±47.5nmol/L) compared to premenopausal women(479.1±52.6nmol/L, p=0.035), and more HDL-P(40.2±1.1μmol/L) compared to premenopausal(34.9±1.5μmol/L, p=0.023) and perimenopausal women(35.4±1.3μmol/L, p=0.033).

CONCLUSION

High fitness positively influences lipoprotein particles in healthy perimenopausal and late postmenopausal women. In healthy fit women, menopause may not have a large influence on lipoprotein particles. Novelty Bullets: • In highly-fit women, menopause may not have a negative influence on lipoprotein particle subclasses. • High fitness is associated with a less atherogenic lipoprotein profile in perimenopausal and late postmenopausal women.

Body mass index and mortality in patients with severe coronary artery diseases: A cohort study from China

BACKGROUND AND AIMS

It is still controversial whether obesity and overweight increase the risk of mortality for patients with coronary artery disease. The current study aimed to investigate the relationship between body mass index (BMI) and mortality in patients with triple-vessel disease (TVD).

METHODS AND RESULTS

From April 2004 to February 2011, 8943 patients with angiographically confirmed TVD were consecutively enrolled. Patients were divided into five groups according to BMI: underweight (<18.5 kg/m²), normal weight (18.5-23.9 kg/m²), overweight: (24-27.9 kg/m²), mild obesity (28-31.9 kg/m²), and severe obesity (≥32 kg/m²). The primary end point was all-cause death. Subgroup analysis was performed for treatment strategies: revascularization and medical treatment alone. During a median follow-up of 7.5 years, lower risks of mortality were observed in patients with overweight (adjusted HR 0.85, 95% CI 0.75-0.97) and mild obesity (adjusted HR 0.83, 95% CI 0.69-1.00) compared to those with normal weight. Polynomial Cox regression suggested a U-shape association between BMI and adjusted mortality risk. In the revascularization subgroup, there was a significantly higher mortality risk in patients with severe obesity (adjusted HR 1.57, 95% CI 1.03-2.40) than in those with normal weight. While in the medical treatment subgroup, mortality risk decreased as BMI increased, with the lowest risk being observed in patients with severe obesity.

CONCLUSION

There is a U-shape relationship between BMI and all-cause death in patients with TVD, with increased risks among both underweight and severely obese patients. This relationship may be influenced by treatment strategies.

Association between body mass index and cortical thickness: among elderly cognitively normal men and women

BACKGROUND

There is increasing evidence of a relationship between underweight or obesity and dementia risk. Several studies have investigated the relationship between body weight and brain atrophy, a pathological change preceding dementia, but their results are inconsistent. Therefore, we aimed to evaluate the relationship between body mass index (BMI) and cortical atrophy among cognitively normal participants.

METHODS

We recruited cognitively normal participants (n = 1,111) who underwent medical checkups and detailed neurologic screening, including magnetic resonance imaging (MRI) in the health screening visits between September 2008 and December 2011. The main outcome was cortical thickness measured using MRI. The number of subjects with five BMI groups in men/women was 9/9, 148/258, 185/128, 149/111, and 64/50 in underweight, normal, overweight, mild obesity, and moderate to severe obesity, respectively. Linear and non-linear relationships between BMI and cortical thickness were examined using multiple linear regression analysis and generalized additive models after adjustment for potential confounders.

RESULTS

Among men, underweight participants showed significant cortical thinning in the frontal and temporal regions compared to normal weight participants, while overweight and mildly obese participants had greater cortical thicknesses in the frontal region and the frontal, temporal, and occipital regions, respectively. However, cortical thickness in each brain region was not significantly different in normal weight and moderate to severe obesity groups. Among women, the association between BMI and cortical thickness was not statistically significant.

CONCLUSIONS

Our findings suggested that underweight might be an important risk factor for pathological changes in the brain, while overweight or mild obesity may be inversely associated with cortical atrophy in cognitively normal elderly males.

Reciprocal Hemizygosity Analysis of Mouse Hepatic Lipase Reveals Influence on Obesity

OBJECTIVES

We previously demonstrated coincident quantitative trait loci (QTLs) for percentage body fat, plasma hepatic lipase (HL) activity, and plasma cholesterol on mouse chromosome 7. In the present study, we investigated whether hepatic lipase (Lipc) is an obesity gene, whether Lipc interacts with an unknown gene on chromosome 7, and how HL activity is linked to the chromosome 7 locus.

RESEARCH METHODS AND PROCEDURES

BSB mice are a model of complex obesity due to interactions among genes from C57BL/6J and Mus spretus (SPRET) in (C57BL/6J x SPRET) x C57BL/6J backcross mice. Five crosses tested the impact on obesity of combinations of inactive (knockout) and wild-type Lipc alleles from C57BL/6J or SPRET in a reciprocal hemizygosity analysis.

RESULTS

The combined data from this allelic series suggest that Lipc alleles, and not alleles from a gene linked to Lipc, influence obesity. No interaction between Lipc and chromosome 7 was demonstrated. We confirmed the chromosome 7 QTLs for obesity, HL activity, and cholesterol. Because obesity and HL activity are not consistently associated in the BSB model, linkage of HL activity to chromosome 7 is not secondary to obesity per se. We also report, for the first time to our knowledge, a QTL in mammals for food intake.

DISCUSSION

This use of reciprocal hemizygosity analysis in mammals, which, to our knowledge, is the first reported, reveals its power to detect previously unknown effects of Lipc on obesity.

Hepatic lipase gene -514C>T variant is associated with exercise training-induced changes in VLDL and HDL by lipoprotein lipase

Our objective was to test the hypothesis that a common polymorphism in the hepatic lipase (HL) gene (LIPC -514C>T, rs1800588) influences aerobic exercise training-induced changes in TG, very-low-density lipoprotein (VLDL), and high-density lipoprotein (HDL) through genotype-specific increases in lipoprotein lipase (LPL) activity and that sex may affect these responses. Seventy-six sedentary overweight to obese men and women aged 50-75 yr at risk for coronary heart disease (CHD) underwent a 24-wk prospective study of the LIPC -514 genotype-specific effects of exercise training on lipoproteins measured enzymatically and by nuclear magnetic resonance, postheparin LPL and HL activities, body composition by dual energy x-ray absorptiometry and computer tomography scan, and aerobic capacity. CT genotype subjects had higher baseline total cholesterol, HDL-C, HDL(2)-C, large HDL, HDL particle size, and large LDL than CC homozygotes. Exercise training elicited genotype-specific decreases in VLDL-TG (-22 vs. +7%; P < 0.05; CC vs. CT, respectively), total VLDL and medium VLDL, and increases in HDL-C (7 vs. 4%; P < 0.03) and HDL(3)-C with significant genotype×sex interactions for the changes in HDL-C and HDL(3)-C (P values = 0.01-0.02). There were also genotype-specific changes in LPL (+23 vs. -6%; P < 0.05) and HL (+7 vs. -24%; P < 0.01) activities, with LPL increasing only in CC subjects (P < 0.006) and HL decreasing only in CT subjects (P < 0.007). Reductions in TG, VLDL-TG, large VLDL, and medium VLDL and increases in HDL(3)-C and small HDL particles correlated significantly with changes in LPL, but not HL, activity only in CC subjects. This suggests that the LIPC -514C>T variant significantly affects training-induced anti-atherogenic changes in VLDL-TG, VLDL particles, and HDL through an association with increased LPL activity in CC subjects, which could guide therapeutic strategies to reduce CHD risk.

The effect of hepatic lipase on coronary artery disease in humans is influenced by the underlying lipoprotein phenotype

Increased or decreased hepatic lipase (HL) activity has been associated with coronary artery disease (CAD). This is consistent with the findings that gene variants that influence HL activity were associated with increased CAD risk in some population studies but not in others. In this review, we will explain the conditions that influence the effects of HL on CAD. Increased HL is associated with smaller and denser LDL (sdLDL) and HDL (HDL(3)) particles, while decreased HL is associated with larger and more buoyant LDL and HDL particles. The effect of HL activity on CAD risk is dependent on the underlying lipoprotein phenotype or disorder. Central obesity with hypertriglyceridemia (HTG) is associated with high HL activity that leads to the formation of sdLDL that is pro-atherogenic. In the absence of HTG, where large buoyant cholesteryl ester-enriched LDL is prominent, elevation of HL does not raise the risk for CAD. In HTG patients, drug therapy that decreases HL activity selectively decreases sdLDL particles, an anti-atherogenic effect. Drug therapy that raises HDL(2) cholesterol has not decreased the risk for CAD. In trials where inhibition of cholesterol ester transfer protein (CETP) or HL occurs, the increase in HDL(2) most likely is due to inhibition of catabolism of HDL(2) and impairment of reverse cholesterol transport (RCT). In patients with isolated hypercholesterolemia, but with normal triglyceride levels and big-buoyant LDL particles, an increase in HL activity is beneficial; possibly because it increases RCT. Drugs that lower HL activity might decrease the risk for CAD only in hypertriglyceridemic patients with sdLDL by selectively clearing sdLDL particles from plasma, which would override the potentially pro-atherogenic effect on RCT. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).

Exercise in aging: its important role in mortality, obesity and insulin resistance

The prevalence of overweight and obesity has increased dramatically over the last several decades. Obesity and physical inactivity increase the risk for cardiovascular disease, Type 2 diabetes mellitus, hypertension, dyslipidemia and certain cancers. Obesity and low levels of physical fitness are also associated with increased risk of all-cause and cardiovascular mortality. Central and total obesity, insulin resistance and inactivity increase with age. Exercise training and increased fitness promote positive changes in body composition and improve insulin sensitivity. This article will describe the effects of exercise training, both aerobic and resistive, on body composition and obesity as well as review studies investigating the effects of exercise training on glucose metabolism and insulin sensitivity in older adults. Adopting a physically active lifestyle should be emphasized in overweight and obese individuals with insulin resistance to reduce the risk for cardiovascular events in the aging population.

Cardiorespiratory fitness and metabolic risk factors in obesity

PURPOSE OF REVIEW

An increase in cardiorespiratory fitness (CRF) through exercise training appears to partly ameliorate the health hazards of obesity and a number of mechanisms might explain the potential benefits. We review recent evidence about the relationships between CRF, exercise training and metabolic risk factors in obesity.

RECENT FINDINGS

Epidemiological data have shown that the anti-inflammatory effects of exercise could be an important mechanism in explaining cardio-protective effects of physical activity. Emerging evidence suggests that exercise training reduces markers of inflammation and improves glucose control in obesity, independent of weight loss. Novel mechanisms appear to involve exercise-induced changes in CD14+CD16+ cell populations, expression of toll-like receptors, and key changes in the metabolic regulation of visceral white adipose tissue. Other promising recent research has focused on exercise-induced signalling pathways governing glucose metabolism, such as insulin receptor substrate and Akt substrate. Using novel imaging techniques, studies have demonstrated exercise-induced improvements in lipoprotein subfraction particle size, and reduction in visceral adipose tissue and liver fat, independent of weight loss. These effects appear to be mostly restricted to interventions consisting of relatively high doses of exercise or exercise combined with calorie restriction, although further work is required to elucidate the dose-response relationships.

SUMMARY

Physical activity and the pursuit of physical fitness are important in the treatment of obesity because exercise training can improve a number of metabolic risk factors independent of weight loss. Thus exercise can provide important health benefits irrespective of weight loss in obese and overweight individuals.

Accuracy of body mass index in diagnosing obesity in the adult general population

BACKGROUND

Body mass index (BMI) is the most widely used measure to diagnose obesity. However, the accuracy of BMI in detecting excess body adiposity in the adult general population is largely unknown.

METHODS

A cross-sectional design of 13 601 subjects (age 20-79.9 years; 49% men) from the Third National Health and Nutrition Examination Survey. Bioelectrical impedance analysis was used to estimate body fat percent (BF%). We assessed the diagnostic performance of BMI using the World Health Organization reference standard for obesity of BF%>25% in men and>35% in women. We tested the correlation between BMI and both BF% and lean mass by sex and age groups adjusted for race.

RESULTS

BMI-defined obesity (> or =30 kg m(-2)) was present in 19.1% of men and 24.7% of women, while BF%-defined obesity was present in 43.9% of men and 52.3% of women. A BMI> or =30 had a high specificity (men=95%, 95% confidence interval (CI), 94-96 and women=99%, 95% CI, 98-100), but a poor sensitivity (men=36%, 95% CI, 35-37 and women=49%, 95% CI, 48-50) to detect BF%-defined obesity. The diagnostic performance of BMI diminished as age increased. In men, BMI had a better correlation with lean mass than with BF%, while in women BMI correlated better with BF% than with lean mass. However, in the intermediate range of BMI (25-29.9 kg m(-2)), BMI failed to discriminate between BF% and lean mass in both sexes.

CONCLUSIONS

The accuracy of BMI in diagnosing obesity is limited, particularly for individuals in the intermediate BMI ranges, in men and in the elderly. A BMI cutoff of> or =30 kg m(-2) has good specificity but misses more than half of people with excess fat. These results may help to explain the unexpected better survival in overweight/mild obese patients.

Association of C-reactive protein with surrogate measures of insulin resistance among nondiabetic US from National Health and Nutrition Examination Survey 1999-2002

BACKGROUND

Increased C-reactive protein (CRP) concentration and insulin resistance (IR) are associated with increased rates of adverse cardiovascular events. We sought to examine the relationship of CRP with surrogate measures of IR among nondiabetic adults in the US.

METHODS

We conducted analyses using data from the National Health and Nutrition Examination Survey 1999-2002. We analyzed a nationally representative sample of 2514 men and nonpregnant women age > or = 20 years who were non-Hispanic white, non-Hispanic black, or Mexican American.

RESULTS

After adjustment for age, sex, race/ethnicity, smoking status, systolic blood pressure, and serum concentrations of HDL cholesterol, LDL cholesterol, and triglyceride, CRP was significantly associated with 10 IR measures (all P values <0.01). The strength of the association attenuated after further adjustment for waist circumference (change in adjusted regression coefficients ranging from 60.0% to 75.1%). The association of CRP with each IR surrogate was similar (standardized regression coefficient ranges from 0.06 to 0.09). The association of CRP (>3 vs <1 mg/L) with the homeostasis model for assessment of IR (> or = 75th vs <75th percentile) was statistically significant among people with a body mass index > or = 30 kg/m(2) (odds ratio, 2.6; 95% CI, 1.3-5.1) or with a body mass index <25 kg/m(2) (odds ratio, 2.5; 95% CI, 1.5-4.2).

CONCLUSIONS

CRP was significantly associated with the surrogate measures of IR among nondiabetic adults. Obesity may play an important role in the association of CRP with IR in this nationally representative sample.

Older Elite Football Players Have Reduced Cardiac and Osteoporosis Risk Factors

INTRODUCTION/PURPOSE

Aging with a sedentary lifestyle is associated with increased risk for developing cardiovascular disease (CVD), osteoporosis, and sarcopenia. The purpose of this study was to determine whether former professional football athleticism would be associated with reduced risk factors for CVD and osteoporosis, and higher muscle mass in later life.

METHODS

Maximal aerobic capacity (VO2max), body composition, and lipid and glucose risk factors for CVD were compared between 16 older former professional football players and never-athletic men matched for age, body mass index, current physical activity, and race. Regional bone mineral density of the football players was compared with age-matched reference norms.

RESULTS

Despite greater physical activity into middle age, the former football players had similar VO2max as the controls. Former football players had 26% lower total-body fat mass, 26% lower visceral adipose tissue area, and 13% higher muscle mass compared with the controls (P < 0.05). High-density lipoprotein cholesterol (HDL-C) levels were 37% higher (P < 0.001), HDL2-C levels were fourfold higher (P < 0.001), and triglycerides were 31% lower (P < 0.05) in the former football players than the controls. The former football players also had 20% and 6% higher total-body bone mineral content and density than the controls (P < 0.05) and higher lumbar spine, femoral neck, and greater trochanter bone mineral density than similar age-referenced norms (P < 0.05).

CONCLUSION

Elite athlete physical activity status in young adulthood, and remaining physically active in middle age, may confer body composition changes that are sustained in older adulthood. In this small sample of older men, former successful professional athletes who remained physically active in middle age have a favorable body composition and reduced risk factors for CVD and osteoporosis compared with healthy age- and BMI-matched older men.

Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies

BACKGROUND

Studies of the association between obesity, and total mortality and cardiovascular events in patients with coronary artery disease (CAD) have shown contradictory results. We undertook a systematic review to determine the extent and nature of this association.

METHODS

We selected cohort studies that provided risk estimates for total mortality, with or without cardiovascular events, on the basis of bodyweight or obesity measures in patients with CAD, and with at least 6 months' follow-up. CAD was defined as history of percutaneous coronary intervention, coronary artery bypass graft, or myocardial infarction. We obtained risk estimates for five predetermined bodyweight groups: low, normal weight (reference), overweight, obese, and severely obese.

FINDINGS

We found 40 studies with 250,152 patients that had a mean follow-up of 3.8 years. Patients with a low body-mass index (BMI) (ie, <20) had an increased relative risk (RR) for total mortality (RR=1.37 [95% CI 1.32-1.43), and cardiovascular mortality (1.45 [1.16-1.81]), overweight (BMI 25-29.9) had the lowest risk for total mortality (0.87 [0.81-0.94]) and cardiovascular mortality (0.88 [0.75-1.02]) compared with those for people with a normal BMI. Obese patients (BMI 30-35) had no increased risk for total mortality (0.93 [0.85-1.03]) or cardiovascular mortality (0.97 [0.82-1.15]). Patients with severe obesity (> or =35) did not have increased total mortality (1.10 [0.87-1.41]) but they had the highest risk for cardiovascular mortality (1.88 [1.05-3.34]).

INTERPRETATION

The better outcomes for cardiovascular and total mortality seen in the overweight and mildly obese groups could not be explained by adjustment for confounding factors. These findings could be explained by the lack of discriminatory power of BMI to differentiate between body fat and lean mass.

What Can We Learn About Diet and Physical Activity From Master Athletes?

Only 13% of those 65 years and older engage in vigorous physical activity 3 or more days a week and obesity rates are increasing by 45% in adults over the age of 60. Physical activity helps prevent chronic disease and improves quality of life, yet few adults of any age are active. One exception is master athletes who participate in competitive sports during the middle and later years. The aerobic fitness of master athletes, as measured by maximal oxygen consumption, shows some decline, but not nearly as much as in sedentary controls. Master athletes have lipid profiles similar to those of young adults, which decreases their risk of heart disease. Master athletes also have better glucose tolerance and lower waist-to-hip ratios than sedentary adults, decreasing their risk for metabolic syndrome and type 2 diabetes. In the few dietary studies that have been conducted, master athletes consume more food energy while maintaining lower body weights than sedentary adults. Learning what motivates master athletes to stay highly active may help health professionals develop strategies to encourage exercise in the sedentary population of older adults.

Cardiovascular disease risk factors in habitual exercisers, lean sedentary men and abdominally obese sedentary men

OBJECTIVE

To investigate whether the favourable cardiovascular disease (CVD) risk factor profile of habitual exercisers is attributable to exercise or leanness.

DESIGN

Cross-sectional study of 113 nonsmoking men aged 30-45 y. CVD risk factors were compared in exercisers (n=39) and sedentary men (n=74), and in subgroups of lean exercisers (n=37), lean sedentary men (n=46) and obese sedentary men (n=28). Waist girth was used to identify lean (<100 cm) and abdominally obese (> or =100 cm) subgroups.

MEASUREMENTS

Blood pressure, physical activity (7-day recall), physical fitness (maximum oxygen consumption) and fasted lipoproteins, apolipoprotein (apo) B, triglycerides, glucose and fibrinogen.

RESULTS

Exercisers were fitter and leaner than sedentary men and had a better CVD risk factor profile. Total cholesterol, LDL-cholesterol and apo B concentrations were lower in lean exercisers than in lean sedentary men, suggesting that exercise influences these risk factors. Indeed, time spent in vigorous activity was the only significant predictor of total cholesterol and LDL-cholesterol in multiple linear regression models. Exercise status had little influence on triglycerides and HDL-cholesterol (HDL-C), and unfavourable levels were only evident among obese sedentary men. Waist girth was the sole predictor of triglycerides and HDL-C, explaining 44 and 31% of the variance, respectively.

CONCLUSIONS

These findings suggest that the CVD risk factor profile of habitual exercisers is attributable to leanness and exercise. Leanness is associated with favourable levels of HDL-C and triglycerides, while exercise is associated with lower levels of total cholesterol, LDL-cholesterol and apo B.

Epistatic interaction between two nonstructural loci on chromosomes 7 and 3 influences hepatic lipase activity in BSB mice

BSB mice exhibit a wide range of obesity despite being produced by a backcross of lean C57BL/6J (B) x lean Mus spretus (SPRET/Pt) F1 animals x B. Previous linkage studies identified a quantitative trait locus (QTL) on mouse chromosome 7 with coincident peaks for hepatic lipase activity, obesity, and plasma cholesterol. However, these mice were not analyzed for gene x gene epistasis. Hepatic lipase activity is correlated with obesity and plasma cholesterol levels. In this study, we identified QTLs for plasma hepatic lipase activity with three statistical mapping methods: maximum likelihood interval mapping, Bayesian nonepistatic mapping, and Bayesian epistatic mapping. Bayesian epistatic mapping detected not only the QTL on chromosome 7 but also an additional QTL on chromosome 3, which has a weak main effect but a strong interaction with chromosome 7. SPRET/Pt alleles of the QTL on each chromosome promote hepatic lipase activity. The proportion of phenotypic variance explained by the epistatic effect is higher than that explained by the main effect of the QTL on chromosome 7.

The yellow agouti mutation alters some but not all responses to diet and exercise

OBJECTIVE

Effects of ectopic expression of the agouti signaling protein were studied on responses to diet restriction and exercise in C57BL/6J (B6) mice and obese B6 mice congenic for the yellow agouti mutation [B6.Cg-Ay (Ay)].

RESEARCH METHODS AND PROCEDURES

Adult male Ay mice were either kept sedentary or exercised on a running wheel and fed ad libitum or diet restricted until weight matched to ad libitum-fed B6 control mice. Body composition, plasma lipids, leptin, and adiponectin were measured. mRNA levels for leptin, adiponectin, lipoprotein lipase, and pyruvate dehydrogenase kinase 4 were measured in a visceral (epididymal) and a subcutaneous (femoral) fat depot by real-time polymerase chain reaction.

RESULTS

Correlations among traits exhibited one of three patterns: similar lines for B6 and Ay mice, different slopes for B6 and Ay mice, and/or different intercepts for B6 and Ay mice. Correlations involving plasma leptin, mesenteric and epididymal adipose weights, or low-density lipoprotein-cholesterol were most likely to have different slopes and/or intercepts in B6 and Ay mice. mRNA levels for leptin, Acrp30, pyruvate dehydrogenase kinase 4, and lipoprotein lipase in epididymal adipose tissue were not correlated with corresponding levels in femoral adipose tissue.

DISCUSSION

The agouti protein interferes with leptin signaling at melanocortin receptors in the hypothalamus of Ay mice. Our results are consistent with the hypothesis that the melanocortin portion of the leptin-signaling pathway mediates effects primarily on certain fat depots and on some, but not all, components of cholesterol homeostasis.

Sugars, hypertriglyceridemia, and cardiovascular disease

Short-term studies consistently show that raising the carbohydrate content of the diet increases serum triacylglycerol concentrations. As compared with starches, sugars (particularly sucrose and fructose) tend to increase serum triacylglycerol concentrations by approximately 60%. The magnitude of the effect depends on other aspects of the diet, including the total amount of carbohydrate and the types of fat, carbohydrate, and fiber, but definitive studies to describe the dose-response relations are not available. Longer-term studies show that some high-carbohydrate diets are not associated with increased fasting serum triacylgycerol concentrations. However, sedentary subjects with upper-body and visceral obesity who have the metabolic syndrome tend to be at higher risk for hypertriglyceridemia in response to high-sucrose and high-carbohydrate diets; moderate weight loss mitigates the effect. Hyperinsulinemia or insulin resistance may play a role in promoting higher rates of VLDL synthesis and hypertriglyceridemia in obesity, but the mechanisms remain unclear. The effect of fructose in promoting triacylglycerol synthesis is independent of insulinemia, however. In terms of the long-term effects of diets high in sugars on the risk of cardiovascular disease, available epidemiologic evidence indicates no association of sugars or total carbohydrate intake per se, but high dietary glycemic load is associated with higher serum triacylglycerol concentrations and greater risk of coronary heart disease in women. Studies are needed to delineate the independent effects of dietary sugars and glycemic load on serum triacylglycerol concentrations in lean and obese men and women and to determine whether the elevations in fasting and fed concentrations of serum triacylglycerol with high-carbohydrate and high-sugars diets are associated with increased risk of cardiovascular disease.

Metabolic effects of nandrolone decanoate and resistance training in men with HIV

Thirty human immunodeficiency virus (HIV)-infected men were randomized to a high dose of nandrolone decanoate weekly (group 1) or nandrolone plus resistance training (group 2) for 12 wk. For the two groups, nandrolone had no significant effects on total cholesterol, LDL cholesterol, LDL phenotype, or fasting triglycerides, although triglycerides decreased by 66 +/- 124 mg/dl for the entire population (P = 0.01). Group 2 subjects had a favorable increase of 5.2 +/- 7.7A in LDL particle size (P = 0.03), whereas there was no change in group 1. Lipoprotein(a) decreased by 7.3 +/- 6.8 mg/dl for group 1 (P = 0.002) and by 6.9 +/- 8.1 for group 2 (P = 0.013). However, HDL cholesterol decreased by 8.7 +/- 7.4 mg/dl for group 1 (P < 0.001) and by 10.6 +/- 5.9 for group 2 (P < 0.001). Percentages of HDL(2b) (9.7-12 nm) and HDL(2a) (8.8-9.7 nm) subfractions decreased similarly for the two groups, whereas HDL(3a) (8.2-8.8 nm) and HDL(3b) (7.8-8.2 nm) increased in the groups during study therapy (P < or = 0.02 for all comparisons). There was no evidence of a decreased insulin sensitivity in either group, whereas fasting glucose, fasting insulin, and homeostasis model assessment improved in group 2 (P < 0.05). These metabolic effects were favorable (other than for HDL), but changes were generally transient (except for HDL in group 2), with measurements returning to baseline 2 mo after the interventions were completed.

Comparison of VO2max and disease risk factors between perimenopausal and postmenopausal women

OBJECTIVE

This study determines whether maximal oxygen consumption (VO2 max) is higher in perimenopausal women compared with similarly aged postmenopausal women and whether the lower VO2 max in postmenopausal women is associated with a higher total and visceral fat mass, less favorable lipid and glucose metabolism, and lower bone mineral density (BMD).

DESIGN

Participants were 18 perimenopausal women (mean +/- SD; irregular menstrual cycle in the past 6 months) aged 49 +/- 4 years and 18 postmenopausal women (no menstrual cycle in the past year) aged 52 +/- 2 years who were matched for body mass index and race. Women were sedentary, and none were on hormone replacement therapy. Body composition (dual-energy x-ray absorptiometry and CT), VO2 max, fasting concentrations of sex steroid hormones, lipoproteins, insulin, and glucose were determined.

RESULTS

VO2 max was 17% lower (22 +/- 3 v 27 +/- 7 mL.kg.min; P </= 0.01) and resting metabolic rate was 5% lower (P = 0.06) in postmenopausal women compared with perimenopausal women. Percent body fat was 11% higher, and visceral fat area was 42% higher in postmenopausal women, whereas total body and lumbar spine (L2 -L4) BMD were 5% and 11% lower, respectively (P < 0.05). Low-density lipoprotein cholesterol, low-density lipoprotein cholesterol.high-density lipoprotein cholesterol ratio, and fasting glucose concentrations were 21%, 20%, and 8% higher, respectively, in postmenopausal versus perimenopausal women (P < 0.05). Except for total body and lumbar spine BMD, the effect of menopause status on these variables is independent of age. In all women, percent body fat, visceral adipose tissue, and low-density lipoprotein cholesterol.high-density lipoprotein cholesterol ratios related indirectly to VO2 max (P < 0.05).

CONCLUSIONS

Our data suggest that postmenopausal women have a lower VO2 max than perimenopausal women of a similar age and adiposity, which may be associated with an increased risk of total and central obesity and cardiovascular disease.

Relationship between physiological loss, performance decrement, and age in master athletes

BACKGROUND

The use of master athletes to describe an idealized rate of physiological loss associated with aging is quite common. The results of such studies suggest that older athletes may be able to reduce the rate of decline in functional loss. The findings of such studies have been questioned due to their limited sample size and the age range and gender of their subjects.

METHODS

We examined a group of 146 male and 82 female master athletes over the age of 40 years. Physiological parameters included maximal oxygen uptake (VO2max), body composition, muscle strength, bone density, and blood chemistries. Medical histories and training records were obtained via questionnaire.

RESULTS

Results demonstrated gender differences in body composition, blood chemistries, blood pressure, VO2max, muscle strength, bone density, and performance (p <.05). All metabolic parameters for men and most for women demonstrated significant losses across the age range (p <.05). In addition, strength and performance for men and women and bone density for women declined significantly with age (p <.05). The demonstrated loss rates did not differ by gender.

CONCLUSIONS

Although limited by the lack of a sedentary comparison group, these data suggest that age-related losses in VO2max may not be different from data previously reported for older sedentary adults and that loss in muscle strength and performance with aging is not linear.