Exercise and cardiovascular disease: a new perspective

Effect of exercise intensity and training on antioxidants and cholesterol profile in cyclists

The aim of this work was to evaluate the effect of different intensity of exercise and different training status on antioxidants and cholesterol profile in cyclists. 33 male cyclists (17 amateur and 16 professional cyclists) participated in this study. The amateurs all trained 14 +/- 1 h each week, and their VO(2) max was 62.5 +/- 1.8 ml/Kg x min; the professionals all trained 24 +/- 1 h each week, and their VO(2) max was 80.2 +/- 1.6 ml/Kg x min. Amateurs were submitted to the maximal and submaximal prolonged exercise tests. Professionals were submitted to a mountain stage (170 km) of cycling competition. Serum lipid and cholesterol profile (triglycerides, total cholesterol, HDL-cholesterol, LDL-cholesterol and VLDL-cholesterol) and plasma antioxidant capacity (ascorbic acid, alpha-tocopherol, retinol, beta-carotene and others) were measured before and after exercise tests. Hematological determinations (number of erythrocytes, hematocrit and hemoglobin concentration) and dietary intake were also measured. No significant differences were observed in basal values (before exercise tests) of amateur and professional cyclists. Negligible differences were found between dietary intake of amateur and professional cyclists, and also the results of hematological values showed there was no effect of degree of hydration or dietary intake on blood levels of studied antioxidant and lipid parameters. An increase in plasma levels of vitamin C, vitamin E, triglycerides and VLDL-cholesterol levels, and also a decrease of beta-carotene and LDL-cholesterol. were observed in well-trained professional cyclists after the cycling stage - an endurance exercise--but not in amateur cyclists. Amateur cyclists showed only mild increases in total cholesterol after maximal and submaximal exercise, while a rise in HDL-cholesterol was only observed after maximal exercise; none of these changes were observed in professional cyclists. Plasma levels of antioxidant vitamins and carotenes, and also serum lipids, total cholesterol and lipoprotein-cholesterol showed an overall response to exercise, and their increase and/or decrease must be explained as a consequence of the different training status of sportsmen and intensity and duration of exercise tests.

Response of oxidative stress biomarkers to a 16-week aerobic physical activity program, and to acute physical activity, in healthy young men and women

Physical activity (PA) is associated with a reduced risk of coronary heart disease, and may favorably modify the antioxidant-prooxidant balance. This study assessed the effects of aerobic PA training on antioxidant enzyme activity, oxidized LDL concentration, and LDL resistance to oxidation, as well as the effect of acute PA on antioxidant enzyme activity before and after the training period. Seventeen sedentary healthy young men and women were recruited for 16 weeks of training. The activity of superoxide dismutase in erythrocytes (E-SOD), glutathione peroxidase in whole blood (GSH-Px), and glutathione reductase in plasma (P-GR), and the oxidized LDL concentration and LDL composition, diameter, and resistance to oxidation were determined before and after training. Shortly before and after this training period they also performed a bout of aerobic PA for 30 min. The antioxidant enzyme activity was also determined at 0 min, 30 min, 60 min, 120 min, and 24 h after both bouts of PA. Training induces an increase in GSH-Px (27.7%), P-GR (17.6%), and LDL resistance to oxidation, and a decrease in oxidized LDL (-15.9%). After the bout of PA, an increase in E-SOD and GSH-Px was observed at 0 min, with a posterior decrease in enzyme activity until 30-60 min, and a tendency to recover the basal values at 120 min and 24 h. Training did not modify this global response pattern. Regular PA increases endogenous antioxidant activity and LDL resistance to oxidation, and decreases oxidized LDL concentration; 30 min of aerobic PA decreases P-GR and B-GSH-Px activity in the first 30-60 min with a posterior recovery.

Effects of an off-site walking program on energy expenditure, serum lipids, and glucose metabolism in middle-aged women

The present study aims to identify the effects of systematic walking on exercise energy expenditure (EEE) and blood profiles in middle-aged women. Fifty-two female nurse managers, aged 32 to 57 years (42.0 +/- 6.2), were randomly assigned to an intervention group (IG) and a control group (CG) for a 12-week study of the walking program. EEE was measured using a microelectronic device. Blood profiles were assessed before and after the walking program. The mean EEE (kcal/kg/d) in the IG and CG was 4.73 +/- 1.02 and 3.88 +/- 0.81 (P = 0.01), indicating an increase of 1.17 +/- 0.98 and 0.46 +/- 0.68 from baseline (P = 0.01), respectively. The mean change in high-density lipoprotein cholesterol in the IG and CG was 1.8 +/- 8.3 mg/dL and -2.9 +/- 7.0 mg/dL (P = 0.051); that in insulin was -4.5 +/- 7.5 microU/dL and -0.6 +/- 4.3 microU/dL (P = 0.046), respectively. These results show that systematic walking increases EEE and improves blood profiles.

Higher antioxidant defences in plasma and low density lipoproteins from rugby players

BACKGROUND

Even if physical activity constitutes a well-known antiatherogenic factor, the precise mechanisms underlying this protective effect are not completely clear.

MATERIALS AND METHODS

Lipid and antioxidant profiles were evaluated in 15 well-trained rugby players and 15 sedentary controls. Lipoprotein fractions were separated by sequential ultracentrifugation and alpha-tocopherol content was determined in each fraction by high-performance liquid chromatography. Susceptibility to in vitro oxidation was also measured in intermediate and low density lipoproteins isolated from both groups of subjects as the production of conjugated dienes.

RESULTS

Although the sportsmen were not receiving any special diet or vitamin supplementation they showed a slightly improved lipoprotein profile, mainly represented by increased high density lipoprotein-cholesterol levels (P < 0.05), and an enhanced antioxidant status. The latter was evidenced by an increment in total radical antioxidant potential (P < 0.001), higher ascorbic acid (P < 0.005) and alpha-tocopherol (P < 0.05) plasma concentrations, and elevated activities of superoxide dismutase (P < 0.001) and arylesterase (P < 0.01). Moreover, only the fraction of intermediate and low density lipoproteins from rugby players presented higher alpha-tocopherol content in comparison with sedentary controls (484 +/- 67 vs. 377 +/- 123 microg dL(-1), respectively; P < 0.01). Nevertheless, the susceptibility to in vitro oxidation of this lipoprotein fraction was not different between both groups.

CONCLUSIONS

Given that intermediate density and low density lipoproteins represent the most atherogenic fraction, this finding, in combination with the improved lipid and antioxidant status, would add to the link between regular physical activity and protection against cardiovascular disease.

Relationship between physical activity and oxidative stress biomarkers in women

PURPOSE

To examine the relationship between physical activity and levels of plasma lipid peroxides, superoxide dismutase in erythrocytes (SOD), and glutathione peroxidase (GSH-Px) in whole blood activities.

METHODS

Cross-sectional study in 488 Spanish women. Two categories of leisure time physical activity were defined according to their intensity: low (<or=6 METs) and high (>6 METs). Energy expenditure in household activities was also recorded. Multivariate linear regression analyses were used to adjust for the effect of physical activity on lipid peroxides and SOD and GSH-Px for confounding variables.

RESULTS

The amount of leisure time physical activity was associated with high activity levels of SOD (P = 0.022) and GSH-Px (P = 0.002). Similar results were obtained when physical activity in household activities was added to total leisure physical activity. Physical activity of low intensity was associated with high SOD activity levels (P = 0.002) and that of high intensity with high GSH-Px activity levels (P = 0.001).

CONCLUSION

The amount and intensity of leisure physical activity were directly related to both antioxidant enzyme activity levels. The findings of this study suggest a modulatory effect of leisure physical activity intensity on antioxidative balance in the studied female population.

Exercise-induced oxidative stress in older adults as a function of habitual activity level

OBJECTIVES

It has been suggested that regular physical activity might maintain and promote the antioxidant defense capacity against oxidative stress. Therefore, we assessed exercise-induced oxidative stress in relation to habitual physical activity level (PAL) in older adults.

DESIGN

The study included a 2-week observation period for the measurement of average daily metabolic rate (ADMR) and PAL. Exercise-induced oxidative stress was measured during a 45-minute cycling test at submaximal intensity.

SETTING

A university medical research center.

PARTICIPANTS

Twenty-six subjects volunteered for the study (n = 26; mean age +/- standard deviation 60 +/- 1; body mass index 27 +/- 1 kg/m2).

MEASUREMENTS

PAL was determined as ADMR combined with a measurement of basal metabolic rate (BMR): PAL = ADMR/BMR. ADMR was measured over 2 weeks with the doubly labeled water method, preceded by a BMR measurement with a ventilated hood. Antipyrine oxidation was used as marker for oxidative stress in vivo. Reaction of antipyrine with hydroxyl radicals results in the formation of para-hydroxyantipyrine (p-APOH) and ortho-hydroxyantipyrine (o-APOH), where o-APOH is not formed through alternative oxygenetic pathways.

RESULTS

PAL was inversely related to the exercise-induced increase in the ratio of o-APOH to native antipyrine (r = 0.49, P = .010). The relationship between PAL and exercise-induced increase in the ratio of p-APOH (r = 0.30, P = .140) or thiobarbituric acid reactive species (r = 0.31, P = .130) did not reach the level of significance.

CONCLUSION

Physically active older adults have a reduced exercise-induced oxidative stress than older adults with a lower level of physical activity. It seems that regular physical activity improves the antioxidant defense capacity.

Changes in low-density lipoprotein electronegativity and oxidizability after aerobic exercise are related to the increase in associated non-esterified fatty acids

The immediate effects of intense aerobic exercise on the composition and oxidizability of low- (LDL) and high-density lipoproteins (HDL) were studied in 11 male athletes. Plasma parameters known to affect lipoprotein oxidizability were also evaluated. Lipophilic antioxidants, including alpha-tocopherol and carotenoids, paraoxonase and malondialdehyde (MDA) in plasma remained unchanged after exercise. Increases in the concentration of uric acid, bilirubin and ascorbic acid after the race resulted in a significant increase in total antioxidant serum capacity. LDL, but not HDL, increased its "in vitro"-induced susceptibility to oxidation and the proportion of electronegative LDL (LDL-). The ability of HDL to inhibit the oxidation of LDL remained unchanged after exercise. The enhanced oxidizability of LDL was not explained by increments in its aldehyde content or by decrements in antioxidants. The major compositional change in LDL was an increase in non-esterified fatty acid (NEFA) content (from 4.00+/-1.24 to 19.00+/-14.18 mol NEFA/mol apoB). NEFA also increased in plasma and HDL. "In vitro" experiments showed that incubation of LDL with increasing amounts of NEFA induced a concentration-dependent increase in the proportion of LDL-. Moreover, a slightly increased NEFA content in LDL (15-50 mol NEFA/mol apoB) induced higher susceptibility to oxidation. These "in vitro" results concur with those observed in LDL obtained from athletes after exercise, i.e. a concentration of approximately 20 mol NEFA/mol apoB increased LDL oxidizability and LDL- proportion. We conclude that changes in the qualitative characteristics of LDL after exercise were unrelated to oxidative stress, but were related to the increase in LDL-associated NEFA content.

Oxidative stress in athletes during extreme endurance exercise

Despite the many known health benefits of exercise, there is a body of evidence suggesting that endurance exercise is associated with oxidative stress. To determine whether extreme endurance exercise induces lipid peroxidation, 11 athletes (3 females, 8 males) were studied during a 50 km ultramarathon (trial 1) and during a sedentary protocol (trial 2) 1 month later. The evening before each trial, with dinner, subjects consumed 75 mg each d(3)-RRR and d(6)-all rac-alpha-tocopheryl acetates. Blood was obtained at baseline, 30 min pre-race, mid-race, post-race, 1 h post-race, 24 h post-race, and at corresponding times during trial 2. All 11 subjects completed the race; average run time was 391 +/- 23 min. Plasma F(2)-isoprostanes increased from 75 +/- 7 pg/ml at pre-race to 131 +/- 17 (p <.02) at post-race, then returned to baseline at 24 h post-race; F(2)-isoprostanes were unchanged during trial 2. Deuterated alpha-tocopherol disappearance rates were faster (2.8 x 10(-4) +/- 0.2 x 10(-4)) during the race compared to the sedentary trial (2.3 x 10(-4) +/- 0.2 x 10(-4); p <.03). These data suggest that extreme endurance exercise results in the generation of lipid peroxidation with a concomitant increase in vitamin E disappearance.

Increased atherosclerosis in myeloperoxidase-deficient mice

Myeloperoxidase (MPO), a heme enzyme secreted by activated phagocytes, generates an array of oxidants proposed to play critical roles in host defense and local tissue damage. Both MPO and its reaction products are present in human atherosclerotic plaque, and it has been proposed that MPO oxidatively modifies targets in the artery wall. We have now generated MPO-deficient mice, and show here that neutrophils from homozygous mutants lack peroxidase and chlorination activity in vitro and fail to generate chlorotyrosine or to kill Candida albicans in vivo. To examine the potential role of MPO in atherosclerosis, we subjected LDL receptor-deficient mice to lethal irradiation, repopulated their marrow with MPO-deficient or wild-type cells, and provided them a high-fat, high-cholesterol diet for 14 weeks. White cell counts and plasma lipoprotein profiles were similar between the two groups at sacrifice. Cross-sectional analysis of the aorta indicated that lesions in MPO-deficient mice were about 50% larger than controls. Similar results were obtained in a genetic cross with LDL receptor-deficient mice. In contrast to advanced human atherosclerotic lesions, the chlorotyrosine content of aortic lesions from wild-type as well as MPO-deficient mice was essentially undetectable. These data suggest an unexpected, protective role for MPO-generated reactive intermediates in murine atherosclerosis. They also identify an important distinction between murine and human atherosclerosis with regard to the potential involvement of MPO in protein oxidation.

Potential role of oxidized lipids and lipoproteins in antioxidant defense

The atherogenic oxidative modification of low-density lipoprotein is suggested to occur in the aortic intima. There is reasonable evidence to suggest that antioxidants might be beneficial in preventing or retarding the progression of atherosclerosis. Exercise, estrogens, and substitution of polyunsaturated fat for saturated fat are beneficial in the prevention of atherosclerosis. Yet, paradoxically, they are capable of inducing an oxidative stress. To reconcile with this paradox, we postulate that under certain conditions an oxidative stress might be beneficial by inducing antioxidant enzymes in arterial cells. However, those with genetic deficiency in antioxidant enzymes or those who poorly respond to oxidative stress or those with overwhelming plasma oxidative stress might need additional antioxidant protection.

Isoflavone phytoestrogens consumed in soy decrease F(2)-isoprostane concentrations and increase resistance of low-density lipoprotein to oxidation in humans

BACKGROUND

Oxidative damage to lipids may be involved in the etiology of atherosclerosis, cardiovascular disease in general, and cancer. The soy isoflavone phytoestrogens, genistein and daidzein, and equol (a daidzein metabolite produced by intestinal microflora) are antioxidants in vitro; equol is a particularly good inhibitor of LDL oxidation and membrane lipid peroxidation.

OBJECTIVE

We sought to investigate the effects of a diet enriched with soy containing isoflavones on in vivo biomarkers of lipid peroxidation and resistance of LDL to oxidation, compared with a diet enriched with soy from which the isoflavones had been extracted.

DESIGN

: A randomized, crossover design was used to compare diets enriched with soy that was low or high in isoflavones in 24 subjects. Plasma concentrations of an F(2)-isoprostane, 8-epi-prostaglandin F(2)(alpha) (8-epi-PGF(2)(alpha)), a biomarker of in vivo lipid peroxidation, and resistance of LDL to copper-ion-induced oxidation were determined.

RESULTS

Plasma concentrations of 8-epi-PGF(2)(alpha) were significantly lower after the high-isoflavone dietary treatment than after the low-isoflavone dietary treatment (326 +/- 32 and 405 +/- 50 ng/L, respectively; P = 0.028) and the lag time for copper-ion-induced LDL oxidation was longer (48 +/- 2.4 and 44 +/- 1.9 min, respectively; P = 0.017). Lag time for oxidation of unfractionated plasma and plasma concentrations of malondialdehyde, LDL alpha-tocopherol, polyunsaturated fatty acids, and isoflavonoids did not differ significantly between dietary treatments.

CONCLUSIONS

Consumption of soy containing naturally occurring amounts of isoflavone phytoestrogens reduced lipid peroxidation in vivo and increased the resistance of LDL to oxidation. This antioxidant action may be significant with regard to risk of atherosclerosis, cardiovascular disease in general, and cancer.

Regulation of the vascular extracellular superoxide dismutase by nitric oxide and exercise training

The bioactivity of endothelium-derived nitric oxide (NO) reflects its rates of production and of inactivation by superoxide (O(2)(*-)), a reactive species dismutated by extracellular superoxide dismutase (ecSOD). We have now examined the complementary hypothesis, namely that NO modulates ecSOD expression. The NO donor DETA-NO increased ecSOD expression in a time- and dose-dependent manner in human aortic smooth muscle cells. This effect was prevented by the guanylate cyclase inhibitor ODQ and by the protein kinase G (PKG) inhibitor Rp-8-CPT-cGMP. Expression of ecSOD was also increased by 8-bromo-cGMP, but not by 8-bromo-cAMP. Interestingly, the effect of NO on ecSOD expression was prevented by inhibition of the MAP kinase p38 but not of the MAP kinase kinase p42/44, suggesting that NO modulates ecSOD expression via cGMP/PKG and p38MAP kinase-dependent pathways, but not through p42/44MAP kinase. In aortas from mice lacking the endothelial nitric oxide synthase (eNOS), ecSOD was reduced more than twofold compared to controls. Treadmill exercise training increased eNOS and ecSOD expression in wild-type mice but had no effect on ecSOD expression in mice lacking eNOS, suggesting that this effect of exercise is meditated by endothelium-derived NO. Upregulation of ecSOD expression by NO may represent an important feed-forward mechanism whereby endothelial NO stimulates ecSOD expression in adjacent smooth muscle cells, thus preventing O(2)(*-)-mediated degradation of NO as it traverses between the two cell types.

Role of chronic exercise in decreasing oxidized LDL-potentiated platelet activation by enhancing platelet-derived no release and bioactivity in rats

This study investigates how chronic exercise affects Ox-LDL mediated-platelet activation. Five-week-old male Wistar rats were assigned to either control or trained groups. Trained rats were treadmill-trained for 10 weeks after familiarization. The following measurements were taken in both control and trained groups: plasma lipid profile, oxidation of LDL, platelet adhesiveness, aggregability, cGMP contents, plasma and platelet-NO metabolite (nitrite plus nitrate) levels, and urinary 8-iso-prostaglandin F2alpha (8-iso-PG F2alpha) levels. Based on those measurements, major findings in this study can be summarized as follows: 1) the trained group prolonged the lag time of isolated LDL subjected to copper-induced in vitro oxidation significantly longer than the control group; 2) although having higher plasma and platelet derived-NO metabolite levels, the trained group had lower urinary excretion of 8-iso-PGF2alpha than the control group; 3) the trained group had a lower platelet adhesiveness and aggregability and higher platelet derived-NO metabolite and cGMP productions than the control group; 4) the trained group had a lower Ox-LDL-potentiated platelet adhesiveness and aggregability and Ox-LDL-attenuated NO metabolite and cGMP productions in platelet than the control group; and 5) treating the platelet with L-arginine inhibited Ox-LDL-potentiated platelet activation in both control and trained groups. Results in this study demonstrate that amounts of preformed lipid peroxides decrease while NO production (which acts as an antioxidant) is significantly increased after chronic exercise. Moreover, exercise training decreases Ox-LDL-potentiated platelet activation most likely by enhancing platelet-derived NO release and bioactivity.