Effects of a moderate exercise session on postprandial lipoproteins, apolipoproteins and lipoprotein remnants in middle-aged men

Effectiveness of statins vs. exercise on reducing postprandial hypertriglyceridemia in dyslipidemic population: A systematic review and network meta-analysis

BACKGROUND

Individuals at risk of suffering cardiovascular disease (CVD) present with larger increases in blood triglyceride (TG) concentration after a high-fat meal than do healthy individuals. These postprandial hypertriglyceride levels are an independent risk factor for CVD. Prescription of statins and a bout of prolonged exercise are both effective in lowering postprandial hypertriglyceride levels. We aimed to evaluate the comparative effectiveness of statins vs. a bout of aerobic exercise in reducing fasting and postprandial TG (PPTG) concentrations in individuals at high risk of developing CVD.

METHODS

Thirty-seven studies from a systematic literature search of the PubMed, EMBASE, and Cochrane databases were included in this review. The selected studies conducted trials involving statin therapy (n = 20) or a bout of aerobic exercise (n = 19) and measured their impact on PPTG levels as the outcome. Two studies analyzed both treatments and were included in duplicate. The meta-analysis was constructed using a random-effects model to calculate the mean difference (MD). The Student t test was used to compare the data sets for statins vs. exercise.

RESULTS

Overall, statin and exercise interventions showed similar reductions in PPTG levels, with an MD of -0.65 mmol/L for statins (95% confidence interval (95%CI): -0.54 to -0.77; p < 0.001) and -0.46 mmol/L for exercise (95%CI: -0.21 to -0.71; p < 0.01). However, statins lowered fasting TG levels more than exercise (MD = -1.54 mmol/L, 95%CI: -2.25 to -0.83; p = 0.009).

CONCLUSION

Although aerobic exercise is effective in lowering blood TG levels, statins seem to be more efficient, especially in the fasted state. A combination of exercise and statins might reveal a valuable approach to the treatment and prevention of CVD. More studies are required to determine the underlying mechanisms and the possible additive effects of these interventions.

HDL-apoA-I kinetics in response to 16 wk of exercise training in men with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by low-circulating concentration of high-density lipoprotein cholesterol (HDL-C) and raised triacylglycerol (TAG). Exercise reduces hepatic fat content, improves insulin resistance and increases clearance of very-low-density lipoprotein-1 (VLDL₁). However, the effect of exercise on TAG and HDL-C metabolism is unknown. We randomized male participants to 16 wk of supervised, moderate-intensity aerobic exercise (n = 15), or conventional lifestyle advice (n = 12). Apolipoprotein A-I (apoA-I) and VLDL-TAG and apolipoprotein B (apoB) kinetics were investigated using stable isotopes (1-[¹³C]-leucine and 1,1,2,3,3-²H₅ glycerol) pre- and postintervention. Participants underwent MRI/spectroscopy to assess changes in visceral fat. Results are means ± SD. At baseline, there were no differences between exercise and control groups for age (52.4 ± 7.5 vs. 52.8 ± 10.3 yr), body mass index (BMI: 31.6 ± 3.2 vs. 31.7 ± 3.6 kg/m²), and waist circumference (109.3 ± 7.5 vs. 110.0 ± 13.6 cm). Percentage of liver fat was 23.8 (interquartile range 9.8-32.5%). Exercise reduced body weight (101.3 ± 10.2 to 97.9 ± 12.2 kg; P < 0.001) and hepatic fat content [from 19.6%, interquartile range (IQR) 14.6-36.1% to 8.9% (4.4-17.8%); P = 0.001] and increased the fraction HDL-C concentration (measured following ultracentrifugation) and apoA-I pool size with no change in the control group. However, plasma and VLDL₁-TAG concentrations and HDL-apoA-I fractional catabolic rate (FCR) and production rate (PR) did not change significantly with exercise. Both at baseline (all participants) and after exercise there was an inverse correlation between apoA-I pool size and VLDL-TAG and -apoB pool size. The modest effect of exercise on HDL metabolism may be explained by the lack of effect on plasma and VLDL₁-TAG.

A single bout of resistance exercise improves postprandial lipid metabolism in overweight/obese men with prediabetes

AIMS/HYPOTHESIS

Prediabetes is associated with postprandial hypertriacylglycerolaemia. Resistance exercise acutely lowers postprandial plasma triacylglycerol (TG); however, the changes in lipid metabolism that mediate this reduction are poorly understood. The aim of this study was to identify the constitutive metabolic mechanisms underlying the changes in postprandial lipid metabolism after resistance exercise in obese men with prediabetes.

METHODS

We evaluated the effect of a single bout of whole-body resistance exercise (seven exercises, three sets, 10-12 repetitions at 80% of one-repetition maximum) on postprandial lipid metabolism in ten middle-aged (50 ± 9 years), overweight/obese (BMI: 33 ± 3 kg/m²), sedentary men with prediabetes (HbA_1c >38 but <48 mmol/mol [>5.7% but <6.5%]), or fasting plasma glucose >5.6 mmol/l but <7.0 mmol/l or 2 h OGTT glucose >7.8 mmol/l but <11.1 mmol/l). We used a randomised, crossover design with a triple-tracer mixed meal test (ingested [(¹³C₄)₃]tripalmitin, i.v. [U-¹³C₁₆]palmitate and [²H₅]glycerol) to evaluate chylomicron-TG and total triacylglycerol-rich lipoprotein (TRL)-TG kinetics. We used adipose tissue and skeletal muscle biopsies to evaluate the expression of genes regulating lipolysis and lipid oxidation, skeletal muscle respirometry to evaluate oxidative capacity, and indirect calorimetry to assess whole-body lipid oxidation.

RESULTS

The single bout of resistance exercise reduced the lipaemic response to a mixed meal in obese men with prediabetes without changing chylomicron-TG or TRL-TG fractional clearance rates. However, resistance exercise reduced endogenous and meal-derived fatty acid incorporation into chylomicron-TG and TRL-TG. Resistance exercise also increased whole-body lipid oxidation, skeletal muscle mitochondrial respiration, oxidative gene expression in skeletal muscle, and the expression of key lipolysis genes in adipose tissue.

CONCLUSIONS/INTERPRETATION

A single bout of resistance exercise improves postprandial lipid metabolism in obese men with prediabetes, which may mitigate the risk for cardiovascular disease and type 2 diabetes.

Effective Weight Loss and Maintenance by Intensive Start with Diet and Exercise

INTRODUCTION

This 24-month study aimed to determine whether exercise intervention added to weight loss treatment at 6 months is effective for weight loss and maintenance.

METHODS

A total of 120 obese subjects (body mass index > 30) were randomly assigned to intensified behavioral modification (iBM) (n = 30), behavioral modification + exercise from 0 to 3 months (circuit weight training group 1 [CWT1]) (n = 30), behavioral modification + exercise from 6 to 9 months (CWT2) (n = 30), and a control group (CON) (n = 30). Health behavior, weight, waist circumference, and 2-h glucose tolerance test with insulin measurements were measured at 0, 3, 9, and 24 months.

RESULTS

Eighty-five subjects (mean age = 46 yr, body mass index = 36.3, 75.3% women) completed the trial. A significant weight loss occurred in CWT1 (-8.5 kg, P > 0.001), iBM (-5.5 kg, P > 0.001), and CWT2 (-4.4 kg, P = 0.007). CWT1 showed the highest reduction in waist circumference at 9 months (mean difference = -11.5 cm, P < 0.001) and 24 months (mean difference = -8.8 cm, P < 0.001). Both fasting and 2-h insulin values improved in the intervention groups compared with CON. A significant decrease in 2-h insulin values from baseline was found in CWT1 and CWT2. Matsuda index improved in the CWT1 group from the baseline to 24 months (2.03, P = 0.025).

CONCLUSION

The most effective weight loss regimen is a combination of iBM and weight training introduced from the very beginning of the weight loss period. Treatment of morbid obesity should include an intensive start with exercise and diet regardless of weight status.

Impaired repletion of intramyocellular lipids in patients with growth hormone deficiency after a bout of aerobic exercise

BACKGROUND

Ectopic lipids such as intramyocellular lipids (IMCL) are depleted by exercise and repleted by diet, whereas intrahepatocellular lipids (IHCL) are increased immediately after exercise. So far, it is unclear how ectopic lipids behave 24 h after exercise and whether the lack of growth hormone (GH) significantly affects ectopic lipids 24 h after exercise.

METHODS

Seven male patients with growth hormone deficiency (GHD) and seven sedentary male control subjects (CS) were included. VO_2max was assessed by spiroergometry; visceral and subcutaneous fat by whole body MRI. ¹H-MR-spectroscopy was performed in M. vastus intermedius and in the liver before and after 2 h of exercise at 50% VO_2max and 24 h thereafter, while diet and physical activity were standardized.

RESULTS

Sedentary male subjects (7 GHD, 7 CS) were recruited. Age, BMI, waist circumference, visceral and subcutaneous fat mass was not significantly different between GHD and CS. VO_2max was significantly lower in GHD vs. CS. IMCL were diminished through aerobic exercise in both groups: (-11.5 ± 21.9% in CS; -8.9% ±19.1% in GHD) and restored after 24 h in CS (-5.5 ± 26.6% compared to baseline) but not in GHD (-17.9 ± 15.3%). IHCL increased immediately after exercise and decreased to baseline within 24 h.

CONCLUSION

These findings suggest that GHD may affect repletion of IMCL 24 h after aerobic exercise.

The Influence of Pre-Exercise Glucose versus Fructose Ingestion on Subsequent Postprandial Lipemia

Ingestion of low glycemic index (LGI) carbohydrate (CHO) before exercise induced less insulin response and higher fat oxidation than that of high GI (HGI) CHO during subsequent exercise. However, the effect on the subsequent postprandial lipid profile is still unclear. Therefore, the aim of this study was to investigate ingestion of CHO drinks with different GI using fructose and glucose before endurance exercise on the subsequent postprandial lipid profile. Eight healthy active males completed two experimental trials in randomized double-blind cross-over design. All participants ingested 500 mL CHO (75 g) solution either fructose (F) or glucose (G) before running on the treadmill at 60% VO₂max for 1 h. Participants were asked to take an oral fat tolerance test (OFTT) immediately after the exercise. Blood samples were obtained for plasma and serum analysis. The F trial was significantly lower than the G trial in TG total area under the curve (AUC; 9.97 ± 3.64 vs. 10.91 ± 3.56 mmol × 6 h/L; p = 0.033) and incremental AUC (6.57 ± 2.46 vs. 7.14 ± 2.64 mmol/L × 6 h, p = 0.004). The current data suggested that a pre-exercise fructose drink showed a lower postprandial lipemia than a glucose drink after the subsequent high-fat meal.

Cardiorespiratory fitness is a stronger indicator of cardiometabolic risk factors and risk prediction than self-reported physical activity levels

This study investigated the relationships of self-reported physical activity levels and cardiorespiratory fitness in 81 males to assess which measurement is the greatest indicator of cardiometabolic risk. Physical activity levels were determined by the General Practice Physical Activity Questionnaire tool and cardiorespiratory fitness assessed using the Chester Step Test. Cardiovascular disease risk was estimated using the QRISK2, Framingham Lipids, Framingham body mass index and Joint British Societies' Guidelines-2 equations, and type 2 diabetes mellitus risk calculated using QDiabetes, Leicester Risk Assessment, Finnish Diabetes Risk Score and Cambridge Risk Score models. Categorising employees by cardiorespiratory fitness categories ('Excellent/Good' vs 'Average/Below Average') identified more differences in cardiometabolic risk factor (body mass index, waist circumference, total cholesterol, total cholesterol:high-density lipoprotein ratio, high-density lipoprotein cholesterol, triglycerides, HbA(1c)) scores than physical activity (waist circumference only). Cardiorespiratory fitness levels also demonstrated differences in all four type 2 diabetes mellitus risk prediction models and both the QRISK2 and Joint British Societies' Guidelines-2 cardiovascular disease equations. Furthermore, significant negative correlations (p < 0.001) were observed between individual cardiorespiratory fitness values and estimated risk in all prediction models. In conclusion, from this preliminary observational study, cardiorespiratory fitness levels reveal a greater number of associations with markers of cardiovascular disease or type 2 diabetes mellitus compared to physical activity determined by the General Practice Physical Activity Questionnaire tool.

Acute metabolic response to fasted and postprandial exercise

The aim of this study was to analyze the acute metabolic response to exercise in fasting and postprandial. For this, ten individuals were submitted to an incremental treadmill test, with an initial speed of 5 and 1 km/h increments every minute, with no inclination, and a body composition assessment. After this 1st day, all volunteers were submitted to two experimental procedures (fasting and postprandial), with an aerobic exercise performed for 36 minutes at 65% of maximal oxygen consumption. At postprandial procedure, all subjects ingested a breakfast containing 59.3 g of carbohydrate (76.73%), 9.97 g of protein (12.90%), 8.01 g of lipids (10.37%), with a total energy intake of 349.17 kcal. An analysis of plasma concentration of triglycerides, lactate, and glucose was performed in two stages: before and after exercise. The Shapiro–Wilk test was used to verify the normality of the data. For analysis of glucose concentration, plasma lactate, and triglycerides, we used a repeated measures analysis of variance factorial 2×2, with Bonferroni multiple comparison test. The significance level of P<0.05 was adopted. The results indicated a maintenance level of glucose at fasting and a decrease in glucose concentration at postprandial exercise. Both conditions increase plasma lactate. Triglycerides also increased in the two experimental conditions; however, after exercise fasting, the increase was significantly higher than in the postprandial exercise. These data suggest that both exercises could increase plasma lactate and triglycerides. However, exercise performed in fasting condition decreases glucose concentration and increases triglycerides, even more than postprandial exercise.

Energy replacement using glucose does not increase postprandial lipemia after moderate intensity exercise

Background

Aerobic exercise can decrease postprandial triglyceride (TG) concentrations but the relationship between exercise-induced energy deficits and postprandial lipemia is still unclear. The aim of the present study was to examine the effect of a single bout of aerobic exercise, with and without energy replacement, on postprandial lipemia and on peripheral blood mononuclear cell (PBMC) mRNA expression of very low density lipoprotein (VLDL) and low density lipoprotein (LDL) receptors and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR).

Methods

Nine healthy male humans completed three two-day trials in a random order. On day 1, volunteers rested (CON), completed 60 minutes of treadmill walking at 50% of VO_2peak (EX) or completed the same bout of walking but with the energy replaced afterwards with a glucose solution (EXG). On day 2, volunteers rested and consumed a high fat test meal in the morning.

Results

Total and incremental TG AUC were significantly lower on the EXG (P < 0.05) and EX (P < 0.05) trials than the CON trial with no difference between the two exercise trials. No significant difference was observed in VLDL or LDL receptor mRNA expression among the trials (P > 0.05).

Conclusions

In conclusion, energy replacement by glucose did not affect the decrease in postprandial TG concentrations observed after moderate intensity exercise and exercise does not affect changes in PBMC HMGCR, VLDL and LDL receptor mRNA expression.

The effect of short-duration sprint interval exercise on plasma postprandial triacylglycerol levels in young men

It is well established that regular exercise can reduce the risk of cardiovascular disease, although the most time-efficient exercise protocol to confer benefits has yet to be established. The aim of the current study was to determine the effects of short-duration sprint interval exercise on postprandial triacylglycerol. Fifteen healthy male participants completed two 2 day trials. On day 1, participants rested (control) or carried out twenty 6 s sprints, interspersed with 24 s recovery (sprint interval exercise--14 min for total exercise session). On day 2, participants consumed a high-fat meal for breakfast with blood samples collected at baseline, 2 h and 4 h. Gas exchange was also measured at these time points. On day 2 of control and sprint interval exercise trials, there were no differences (P < 0.05) between trials in plasma glucose, triacylglycerol, insulin or respiratory exchange ratio (RER). The area under the curve for plasma triacylglycerol was 7.67 ± 2.37 mmol · l(-1) x 4 h(-1) in the control trial and 7.26 ± 2.49 mmol · l(-1) x 4 h(-1) in the sprint interval exercise trial. Although the sprint exercise protocol employed had no significant effect on postprandial triacylglycerol, there was a clear variability in responses that warrants further investigation.

Acute changes in lipoprotein subclasses during exercise

OBJECTIVE

Lipids are important substrates for oxidation in the basal fasting state and during exercise. Studies have demonstrated beneficial changes in lipoprotein subclass composition the day after an exercise bout. However, the acute effect of exercise on TG concentration and lipoprotein subclass composition remains unclear.

MATERIALS/METHODS

Sixteen lean, healthy individuals (8 men and 8 women) were recruited (age 20-30 years, BMI<25 kg/m(2)). The subjects were studied during basal fasting conditions as well as during and after 90 min of cycling at 50% of VO2peak. Lipoprotein subclass composition was measured with (1)H NMR spectroscopy.

RESULTS

During exercise, LDL and HDL particle concentration increased significantly (p<0.05) despite lower total TG concentration. In addition, exercise resulted in a shift towards smaller VLDL particles in men (p<0.05), but VLDL-TG concentration was unaltered.

CONCLUSIONS

Acute exercise induces beneficial changes in lipoprotein subclass composition. These changes are similar to the effects of exercise training.

The latest on the effect of prior exercise on postprandial lipaemia

This review examines the effect of prior exercise on postprandial triacylglycerol (pTAG) concentrations, an independent risk factor for cardiovascular diseases. Numerous studies have shown that a single bout of exercise reduces pTAG concentrations; however, several modulators such as exercise energy expenditure/deficit, mode of exercise (aerobic/resistance/high intensity/intermittent exercise or combinations), type of meal (moderate or high fat), time frame between exercise and meal and target group may individually or in conjunction influence this effect. On the other hand, at least for aerobic exercise, training reduces pTAG concentrations transiently (~2 days); therefore, exercise sessions should be frequent enough to maintain this clinically significant improvement. For the healthy population, it seems that a subject's preference and ability determine which type of exercise to undertake to attenuate pTAG concentrations; an energy expenditure of ~30 kJ/kg of body mass (or ~2-2.5 MJ) not combined with a corresponding increase in energy intake is required; for resistance or intermittent exercise, for those following a moderate rather than a high-fat diet, and for those with obesity (expressed as kJ/kg of body mass), a smaller energy expenditure is probably sufficient. More studies are needed to investigate dose-response/plateau effects, as well as the threshold of energy expenditure in those with diabetes mellitus and other high-risk populations. Finally, investigation of the underlying mechanisms may be clinically helpful in individualizing the appropriate intervention.

The effect of aerobic exercise intensity on attenuation of postprandial lipemia is dependent on apolipoprotein E genotype

OBJECTIVE

To investigate the effect of aerobic exercise intensity on postprandial lipemia according to allelic variants of the apolipoprotein E gene.

METHODS

Three groups of 10 healthy men each were formed based genotyping of the APOE gene, rested or performed 500 Kcal tests in a random sequence separated by a minimum 48 h interval, as follows: (a) no exercise (control), (b) intense intermittent exercise, (c) moderate continuous exercise. Each test series was completed 30-min before ingestion of a high-fat meal (1 g fat/kg). Venous blood was collected before and at 1, 2, 3 and 4 h after the high-fat meal. Postprandial lipemia was assessed using the area under the curve approach as well as the kinetic profile of mean lipid variables. Statistical significance was adopted at P ≤ 0.05 level.

RESULTS

The main results show that, in the moderate continuous exercise, total postprandial cholesterolemia was higher in ɛ4 than in ɛ2 carriers, whereas under intense intermittent exercise, total and LDL cholesterolemia were higher in ɛ4 than in ɛ2 and ɛ3 carriers. There was no difference in the lipemic profile of the subjects across APOE genotypes at baseline.

CONCLUSION

Moderate and intense exercise were effective in attenuating PPL in both ɛ2 and ɛ3 subjects, with ɛ2 subjects being more susceptible to the lipid lowering effect of moderate training than ɛ3 subjects. Carriers of the ɛ4 allele, however, showed no attenuation of postprandial lipemia.

Lipoprotein particle distribution and skeletal muscle lipoprotein lipase activity after acute exercise

BACKGROUND

Many of the metabolic effects of exercise are due to the most recent exercise session. With recent advances in nuclear magnetic resonance spectroscopy (NMRS), it is possible to gain insight about which lipoprotein particles are responsible for mediating exercise effects.

METHODS

Using a randomized cross-over design, very low density lipoprotein (VLDL) responses were evaluated in eight men on the morning after i) an inactive control trial (CON), ii) exercising vigorously on the prior evening for 100 min followed by fasting overnight to maintain an energy and carbohydrate deficit (EX-DEF), and iii) after the same exercise session followed by carbohydrate intake to restore muscle glycogen and carbohydrate balance (EX-BAL).

RESULTS

The intermediate, low and high density lipoprotein particle concentrations did not differ between trials. Fasting triglyceride (TG) determined biochemically, and mean VLDL size were lower in EX-DEF but not in EX-BAL compared to CON, primarily due to a reduction in VLDL-TG in the 70-120 nm (large) particle range. In contrast, VLDL-TG was lower in both EX-DEF and EX-BAL compared to CON in the 43-55 nm (medium) particle range. VLDL-TG in smaller particles (29-43 nm) was unaffected by exercise. Because the majority of VLDL particles were in this smallest size range and resistant to change, total VLDL particle concentration was not different between any of these conditions. Skeletal muscle lipoprotein lipase (LPL) activity was also not different across these 3 trials. However, in CON only, the inter-individual differences in LPL activity were inversely correlated with fasting TG, VLDL-TG, total, large and small VLDL particle concentration and VLDL size, indicating a regulatory role for LPL in the non-exercised state.

CONCLUSIONS

These findings reveal a high level of differential regulation between different sized triglyceride-rich lipoproteins following exercise and feeding, in the absence of changes in LPL activity.

The chronic effects of fish oil with exercise on postprandial lipaemia and chylomicron homeostasis in insulin resistant viscerally obese men

Background

Visceral obesity and insulin resistance are associated with a postprandial accumulation of atherogenic chylomicron remnants that is difficult to modulate with lipid-lowering therapies. Dietary fish oil and exercise are cardioprotective interventions that can significantly modify the metabolism of TAG-rich lipoproteins. In this study, we investigated whether chronic exercise and fish oil act in combination to affect chylomicron metabolism in obese men with moderate insulin resistance.

Methods

The single blind study tested the effect of fish oil, exercise and the combined treatments on fasting and postprandial chylomicron metabolism. Twenty nine men with metabolic syndrome were randomly assigned to take fish oil or placebo for four weeks, before undertaking an additional 12 week walking program. At baseline and at the end of each treatment, subjects were tested for concentrations of fasting apo B48, plasma lipids and insulin. Postprandial apo B48 and TAG kinetics were also determined following ingestion of a fat enriched meal.

Results

Combining fish oil and exercise resulted in a significant reduction in the fasting apo B48 concentration, concomitant with attenuation of fasting TAG concentrations and the postprandial TAG_IAUC response (p < 0.05). Fish oil by itself reduced the postprandial TAG response (p < 0.05) but not postprandial apo B48 kinetics. Individual treatments of fish oil and exercise did not correspond with improvements in fasting plasma TAG and apo B48.

Conclusion

Fish oil was shown to independently improve plasma TAG homeostasis but did not resolve hyper-chylomicronaemia. Instead, combining fish oil with chronic exercise reduced the plasma concentration of pro-atherogenic chylomicron remnants; in addition it reduced the fasting and postprandial TAG response in viscerally obese insulin resistant subjects.

Effects of moderate exercise on VLDL₁ and Intralipid kinetics in overweight/obese middle-aged men

Prior moderate exercise reduces plasma triglyceride (TG)-rich lipoprotein concentrations, mainly in the large very low-density lipoprotein (VLDL₁) fraction, but the mechanism responsible is unclear. We investigated the effects of brisk walking on TG-rich lipoprotein kinetics using a novel method. Twelve overweight/obese middle-aged men underwent two kinetic studies, involving infusion of Intralipid to block VLDL₁ catabolism, in random order. On the afternoon prior to infusion, subjects either walked on a treadmill for 2 h at ∼50% maximal oxygen uptake or performed no exercise. Multiple blood samples were taken during and after infusion for separation of Intralipid (S(f) 400) and VLDL₁ (S(f) 60-400). VLDL₁-TG and -apoB production rates were calculated from their linear rises during infusion; fractional catabolic rates (FCR) were calculated by dividing linear rises by fasting concentrations. Intralipid-TG FCR was determined from the postinfusion exponential decay. Exercise reduced fasting VLDL₁-TG concentration by 30% (P = 0.007) and increased TG enrichment of VLDL₁ particles [30% decrease in cholesteryl ester (CE)/TG ratio (P = 0.007); 26% increase in TG/apoB ratio (P = 0.059)]. Exercise also increased VLDL₁-TG, VLDL₁-apoB, and Intralipid-TG FCRs by 82, 146, and 43%, respectively (all P < 0.05), but had no significant effect on VLDL₁-TG or -apoB production rates. The exercise-induced increase in VLDL₁-apoB FCR correlated strongly with the exercise-induced changes in VLDL₁ CE/TG (r = -0.659, r = 0.020) and TG/apoB (r = 0.785, P = 0.002) ratios. Thus, exercise-induced reductions in VLDL₁ concentrations are mediated by increased catabolism, rather than reduced production, which may be facilitated by compositional changes to VLDL₁ particles that increase their affinity for clearance from the circulation.

Physical activity and postprandial lipidemia: are energy expenditure and lipoprotein lipase activity the real modulators of the positive effect?

Historically, the link between elevated cholesterol and increased risk of cardiovascular disease has been based on fasting measurements. This is appropriate for total, low-density lipoprotein and high-density lipoprotein cholesterol. However, triglyceride concentrations vary considerably throughout the day in response to the regular consumption of food and drink. Recent findings indicate that postprandial triglyceride concentrations independently predict future cardiovascular risk. Potential modulators of postprandial lipidemia include meal composition and physical activity. Early cross sectional studies indicated that physically active individuals had a lower postprandial lipidemic response compared to inactive individuals. However, the effect of physical activity on postprandial lipidemia is an acute phenomenon, which dissipates within 60 h of a single bout of exercise. Total exercise induced energy expenditure, rather than duration or intensity of the physical activity is commonly reported to be a potent modulator of postprandial lipidemia. However, the pooled results of studies in this area suggest that energy expenditure exerts most of its influence on fasting triglyceride concentrations rather than on the incremental change in triglyceride concentrations seen following meal consumption. It seems more likely that energy expenditure is one component of a multifactorial list of mediators that may include local muscle contractile activity, and other yet to be elucidated mechanisms.

Post-prandial capillary triacylglycerol responses to moderate exercise in centrally obese middle-aged men

In this study, we wished to determine whether 30 min of moderate-intensity exercise, corresponding to minimal recommended guidelines, attenuates post-prandial capillary triacylglycerol concentrations in obese men. Ten middle-aged, centrally obese men (age 46 +/- 2 years, body mass index 31.6 +/- 1.0 kg · m(-2), waist circumference 104.6 +/- 2.2 cm) completed two 2-day trials (exercise and control) at least one week apart in a randomized, repeated-measures design. On day 1, participants either cycled for 30 min at approximately 60% of maximal heart rate in the afternoon or rested (no exercise). On day 2 of both trials, after a 10-h overnight fast, participants consumed a test meal of moderate fat content (35%) for breakfast. Capillary blood samples were collected in the fasted state (0 h) and at 2, 4, and 6 h post-prandially on day 2. Total area under the capillary triacylglycerol concentration versus time curve was significantly lower on the exercise than control trial (P = 0.023). One 30-min session of moderate-intensity cycling is effective in lowering post-prandial capillary triacylglycerol concentration in obese middle-aged men. These findings may have important implications for exercise recommendations as a means to reduce the risk of cardiovascular disease if such exercise is performed for an extended period.

The influence of intense intermittent versus moderate continuous exercise on postprandial lipemia

INTRODUCTION

Postprandial lipemia is characterized by an increased concentration of circulating lipids after fat intake and is an independent risk factor for cardiovascular disease. Exercise is known to reduce postprandial lipemia and its negative clinical outcomes.

OBJECTIVE

This study investigated the effect of intense intermittent versus moderate continuous exercise using the same energy expenditure in postprandial lipemia.

MATERIALS AND METHODS

Twenty healthy men (aged 21.5 ± 3.5 years) performed a random sequence of either rest or 500 Kcal tests separated by a minimum 48 h interval as follows: (a) no exercise (control), (b) intense intermittent exercise, or (c) moderate continuous exercise. Each test series was completed 30 min before ingestion of a high-fat meal (1 g fat/kg). Venous blood was collected before and at 1, 2, 3 and 4 hours after the high-fat meal. Postprandial lipemia was assessed using the area under the curve approach as well as a kinetic profile of mean lipid variables. Statistical significance was tested at the p<0.05 level.

RESULTS

With both statistical approaches, intense intermittent and moderate continuous exercises were both effective in reducing postprandial triglycerides; however, only intense intermittent exercise reduced the levels of postprandial very low density lipoprotein. Intense intermittent and continuous exercise produced lower levels of insulinemia using the area under the curve analysis only.

CONCLUSION

Intense intermittent or continuous exercise with an energy expenditure of 500 kcal completed 30 min before ingestion of high-fat meal reduced postprandial lipid levels to different levels in physically active men. Understanding these relevant differences will enable clinicians to provide the best exercise prescription for patients.

Acute resistance exercise attenuates fasting and postprandial triglyceridemia in women by reducing triglyceride concentrations in triglyceride-rich lipoproteins

A single bout of endurance exercise lowers fasting and postprandial triglyceride (TG) concentrations in both men and women, by reducing TG in triglyceride-rich lipoproteins (TRLs). The effect of resistance exercise on TRL-TG metabolism is not known; previous studies only measured total plasma TG concentrations and provide conflicting results. Furthermore, none has specifically examined women. We therefore sought to evaluate the effect of a single bout of resistance exercise on TRL-TG metabolism in women. We measured the concentrations of TG in total plasma and TRLs in the fasting state and during an oral fat tolerance test in five healthy untrained women (age: 32 ± 5 years; body mass index: 21.5 ± 1.7 kg/m(2); peak oxygen consumption: 31 ± 4 mL/kg min) in the morning, on two separate occasions: once after a single ~95-min bout of moderate-intensity whole-body resistance exercise (energy expenditure: 2.9 ± 0.1 MJ) and once after an equivalent period of rest, on the preceding afternoon. Fasting plasma TG and TRL-TG concentrations were 22 ± 12 and 40 ± 21% lower, respectively, and postprandial plasma TG and TRL-TG areas-under-the-curve were 24 ± 13 and 27 ± 10% lower, respectively, after exercise than rest (all P values <0.05). Effect sizes ranged from -0.52 to -0.90. Non-TRL-TG concentrations in the fasting and postprandial states were not different between trials (P > 0.60). We conclude that a single bout of resistance exercise attenuates fasting and postprandial triglyceridemia in women by reducing TRL-TG concentrations.

Physical inactivity and cardiovascular risk: baseline observations from men and premenopausal women

INTRODUCTION

Physical activity or exercise is a proven deterrent of cardiovascular (CV) diseases.

PURPOSE

In this study, we examined the relationships between baseline values of parameters related to physical activity and known markers of CV disease, including markers of oxidative stress.

METHODS

A total of 455 healthy men and women between the ages of 18 and 50 were recruited to participate in the study. Levels of lipids/lipoproteins and markers of oxidative stress and inflammation were measured along with the VO(2) and duration time spent on treadmill.

RESULTS

Women, in general, had a significantly (P<0.0001) higher plasma high density lipoprotein (1.51+/-0.30 mmol/l), decreased (P<0.0001) low density lipoprotein (LDL) (2.75+/-0.66 mmol/l), and decreased (P<0.0001) triglycerides levels (2.09+/-0.85 mmol/l), compared with males (1.21+/-0.23 mmol/l, 2.92+/-0.81 mmol/l, and 3.02+/-1.34 mmol/l, respectively). There was a direct correlation between the levels of plasma LDL and the levels oxidized LDL levels (P<0.0001) in both men and women. Despite a better antiatherogenic lipid profile, the levels of C-reactive protein in women were significantly (P<0.0001) elevated (3.78+/-3.66 ng/ml) as compared with those in men (1.82+/-2.37 ng/ml).

CONCLUSION

These results suggest intrinsic sex differences between men and women in relation to atherogenic risk.

Raisins and walking alter appetite hormones and plasma lipids by modifications in lipoprotein metabolism and up-regulation of the low-density lipoprotein receptor

The purpose of this study was to determine the effects of consuming raisins, increasing steps walked, or a combination of these interventions on lipoprotein metabolism and appetite hormones by assessing plasma apolipoprotein concentrations, cholesterol ester transfer protein activity, low-density lipoprotein (LDL) receptor messenger RNA (mRNA) abundance, and plasma ghrelin and leptin concentrations. Thirty-four subjects (17 men and 17 postmenopausal women) were matched for weight and sex and randomly assigned to consume 1 cup raisins per day (RAISIN), increase the amount of steps walked per day (WALK), or a combination of both interventions (RAISIN + WALK). The subjects completed a 2-week run-in period, followed by a 6-week intervention. Ribonucleic acid was extracted from mononuclear cells, and LDL receptor mRNA abundance was quantified by use of reverse transcriptase polymerase chain reaction. Plasma apolipoproteins were measured by Luminex (Austin, TX) technology. Apoproteins A-1, B, C-II, and E and cholesterol ester transfer protein activity were not altered for any of the groups. In contrast, apolipoprotein C-III was significantly decreased by 12.3% only in the WALK group (P < .05). Low-density lipoprotein receptor mRNA abundance was increased for all groups after the intervention (P < .001). There was a significant group effect for plasma leptin (P = .026). Plasma concentrations increased for RAISIN and RAISIN + WALK. Similarly, plasma ghrelin concentrations were elevated postintervention for both groups consuming raisins (P < .05). These data suggest that walking and raisin consumption decrease plasma LDL cholesterol by up-regulating the LDL receptor and that raisin consumption may reduce hunger and affect dietary intake by altering hormones influencing satiety.

Exercise of low energy expenditure along with mild energy intake restriction acutely reduces fasting and postprandial triacylglycerolaemia in young women

A single bout of prolonged, moderate-intensity endurance exercise lowers fasting and postprandial TAG concentrations the next day. However, the TAG-lowering effect of exercise is dose-dependent and does not manifest after light exercise of low energy cost ( < 2 MJ). We aimed to investigate whether superimposing mild energy intake restriction to such exercise, in order to augment total energy deficit, potentiates the hypotriacylglycerolaemic effect. Eight healthy, sedentary, premenopausal women (age 27.1 (sem 1.3) years; BMI 21.8 (sem 0.9) kg/m2) performed two oral fat tolerance tests in the morning on two different occasions: once after a single bout of light exercise (100 min at 30 % of peak oxygen consumption; net energy expenditure 1.04 (sem 0.01) MJ) coupled with mild energy intake restriction (1.39 (sem 0.22) MJ) on the preceding day, and once after resting coupled with isoenergetic feeding on the preceding day (control). Fasting plasma TAG, TAG in the TAG-rich lipoproteins (TRL-TAG) and serum insulin concentrations were 18, 34 and 30 % lower, respectively, after exercise plus diet compared with the control trial (P < 0.05). Postprandial concentrations of plasma TAG and TRL-TAG were 19 and 27 % lower after exercise plus diet compared with the control condition (P < 0.01), whereas postprandial insulin concentrations were not different. It is concluded that a combination of light exercise along with mild hypoenergetic diet may be a practical and feasible intervention to attenuate fasting and postprandial triacylglycerolaemia, especially for people who cannot exercise for prolonged periods of time at moderate-to-high intensities, such as many sedentary individuals.

Energy replacement attenuates the effects of prior moderate exercise on postprandial metabolism in overweight/obese men

BACKGROUND

The extent to which exercise-induced changes to postprandial metabolism are dependant on the associated energy deficit is not known.

OBJECTIVE

To determine the effects of exercise, with and without energy replacement, on postprandial metabolism.

DESIGN

Each subject underwent three 2-day trials in random order. On day 1 of each trial subjects rested (control), walked at 50% maximal oxygen uptake to induce a net energy expenditure of 27 kJ kg(-1) body mass (energy-deficit) or completed the same walk with the net energy expended replaced (energy-replacement). On day 2 subjects completed an 8.5-h metabolic assessment. For 3 days prior to day 2, subjects consumed an isocaloric diet, avoided planned exercise (apart from exercise interventions) and alcohol.

SUBJECTS

A total of 13 overweight/obese men (age: 40+/-8 years, body mass index: 31.1+/-3.0 kg m(-2)).

MEASUREMENTS

Postprandial triglyceride, insulin, glucose, non-esterified fatty acid and 3-hydroxybutyrate concentrations and substrate utilization rates were determined.

RESULTS

Energy-deficit lowered postprandial triglyceride concentrations by 14 and 10% compared with control and energy-replacement (P<0.05 for both). Energy-deficit increased postprandial 3-hydroxybutyrate concentrations by 40 and 19% compared with control and energy-replacement (P<0.05 for both). Postprandial insulin concentrations were 18 and 10% lower for energy-deficit and energy-replacement compared with control and 10% lower for energy-deficit than energy-replacement (P<0.05 for all). Postprandial fat oxidation increased by 30 and 14% for energy-deficit and energy-replacement compared to control and was 12% higher for energy-deficit than energy-replacement (P<0.05 for all).

CONCLUSION

Exercise with energy replacement lowered postprandial insulinaemia and increased fat oxidation. However an exercise-induced energy deficit augmented these effects and was necessary to lower postprandial lipaemia.

ApoB but not LDL-cholesterol is reduced by exercise training in overweight healthy men. Results from the 1-year randomized Oslo Diet and Exercise Study

OBJECTIVES

(i) To estimate changes in apoB and apoB/apoA-I, reflecting the balance between atherogenic and anti-atherogenic lipoprotein particles, by exercise training and compare with changes in LDL-C and TC/HDL-C ratio, and (ii) To compare strengths of relationships between physical fitness and various lipoprotein variables.

DESIGN, SETTING, AND SUBJECTS

The study was a 1-year open randomized trial comprising 219 healthy middle-aged subjects aged 40-49 years who were allocated to exercise or no exercise, dietary advice or no advice in a 2 x 2 factorial design. This study includes 188 men who completed the trial, 45 to diet, 48 to exercise, 58 to diet + exercise and 37 to control.

INTERVENTIONS

Exercise; supervised endurance exercise three times a week. Diet; reduce weight, increase intake of fish and reduce total fat intake.

MAIN OUTCOME MEASURE

One-year change in apoB and apoB/apoA-I ratio.

RESULTS

Exercisers decreased their ApoB and ApoB/ApoA-I values significantly compared to non-exercisers. LDL-C was not, but LDL-C/HDL-C was marginally but statistically significantly reduced by exercise. One-year change in ApoB and ApoB/ApoA-I correlated more strongly to 1-year changes in physical fitness than LDL-C or LDL-C/HDL-C. Adjusting for changes in LDL-C or LDL-C/HDL-C did not influence the correlation between changes in fitness and ApoB or ApoB/ApoA-I. However, adjusting for changes in ApoB or ApoB/ApoA-I wiped out the correlation between change in fitness and LDL-C or LDL-C/HDL-C. Relationships weakened when adjusting for changes in waist circumference, but Apo B or ApoB/ApoA-I still correlated significantly to changes in fitness.

CONCLUSION

Physical exercise reduced the atherogenic burden as experienced by the reduction in apoB or apoB/apoA-I levels, but not by LDL-C in healthy middle-aged men. Possibly, regular physical activity might increase the LDL-C particle size, thereby making LDL less atherogenic. Monitoring of apolipoproteins rather than the cholesterol moiety of lipoproteins might improve the assessment of lipoprotein changes after exercise training.

Prior exercise does not affect chylomicron particle number following a mixed meal of moderate fat content

Background

A single session of exercise has been reported to reduce fasting and postprandial triacylglycerol concentrations on the subsequent day. It is possible that exercise also reduces chylomicron particle number, which may underlie the observed reduction in postprandial triacylglycerol concentration. In the present study we aimed to determine whether a single session of exercise reduces fasting and postprandial chylomicron particle number on the subsequent day. In a randomised crossover design eight lean and healthy male and female subjects attended two postprandial testing days. On the previous day the subjects either performed 90 minutes of moderate intensity exercise or did not perform any exercise. Fasting blood samples were then collected prior to ingestion of a moderate fat mixed meal (0.44 g fat, 0.94 g carbohydrate, 0.27 g protein/kg body weight), blood was then collected after 1 h, 2 h, 4 h, 6 h, and 8 h.

Results

The fasting and postprandial apolipoprotein B48 concentration (marker of chylomicron particle number) was not affected by prior exercise. However exercise reduced fasting triacylglycerol concentration by 16% (P < 0.05) and there was a trend towards a reduction in the total area under the postprandial triacylglycerol curve (23%; P = 0.053). However when corrected for baseline concentration postprandial triacylglycerol concentration was not affected by prior exercise.

Conclusion

A single session of exercise of moderate intensity and 90 minutes duration reduces fasting triacylglycerol levels, however fasting and postprandial chylomicron particle number was unaffected. Furthermore it appears that previously observed reductions in postprandial triacylglycerol levels following exercise are only mediated following consumption of high, non-physiologically relevant doses of fat.

Effect of prior moderate exercise on postprandial metabolism in men with type 2 diabetes: heterogeneity of responses

Prior moderate exercise has been shown consistently to reduce postprandial triglyceride (TG) concentrations in non-diabetic adults, but its effects in men with type 2 diabetes are not known. This study aimed to determine the effect of moderate exercise on postprandial metabolism in men with type 2 diabetes. Ten middle-aged men with type 2 diabetes underwent two oral fat tolerance tests (blood taken fasting and for 8 h after a meal containing 80 g fat, 70 g carbohydrate) in random order. On the afternoon before one test, participants performed a 90-min treadmill walk (Exercise); no exercise was performed before the CONTROL test. Exercise significantly reduced fasting glucose (

CONTROL

9.08+/-0.75 mmol l(-1), Exercise: 8.40+/-0.72 mmol l(-1), p=0.033) and insulin (

CONTROL

8.01+/-0.98 microU ml(-1), Exercise: 6.81+/-0.93 microU ml(-1), p=0.046) and increased fasting 3-hydroxybutyrate (

CONTROL

87.1+/-19.2 micromol l(-1), Exercise: 134.3+/-28.4 micromol l(-1), p=0.011); reduced postprandial insulin by 11.0% (p=0.04) and increased postprandial 3-hydroxybutyrate by 31.8% (p=0.03); but did not significantly change fasting or postprandial triglyceride or NEFA concentrations. However, the exercise-induced change in postprandial triglyceride concentration ranged from -32.3 to +28.3% and the exercise-induced change in fasting 3-hydroxybutyrate concentration (a marker of hepatic fatty acid oxidation) was highly correlated with the exercise-induced changes in fasting and postprandial triglyceride (r=0.68, p=0.03 for both). Thus, inter-individual variation in propensity to increase hepatic fatty acid oxidation following exercise may account for the considerable heterogeneity in triglyceride responses to moderate exercise observed in men with type 2 diabetes.