Effects of prior moderate exercise on postprandial metabolism and vascular function in lean and centrally obese men

Sauna bathing and mortality risk: unraveling the interaction with systolic blood pressure in a cohort of Finnish men

Objectives: This cohort study aimed to investigate the potential interplay between systolic blood pressure (SBP), frequency of sauna bathing (FSB), and all-cause mortality risk among Caucasian men. Design: A prospective study was conducted, involving 2575 men aged 42 to 61 years. Baseline assessments included resting blood pressure measurements and self-reported sauna bathing habits. SBP levels were categorized as normal (<140 mmHg) or high (≥140 mmHg), while FSB was classified as low (≤2 sessions/week) or high (3-7 sessions/week). Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using Cox regression analysis, while adjusting for lifestyle factors, lipids, inflammation, and comorbidities. Results: Over a median follow-up of 27.8 years, 1,618 deaths were recorded. In the adjusted analysis, individuals with high SBP versus low SBP showed a 29% increased all-cause mortality risk (HR 1.29, 95% CI 1.16-1.43). Similarly, those with low FSB versus high FSB exhibited a 16% elevated mortality risk (HR 1.16, 95% CI 1.02-1.31). When considering combined effects, participants with high SBP-low FSB had a 47% higher mortality risk (HR 1.47, 95% CI 1.24-1.74) compared to those with normal SBP-high FSB. However, no significant association was observed between individuals with high SBP-high FSB and mortality risk (HR 1.24, 95% CI 0.98-1.57). There were potential additive and multiplicative interactions between SBP and sauna bathing concerning mortality risk. Conclusions: This study reveals a potential interplay between SBP, sauna bathing, and mortality risk in Finnish men. Frequent sauna bathing may mitigate the increased mortality risk associated with elevated SBP.

Leptin-dependent differential remodeling of visceral and pericardial adipose tissue following chronic exercise and psychosocial stress

Obesity is driven by an imbalance between caloric intake and energy expenditure, causing excessive storage of triglycerides in adipose tissue at different sites around the body. Increased visceral adipose tissue (VAT) is associated with diabetes, while pericardial adipose tissue (PAT) is associated with cardiac pathology. Adipose tissue can expand either through cellular hypertrophy or hyperplasia, with the former correlating with decreased metabolic health in obesity. The aim of this study was to determine how VAT and PAT remodel in response to obesity, stress, and exercise. Here we have used the male obese Zucker rats, which carries two recessive fa alleles that result in the development of hyperphagia with reduced energy expenditure, resulting in morbid obesity and leptin resistance. At 9 weeks of age, a group of lean (Fa/Fa or Fa/fa) Zucker rats (LZR) and obese (fa/fa) Zucker rats (OZR) were treated with unpredictable chronic mild stress or exercise for 8 weeks. To determine the phenotype for PAT and VAT, tissue cellularity and gene expression were analyzed. Finally, leptin signaling was investigated further using cultured 3T3-derived adipocytes. Tissue cellularity was determined following hematoxylin and eosin (H&E) staining, while qPCR was used to examine gene expression. PAT adipocytes were significantly smaller than those from VAT and had a more beige-like appearance in both LZR and OZR. In the OZR group, VAT adipocyte cell size increased significantly compared with LZR, while PAT showed no difference. Exercise and stress resulted in a significant reduction in VAT cellularity in OZR, while PAT showed no change. This suggests that PAT cellularity does not remodel significantly compared with VAT. These data indicate that the extracellular matrix of PAT is able to remodel more readily than in VAT. In the LZR group, exercise increased insulin receptor substrate 1 (IRS1) in PAT but was decreased in the OZR group. In VAT, exercise decreased IRS1 in LZR, while increasing it in OZR. This suggests that in obesity, VAT is more responsive to exercise and subsequently becomes less insulin resistant compared with PAT. Stress increased PPAR-γ expression in the VAT but decreased it in the PAT in the OZR group. This suggests that in obesity, stress increases adipogenesis more significantly in the VAT compared with PAT. To understand the role of leptin signaling in adipose tissue remodeling mechanistically, JAK2 autophosphorylation was inhibited using 5 μM 1,2,3,4,5,6-hexabromocyclohexane (Hex) in cultured 3T3-derived adipocytes. Palmitate treatment was used to induce cellular hypertrophy. Hex blocked adipocyte hypertrophy in response to palmitate treatment but not the increase in lipid droplet size. These data suggest that leptin signaling is necessary for adipocyte cell remodeling, and its absence induces whitening. Taken together, our data suggest that leptin signaling is necessary for adipocyte remodeling in response to obesity, exercise, and psychosocial stress.

Nutrition Interactions With Exercise Training on Endothelial Function

Exercise is advised to improve overall cardiovascular health and endothelial function. However, the role of nutrition on this exercise-induced endothelial adaptation is not clear. Here, we hypothesize that nutrients interact with exercise to influence endothelial function and chronic disease risk.

Effects of accumulated versus continuous individualized exercise on postprandial glycemia in young adults with obesity

BACKGROUND

Elevated postprandial glucose (PPG) is an independent risk factor for cardiovascular disease. Post-meal exercise effectively reduces PPG concentrations. However, the effect of accumulated versus continuous post-meal exercise on PPG control remains unclear. This study aimed to investigate the effects of individualized accumulated or continuous exercise on PPG in young adults with obesity.

METHODS

Twenty young adults with obesity (11 males) completed three 4-h randomized crossover trials with 6-14-day washout periods: (1) sitting (SIT), (2) one 30-min walking bout (CONT), and (3) three 10-min walking bouts separated by 20-min resting (ACCU). Walking was initiated 20 min before individual PPG peak after breakfast, which was predetermined by continuous glucose monitoring. Blood samples were collected at 15-30 min intervals, and the 24-h glucose was monitored via continuous glucose monitoring.

RESULTS

The 4-h PPG incremental area under the curve (iAUC) was 12.1%±30.9% and 21.5%±21.5% smaller after CONT (P = 0.022) and ACCU (P < 0.001), respectively, than after SIT. PPG concentrations were lower during CONT at 30-60 min and during ACCU at 30-105 min after breakfast than during SIT (all P < 0.05). The 4-h plasma insulin and C-peptide iAUC, and mean amplitude of glycemic excursions were lower after CONT and ACCU than after SIT (all P < 0.05).

CONCLUSIONS

Both continuous and accumulated exercises reduced PPG, insulin, and C-peptide concentrations and improved glucose fluctuations. Accumulated exercise maintained lower PPG concentrations for a longer time than continuous exercise in young adults with obesity.

CLINICAL TRIAL INFORMATION

Clinical trial registration No. ChiCTR 2000035064, URL: http://www.chictr.org.cn/showproj.aspx?proj=56584; (registered July 29, 2020).HIGHLIGHTS Both continuous and accumulated walking lowered post-meal glucose, insulin and C-peptide levels and improved glucose fluctuation.Postprandial glucose was kept lower for a longer time in accumulated than continuous walking.Accumulated post-meal exercise (e.g. three 10-min bouts of walking) could be recommended as a feasible and practical alternative protocol for postprandial glucose control, especially for those who have difficulty performing sufficient exercise in one session.

Changes in Arterial Stiffness in Response to Various Types of Exercise Modalities: A Narrative Review on Physiological and Endothelial Senescence Perspectives

Arterial stiffness is a reliable independent predictor of cardiovascular events. Exercise training might enhance arterial compliance through improved metabolic health status. Different modes of exercise may have different effects on arterial stiffness. However, the interactions among different modes of exercise on endothelial senescence, the development of arterial vascular stiffness, and the associated molecular mechanisms are not completely understood. In this narrative review, we evaluate the current evidence focusing on the effects of various exercise modes on arterial stiffness and vascular health, and the known underlying physiological mechanisms are discussed as well. Here, we discuss the most recent evidence of aerobic exercise, high-intensity interval training (HIIT), and resistance exercise (RE) on arterial stiffness and endothelial senescence in physiological and cellular studies. Indeed, aerobic, HIIT, and progression RE-induced arterial compliance may reduce arterial stiffness by effectively promoting nitric oxide (NO) bioavailability and reducing endothelial senescence. However, the transient increase in inflammation and sympathetic activation may contribute to the temporary elevation in arterial stiffness following whole-body high-intensity acute resistance exercise.

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.

Effect of Prior Exercise on Postprandial Lipemia: An Updated Meta-Analysis and Systematic Review

The purpose of this systematic review was to synthesize the results from current literature examining the effects of prior exercise on the postprandial triglyceride (TG) response to evaluate current literature and provide future direction. A quantitative review was performed using meta-analytic methods to quantify individual effect sizes. A moderator analysis was performed to investigate potential variables that could influence the effect of prior exercise on postprandial TG response. Two hundred and seventy-nine effects were retrieved from 165 studies for the total TG response and 142 effects from 87 studies for the incremental area under the curve TG response. There was a moderate effect of exercise on the total TG response (Cohen's d = -0.47; p < .0001). Moderator analysis revealed exercise energy expenditure significantly moderated the effect of prior exercise on the total TG response (p < .0001). Exercise modality (e.g., cardiovascular, resistance, combination of both cardiovascular and resistance, or standing), cardiovascular exercise type (e.g., continuous, interval, concurrent, or combined), and timing of exercise prior to meal administration significantly affected the total TG response (p < .001). Additionally, exercise had a moderate effect on the incremental area under the curve TG response (Cohen's d = -0.40; p < .0001). The current analysis reveals a more homogeneous data set than previously reported. The attenuation of postprandial TG appears largely dependent on exercise energy expenditure (∼2 MJ) and the timing of exercise. The effect of prior exercise on the postprandial TG response appears to be transient; therefore, exercise should be frequent to elicit an adaptation.

Circulating MicroRNA Responses to Postprandial Lipemia with or without Prior Exercise

Repeated exposure to a high-fat meal triggers inflammation and oxidative stress, contributing to the onset of cardiometabolic diseases. Regular exercise prevents cardiometabolic diseases and a prior bout of acute endurance exercise can counteract the detrimental cardiovascular effects of a subsequent high-fat meal. Circulating microRNAs (ci-miRs) are potential mediators of these vascular effects through regulation of gene expression at the posttranscriptional level. Therefore, we investigated the expression of ci-miRs related to vascular function (miR-21, miR-92a, miR-126, miR-146a, miR-150, miR-155, miR-181b, miR-221, miR-222) in plasma from healthy, recreationally to highly active, Caucasian adult men after a high-fat meal with (EX) and without (CON) a preceding bout of cycling exercise. Ci-miR-155 was the only ci-miR for which there was a significant interaction effect of high-fat meal and exercise (p=0.050). Ci-miR-155 significantly increased in the CON group at two (p=0.007) and four hours (p=0.010) after the high-fat meal test, whereas it significantly increased in the EX group only four hours after the meal (p=0.0004). There were significant main effects of the high-fat meal on ci-miR-21 (p=0.01), ci-miR-126 (p=0.02), ci-miR-146a (p=0.02), ci-miR-181b (p=0.02), and ci-miR-221 (p=0.008). Collectively, our results suggest that prior exercise does not prevent high-fat meal-induced increases in vascular-related ci-miRs.

A Single Bout of Upper-Body Exercise Has No Effect on Postprandial Metabolism in Persons with Chronic Paraplegia

PURPOSE

The acute effects of a single bout of upper-body exercise on postprandial metabolism in persons with spinal cord injury are currently not well understood. The primary aim of this study was to evaluate the effects of a single bout of upper-body high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MICE) in comparison with a no-exercise control (REST) condition on postprandial metabolic responses in persons with chronic paraplegia.

METHODS

Ten participants (eight males, two females; age, 49 ± 10 yr; time since injury, 22 ± 13 yr) with chronic paraplegia took part in a randomized crossover study, consisting of three trials: HIIE (8 × 60 s at 70% peak power output [PPEAK]), MICE (25 min at 45% PPEAK), and REST, at least 3 d apart. Exercise was performed in the fasted state, and participants consumed a mixed-macronutrient liquid meal 1-h postexercise. Venous blood and expired gas samples were collected at regular intervals for 6-h postmeal consumption.

RESULTS

There were no significant differences in postprandial incremental area under the curve for triglycerides (P = 0.59) or glucose (P = 0.56) between conditions. Insulin incremental area under the curve tended to be lower after MICE (135 ± 85 nmol·L-1 per 360 min) compared with REST (162 ± 93 nmol·L-1 per 360 min), but this did not reach statistical significance (P = 0.06, d = 0.30). Participants reported a greater fondness (P = 0.04) and preference for HIIE over MICE.

CONCLUSIONS

After an overnight fast, a single bout of upper-body exercise before eating has no effect on postprandial metabolism in persons with chronic paraplegia, irrespective of exercise intensity. This suggests that alternative exercise strategies may be required to stimulate postprandial substrate oxidation for this population.

Interrupting Prolonged Sitting Reduces Postprandial Glucose Concentration in Young Men With Central Obesity

CONTEXT

Prolonged sitting elevates postprandial metabolic markers, resulting in increased risks of cardiovascular diseases and type 2 diabetes. Interrupting prolonged sitting may reduce these risks. However, more information is needed to understand the patterns of interrupting prolonged sitting to obtain metabolic health benefits.

OBJECTIVE

This study examined the effects of interrupting prolonged sitting with different intensities and durations of walking with an equivalent energy expenditure on postprandial metabolic responses in young Chinese men with central obesity.

DESIGN

A randomized crossover experimental trial was conducted.

SETTING

Participants underwent three 6-hour experiments with a 7-day washout period between each experiment: prolonged sitting, 3 min of light-intensity walking every 30 minutes, and 1.5 minutes of moderate-intensity walking every 30 minutes.

PARTICIPANTS AND SAMPLES

Baseline (fasting) and 6-hour postprandial metabolic glucose and lipid levels were analyzed among 18 young Chinese men with central obesity.

MAIN OUTCOME MEASURES

Generalized estimating equations (adjusted for the potential confounders explaining residual outcome variance (body mass index) and age), trial order, preprandial values, and lead-in activity) were used, and the incremental areas under the curve (iAUC) of each outcome were compared between prolonged sitting and interrupted prolonged sitting conditions.

RESULTS

Compared with prolonged sitting, both interrupting prolonged sitting conditions reduced the iAUCs for glucose (P < .05) but not insulin, C-peptide, triglycerides, or nonesterified fatty acids.

CONCLUSIONS

Both conditions of interrupted prolonged sitting reduced postprandial glucose concentrations in young Chinese men with central obesity when the energy expenditure was equivalent.

Frequency of interruptions to prolonged sitting and postprandial metabolic responses in young, obese, Chinese men

This study aimed to examine the effects of 3-min light-intensity walking every 30 min (3-min) and 6-min light-intensity walking every 60 min (6-min) compared with prolonged sitting (SIT) on the postprandial metabolic responses in young, centrally obese, Chinese men. Twenty-one Chinese men with central obesity (age, 23 ± 4 years; body mass index, 29.8 ± 3.2 kg·m^-2; waist circumference, 98.7 ± 7.1 cm; mean ± SD) underwent three 6-h experiments with a 7-day washout period, SIT, 3-min, and 6-min, in randomized order. Compared with SIT, neither walking condition showed differences in total and net incremental area under the curve (tAUC and iAUC, respectively) for glucose, insulin, nor non-esterified fatty acids. The tAUC and iAUC for triglycerides for the SIT condition (10.8 [9.3, 12.2] and 4.4 [3.7, 5.1] mmol·h·L^-1, respectively; mean [95% confidence interval]) was higher than 3-min (10.4 [9.0, 11.8] and 3.8 [3.3, 4.3] mmol·h·L^-1, respectively, both Ps <0.05) and 6-min (9.6 [8.1, 11.0] and 3.5 [2.9, 4.2] mmol·h·L^-1, respectively, both Ps <0.01) conditions. Interrupting prolonged sitting regardless of frequency-reduced postprandial triglycerides. A higher volume of physical activity may be required to obtain greater glycaemic benefits in young Chinese men with central obesity.

Effects of statins and exercise on postprandial lipoproteins in metabolic syndrome vs metabolically healthy individuals

AIMS

To determine if the combination of exercise and statin could normalize postprandial triglyceridaemia (PPTG) in hypercholesteraemic individuals.

METHODS

Eight hypercholesteraemic (blood cholesterol 182 ± 38 mg dL^-1 ; low-density lipoprotein-cholesterol [LDL-c] 102 ± 32 mg dL^-1 ) overweight (body mass index 30 ± 4 kg m^-2 ) individuals with metabolic syndrome (MetS) were compared to a group of 8 metabolically healthy (MetH) controls (blood cholesterol 149 ± 23 mg dL^-1 ; LDL-c 77 ± 23 mg dL^-1 , and body mass index 23 ± 2 kg m^-2 ). Each group underwent 2 PPTG tests, either 14 hours after a bout of intense exercise or without previous exercise. Additionally, MetS individuals were tested 96 hours after withdrawal of their habitual statin medication to study medication effects.

RESULTS

A bout of exercise before the test meal did not reduce PPTG in MetS (P = .347), but reduced PPTG by 46% in MetH (413 ± 267 to 224 ± 142 mg dL^-1 for 5 h incremental area under the curve; P = .02). In both trials (i.e., either after a bout of intense exercise or without previous exercise), statin withdrawal in MetS greatly increased PPTG (average 65%; P < .01), mean LDL-c (average 25%; P < .01), total cholesterol (average 16%; P < .01) and apolipoprotein (Apo) B48 (24%; P < .01), without interference from exercise. However, Apo B100 was not affected by statin withdrawal.

CONCLUSION

Hypercholesteraemic MetS individuals (compared to MetH controls) fail to show an effect of exercise on reducing PPTG. However, chronic statin medication blunts the elevations in triglyceride after a fat meal (i.e., incremental area under the curve of PPTG) reducing their cardiovascular risk associated with their atherogenic dyslipidaemia. Statin decreases PPTG by reducing the secretion or accelerating the catabolism of intestinal Apo B48.

High-intensity interval exercise lowers postprandial glucose concentrations more in obese adults than lean adults

AIMS

To compare postprandial glucose responses to high-intensity interval exercise (HIE) between obese and lean individuals.

METHODS

Thirty healthy young adult males (15 obese, 15 lean) ate a standardised meal, then performed HIE (4 × 30-s Wingate cycling/4-min rest) or a no-exercise control trial (CON). Blood glucose was measured preprandially and up to 150 min postprandially.

RESULTS

Compared to CON, HIE reduced postprandial glucose concentrations at 120-150 min in obese (p < 0.001) and lean men (p < 0.05), with greater reductions in obese than lean subjects at 120 (-27.0% vs. -8.3%), 135 (-31.9% vs. -15.7%), and 150 min (-21.8% vs. -10.6%). The total glucose area under the curve (AUC) for the testing period was lower with HIE than CON among obese men (p < 0.05), but not lean men (p > 0.05). We found moderate correlations between body mass and postprandial glucose changes (r = 0.39-0.44, p < 0.05), and between glucose AUC and body mass and fat free mass (r = 0.39-0.48, p < 0.05).

CONCLUSIONS

Our findings suggest that HIE may act as a time-efficient lifestyle intervention strategy for improving obesity-related diabetes risk factors, and might play a role in primary diabetes prevention for the healthy but sedentary population.

Increased usual physical activity is associated with a blunting of the triglyceride response to a high-fat meal

BACKGROUND

Postprandial lipemia (PPL), defined as a prolonged or elevated rise in triglycerides that accompanies fat feeding, is a significant risk factor for coronary heart disease and associated comorbidities. The impact of PPL on coronary heart disease risk is underscored by the preponderance of each day spent in the postprandial state.

OBJECTIVE

In this study, we evaluated cross-sectionally the association between usual (ie, noninterventional) physical activity and the 6-hour triglyceride response to a standardized high-fat meal.

METHODS

The high-fat meal intervention was carried out in 671 apparently healthy individuals as part of the Heredity and Phenotype Intervention Heart Study. Triglyceride levels were measured in the fasting state and during 6 hours after administration of a standardized fat challenge. We defined PPL response as the triglyceride area under the fat load curve (AUC) and measured physical activity using accelerometers that were worn continuously over a 7-day period.

RESULTS

Physical activity levels decreased with increasing age and were higher in men than women (both P < .001). The triglyceride AUC increased with increasing age in both men and women (both P < .001) and was also higher in men than in women (age-adjusted P = 9.2 × 10^-12). Higher physical activity levels were associated with a lower triglyceride AUC (P = .003), adjusting for age, sex, body mass index, and fasting low-density lipoprotein.

CONCLUSION

These results suggest that the protective benefits of physical activity on cardiovascular health may operate, at least in part, through reduction of the PPL triglyceride response.

Exercise and postprandial lipemia: effects on vascular health in inactive adults

BACKGROUND

There is evidence to suggest that postprandial lipemia are is linked to the impairment of endothelial function, which is characterized by an imbalance between the actions of vasodilators and vasoconstrictors. The aim of this study was to determine the effects of a 12-week high-intensity training (HIT) and moderate continuous training (MCT) protocol on postprandial lipemia, vascular function and arterial stiffness in inactive adults after high-fat meal (HFM) ingestion.

METHODS

A randomized clinical trial was conducted in 20 healthy, inactive adults (31.6 ± 7.1 years). Participants followed the two exercise protocols for 12 weeks. To induce a state of postprandial lipemia (PPL), all subjects received a HFM. Endothelial function was measured using flow-mediated vasodilation (FMD), normalized brachial artery FMD (nFMD), aortic pulse wave velocity (PWV) and augmentation index (AIx). Plasma total cholesterol, high-density lipoprotein cholesterol (HDL-c), triglycerides and glucose were also measured.

RESULTS

The effects of a HFM were evaluated in a fasted state and 60, 120, 180, and 240 min postprandially. A significant decrease in serum glucose between 0 min (fasted state) and 120 min postprandially was found in the HIT group (P = 0.035). Likewise, FMD (%) was significantly different between the fasted state and 60 min after a HFM in the HIT group (P = 0.042). The total cholesterol response expressed as area under curve (AUC)(0-240) was lower following HIT than following MCT, but no significant differences were observed (8%, P > 0.05). Similarly, triglycerides AUC(0-240) was also lower after HIT compared with MCT, which trended towards significance (24%, P = 0.076). The AUC(0-240) for the glucose response was significantly lower following HIT than MCT (10%, P = 0.008). FMD and nFMD AUC(0-240) were significantly higher following HIT than following MCT (46.9%, P = 0.021 and 67.3%, P = 0.009, respectively). PWV AUC(0-240) did not differ following between the two exercise groups (2.3%, P > 0.05).

CONCLUSIONS

Supervised exercise training mitigates endothelial dysfunction and glucose response induced by PPL. Exercise intensity plays an important role in these protective effects, and medium-term HIT may be more effective than MCT in reducing postprandial glucose levels and attenuating vascular impairment.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT02738385 Date of registration: April 14, 2016.

Hemostasis, endothelial stress, inflammation, and the metabolic syndrome

Obesity and the metabolic syndrome (MS) are two of the pressing healthcare problems of our time. The MS is defined as increased abdominal obesity in concert with elevated fasting glucose levels, insulin resistance, elevated blood pressure, and plasma lipids. It is a key risk factor for type 2 diabetes mellitus (T2DM) and for cardiovascular complications and mortality. Here, we review work demonstrating that various aspects of coagulation and hemostasis, as well as vascular reactivity and function, become impaired progressively during chronic ingestion of a western diet, but also acutely after meals. We outline that both T2DM and cardiovascular disease should be viewed as inflammatory diseases and describe that chronic overload of free fatty acids and glucose can trigger inflammatory pathways directly or via increased production of ROS. We propose that since endothelial stress and increases in platelet activity precede inflammation and overt symptoms of the MS, they are likely the first hit. This suggests that endothelial activation and insulin resistance are probably causative in the observed chronic low-level metabolic inflammation, and thus both metabolic and cardiovascular complications linked to consumption of a western diet.

High-intensity interval exercise attenuates but does not eliminate endothelial dysfunction after a fast food meal

We investigated whether two different bouts of high-intensity interval exercise (HIIE) could attenuate postprandial endothelial dysfunction. Thirteen young (27 ± 1 yr), nonexercise-trained men underwent three randomized conditions: 1) four 4-min intervals at 85-95% of maximum heart rate separated by 3 min of active recovery (HIIE 4 × 4), 2) 16 1-min intervals at 85-95% of maximum heart rate separated by 1 min of active recovery (HIIE 16 × 1), and 3) sedentary control. HIIE was performed in the afternoon, ~18 h before the morning fast food meal (1,250 kcal, 63g of fat). Brachial artery flow-mediated dilation (FMD) was performed before HIIE ( baseline 1), during fasting before meal ingestion ( baseline 2), and 30 min, 2 h, and 4 h postprandial. Capillary glucose and triglycerides were assessed at fasting, 30 min, 1 h, 2 h, and 4 h (triglycerides only). Both HIIE protocols increased fasting FMD compared with control (HIIE 4 × 4: 6.1 ± 0.4%, HIIE 16 × 1: 6.3 ± 0.5%, and control: 5.1 ± 0.4%, P < 0.001). For both HIIE protocols, FMD was reduced only at 30 min postprandial but never fell below baseline 1 or FMD during control at any time point. In contrast, control FMD decreased at 2 h (3.8 ± 0.4%, P < 0.001) and remained significantly lower than HIIE 4 × 4 and 16 × 1 at 2 and 4 h. Postprandial glucose and triglycerides were unaffected by HIIE. In conclusion, HIIE performed ~18 h before a high-energy fast food meal can attenuate but not entirely eliminate postprandial decreases in FMD. This effect is not dependent on reductions in postprandial lipemia or glycemia. NEW & NOTEWORTHY Two similar high-intensity interval exercise (HIIE) protocols performed ∼18 h before ingestion of a high-energy fast food meal attenuated but did not entirely eliminate postprandial endothelial dysfunction in young men largely by improving fasting endothelial function. Both HIIE protocols produced essentially identical results, suggesting high reproducibility of HIIE effects.

Carbohydrate-Restriction with High-Intensity Interval Training: An Optimal Combination for Treating Metabolic Diseases?

Lifestyle interventions incorporating both diet and exercise strategies remain cornerstone therapies for treating metabolic disease. Carbohydrate-restriction and high-intensity interval training (HIIT) have independently been shown to improve cardiovascular and metabolic health. Carbohydrate-restriction reduces postprandial hyperglycemia, thereby limiting potential deleterious metabolic and cardiovascular consequences of excessive glucose excursions. Additionally, carbohydrate-restriction has been shown to improve body composition and blood lipids. The benefits of exercise for improving insulin sensitivity are well known. In this regard, HIIT has been shown to rapidly improve glucose control, endothelial function, and cardiorespiratory fitness. Here, we report the available evidence for each strategy and speculate that the combination of carbohydrate-restriction and HIIT will synergistically maximize the benefits of both approaches. We hypothesize that this lifestyle strategy represents an optimal intervention to treat metabolic disease; however, further research is warranted in order to harness the potential benefits of carbohydrate-restriction and HIIT for improving cardiometabolic health.

Effects of aerobic exercise on lipids and lipoproteins

Dyslipidemia is the risk of cardiovascular disease, and their relationship is clear. Lowering serum cholesterol can reduce the risk of coronary heart disease. At present, the main treatment is taking medicine, however, drug treatment has its limitations. Exercise not only has a positive effect on individuals with dyslipidemia, but can also help improve lipids profile. This review is intending to provide information on the effects of exercise training on both tranditional lipids, for example, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides and new lipids and lipoproteins such as non-high-density lipoprotein cholesterol, and postprandial lipoprotein. The mechanisms of aerobic exercise on lipids and lipoproteins are also briefly described.

Effect of a single bout of aerobic exercise on high-fat meal-induced inflammation

BACKGROUND AND AIMS

Chronic low-grade inflammation is involved in the development of metabolic disorders including atherosclerosis, type 2 diabetes (T2D) and metabolic syndrome. Aerobic exercise has been shown to be anti-inflammatory and attenuate postprandial blood lipids, however, the effect of exercise on postprandial inflammation remains unclear. The aim of this study was to determine the protective effect of a single bout of aerobic exercise against postprandial lipemia and peripheral blood mononuclear cell (PBMC) inflammation and to evaluate associations with changes in the energy-sensing enzyme, AMP-activated protein kinase (AMPK).

MATERIALS AND METHODS

Healthy male subjects (n=12, age=23±2, %Fat=19±2) reported to the laboratory following an overnight fast (12-14h) on two separate occasions for consumption of a high-fat meal (HFM). Participants completed an acute bout of aerobic exercise the afternoon prior to one of the HFM visits.

RESULTS AND CONCLUSION

Results indicate that the single bout of moderate aerobic exercise increased AMPK signaling in PBMCs, as shown by increased phosphorylated acetyl-CoA carboxylase (p-ACC). This may be due to decreases in the AMPK inhibitory kinases PKD and GSK3β. Additionally, prior moderate intensity exercise decreased postprandial lipemia (PPL) and some mediators of the inflammatory pathway, such as p-NF-κB. These findings that acute aerobic exercise improves AMPK and NF-κB signaling in human PBMCs contribute support to the anti-inflammatory roles of exercise.

Realistic Test-Meal Protocols Lead to Blunted Postprandial Lipemia but Similar Inflammatory Responses Compared with a Standard High-Fat Meal

Background: A substantial increase in triglycerides (TGs) after a meal is associated with an increased risk of cardiovascular disease. Most studies investigating the effects of a meal on TGs have not used meals that reflect typical consumption. Objective: The objective of this study was to compare the TG and inflammatory responses of true-to-life meals, containing moderate fat and energy contents, with a high-fat, high-energy, low-carbohydrate meal (HFM) typically used to test TG responses. Methods: Nine healthy, insufficiently active men [mean ± SD age: 25.1 ± 6.7 y; body mass index (in kg/m2): 25.8 ± 7.0; <150 min moderate- to vigorous-intensity physical activity/wk] completed 3 meal trials in random order: an HFM (17 kcal/kg, 60% fat), a moderate-fat meal (MFM; 8.5 kcal/kg, 30% fat), and a biphasic meal (BPM), in which participants consumed the full MFM at baseline and 3 h postmeal. Blood samples were collected via an indwelling catheter at baseline and hourly for 6 h. Results: Peak blood TGs were significantly greater (P = 0.003) after the HFM (285.2 ± 169.7 mg/dL) than after the MFM (156.0 ± 98.7 mg/dL), but the BPM (198.3 ± 182.8 mg/dL) was not significantly different from the HFM (P = 0.06) or the MFM (P = 0.99). Total area under the curve for TGs was greater after the HFM (1348.8 ± 783.7 mg/dL × 6 h) than after the MFM (765.8 ± 486.8 mg/dL × 6 h; P = 0.0005) and the BPM (951.8 ± 787.7 mg/dL × 6 h; P = 0.03), although the MFM and BPM were not significantly different (P = 0.72). There was a significant time-by-meal interaction for interferon γ, but not for interleukins 6, 8, or 10. Conclusion: These findings in insufficiently active, healthy young men suggest that the large TG response after HFMs in previous studies may not reflect the metabolic state of many individuals in daily life.

Assessing the evidence: Exploring the effects of exercise on diabetic microcirculation

Diabetes mellitus (DM) is associated with cardiovascular complications. Impairment of glycemic control induces noxious glycations, an increase in oxydative stress and dearangement of various metabolic pathways. DM leads to dysfunction of micro- and macrovessels, connected to metabolic, endothelial and autonomic nervous system. Thus, assessing vascular reactivity might be one of the clinical tools to evaluate the impact of harmful effects of DM and potential benefit of treatment; skin and skeletal muscle microcirculation have usually been tested. Physical exercise improves vascular dysfunction through various mechanisms, and is regarded as an additional effective treatment strategy of DM as it positively impacts glycemic control, improves insulin sensitivity and glucose uptake in the target tissues, thus affecting glucose and lipid metabolism, and increases the endothelium dependent vasodilation. Yet, not all patients respond in the same way so titrating the exercise type individualy would be desirable. Resistance training has, apart from aerobic one, been shown to positively correlate to glycemic control, and improve vascular reactivity. It has been prescribed in various forms or in combination with aerobic training. This review would assess the impact of different modes of exercise, the mechanisms involved, and its potential positive and negative effects on treating patients with Type I and Type II DM, focusing on the recent literature.

Adiposity, physical activity and risk of diabetes mellitus: prospective data from the population-based HUNT study, Norway

BACKGROUND

Physical activity may counteract the adverse effects of adiposity on cardiovascular mortality; however, the evidence of a similar effect on diabetes is sparse. This study examines whether physical activity may compensate for the adverse effect of adiposity on diabetes risk.

METHODS

The study population consisted of 38 231 individuals aged 20 years or more who participated in two consecutive waves of the prospective longitudinal Nord-Trøndelag Health Study in Norway: in 1984-1986 and in 1995-1997. A Poisson regression model with SEs derived from robust variance was used to estimate adjusted risk ratios of diabetes between categories of body mass index and physical activity.

RESULTS

Risk of diabetes increased both with increasing body mass (P_trend <0.001) and with decreasing physical activity level (P_trend <0.001 in men and 0.01 in women). Combined analyses showed that men who were both obese and had low activity levels had a risk ratio of 17 (95% CI 9.52 to 30) compared to men who were normal weight and highly active, whereas obese men who reported high activity had a risk ratio of 13 (95% CI 6.92 to 26). Corresponding analysis in obese women produced risk ratios of 15 (95% CI 9.18 to 25) and 13 (95% CI 7.42 to 21) among women reporting low and high activity levels, respectively.

CONCLUSIONS

This study shows that overweight and obesity are associated with a substantially increased risk of diabetes, particularly among those who also reported being physically inactive. High levels of physical activity were associated with a lower risk of diabetes within all categories of body mass index, but there was no clear evidence that being physically active could entirely compensate for the adverse effect of adiposity on diabetes risk.

Postprandial lipemic and inflammatory responses to high-fat meals: a review of the roles of acute and chronic exercise

Postprandial lipemia is an independent risk factor for development of cardiovascular disease. Postprandial inflammation following the prolonged elevation of triglycerides occurring subsequent to ingestion of high-fat meals, provides a likely explanation for increased disease risk. Substantial evidence has shown that acute exercise is an effective modality for attenuation of postprandial lipemia following a high-fat meal. However, much of the evidence pertaining to exercise intensity, duration, and overall energy expenditure for reducing postprandial lipemia is inconsistent. The effects of these different exercise variables on postprandial inflammation is largely unknown. Long-term, frequent exercise, however, appears to effectively reduce systemic inflammation, especially in at-risk or diseased individuals. With regard to an acute postprandial response, without a recent bout of exercise, high levels of chronic exercise do not appear to reduce postprandial lipemia. This review summarizes the current literature on postprandial and inflammatory responses to high-fat meals, and the roles that both acute and chronic exercise play. This review may be valuable for health professionals who wish to provide evidence-based, pragmatic advice for reducing postprandial lipemia and cardiovascular disease risk for their patients. A brief review of proposed mechanisms explaining how high-fat meals may result in pro-inflammatory and pro-atherosclerotic environments is also included.

High trans but not saturated fat beverage causes an acute reduction in postprandial vascular endothelial function but not arterial stiffness in humans

A diet high in trans-fatty acids (TFAs) is associated with a higher risk of cardiovascular disease (CVD) than a diet high in saturated fatty acids (SFAs), but the mechanisms remain unclear. We hypothesized that a beverage high in TFAs would cause a larger reduction in postprandial endothelial function and an increase in arterial stiffness, in part from greater reductions in insulin sensitivity, compared with a beverage high in SFAs. Eleven healthy adults (aged 47±5 years) ingested a warm test beverage (520 kcal, 56 g total fat, 5 g carbohydrate, 1 g protein) high in either TFAs or SFAs in a randomized cross-over study. Ingestion of the beverage high in TFAs (p<0.01) but not high in SFAs (p=0.49) decreased endothelial function (brachial artery flow-mediated dilation, mmΔ) at 3-4 hours (p<0.01 for time; p=0.034 for interaction), but did not alter aortic stiffness or carotid β-stiffness. The homeostasis model of insulin resistance (interaction p=0.062) tended to decrease after SFAs but not TFAs. A beverage high in TFAs but not SFAs results in a postprandial reduction in endothelial function and a trend for decreased insulin sensitivity, potentially explaining the higher risk of CVD with a diet high in TFAs.

Increased Pre- and Post-Meal Free Fatty Acid Levels in Black, Obese Adolescents

BACKGROUND

Black adolescents are at increased risk of cardiometabolic disease but have lower fasting triglyceride, which is usually associated with decreased risk. No one has studied racial differences in triglycerides or free fatty acids (FFAs) after a high-fat meal.

METHODS

Oral glucose tolerance testing was used to assess insulin secretion, sensitivity, and disposition index (DI). Endothelial function, triglycerides, FFA, c-reactive protein, interleukin 6 (IL6), and adiponectin were measured both pre- and 3 hr postprandially (McDonald's Big Breakfast(®) and 12 ounce Sprite(®)) in obese adolescents (10-13 years, 9 black and 7 white). Endothelial function was assessed using reactive hyperemic changes in forearm vascular resistance (FVR).

RESULTS

Oral glucose tolerance test (OGTT) showed no difference in insulin sensitivity, but blacks tended to have (P = 0.08) higher insulin secretion and had increased DI (P = 0.003). After a high-fat meal, triglycerides increased in both groups (P < 0.001), tended to be lower in blacks compared with whites preprandially (64 ± 33 mg/dL vs 110 ± 80, P = 0.064), and was lower postprandially (112 ± 63 vs 188 ± 112, P = 0.039). Pre- and postprandial FFA (Black: 0.58 ± 0.15 and 0.39 ± 0.18 vs. white: 0.44 ± 0.14 and 0.26 ± 0.06, P = 0.020) and adiponectin (P = 0.002) were increased in blacks. FFA decreased in both groups postprandially (P = 0.002). IL6 increased after the meal (P = 0.022). Endothelial function decreased postprandially (P < 0.02), but this was due to a decrease in preocclusion FVR.

CONCLUSIONS

These results indicate that differences in fat metabolism are present in both black and white obese adolescents. How these differences explain higher rates of cardiometabolic disease in blacks is unclear.

Effects of thirty and sixty minutes of moderate-intensity aerobic exercise on postprandial lipemia and inflammation in overweight men: a randomized cross-over study

BACKGROUND

The transient rise in blood lipids following a high-fat meal (HFM), known as postprandial lipemia, is linked to systemic inflammation and cardiovascular disease, but can be blunted by exercise. However, minimal research has investigated the effects of realistic exercise bouts on postprandial lipemia and inflammation in at-risk individuals. The purpose of this study was to assess the effects of moderate-intensity aerobic exercise lasting 30 or 60 min performed the evening before a HFM, on postprandial lipemia and inflammation in overweight, insufficiently active men.

METHODS

In this randomized-crossover study, twelve participants remained sedentary (CON), or performed a brisk walk on a treadmill at 60 % VO2peak for either 30 min (EX-30) or 60 min (EX-60), after which they consumed a small snack (270 kcal) to partially replace exercise energy expenditure. Following a 12-h overnight fast, participants consumed a standard HFM (1 g fat/kg; 1 g CHO/kg; 1117.8 ± 117.0 kcal). Blood draws were performed at baseline (pre-HFM) and 1, 2, 4, 6, and 8 h post-HFM to assess glucose, insulin, lipids, and systemic inflammation.

RESULTS

There were no significant differences (p > 0.05) in fasting triglycerides between EX-60 (118.7 ± 68.3 mg/dL), CON (134.8 ± 66.2 mg/dL) or EX-30 (135.5 ± 85.4 mg/dL). There were no differences in peak, time-to-peak, total or incremental area-under-the-curve between trials for triglyceride response (p > 0.05). There was no significant main effect of time (p > 0.05) in IL-1ra, IL-4, IL-5, IL-6, IL-10 or TNF-α from baseline to 8 h post-HFM in any trial.

CONCLUSIONS

In summary, we found that in overweight, insufficiently active men, neither 30 nor 60 min of moderate-intensity exercise performed 12 h prior to a HFM attenuated postprandial lipemia or inflammation, which could potentially be explained by the partial caloric replacement of exercise energy expenditure.

Effect of acute interval sprinting exercise on postprandial lipemia of sedentary young men

[Purpose]

Postprandial lipemia (PPL) contributesto the development of atherosclerosis. In females, repeated 8-second bouts of interval sprinting exercise reduced PPL, however, the effect of 8-second bouts of interval sprinting on PPL of overweight males is undetermined. Thus, the effect of 8-secondsof interval sprinting for 20 min, the night before ingestion of a high-fat meal (HFM), on plasma triacylglycerol(TG) levelswas examined.

[Methods]

Ten overweight males acted as participants (BMI = 26±3.0kg/m2, age 22 ± 2.5 years). A crossover design was employed withinterval sprinting and a noexercise condition separated by 7days. Participants consumed a milkshake (high-fat meal;HFM = 4170 kJ/993 Kcal) the morning after an overnight fast, followed by 4 hourly blood samples. Participants performedone bout of interval sprinting (8seconds sprinting at 110-115rpm, 12seconds active recovery at ~60rpm for 20 minutes) the evening before the consumption of the HFM.

[Results]

Postprandial TG was 22.5% lower in the interval sprinting compared to the noexercise condition when comparing the change in total area under the curve (ΔAUCT): ISE(7.15±1.90mmolL^-1h^-1) versus noexercise (9.22±3.44mmolL^-1h^-1), p=.014. The correlation between fasting TG levels in the noexercise condition and total reduction in AUCT between the conditions was significant (r=.87, p=.001).

[Conclusion]

One 20-min bout of interval sprinting,the night before consumption of a HFM,significantly attenuated the PPL response of sedentary males.

Consumption of Fish Oil Providing Amounts of Eicosapentaenoic Acid and Docosahexaenoic Acid That Can Be Obtained from the Diet Reduces Blood Pressure in Adults with Systolic Hypertension: A Retrospective Analysis

BACKGROUND

Although many randomized controlled trials (RCTs) have examined the effects of the n-3 (ω-3) fatty acids eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) on blood pressure (BP) and vascular function, the majority have used doses of EPA+DHA of >3 g/d, which are unlikely to be achieved by dietary manipulation.

OBJECTIVE

The objective was to examine, by using a retrospective analysis from a multicenter RCT, the impact of recommended EPA+DHA intakes achievable through diet on systolic and diastolic BPs and microvascular function in adults in the United Kingdom.

METHODS

In a double-blind, placebo-controlled RCT, healthy men and women (n = 312) consumed a control oil or fish oil (FO) providing 0.7 or 1.8 g EPA+DHA/d, in random order, each for 8 wk. Fasting BP and microvascular function (using laser Doppler iontophoresis) were assessed and plasma collected for the quantification of markers of vascular function. Participants were retrospectively genotyped for the endothelial nitric oxide synthase (eNOS) rs1799983 variant.

RESULTS

No effects of n-3 fatty acid treatment or any treatment × eNOS genotype interactions were evident in the group as a whole for any of the clinical or biochemical outcomes. Assessment of response according to hypertension status at baseline indicated a significant (P = 0.046) FO-induced reduction (mean: 5 mm Hg) in systolic BP, specifically in those with isolated systolic hypertension (n = 31). No dose response was observed.

CONCLUSIONS

These findings indicate that in adults with isolated systolic hypertension, daily doses of EPA+DHA as low as 0.7 g show clinically meaningful BP reductions, which, at a population level, could be associated with lower cardiovascular disease risk. Confirmation of findings in an RCT in which participants are prospectively recruited on the basis of BP status is required to draw definite conclusions.

Estresse oxidativo e a função endotelial: efeitos do exercício físico associado à lipemia pós-prandial

Resumo Estratégias que possam prevenir o aparecimento da aterosclerose são de extrema importância para a saúde pública. O aumento da lipemia pós-prandial tem sido investigado, dentre os fatores de risco modificáveis para o desenvolvimento dessa doença, pois pode induzir dano oxidativo e disfunção endotelial. Nesse sentido, o exercício físico é indicado na prevenção do desenvolvimento desses fatores de risco. Esta revisão tem como objetivo realizar um levantamento e comparar os estudos publicados na literatura acerca dos efeitos agudos e subagudos do exercício físico associado à lipemia pós-prandial sobre o estresse oxidativo e a função endotelial. A busca foi realizada nos idiomas português, espanhol e inglês, compreendendo trabalhos publicados até fevereiro de 2015. Com base nos estudos selecionados, conclui-se que os efeitos agudos e subagudos do exercício físico podem ser capazes de atenuar os parâmetros de risco cardiovascular após o consumo de refeição hiperlipídica.

Fast food increases postprandial cardiac workload in type 2 diabetes independent of pre-exercise: A pilot study

BACKGROUND

Type 2 diabetes aggravates the postprandial metabolic effects of food, which increase cardiovascular risk. We investigated the acute effects of fast food on postprandial left ventricular (LV) function and the potential effects of pre-exercise in type 2 diabetes individuals.

METHODS

We used a cross-over study including 10 type 2 diabetes individuals (7 male and 3 females; 53.4 ± 8.1 years; 28.3 ± 3.8 kg/m(2); type 2 diabetes duration 3.1 ± 1.8 years) and 10 controls (7 male and 3 females; 52.8 ± 10.1 years; 28.5 ± 4.2 kg/m(2)) performing high intensity interval exercise (HIIE; 40 min, 4 × 4 min intervals, 90-95% HRmax), moderate intensity exercise (MIE; 47 min, 70% HRmax) and no exercise (NE) in a random order 16-18 hours prior to fast-food ingestion. Baseline echocardiography, blood pressure and biochemical measurements were recorded prior to and 16-18 hours after exercise, and 30 minutes, 2 hours and 4 hours after fast food ingestion.

RESULTS

LV diastolic (peak early diastolic tissue velocity, peak early diastolic filling velocity), and systolic workload (global strain rate, peak systolic tissue velocity, rate pressure product) increased after consumption of fast food in both groups. In contrast to controls, the type 2 diabetes group had prolonged elevations in resting heart rate and indications of prolonged elevations in diastolic workload (peak early diastolic tissue velocity) as well as reduced systolic blood pressure after fast food consumption. No significant modifications due to exercise in the postprandial phase were seen in any group.

CONCLUSIONS

Our findings indicate that fast-food induces greater and sustained overall cardiac workload in type 2 diabetes individuals versus body mass index and age matched controls; exercise 16-18 hours pre-meal has no acute effects to the postprandial phase.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01991769.

Exercise intensity and the protection from postprandial vascular dysfunction in adolescents

Acute exercise transiently improves endothelial function and protects the vasculature from the deleterious effects of a high-fat meal (HFM). We sought to identify whether this response is dependent on exercise intensity in adolescents. Twenty adolescents (10 male, 14.3 ± 0.3 yr) completed three 1-day trials: 1) rest (CON); 2) 8 × 1 min cycling at 90% peak power with 75 s recovery [high-intensity interval exercise (HIIE)]; and 3) cycling at 90% of the gas exchange threshold [moderate-intensity exercise (MIE)] 1 h before consuming a HFM (1.50 g/kg fat). Macrovascular and microvascular endothelial function was assessed before and immediately after exercise and 3 h after the HFM by flow-mediated dilation (FMD) and laser Doppler imaging [peak reactive hyperemia (PRH)]. FMD and PRH increased 1 h after HIIE [P < 0.001, effect size (ES) = 1.20 and P = 0.048, ES = 0.56] but were unchanged after MIE. FMD and PRH were attenuated 3 h after the HFM in CON (P < 0.001, ES = 1.78 and P = 0.02, ES = 0.59). FMD remained greater 3 h after the HFM in HIIE compared with MIE (P < 0.001, ES = 1.47) and CON (P < 0.001, ES = 2.54), and in MIE compared with CON (P < 0.001, ES = 1.40). Compared with CON, PRH was greater 3 h after the HFM in HIIE (P = 0.02, ES = 0.71) and MIE (P = 0.02, ES = 0.84), with no differences between HIIE and MIE (P = 0.72, ES = 0.16). Plasma triacylglycerol concentration and total antioxidant status concentration were not different between trials. We conclude that exercise intensity plays an important role in protecting the vasculature from the deleterious effects of a HFM. Performing HIIE may provide superior vascular benefits than MIE in adolescent groups.

Effect of repeated sprints on postprandial endothelial function and triacylglycerol concentrations in adolescent boys

This study investigated whether repeated, very short duration sprints influenced endothelial function (indicated by flow-mediated dilation) and triacylglycerol concentrations following the ingestion of high-fat meals in adolescent boys. Nine adolescent boys completed two, 2-day main trials (control and exercise), in a counter-balanced, cross-over design. Participants were inactive on day 1 of the control trial but completed 40 × 6 s maximal cycle sprints on day 1 of the exercise trial. On day 2, capillary blood samples were collected and flow-mediated dilation measured prior to, and following, ingestion of a high-fat breakfast and lunch. Fasting flow-mediated dilation and plasma triacylglycerol concentration were similar in the control and exercise trial (P > 0.05). In the control trial, flow-mediated dilation was reduced by 20% and 27% following the high-fat breakfast and lunch; following exercise these reductions were negated (main effect trial, P < 0.05; interaction effect trial × time, P < 0.05). The total area under the plasma triacylglycerol concentration versus time curve was 13% lower on day 2 in the exercise trial compared to the control trial (8.65 (0.97) vs. 9.92 (1.16) mmol · l(-1) · 6.5 h, P < 0.05). These results demonstrate that repeated 6 s maximal cycle sprints can have beneficial effects on postprandial endothelial function and triacylglycerol concentrations in adolescent boys.

Doctors record higher blood pressures than nurses: systematic review and meta-analysis

BACKGROUND

The magnitude of the 'white coat effect', the alerting rise in blood pressure, is greater for doctors than nurses. This could bias interpretation of studies on nurse-led care in hypertension, and risks overestimating or overtreating high blood pressure by doctors in clinical practice.

AIM

To quantify differences between blood pressure measurements made by doctors and nurses.

DESIGN AND SETTING

Systematic review and meta-analysis using searches of MEDLINE, CENTRAL, CINAHL, Embase, journal collections, and conference abstracts.

METHOD

Studies in adults reporting mean blood pressures measured by doctors and nurses at the same visit were selected, and mean blood pressures extracted, by two reviewers. Study risk of bias was assessed using modified Cochrane criteria. Outcomes were pooled across studies using random effects meta-analysis.

RESULTS

In total, 15 studies (11 hypertensive; four mixed hypertensive and normotensive populations) were included from 1899 unique citations. Compared with doctors' measurements, nurse-measured blood pressures were lower (weighted mean differences: systolic -7.0 [95% confidence interval {CI} = -4.7 to -9.2] mmHg, diastolic -3.8 [95% CI = -2.2 to -5.4] mmHg). For studies at low risk of bias, differences were lower: systolic -4.6 (95% CI = -1.9 to -7.3) mmHg; diastolic -1.7 (95% CI = -0.1 to -3.2) mmHg. White coat hypertension was diagnosed more frequently based on doctors' than on nurses' readings: relative risk 1.6 (95% CI =1.2 to 2.1).

CONCLUSIONS

The white coat effect is smaller for blood pressure measurements made by nurses than by doctors. This systematic difference has implications for hypertension diagnosis and management. Caution is required in pooling data from studies using both nurse- and doctor-measured blood pressures.

Breaking up prolonged sitting with light-intensity walking improves postprandial glycemia, but breaking up sitting with standing does not

OBJECTIVES

To explore the effects of breaking up prolonged sitting time with standing or light-intensity walking on a range of cardiometabolic risk markers.

DESIGN

A randomised three-period, three-treatment acute crossover trial.

METHODS

Ten non-obese adults took part in three trials: (1) uninterrupted sitting; (2) seated with 2-min bouts of standing every 20 min; and (3) seated with 2-min bouts of light-intensity walking every 20 min. Two standardised test drinks (total 80.3 carbohydrate, 50 g fat) were provided after an initial 1-h period of uninterrupted sitting. Plasma glucose and blood pressure were assessed hourly to calculate area under the curve. Total cholesterol, HDL, and triglycerides were assessed at baseline and 5-h. ANOVAs were used to explore between-trial differences.

RESULTS

Glucose area under the curve was lower in the activity-break condition compared to the uninterrupted sitting and standing-break conditions: mean area under the curve 18.5 (95% CI 17, 20), 22.0 (20.5, 23.5), and 22.2 (20.7, 23.7) mmol L/5-h, respectively, p<0.001; no difference between uninterrupted sitting and standing-break conditions (p>0.05). Systolic and diastolic blood pressure area under the curve did not differ significantly between conditions, nor did responses in lipid parameters (p>0.05).

CONCLUSIONS

This study suggests that interrupting sitting time with frequent brief bouts of light-intensity activity, but not standing, imparts beneficial postprandial responses that may enhance cardiometabolic health. These findings may have importance in the design of effective interventions to reduce cardiometabolic disease risk.

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.

Effect of prior exercise on postprandial lipemia: an updated quantitative review

Reducing postprandial triglycerides (TG) can lower the risk for cardiovascular disease. The purpose of this study was to perform a meta-analytic review of the literature to estimate the effect of prior exercise on postprandial lipemia. A total of 121 effects were found from 76 studies for the total TG response and 70 effects from 44 studies for the incremental area under the curve (iAUC) TG response. The weighted mean effect was moderate for the total TG response, Cohen's d = −0.60 ( P < 0.0001), and for the iAUC response, Cohen's d = −0.59 ( P < 0.0001). Moderator analysis revealed women exhibited a larger reduction ( P < .01) in the total TG response following exercise ( d = −0.96) than men ( d = −0.57); high-intensity interval training induced a larger reduction ( P < .05) in the iAUC response ( d = −1.49) than aerobic ( d = −0.58) or resistance ( d = −0.13) exercise, and participants maintaining an energy deficit following exercise exhibited a greater reduction in the iAUC response ( d = −0.67) compared with participants in energy balance ( d = −0.28). We conclude that prior acute exercise reduces postprandial lipemia, with the magnitude of effect influenced by sex, type of exercise, and energy deficit following exercise.

Sexual dimorphism in the effects of exercise on metabolism of lipids to support resting metabolism

Exercise training is generally a healthful activity and an effective intervention for reducing the risk of numerous chronic diseases including cardiovascular disease and diabetes. This is likely both a result of prevention of weight gain over time and direct effects of exercise on metabolism of lipids and the other macronutrient classes. Importantly, a single bout of exercise can alter lipid metabolism and metabolic rate for hours and even into the day following exercise, so individuals who regularly exercise, even if not performed every single day, overall could experience a substantial change in their resting metabolism that would reduce risk for metabolic diseases. However, resting metabolism does not respond similarly in all individuals to exercise participation, and indeed gender or sex is a major determinant of the response of resting lipid metabolism to prior exercise. In order to fully appreciate the metabolic effects and health benefits of exercise, the differences between men and women must be considered. In this article, the differences in the effects of exercise on resting metabolic rate, fuel selection after exercise, as well as the shuttling of triglyceride and fatty acids between tissues are discussed. Furthermore, concepts related to sex differences in the precision of homeostatic control and sex differences in the integration of metabolism between various organs are considered.

Serial assessment of local peripheral vascular function after eccentric exercise

Muscle damage is a common response to unaccustomed eccentric exercise; however, the effects of skeletal muscle damage on local vascular function and blood flow are poorly understood. This study examined serial local vascular responses to flow-mediated (endothelial-dependent) and nitroglycerin-mediated (endothelial-independent) dilation in the brachial artery after strenuous eccentric exercise and serially assessed resting blood flow. Ten healthy males performed 50 maximal eccentric unilateral arm contractions to induce muscle damage to the biceps brachii. Changes in maximal isometric strength and vascular responses were assessed 1, 24, 48, and 96 h after exercise. Mean blood velocities and arterial diameters, measured with Doppler ultrasound, were used to calculate blood flow and shear stress (expressed as area under the curve). Eccentric exercise resulted in impaired maximal isometric strength for up to 96 h (p < 0.001). Reductions in flow-mediated dilation (before exercise, 9.4% ± 2.6%; 1 h after exercise, 5.1% ± 2.2%) and nitroglycerin responses (before exercise, 26.3% ± 6.5%; 1 h after exercise, 20.7% ± 4.7%) were observed in the 1 h after exercise and remained lower for 96 h (p < 0.05). The shear stress response was attenuated immediately after exercise and remained impaired for 48 h (p < 0.05). Resting blood pressure and muscle blood flow remained similar throughout the study. Results suggest that muscle damage from eccentric exercise leads to impaired local endothelial and vascular smooth muscle function. Lower shear stress after exercise might contribute to the observed reduction in flow-mediated dilation responses, but the mechanism responsible for the attenuated endothelial-independent vasodilation remains unclear.

The endotoxin/toll-like receptor-4 axis mediates gut microvascular dysfunction associated with post-prandial lipidemia

Background

Postprandial lipidemia is important in the development of coronary artery disease (CAD). Consumption of a meal high in monounsaturated fat was correlated with acute impairment of endothelial function. However, the mechanisms underlying impaired endothelial function in the postprandial state have not yet been elucidated. The effects of polyunsaturated fat (corn oil) and monounsaturated fat (olive oil) on vascular dysfunction in intestinal postcapillary venules and arterioles were examined in wild-type (WT) mice, mice genetically deficient in TLR4 (TLR4^-/-) and mice pre-treated with antibiotics by intravital microscopy which was performed 1.0, 1.5, 2.0, 2.5 hours after oil administration. After intravital microscopy, samples of jejunum were therefore collected to test TLR4, pNF-kB p65 and SIRT1 protein expression by western blotting.

Results

Our findings showed that feeding mono-unsaturated olive oil or polyunsaturated corn oil promoted leukocyte and platelet trafficking in the gut microvasculature, and impaired endothelium-dependent arteriolar vasodilator responses during postprandial lipidemia. The expression of TLR4, pNF-kB p65 was significantly increased in mice gavaged with olive oil at 2 h and was significantly reduced in mice gavaged for 7 days with antibiotics and in TLR4 knockout (TLR4^-/-) mice. At the same time, SIRT1 protein expression is diminished by feeding olive oil for 2 h, a phenomenon that is attenuated in mice pre-treated with antibiotics and in TLR4^-/- mice. Corn oil treated mice exhibited a pattern of response similar to olive oil.

Conclusions

Dietary oils may be negative regulators of SIRT1 which activate the innate immune response through the endotoxin/TLR4 axis. Our findings establish a link between innate immunity (i.e. the endotoxin/TLR4 axis) and epigenetic controls mediated by SIRT1 in the genesis of diet associated vascular stress.

Postprandial hypertriglyceridemia and cardiovascular disease: current and future therapies

Exaggerated postprandial hypertriglyceridemia is a risk factor for cardiovascular disease. This metabolic abnormality is principally due to overproduction and/or decreased catabolism of triglyceride-rich lipoproteins (TRLs) and is a consequence of pathogenic genetic variations and other coexistent medical conditions, particularly obesity and insulin resistance. Accumulation of TRL in the postprandial state promotes the formation of small, dense low-density lipoproteins, as well as oxidative stress, inflammation, and endothelial dysfunction, all of which compound the risk of cardiovascular disease. The cardiovascular benefits of lifestyle modification (weight loss and exercise) and conventional lipid-lowering therapies (statins, fibrates, niacin, ezetimibe, and n-3 fatty acid supplementation) could involve their favorable effects on TRL metabolism. New agents, such as dual peroxisome-proliferator-activated receptor α/δ agonists, diacylglycerol, inhibitors of diacylglycerol acyltransferase 1 and microsomal triglyceride transfer protein, antisense oligonucleotides for apolipoprotein B-100 and apolipoprotein C-III, and incretin-based therapies, may enhance the treatment of postprandial lipemia, but their efficacy needs to be tested in clinical end point trials. Further work is required to develop a simple clinical protocol for investigating postprandial lipemia, as well as internationally agreed management guidelines for this type of dyslipidemia.

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.