The effect of acute aerobic exercise on pulse wave velocity and oxidative stress following postprandial hypertriglyceridemia in healthy men

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.

Acute exercise and high-glucose ingestion elicit dynamic and individualized responses in systemic markers of redox homeostasis

Background

Biomarkers of oxidation-reduction (redox) homeostasis are commonly measured in human blood to assess whether certain stimuli (e.g., high-glucose ingestion or acute exercise) lead to a state of oxidative distress (detrimental to health) or oxidative eustress (beneficial to health). Emerging research indicates that redox responses are likely to be highly individualized, yet few studies report individual responses. Furthermore, the effects of complex redox stimuli (e.g., high-glucose-ingestion after exercise) on redox homeostasis remains unclear. We investigated the effect of acute exercise (oxidative eustress), high-glucose ingestion (oxidative distress), and high-glucose ingestion after exercise (both oxidative eu/distress), on commonly measured redox biomarkers in serum/plasma.

Methods

In a randomized crossover fashion, eight healthy men (age: 28 ± 4 years; BMI: 24.5 ± 1.5 kg/m2 [mean ± SD]) completed two separate testing conditions; 1) consumption of a high-glucose mixed-nutrient meal (45% carbohydrate [1.1 g glucose.kg-1], 20% protein, and 35% fat) at rest (control trial), and 2) consumption of the same meal 3 h and 24 h after 1 h of moderate-intensity cycling exercise (exercise trial). Plasma and serum were analyzed for an array of commonly studied redox biomarkers.

Results

Oxidative stress and antioxidant defense markers (hydrogen peroxide, 8-isoprostanes, catalase, superoxide dismutase, and nitrate levels) increased immediately after exercise (p < 0.05), whereas nitric oxide activity and thiobarbituric acid reactive substances (TBARS) remained similar to baseline (p > 0.118). Nitric oxide activity and nitrate levels decreased at 3 h post-exercise compared to pre-exercise baseline levels. Depending on when the high-glucose mixed nutrient meal was ingested and the postprandial timepoint investigated, oxidative stress and antioxidant defense biomarkers either increased (hydrogen peroxide, TBARS, and superoxide dismutase), decreased (hydrogen peroxide, 8-isoprostanes, superoxide dismutase, nitric oxide activity, nitrate, and nitrite), or remained similar to pre-meal baseline levels (hydrogen peroxide, 8-isoprostanes, TBARS, catalase, superoxide dismutase and nitrite). Redox responses exhibited large inter-individual variability in the magnitude and/or direction of responses.

Conclusion

Findings highlight the necessity to interpret redox biomarkers in the context of the individual, biomarker measured, and stimuli observed. Individual redox responsiveness may be of physiological relevance and should be explored as a potential means to inform personalized redox intervention.

Postexercise Arterial Compliance and Hemodynamic Responses to Various Durations and Intensities of Aerobic Exercise

ABSTRACT

Karabulut, M, Bitting, M, and Bejar, J. Postexercise arterial compliance and hemodynamic responses to various durations and intensities of aerobic exercise. J Strength Cond Res 37(3): 589-596, 2023-The purpose of this study was to determine the effects of various aerobic training protocols using different intensities and durations on arterial compliance and hemodynamic responses. Seventeen male subjects (age = 23.1 ± 2.8 years) performed a maximal oxygen consumption (V̇ o2 max) test, followed by 3 randomly assigned exercise test sessions, each on a separate day. At the beginning of each test session, pre-exercise baseline assessments of arterial elasticity, hemodynamic variables, and pulse wave velocity (PWV) were performed after a 10-minute rest. After baseline measurements, participants performed either a bout of aerobic exercise on a treadmill for 60 minutes at 65% of V̇ o2 max (60min); 20 minutes at 40% of V̇ o2 max (20min); or for 20 minutes at 40% of V̇ o2 max with blood flow restriction (BFR; 20min-BFR). All baseline measurements were repeated at the completion of each testing session. Significance for this study was set at p ≤ 0.05. The 60min session resulted in significant increases in small artery elasticity (SAE) compared with the 20min-BFR session ( p < 0.03) and decreases in both systemic vascular resistance (SVR) and total vascular impedance (TVI) compared with both 20min sessions ( p < 0.01). The carotid to radial PWV was significantly lower after both the 60min and the 20min-BFR sessions compared with the 20min session ( p < 0.02). The findings indicate that the duration and the intensity of exercise are important factors for improving SAE, SVR, and TVI. In addition, 20min-BFR at 40% V̇ o2 max may result in site-specific modifications in PWV that is comparable with those seen after 60 minutes of exercise at 65% V̇ o2 max.

Circadian Clocks, Redox Homeostasis, and Exercise: Time to Connect the Dots?

Compelling research has documented how the circadian system is essential for the maintenance of several key biological processes including homeostasis, cardiovascular control, and glucose metabolism. Circadian clock disruptions, or losses of rhythmicity, have been implicated in the development of several diseases, premature ageing, and are regarded as health risks. Redox reactions involving reactive oxygen and nitrogen species (RONS) regulate several physiological functions such as cell signalling and the immune response. However, oxidative stress is associated with the pathological effects of RONS, resulting in a loss of cell signalling and damaging modifications to important molecules such as DNA. Direct connections have been established between circadian rhythms and oxidative stress on the basis that disruptions to circadian rhythms can affect redox biology, and vice versa, in a bi-directional relationship. For instance, the expression and activity of several key antioxidant enzymes (SOD, GPx, and CAT) appear to follow circadian patterns. Consequently, the ability to unravel these interactions has opened an exciting area of redox biology. Exercise exerts numerous benefits to health and, as a potent environmental cue, has the capacity to adjust disrupted circadian systems. In fact, the response to a given exercise stimulus may also exhibit circadian variation. At the same time, the relationship between exercise, RONS, and oxidative stress has also been scrutinised, whereby it is clear that exercise-induced RONS can elicit both helpful and potentially harmful health effects that are dependent on the type, intensity, and duration of exercise. To date, it appears that the emerging interface between circadian rhythmicity and oxidative stress/redox metabolism has not been explored in relation to exercise. This review aims to summarise the evidence supporting the conceptual link between the circadian clock, oxidative stress/redox homeostasis, and exercise stimuli. We believe carefully designed investigations of this nexus are required, which could be harnessed to tackle theories concerned with, for example, the existence of an optimal time to exercise to accrue physiological benefits.

Reactive oxygen species in exercise and insulin resistance: Working towards personalized antioxidant treatment

Reactive oxygen species (ROS) are well known for their role in insulin resistance and the development of cardiometabolic disease including type 2 diabetes mellitus (T2D). Conversely, evidence supports the notion that ROS are a necessary component for glucose cell transport and adaptation to physiological stress including exercise and muscle contraction. Although genetic rodent models and cell culture studies indicate antioxidant treatment to be an effective strategy for targeting ROS to promote health, human findings are largely inconsistent. In this review we discuss human research that has investigated antioxidant treatment and glycemic control in the context of health (healthy individuals and during exercise) and disease (insulin resistance and T2D). We have identified key factors that are likely to influence the effectiveness of antioxidant treatment: 1) the context of treatment including whether oxidative distress or eustress is present (e.g., hyperglycemia/lipidaemia or during exercise and muscle contraction); 2) whether specific endogenous antioxidant deficiencies are identified (redox screening); 3) whether antioxidant treatment is specifically designed to target and restore identified deficiencies (antioxidant specificity); 4) and the bioavailability and bioactivity of the antioxidant which are influenced by treatment dose, duration, and method of administration. The majority of human research has failed to account for these factors, limiting their ability to robustly test the effectiveness of antioxidants for health promotion and disease prevention. We propose that a modern "redox screening" and "personalized antioxidant treatment" approach is required to robustly explore redox regulation of human physiology and to elicit more effective antioxidant treatment in humans.

The Effect of a Single Bout of Continuous Aerobic Exercise on Glucose, Insulin and Glucagon Concentrations Compared to Resting Conditions in Healthy Adults: A Systematic Review, Meta-Analysis and Meta-Regression

Background

Elevated glucose and insulin levels are major risk factors in the development of cardiometabolic disease. Aerobic exercise is widely recommended to improve glycaemic control, yet its acute effect on glycaemia and glucoregulatory hormones has not been systematically reviewed and analysed in healthy adults.

Objective

To determine the effect of a single bout of continuous aerobic exercise on circulating glucose, insulin, and glucagon concentrations in healthy adults.

Methods

CENTRAL, CINAHL, Embase, Global Health, HMIC, Medline, PubMed, PsycINFO, ScienceDirect, Scopus and Web of Science databases were searched from inception to May 2020. Papers were included if they reported a randomised, crossover study measuring glucose and/or insulin and/or glucagon concentrations before and immediately after a single bout of continuous aerobic exercise (≥ 30 min) compared to a time-matched, resting control arm in healthy adults. The risk of bias and quality of evidence were assessed using the Cochrane Risk of Bias Tool and GRADE approach, respectively. Random-effects meta-analyses were performed for glucose, insulin, and glucagon. Sub-group meta-analyses and meta-regression were performed for categorical (metabolic state [postprandial or fasted], exercise mode [cycle ergometer or treadmill]) and continuous (age, body mass index, % males, maximal aerobic capacity, exercise duration, exercise intensity) covariates, respectively.

Results

42 papers (51 studies) were considered eligible: glucose (45 studies, 391 participants), insulin (38 studies, 377 participants) and glucagon (5 studies, 47 participants). Acute aerobic exercise had no significant effect on glucose concentrations (mean difference: − 0.05 mmol/L; 95% CI, − 0.22 to 0.13 mmol/L; P = 0.589; I²: 91.08%, large heterogeneity; moderate-quality evidence). Acute aerobic exercise significantly decreased insulin concentrations (mean difference: − 18.07 pmol/L; 95% CI, − 30.47 to − 5.66 pmol/L; P = 0.004; I²: 95.39%, large heterogeneity; moderate-quality evidence) and significantly increased glucagon concentrations (mean difference: 24.60 ng/L; 95% CI, 16.25 to 32.95 ng/L; P < 0.001; I²: 79.36%, large heterogeneity; moderate-quality evidence). Sub-group meta-analyses identified that metabolic state modified glucose and insulin responses, in which aerobic exercise significantly decreased glucose (mean difference: − 0.27 mmol/L; 95% CI, − 0.55 to − 0.00 mmol/L; P = 0.049; I²: 89.72%, large heterogeneity) and insulin (mean difference: − 42.63 pmol/L; 95% CI, − 66.18 to − 19.09 pmol/L; P < 0.001; I²: 81.29%, large heterogeneity) concentrations in the postprandial but not fasted state. Meta-regression revealed that the glucose concentrations were also moderated by exercise duration and maximal aerobic capacity.

Conclusions

Acute aerobic exercise performed in the postprandial state decreases glucose and insulin concentrations in healthy adults. Acute aerobic exercise also increases glucagon concentrations irrespective of metabolic state. Therefore, aerobic exercise undertaken in the postprandial state is an effective strategy to improve acute glycaemic control in healthy adults, supporting the role of aerobic exercise in reducing cardiometabolic disease incidence.

PROSPERO registration number

CRD42020191345.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40279-021-01473-2.

Postprandial lipemia causes oxidative stress in dogs

Oxidative stress (OS) has been strongly associated with postprandial lipemia (PPL) in humans, and still requires further investigation in dogs. However, since lipemia interferes with spectrophotometric determinations such as those used to assess OS, the present study investigated the effect of PPL on OS parameters of healthy dogs. Twenty dogs had lipemic postprandial samples compared to the average of two non-lipemic moments. Subsequently, PPL was simulated in vitro using a commercial lipid emulsion and twelve pools of non-lipemic serum of these dogs were used to simulate the minimum, median and maximum concentrations of triglycerides obtained during the lipemic state. Serum OS parameters were assessed using the antioxidants uric acid, albumin and total bilirubin; total antioxidant capacity (TAC); total oxidant capacity (TOC); and lipid peroxidation. In vivo PPL caused an increase in albumin, TAC-CUPRAC, TAC-FRAP, uric acid (p < 0.0001), TOC (p = 0.0012) and total bilirubin (p = 0.0245); reduction of TAC-ABTS (p = 0.0008); and did not alter the lipid peroxidation (p = 0.8983). In vitro, levels of albumin increased at the three lipemic concentrations (p < 0.0001), uric acid increased in the median and maximum levels (p < 0.0001), and total bilirubin concentration increased only at the maximum lipemic level (p = 0.0012). All lipemic levels tested increased TAC-ABTS (p = 0.0011) and TAC-FRAP (p < 0.0001). TAC-CUPRAC (p = 0.5002), TOC (p = 0.5938) and lipid peroxidation (p = 0.4235) were not affected by in vitro lipemia. In conclusion, both the in vivo postprandial state and in vitro simulated lipemia affect oxidative stress markers in dogs depending on the oxidative stress marker, and thus the postprandial state and/or lipemic samples should be avoided.

The Acute Effect of Exercise on Arterial Stiffness in Healthy Subjects: A Meta-Analysis

Arterial stiffness has been shown to be a subclinical marker associated with cardiovascular disease. Meanwhile, long-term exercise has been demonstrated to reduce arterial stiffness, providing a decrease in cardiovascular risk. However, the acute effect of exercise on arterial stiffness is unclear. This systematic review and meta-analysis aimed to assess the acute effect of exercise interventions on arterial stiffness in healthy adults. We searched the Cochrane Central Register of Controlled Trials, MEDLINE (via Pubmed), Scopus, and Web of Science databases, from their inception to 30 June 2020. A meta-analysis was performed to evaluate the acute effect of exercise on arterial stiffness using random-effects models to calculate pooled effect size estimates and their corresponding 95% CI. Pulse wave velocity was measured as an arterial stiffness index. The 30 studies included in the meta-analysis showed that pulse wave velocity was not modified immediately after exercise (0 min post) (ES: 0.02; 95% CI: −0.22, 0.26), but subsequently decreased 30 min after exercise (ES: −0.27; 95% CI: −0.43, −0.12). Thereafter, pulse wave velocity increased to its initial value 24 h after exercise (ES: −0.07; 95% CI: −0.21, 0.07). Our results show that, although there is a significant reduction in pulse wave velocity 30 min after exercise, the levels of arterial stiffness return to their basal levels after 24 h. These findings could imply that, in order to achieve improvements in pulse wave velocity, exercise should be performed on a daily basis.

No Evidence That Hyperpnea-Based Respiratory Muscle Training Affects Indexes of Cardiovascular Health in Young Healthy Adults

Introduction

The chronic effects of respiratory muscle training (RMT) on the cardiovascular system remain unclear. This investigation tested to which degree a single sessions of RMT with or without added vibration, which could enhance peripheral blood flow and vascular response, or a 4-week RMT program could result in changes in pulse wave velocity (PWV), blood pressure (systolic, SBP; diastolic, DBP) and other markers of cardiovascular health.

Methods

Sixteen young and healthy participants (8 m/8f) performed 15 min of either continuous normocapnic hyperpnea (RMET), sprint-interval-type hyperpnea (RMSIT) or a control session (quiet sitting). Sessions were performed once with and once without passive vibration of the lower limbs. To assess training-induced adaptations, thirty-four young and healthy participants (17 m/17f) were measured before and after 4 weeks (three weekly sessions) of RMET (n = 13, 30-min sessions of normocapnic hyperpnea), RMSIT [n = 11, 6 × 1 min (1 min break) normocapnic hyperpnea with added resistance] or placebo (n = 10).

Results

SBP was elevated from baseline at 5 min after each RMT session, but returned to baseline levels after 15 min, whereas DBP was unchanged from baseline following RMT. Carotid-femoral PWV (PWV_CF) was elevated at 5 and 15 min after RMT compared to baseline (main effect of time, P = 0.001), whereas no changes were seen for carotid-radial PWV (PWV_CR) or the PWV_CF/PWV_CR ratio. Vibration had no effects in any of the interventions. Following the 4-week training period, no differences from the placebo group were seen for SBP (P = 0.686), DBP (P = 0.233), PWV_CF (P = 0.844), PWV_CR (P = 0.815) or the PWV_CF/PWV_CR ratio (P = 0.389).

Discussion/Conclusion

Although 15 min of RMT sessions elicited transient increases in PWV_CF and SBP, no changes were detected following 4 weeks of either RMET or RMSIT. Adding passive vibration of the lower limbs during RMT sessions did not provide additional value to the session with regards to vascular responses.

Preceding exercise and postprandial hypertriglyceridemia: effects on lymphocyte cell DNA damage and vascular inflammation

Background

Exercise has proved effective in attenuating the unfavourable response normally associated with postprandial hypertriglyceridemia (PHTG) and accompanying oxidative stress. Yet, the acute effects of prior exercise and PHTG on DNA damage remains unknown. The purpose of this study was to examine if walking alters PHTG-induced oxidative damage and the interrelated inflammatory mechanisms.

Methods

Twelve apparently healthy, recreationally active, male participants (22.4 ± 4.1 years; 179.2 ± 6 cm; 84.2 ± 14.7 kg; 51.3 ± 8.6 ml·kg^− 1·min^− 1) completed a randomised, crossover study consisting of two trials: (1) a high-fat meal alone (resting control) or (2) a high-fat meal immediately following 1 h of moderate exercise (65% maximal heart rate). Venous blood samples were collected at baseline, immediately post-exercise or rest, as well as at 2, 4 and 6 h post-meal. Biomarkers of oxidative damage (DNA single-strand breaks, lipid peroxidation and free radical metabolism) and inflammation were determined using conventional biochemistry techniques.

Results

DNA damage, lipid peroxidation, free radical metabolism and triglycerides increased postprandially (main effect for time, p < 0.05), regardless of completing 1 h of preceding moderate intensity exercise. Plasma antioxidants (α-tocopherol and γ-tocopherol) also mobilised in response to the high-fat meal (main effect for time, p < 0.05), but no changes were detected for retinol-binding protein-4.

Conclusion

The ingestion of a high fat meal induces postprandial oxidative stress, inflammation and a rise in DNA damage that remains unaltered by one hour of preceding exercise.

Acute effect of healthy walking on arterial stiffness in patients with type 2 diabetes and differences by age and sex: a pre-post intervention study

BACKGROUND

Daily aerobic exercise such as healthy walking could have an immediate effect on parameters of arterial stiffness; however, there is little evidence in the diabetic population. Our aim, therefore, is to evaluate the association between healthy walking and acute effects on the parameters of arterial stiffness in subjects with type 2 diabetes.

METHODS

The Effectiveness of a multifactorial intervention in diabetics study (EMID), is a study based on an application for smartphones, healthy walking and a nutritional workshop in patients with type 2 diabetes in primary care, is a randomized controlled trial of two parallel groups. This is a subanalysis of the intervention group to evaluate the response to the healthy walking according to age and sex, in 89 subjects with type 2 diabetes, aged between 40 and 70 years. The intervention was a 4 km of a healthy walking at low-moderate intensity. To value our aim, the main study variables were measured before and after it.

RESULTS

The study population had an average age of 65.0 years (61.2-68.1). After the healthy walking, there was a decrease in the parameters of arterial stiffness: Cardio ankle vascular index (CAVI) of - 0.2 (95%CI:-0.4 to - 0.1) and pulse pressure (PP) of the lower extremities of - 3.9 mmHg (95%CI: -5.9 to - 2.0). Furthermore, in the lower extremities there was a decrease in systolic blood pressure of - 5.3 mmHg (95% CI: -7.3 mmHg to - 3.3 mmHg), in diastolic blood pressure of - 1.5 mmHg (95% CI: -2.6 mmHg to - 0.4 mmHg) (p < 0.05 for all). It is observed that males have an OR of 2.981 (IC = 95% 1.095 to 8.119) to achieve a reduction in the CAVI (p < 0.05) and an OR of 2.433 (95%CI: 0.871 to 6.794) in the ankle PP (p > 0.05), compared with females.

CONCLUSIONS

The findings of this study suggest that daily aerobic exercise at a low to moderate intensity, such as healthy walking, has an immediate beneficial effect on the cardio-ankle vascular index, especially in males.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02991079 .

Carotid Arterial Stiffness and Hemodynamic Responses to Acute Cycling Intervention at Different Times during 12-Week Supervised Exercise Training Period

This paper studied the alterations in arterial stiffness and hemodynamic responses during resting state and immediately following acute cycling intervention at different times across 12-week supervised exercise training. Twenty-six sedentary young males participated in the exercise training program at moderate intensity. Arterial stiffness and hemodynamic variables of the right common carotid artery were measured and computed during resting state and immediately following acute cycling intervention at weeks 0, 4, 8, and 12. Across the 12-week exercise training, carotid arterial stiffness was decreased at weeks 8 and 12 and hemodynamic variables were improved at week 12 during resting state. In response to acute cycling intervention, carotid arterial stiffness exhibited an acute increase foremost at 8 weeks, and arterial maximal and mean diameters showed acute decreases at weeks 0 and 4. Despite significant differences in arterial stiffness and hemodynamic variables between resting state and immediately after acute intervention for each time period, these differences presented a progressive decrease across the 12-week exercise training. In conclusion, long-term exercise training not only improved carotid arterial stiffness and hemodynamic alterations when at rest but also negated the acute responses of carotid arterial stiffness and hemodynamic variables to acute cycling intervention.

Acute effects of repeated bouts of aerobic exercise on arterial stiffness after glucose ingestion

The aim of this study was to investigate the acute repeated bouts of aerobic exercise decrease leg arterial stiffness. However, the influence of repeated bouts of aerobic exercise on arterial stiffness after glucose ingestion is unknown. The present study investigates the acute effects of repeated bouts of aerobic exercise on arterial stiffness after the 75-g oral glucose tolerance test (OGTT). Ten healthy young men (age, 23.2 ± 0.9 years) performed repeated bouts of aerobic exercise trial (RE, 65% peak oxygen uptake; two 15 min bouts of cycling performed 20 min apart) and control trial (CON, seated and resting in a quiet room) at 80 min before the 75-g OGTT on separate days in a randomized, controlled crossover fashion. Carotid-femoral (aortic) and femoral-ankle (leg) pulse wave velocity, carotid augmentation index, brachial and ankle blood pressure, heart rate and blood glucose and insulin levels were measured before (baseline) and 30, 60 and 120 min after the 75-g OGTT. Leg pulse wave velocity, ankle systolic blood pressure and blood glucose levels increased from baseline after the 75-g OGTT in the CON trial, but not in the RE trial. The present findings indicate that acute repeated bouts of aerobic exercise before glucose ingestion suppress increases in leg arterial stiffness following glucose ingestion. Abbreviations: RE trial repeated bouts of aerobic exercise trial; CON trial control trial; BG blood glucose; VO_2peak peak oxygen uptake; PWV Pulse wave velocity; AIx carotid augmentation index; BP blood pressure; HR heart rate; CVs coefficients of variation; RPE Ratings of perceived exertion; SE standard error.

The Effects of Acute Interval Exercise and Strawberry Intake on Postprandial Lipemia

PURPOSE

Raised postprandial triglycerides (TAG) and related oxidative stresses are strongly associated with increased cardiovascular disease risk. Acute exercise and strawberry ingestion independently ameliorate postprandial lipid excursions and oxidative stress. However, the combined effects of these lifestyle interventions are unknown. We investigated whether acute exercise and strawberry consumption improved postprandial responses to an oral fat tolerance test (OFTT) in overweight/obese males.

METHODS

Overweight/obese adult males underwent four separate OFTT (73 g fat, 33 g carbohydrate) with blood sampled at baseline and hourly for 4 h after OFTT. Two OFTT contained 25 g freeze-dried strawberries and two contained strawberry flavoring (placebo). Participants performed 40 min of submaximal high-intensity interval cycling exercise 16 h before one strawberry and one placebo OFTT and rested before the remaining two OFTT. Serum TAG was analyzed, and TAG area under the curve (AUC) and incremental AUC (iAUC) were calculated. Oxidative stress markers were measured at baseline and 4 h. Differences between conditions (strawberry/placebo and exercise/rest) were assessed using repeated-measures ANOVA.

RESULTS

Ten males (age = 31.5, interquartile range = 17.8 yr, body mass index = 29.9 ± 1.8 kg·m) completed the study. TAG AUC was 1.5 mmol per 4 h·L lower for the exercise conditions compared with the rest conditions (95% confidence interval [CI] = -2.3 to -0.8 mmol per 4 h·L, P = 0.001). TAG AUC was not different between strawberry and placebo conditions (95% CI = -1.3 to 0.6 mmol per 4 h·L, P = 0.475). TAG iAUC was 0.5 mmol per 4 h·L greater for the strawberry compared with the placebo conditions (95% CI = 0.1 to 1.0 mmol per 4 h·L, P = 0.021). There were no changes in markers of lipid related oxidative stress (P > 0.05).

CONCLUSION

Acute submaximal high-intensity interval cycling exercise appears effective in reducing postprandial lipemia in overweight/obese adult males. However, strawberry ingestion did not improve postprandial TAG.

Acute changes in arterial stiffness following exercise in people with metabolic syndrome

BACKGROUND

This study aims to examine the changes in arterial stiffness immediately following sub-maximal exercise in people with metabolic syndrome.

METHODS

Ninety-four adult participants (19-80 years) with metabolic syndrome gave written consent and were measured for arterial stiffness using a SphygmoCor (SCOR-PVx, Version 8.0, Atcor Medical Private Ltd, USA) immediately before and within 5-10min after an incremental shuttle walk test. The arterial stiffness measures used were pulse wave velocity (PWV), aortic pulse pressure (PP), augmentation pressure, augmentation index (AI), subendocardial viability ratio (SEVR) and ejection duration (ED).

RESULTS

There was a significant increase (p<0.05) in most of the arterial stiffness variables following exercise. Exercise capacity had a strong inverse correlation with arterial stiffness and age (p<0.01).

CONCLUSION

Age influences arterial stiffness. Exercise capacity is inversely related to arterial stiffness and age in people with metabolic syndrome. Exercise induced changes in arterial stiffness measured using pulse wave analysis is an important tool that provides further evidence in studying cardiovascular risk in metabolic syndrome.

Effects of an adapted cardiac rehabilitation programme on arterial stiffness in patients with type 2 diabetes without cardiac disease diagnosis

PURPOSE

To determine the effects of a 12-week cardiac rehabilitation programme of aerobic and resistance exercise training on arterial stiffness, peak calf vasodilatory reserve, and haemostatic markers in patients with type 2 diabetes.

METHODS

Observational cohort study examining effects of 12 weeks of exercise training in 23 subjects (13 men, 10 women; mean age of 56.1 ± 10.1 years) with type 2 diabetes mellitus. Subjects performed exercise training for 12 weeks [aerobic training 5 days/week, 70%-75% peak cardiovascular fitness (VO_2peak) and resistance training 2-3 days/week, 60% of one repetition maximum]. Vascular stiffness (pulse-wave velocity), augmentation index, peak calf vasodilatory reserve, and VO_2peak were measured pre- and post-exercise training. Secondary outcomes included heart rate variability and haemostatic measures.

RESULTS

VO_2peak increased by 16% (20.1 ± 5.5 vs 23.2 ± 8.8 mL/kg/min, p = 0.002) and abdominal circumference was reduced (101.9 ± 13.3 vs 97.9 ± 12.7 cm, p < 0.03). Vascular function was improved including central arterial stiffness (central pulse-wave velocity: 8.44 ± 1.75 vs 8.02 ± 1.60 m/s, p = 0.026) and the aortic augmentation index (21.7 ± 10.6% vs 18.3 ± 12.6%, p = 0.005); peak calf vasodilatory reserve increased from 30.3 ± 10.6 mL/100 mL/min to 38.0 ± 15.3 mL/100 mL/min ( p = 0.04). No changes were seen in heart rate variability, blood lipids, glycated haemoglobin and C-reactive protein.

CONCLUSION

A 12-week cardiac rehabilitation programme of aerobic and resistance training significantly reduces arterial stiffness and improves aerobic fitness in individuals with type 2 diabetes mellitus.

Acute Low-Volume High-Intensity Interval Exercise and Continuous Moderate-Intensity Exercise Elicit a Similar Improvement in 24-h Glycemic Control in Overweight and Obese Adults

Background: Acute exercise reduces postprandial oxidative stress and glycemia; however, the effects of exercise intensity are unclear. We investigated the effect of acute low-volume high-intensity interval-exercise (LV-HIIE) and continuous moderate-intensity exercise (CMIE) on glycemic control and oxidative stress in overweight and obese, inactive adults.

Methods: Twenty-seven adults were randomly allocated to perform a single session of LV-HIIE (9 females, 5 males; age: 30 ± 1 years; BMI: 29 ± 1 kg·m⁻²; mean ± SEM) or CMIE (8 females, 5 males; age: 30 ± 2.0; BMI: 30 ± 2.0) 1 h after consumption of a standard breakfast. Plasma redox status, glucose and insulin were measured. Continuous glucose monitoring (CGM) was conducted during the 24-h period before (rest day) and after exercise (exercise day).

Results: Plasma thiobarbituric acid reactive substances (TBARS; 29 ±13%, p < 0.01; mean percent change ±90% confidence limit), hydrogen peroxide (44 ± 16%, p < 0.01), catalase activity (50 ± 16%, p < 0.01), and superoxide dismutase activity (21 ± 6%, p < 0.01) significantly increased 1 h after breakfast (prior to exercise) compared to baseline. Exercise significantly decreased postprandial glycaemia in whole blood (−6 ± 5%, p < 0.01), irrespective of the exercise protocol. Only CMIE significantly decreased postprandial TBARS (CMIE: −33 ± 8%, p < 0.01; LV-HIIE: 11 ± 22%, p = 0.34) and hydrogen peroxide (CMIE: −25 ± 15%, p = 0.04; LV-HIIE: 7 ± 26%; p = 0.37). Acute exercise provided a similar significant improvement in 24-h average glucose levels (−5 ± 2%, p < 0.01), hyperglycemic excursions (−37 ± 60%, p < 0.01), peak glucose concentrations (−8 ± 4%, p < 0.01), and the 2-h postprandial glucose response to dinner (−9 ± 4%, p < 0.01), irrespective of the exercise protocol.

Conclusion: Despite elevated postprandial oxidative stress compared to CMIE, LV-HIIE is an equally effective exercise mode for improving 24-h glycemic control in overweight and obese adults.

Exercise and Glycemic Control: Focus on Redox Homeostasis and Redox-Sensitive Protein Signaling

Physical inactivity, excess energy consumption, and obesity are associated with elevated systemic oxidative stress and the sustained activation of redox-sensitive stress-activated protein kinase (SAPK) and mitogen-activated protein kinase signaling pathways. Sustained SAPK activation leads to aberrant insulin signaling, impaired glycemic control, and the development and progression of cardiometabolic disease. Paradoxically, acute exercise transiently increases oxidative stress and SAPK signaling, yet postexercise glycemic control and skeletal muscle function are enhanced. Furthermore, regular exercise leads to the upregulation of antioxidant defense, which likely assists in the mitigation of chronic oxidative stress-associated disease. In this review, we explore the complex spatiotemporal interplay between exercise, oxidative stress, and glycemic control, and highlight exercise-induced reactive oxygen species and redox-sensitive protein signaling as important regulators of glucose homeostasis.

Effect of dehydration heat exposure on thoracic aorta reactivity in rats

The aim of the present study was to investigate the effect of one week dehydration heat exposure on thoracic aorta reactivity in rats. Eighteen Male Sprague-Dawley rats were randomly divided into 3 groups (n=6 each group): Control group (CN), heat exposure group (HE), dehydration heat exposure group (DHE). The CN group was exposed to a room temperature of 24°C, while the HE and DHE groups were exposed to a heat temperature of 32°C. After 7 days of heat exposure, the heart rate and blood pressure of the rats were measured, and the noradrenaline (NA)-induced contraction on the aorta rings was measured by tension recording. The average contents of malondialdehyde (MDA) and superoxide dismutase (SOD) in serum were detected using ELISA. The expression of apoptotic genes in the thoracic aorta was measured using RT-PCR. Compared with CN, the heart rate in the HE and DHE groups had a tendency to become retarded, but there was no significant difference (P>0.05). In the HE group, the systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) of the rats were significantly higher than that of the CN (P<0.05). In the DHE group, the SBP of rats was significantly higher than that of the CN (P<0.05), while the SBP, DBP, and MAP of the rats were decreased compared to the rats in the HE group, although there was no statistical significance (P>0.05). In the HE and DHE groups, the NA-induced contraction on the rats thoracic aorta ring was larger than that of the CN (P<0.05), albeit there was no significant difference between the HE and DHE groups (P>0.05). The serum SOD content decreased in the HE and DHE groups, however, the reduction was significant only in the DHE group (P<0.05). The content of MDA in serum was significantly increased in the DHE group (P<0.05). The expression of BAX was significantly upregulated whereas Bcl2 expression was decreased in the DHE group (P<0.05). The results showed that a high temperature was harmful to the body, especially in the case of lack of food and water. Additionally, the heat exposure elevated blood pressure, and increased arterial reactivity, which were related to the elevated production of MDA, led to the impaired production of SOD, and an increase of cell apoptosis. These findings are useful to understand the influence of dehydrated heat exposure on the vascular function, and they provide certain theoretical and experimental guidance for protection under high temperature.

Acute effects of aerobic exercise intensity on arterial stiffness after glucose ingestion in young men

Arterial stiffness increases after glucose ingestion. Acute low- and moderate-intensity aerobic exercise decreases arterial stiffness. However, the acute effects of 30 min of cycling at low- and moderate-intensity [25% (LE trial) and 65% (ME trial) peak oxygen uptake, respectively] on arterial stiffness at 30, 60 and 120 min of a postexercise glucose ingestion. Ten healthy young men (age, 22·4 ± 0·5 years) performed LE and ME trials on separate days in a randomized controlled crossover fashion. Carotid-femoral (aortic) pulse wave velocity (PWV), femoral-ankle (leg) PWV, carotid augmentation index (AIx) and carotid blood pressure (BP) (applanation tonometry), brachial and ankle BP (oscillometric device), heart rate (HR) (electrocardiography), blood glucose (UV-hexokinase method) and blood insulin (CLEIA method) levels were measured at before (baseline) and at 30, 60 and 120 min after the 75-g OGTT. Leg PWV, ankle pulse pressure and BG levels significantly increased from baseline after the 75-g OGTT in the LE trial (P<0·05), but not in the ME trial. Insulin levels and HR significantly increased from baseline after the 75-g OGTT in both trials (P<0·05). Aortic PWV, carotid AIx, brachial BP and carotid BP did not change from baseline after the 75-g OGTT in both trials. The present findings indicate that aerobic exercise at moderate intensity before glucose ingestion suppresses increases leg arterial stiffness after glucose ingestion.

Effect of exercise intensity on postprandial lipemia, markers of oxidative stress, and endothelial function after a high-fat meal

The aim of this study was to compare the effects of 2 different exercise intensities on postprandial lipemia, oxidative stress markers, and endothelial function after a high-fat meal (HFM). Eleven young men completed 2-day trials in 3 conditions: rest, moderate-intensity exercise (MI-Exercise) and heavy-intensity exercise (HI-Exercise). Subjects performed an exercise bout or no exercise (Rest) on the evening of day 1. On the morning of day 2, an HFM was provided. Blood was sampled at fasting (0 h) and every hour from 1 to 5 h during the postprandial period for triacylglycerol (TAG), thiobarbituric acid reactive substance (TBARS), and nitrite/nitrate (NOx) concentrations. Flow-mediated dilatation (FMD) was also analyzed. TAG concentrations were reduced in exercise conditions compared with Rest during the postprandial period (P < 0.004). TAG incremental area under the curve (iAUC) was smaller after HI-Exercise compared with Rest (P = 0.012). TBARS concentrations were reduced in MI-Exercise compared with Rest (P < 0.041). FMD was higher in exercise conditions than Rest at 0 h (P < 0.02) and NOx concentrations were enhanced in MI-Exercise compared with Rest at 0 h (P < 0.01). These results suggest that acute exercise can reduce lipemia after an HFM. However, HI-Exercise showed to be more effective in reducing iAUC TAG, which might suggest higher protection against postprandial TAG enhancement. Conversely, MI-Exercise can be beneficial to attenuate the susceptibility of oxidative damage induced by an HFM and to increase endothelial function in the fasted state compared with Rest.

The acute effect of maximal exercise on central and peripheral arterial stiffness indices and hemodynamics in children and adults

This study compared the effects of a bout of maximal running exercise on arterial stiffness in children and adults. Right carotid blood pressure and artery stiffness indices measured by pulse wave velocity (PWV), compliance and distensibility coefficients, stiffness index α and β (echo-tracking), contralateral carotid blood pressure, and upper and lower limb and central/aortic PWV (applanation tonometry) were taken at rest and 10 min after a bout of maximal treadmill running in 34 children (7.38 ± 0.38 years) and 45 young adults (25.22 ± 0.91 years) having similar aerobic potential. Two-by-two repeated measures analysis of variance and analysis of covariance were used to detect differences with exercise between groups. Carotid pulse pressure (PP; η(2) = 0.394) increased more in adults after exercise (p < 0.05). Compliance (η(2) = 0.385) decreased in particular in adults and in those with high changes in distending pressure, similarly to stiffness index α and β. Carotid PWV increased more in adults and was related to local changes in PP but not mean arterial pressure (MAP). Stiffness in the lower limbs decreased (η(2) = 0.115) but apparently only in those with small MAP changes (η(2) = 0.111). No significant exercise or group interaction effects were found when variables were adjusted to height. An acute bout of maximal exercise can alter arterial stiffness and hemodynamics in the carotid artery and within the active muscle beds. Arterial stiffness and hemodynamic response to metabolic demands during exercise in children simply reflect their smaller body size and may not indicate a particular physiological difference compared with adults.

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.

Effects of Breaking Sitting by Standing and Acute Exercise on Postprandial Oxidative Stress

Background:

Sedentary behavior, which includes sitting and TV viewing, has been identified as an independent risk factor for type 2 diabetes and cardiovascular disease. Breaking sedentary behavior improves metabolic health such as postprandial glycaemia and insulinemia. However, the mechanisms underlying this effect are unclear.

Objectives:

Here, we examined whether breaking sitting by standing and acute exercise reduces postprandial oxidative stress.

Patient and Methods:

Fifteen participants performed 3 trials (sitting, standing, and exercise), each lasting 2 days, in a randomised order. On day one of sitting trial, participants sat in a chair. For the standing trial, the participants stood 6 times, for a 45-minute period each time. For the exercise trial, the participants walked or ran at approximately 60% of age-predicted maximum heart rate for 30 minutes. On day two of each trial, participants rested and consumed the standardised breakfast and lunch. Blood samples were collected in the morning and afternoon on day one, and fasting and at 2, 4, and 6 hours postprandially on day two.

Results:

The concentrations of serum derivatives of reactive oxygen metabolites (d-ROMs) measured at 4 hours (P = 0.064) and 6 hours (P = 0.071) tended to be higher than that in the fasting state in the sitting trial, but not standing and exercise trial (two-factor analysis of variance (ANOVA), trial × time interaction, P = 0.006).

Conclusions:

Our results indicate the importance of reducing sitting time for improving postprandial oxidative stress status.

Does moderate intensity exercise attenuate the postprandial lipemic and airway inflammatory response to a high-fat meal?

We investigated whether an acute bout of moderate intensity exercise in the postprandial period attenuates the triglyceride and airway inflammatory response to a high-fat meal (HFM) compared to remaining inactive in the postprandial period. Seventeen (11 M/6 F) physically active (≥ 150 min/week of moderate-vigorous physical activity (MVPA)) subjects were randomly assigned to an exercise (EX; 60% VO 2peak) or sedentary (CON) condition after a HFM (10 kcal/kg, 63% fat). Blood analytes and airway inflammation via exhaled nitric oxide (eNO) were measured at baseline, and 2 and 4 hours after HFM. Airway inflammation was assessed with induced sputum and cell differentials at baseline and 4 hours after HFM. Triglycerides doubled in the postprandial period (~113 ± 18%, P < 0.05), but the increase did not differ between EX and CON. Percentage of neutrophils was increased 4 hours after HFM (~17%), but the increase did not differ between EX and CON. Exhaled nitric oxide changed nonlinearly from baseline to 2 and 4 hours after HFM (P < 0.05, η (2) = 0.36). Our findings suggest that, in active individuals, an acute bout of moderate intensity exercise does not attenuate the triglyceride or airway inflammatory response to a high-fat meal.

Improvement of thoracic aortic vasoreactivity by continuous and intermittent exercise in high-fat diet-induced obese rats

The aim of the present study was to explore the effects of continuous and intermittent exercise on the thoracic aortic vasoreactivity and free radical metabolism in rats fed with a high-fat diet (HD). Sprague-Dawley (SD) rats were randomly divided into four groups (n=8, each group): Conventional diet (CD), HD, HD with continuous exercise (HCE) and HD with intermittent exercise (HIE). HCE rats swam once/day for 90 min; HIE rats performed swimming exercises 3 times/day, 30 min each time with an interval of 4 h. In these two groups, the exercise was conducted 5 days a week for 8 weeks. Rats in the CD and HD groups were fed without swimming training. At the end of the exercise, all the rats were sacrificed and the blood, thoracic aorta and myocardium were collected immediately. The thoracic aortic vasoreactivity, the plasma total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), superoxide dismutase (SOD), malondialdehyde (MDA) and vascular endothelial nitric oxide synthase (eNOS) gene expression were measured. Compared to the control group, in the HD group the enhanced contractile response of the thoracic aortic rings to noradrenaline (NA) was observed (P<0.01). The levels of TC and LDL (P<0.01) were also increased in serum while the HDL level was reduced without statistical significance. In addition, the MDA content was upregulated in the myocardium, but the SOD level decreased (P<0.01). Furthermore, the expression of vascular eNOS mRNA was reduced (P<0.01). However, following the exercise the contraction of the thoracic aorta vascular rings to NA was reduced in the HCE and HIE groups (P<0.01), and the decreased contractile response was more evident in the HIE group compared to the HCE group (P<0.01). Additionally, in the HCE group the level of TG (P<0.01) was decreased, while the HDL (P<0.01) level was increased. Although the reduction of the TC and LDL level was also observed there was no significant difference compared to the HD group. In the HIE group, the TG, TC and LDL were downregulated while the HDL was enhanced (P<0.01). The TC and LDL levels were decreased more than those of the HCE group; however, there was no significant difference in the TG and HDL levels between these two groups; additionally, in these two exercise groups, the MDA level was decreased in the myocardium (P<0.01) while the SOD level was increased (P<0.01). Furthermore, the expression of eNOS was upregulated (P<0.01), but the increase was much more in the HIE group than that in the HCE group. In conclusion, exercise may attenuate the aggravated contraction induced by NA and improve the activity of the thoracic aorta in obese rats, which may be associated with enhanced antioxidant enzyme activity and reduced free radical generating. Additionally, intermittent exercise is better than the continuous exercise in improving the thoracic aorta vasoreactivity.

Dichotomous mechanisms of aortic stiffening in high-fat diet fed young and old B6D2F1 mice

Abstract Advancing age is associated with increased stiffness of large elastic arteries as assessed by aortic pulse wave velocity (PWV). Greater PWV, associated with increased risk of cardiovascular diseases, may result from altered expression of the extracellular matrix proteins, collagen and elastin, as well as cross-linking of proteins by advanced glycation end products (AGEs). Indeed, aortic PWV is greater in old (28-31 months) normal chow (NC, 16% fat by kcal)-fed male B6D2F1 mice compared with young (Y: 5-7 months) NC-fed mice (397 ± 8 vs. 324 ± 14 cm/s, P < 0.05). Aging also induces a ~120% increase in total aortic collagen content assessed by picosirius red stain, a ~40% reduction in medial elastin assessed by Verhoeff's Van Geison stain, as well as a 90% greater abundance of AGEs in the aorta (P < 0.05). The typical American diet contains high dietary fat and may contribute to the etiology of arterial stiffening. To that end, we hypothesized that the age-associated detriments in arterial stiffening are exacerbated in the face of high dietary fat. In young animals, high-fat (40% fat by kcal) diet increases aortic stiffness by 120 ± 18 cm/s relative to age-matched NC-fed mice (P < 0.001). High-fat was without effect on aortic collagen or AGEs content in young animals; however, elastin was greatly reduced (~30%) after high-fat in young mice. In old animals, high-fat increased aortic stiffness by 108 ± 47 cm/s but was without effect on total collagen content, medial elastin, or AGEs. These data demonstrate that both aging and high-fat diet increase aortic stiffness, and although a reduction in medial elastin may underlie increased stiffness in young mice, stiffening of the aorta in old mice after high-fat diet does not appear to result from a similar structural modification.

Acute effects of continuous and interval low-intensity exercise on arterial stiffness in healthy young men

PURPOSE

To examine and compare systemic arterial stiffness responses in humans to acute continuous and interval low-intensity exercise.

METHODS

Fifteen healthy young men (21.2 ± 0.4 years) underwent non-exercise control (CON), continuous exercise (CE), and interval exercise trial (IE) in a randomized balanced self-control crossover design. Systemic arterial stiffness (Cardio-ankle vascular index, CAVI) was measured at baseline (BL), immediately after (0 min) and 40 min after exercise in CE and IE trials, and at corresponding time points in CON trial. Subjects cycled continuously for 30 min at 35 % heart rate reserve after BL measurement in CE trial, whereas in IE trial, subjects cycled two bouts of 15-min separated by a 20-min rest at the same intensity.

RESULTS

There were no significant CAVI changes with time in CON trial (6.7 ± 0.1, 6.7 ± 0.1, 6.6 ± 0.1 at BL, 0 and 40 min, respectively). In CE trial, CAVI decreased immediately after exercise (0 min) and returned to baseline after 40 min of recovery (6.5 ± 0.1, 5.5 ± 0.2, 6.4 ± 0.1 at BL, 0 and 40 min, respectively). IE elicited similar CAVI reduction from 6.7 ± 0.1 at baseline to 5.6 ± 0.2 at 0 min: however, CAVI at 40 min remained significantly low compared to that of CON trial at corresponding time point (6.0 ± 0.1 vs. 6.6 ± 0.1, P < 0.001).

CONCLUSION

Both acute continuous and interval low-intensity exercise elicits transient improvement in systemic arterial stiffness in humans. Despite equivalent exercise intensity and duration, interval exercise resulted in improved arterial stiffness for longer duration.

Women experience lower postprandial oxidative stress compared to men

Background

Women have enhanced triglyceride (TAG) removal from the circulation following consumption of high-fat loads, potentially leading to decreased reactive oxygen and nitrogen species (RONS) generation. This may have implications related to long-term health outcomes. We examined the oxidative stress response to high-fat feeding between men and women to determine if women are less prone to postprandial oxidative stress as compared to men.

Methods

A total of 49 women (mean age: 31 ± 12 yrs) and 49 men (mean age: 27 ± 9 yrs) consumed a high-fat meal in the morning hours following a 10–12 hour overnight fast. Blood samples were collected before and at 2 and 4 hours after the meal. Samples were analyzed for TAG, various markers of oxidative stress (malondialdehyde [MDA], hydrogen peroxide [H₂O₂], Advanced Oxidation Protein Products [AOPP], nitrate/nitrite [NOx]), and Trolox-Equivalent Antioxidant Capacity (TEAC). Area under the curve (AUC) was calculated for each variable. Effect size calculations were performed using Cohen’s d. Data from the total sample of 98 subjects were collected as a part of six previously conducted studies in our lab focused on postprandial oxidative stress, between 2007 and 2012.

Results

AUC was higher for men compared to women for TAG (249.0 ± 21.5 vs. 145.0 ± 9.8 mg·dL^-1·4 hr^-1; p < 0.0001; effect size = 0.89), MDA (2.7 ± 0.2 vs. 2.2 ± 0.1 μmol·L^-1·4 hr^-1; p = 0.009; effect size = 0.47), H₂O₂ (29.9 ± 2.4 vs. 22.5 ± 1.6 μmol·L^-1·4 hr^-1; p = 0.001; effect size = 0.55), AOPP (92.8 ± 6.9 vs. 56.4 ± 3.7 μmol·L^-1·4 hr^-1; p < 0.0001; effect size = 1.38), and TEAC (1.7 ± 0.1 vs. 1.3 ± 0.0 mmol·L^-1·4 hr^-1; p = 0.002; effect size = 0.91). No significant difference was noted for NOx (42.2 ± 4.6 vs. 38.3 ± 3.5 μmol·L^-1·4 hr^-1 for men and women, respectively; p = 0.09; effect size = 0.17).

Conclusion

In the context of the current design, women experienced lower postprandial oxidative stress compared to men. Future work is needed to determine the potential health implications of lower postprandial oxidative stress in women.

High-fat feeding, but not strenuous exercise, increases blood oxidative stress in trained men

Two prevalent origins of oxidative stress in Western society are the ingestion of high-fat meals and the performance of strenuous exercise. The purpose of this investigation was to compare the magnitude of increase in blood oxidative stress following acute feeding and acute exercise. Twelve exercise-trained men consumed a high-fat meal or performed 1 of 3 exercise bouts (steady-state aerobic; high-intensity, moderate-duration interval sprints; maximal intensity, short-duration interval sprints) in a random order, crossover design. Blood was collected before and at times following feeding and exercise. Samples were analyzed for trigylcerides, malondialdehyde (MDA), hydrogen peroxide (H(2)O(2)), advanced oxidation protein products (AOPP), nitrate/nitrite (NOx), trolox-equivalent antioxidant capacity (TEAC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). A significant condition effect was noted for MDA (p = 0.01), H(2)O(2) (p < 0.0001), and AOPP (p = 0.0006), with values highest for the meal condition. An increase of 88%, 247%, and 96% was noted from pre- to post-feeding for MDA, H(2)O(2), and AOPP, respectively. A condition effect was also noted for TEAC (p = 0.04) and CAT (p = 0.05), with values lowest for the meal condition (TEAC) and the meal and aerobic exercise condition (CAT). NOx, SOD, and GPx were relatively unaffected by feeding and exercise, while MDA, H(2)O(2), and AOPP experienced little change from pre- to postexercise (p > 0.05). These results illustrate that the magnitude of blood oxidative stress following a high-fat meal is significantly greater than that elicited by either aerobic or anaerobic exercise in a sample of exercise-trained men.

Moderate-intensity, premeal cycling blunts postprandial increases in monocyte cell surface CD18 and CD11a and endothelial microparticles following a high-fat meal in young adults

High-fat meals promote transient increases in proatherogenic factors, implicating the postprandial state in cardiovascular disease (CVD) progression. Although low-grade inflammation is associated with CVD, little research has assessed postprandial inflammation. Because of its anti-inflammatory properties, premeal exercise may counteract postprandial inflammation. The purpose of this study was to determine postprandial alterations in monocytes and circulating markers of endothelial stress and inflammation following a high-fat meal in young adults with or without premeal cycle exercise. Each subject completed two trials and was randomized to rest or cycle at a moderate intensity prior to eating a high-fat meal. Flow cytometry was used to assess monocyte cell surface receptor expression and concentration of endothelial microparticles (EMP). Plasma cytokines were assessed using Luminex MagPix. Statistical analysis was completed using separate linear mixed models analyses with first-order autoregressive (AR(1)) heterogeneous covariance structure. Significance was set at P ≤ 0.05. Percentage increases in classic monocyte CD11a and CD18 were greater overall in the postprandial period in the meal-only condition compared with the meal + exercise condition (P < 0.05). EMP concentration was 47% greater 3 h after the meal compared with premeal values in the meal-only condition (P < 0.05); no significant increase was observed in the meal + exercise condition. Premeal cycling blunted postprandial increases in EMP and CD11a and CD18. Acute, moderate-intensity exercise may help counteract possibly deleterious postprandial monocyte and endothelial cell activation.

Impact of short-term dietary modification on postprandial oxidative stress

Background

We have recently reported that short-term (21-day) dietary modification in accordance with a stringent vegan diet (i.e., a Daniel Fast) lowers blood lipids as well as biomarkers of oxidative stress. However, this work only involved measurements obtained in a fasted state. In the present study, we determined the postprandial response to a high-fat milkshake with regards to blood triglycerides (TAG), biomarkers of oxidative stress, and hemodynamic variables before and following a 21-day Daniel Fast.

Methods

Twenty-two subjects (10 men and 12 women; aged 35 ± 3 years) completed a 21-day Daniel Fast. To induce oxidative stress, a milkshake (fat = 0.8 g·kg^-1; carbohydrate = 1.0 g·kg^-1; protein = 0.25 g·kg^-1) was consumed by subjects on day one and day 22 in a rested and 12-hour fasted state. Before and at 2 and 4 h after consumption of the milkshake, heart rate (HR) and blood pressure were measured. Blood samples were also collected at these times and analyzed for TAG, malondialdehyde (MDA), hydrogen peroxide (H₂O₂), advanced oxidation protein products (AOPP), nitrate/nitrite (NOx), and Trolox Equivalent Antioxidant Capacity (TEAC).

Results

A time effect was noted for HR (p = 0.006), with values higher at 2 hr post intake of the milkshake as compared to pre intake (p < 0.05). Diastolic blood pressure was lower post fast as compared to pre fast (p = 0.02), and a trend for lower systolic blood pressure was noted (p = 0.07). Time effects were noted for TAG (p = 0.001), MDA (p < 0.0001), H₂O₂ (p < 0.0001), AOPP (p < 0.0001), and TEAC (p < 0.0001); all concentrations were higher at 2 h and 4 h post intake compared to pre intake, except for TEAC, which was lower at these times (p < 0.05). A condition effect was noted for NOx (p = 0.02), which was higher post fast as compared to pre fast. No pre/post fast × time interactions were noted (p > 0.05), with the area under the curve from pre to post fast reduced only slightly for TAG (11%), MDA (11%), H₂O₂ (8%), and AOPP (12%), with a 37% increase noted for NOx.

Conclusion

Partaking in a 21-day Daniel Fast does not result in a statistically significant reduction in postprandial oxidative stress. It is possible that a longer time course of adherence to the Daniel Fast eating plan may be needed to observe significant findings.

Effect of cinnamon on gastric emptying, arterial stiffness, postprandial lipemia, glycemia, and appetite responses to high-fat breakfast

Background

Cinnamon has been shown to delay gastric emptying of a high-carbohydrate meal and reduce postprandial glycemia in healthy adults. However, it is dietary fat which is implicated in the etiology and is associated with obesity, type 2 diabetes and cardiovascular disease. We aimed to determine the effect of 3 g cinnamon (Cinnamomum zeylanicum) on GE, postprandial lipemic and glycemic responses, oxidative stress, arterial stiffness, as well as appetite sensations and subsequent food intake following a high-fat meal.

Methods

A single-blind randomized crossover study assessed nine healthy, young subjects. GE rate of a high-fat meal supplemented with 3 g cinnamon or placebo was determined using the ¹³C octanoic acid breath test. Breath, blood samples and subjective appetite ratings were collected in the fasted and during the 360 min postprandial period, followed by an ad libitum buffet meal. Gastric emptying and 1-day fatty acid intake relationships were also examined.

Results

Cinnamon did not change gastric emptying parameters, postprandial triacylglycerol or glucose concentrations, oxidative stress, arterial function or appetite (p < 0.05). Strong relationships were evident (p < 0.05) between GE T_half and 1-day palmitoleic acid (r = -0.78), eiconsenoic acid (r = -0.84) and total omega-3 intake (r = -0.72). The ingestion of 3 g cinnamon had no effect on GE, arterial stiffness and oxidative stress following a HF meal.

Conclusions

3 g cinnamon did not alter the postprandial response to a high-fat test meal. We find no evidence to support the use of 3 g cinnamon supplementation for the prevention or treatment of metabolic disease. Dietary fatty acid intake requires consideration in future gastrointestinal studies.

Trial registration

Trial registration number: at http://www.clinicaltrial.gov: NCT01350284

Serum γ-glutamyltransferase and associated damage among a She Chinese population

OBJECTIVE

It has been suggested that serum γ-glutamyltransferase is independently associated with cardiovascular mortality and atherosclerosis. The present study is to investigate the relationship between serum γ-glutamyltransferase and potential associated damage in an adult She Chinese population.

METHOD

A multistage, stratified, cluster, random sampling method was used to select an ethnically representative group of individuals aged 20-80 years in the general population. Brachial-ankle pulse-wave velocity was used to assess arterial stiffness in the general population and the Toronto Clinical Neuropathy Scoring System was used to detect diabetic peripheral polyneuropathy among populations with diabetes.

RESULTS

A total of 5385 subjects were entered into the analysis. Serum γ-glutamyltransferase levels were classified into four groups using the 25th, 50th and 75th percentiles as cut points (males: < 20, 20-29, 29-52 and > 52 U/l; females: < 13, 13-18, 18-25 and > 25 U/l). As compared with the first quartile, the relative risks of arterial stiffness were 1.418, 1.667 and 2.394 in the other three categories, respectively (test for trend P < 0.05). After adjustment in five models, serum γ-glutamyltransferase was still a risk factor of arterial stiffness. We found inverted U-shape curves in both genders and the third quartile (male: 29 52 U/l; female: 18-25 U/l) had the highest odds ratios of 1.640 and 1.529, respectively.

CONCLUSIONS

We demonstrated that high serum γ-glutamyltransferase concentrations were directly associated with the increased risk of arterial stiffness, in general, and with peripheral polyneuropathy in subjects with diabetes in an ethnic She Chinese population. Alcohol use, gender, BMI and blood pressure were related to serum γ-glutamyltransferase and were involved in the relationship between serum γ-glutamyltransferase and brachial-ankle pulse-wave velocity.

Systemic oxidative stress is increased to a greater degree in young, obese women following consumption of a high fat meal

High fat meals induce oxidative stress, which is associated with the pathogenesis of disease. Obese individuals have elevated resting biomarkers of oxidative stress compared to non-obese. We compared blood oxidative stress biomarkers in obese (n = 14; 30 ± 2 years; BMI 35 ± 1 kg•m⁻²) and non-obese (n = 16; 24 ± 2 years; BMI 23 ± 1 kg•m⁻²) women, in response to a high fat meal. Blood samples were collected pre-meal (fasted), and at 1, 2, 4 and 6 hours post meal, and assayed for trolox equivalent antioxidant capacity (TEAC), xanthine oxidase activity (XO), hydrogen peroxide (H₂O₂), malondialdehyde (MDA), triglycerides (TAG), and glucose. An obesity status effect was noted for all variables (p < 0.001; MDA p = 0.05), with obese women having higher values than non-obese, except for TEAC, for which values were lower. Time main effects were noted for all variables (p ≤ 0.01) except for TEAC and glucose, with XO, H₂O₂, MDA and TAG increasing following feeding with a peak response at the four or six hour post feeding time point. While values tended to decline by six hours post feeding in the non-obese women (agreeing with previous studies), they were maintained (MDA) or continued to increase (XO, H₂O₂ and TAG) in the obese women. While no interaction effects were noted (p > 0.05), contrasts revealed greater values in obese compared to non-obese women for XO, H₂O₂, MDA, TAG and glucose, and lower values for TEAC at times from 1–6 hours post feeding (p ≤ 0.03). We conclude that young, obese women experience a similar pattern of increase in blood oxidative stress biomarkers in response to a high fat meal, as compared to non-obese women. However, the overall oxidative stress is greater in obese women, and values appear to remain elevated for longer periods of time post feeding. These data provide insight into another potential mechanism related to obesity-mediated morbidity.

Lower postprandial oxidative stress in women compared with men

BACKGROUND

Previous studies indicate that oxidative stress is increased following intake of a high-fat meal, mediated in large part by the triglyceride (TG) response to feeding as well as fasting oxidative stress values. It has been suggested that women may process TG more efficiently after high-fat meals, based on the antilipidemic properties of estrogen. It has also been reported that women present with lower fasting oxidative stress values than do men. It is possible that women experience attenuated postprandial oxidative stress compared with men.

OBJECTIVE

The purpose of this study was to compare the postprandial TG and oxidative stress response after a lipid meal in healthy men and women.

METHODS

This study was conducted at The University of Memphis in Memphis, Tennessee, from October to December 2008. Blood samples were collected before (in a 10-hour fasted state), and at 1, 2, 4, and 6 hours after ingestion of a lipid load (heavy whipping cream at 1 g · kg(-1)). Blood samples were analyzed for TG, malondialdehyde (MDA), hydrogen peroxide (H(2)O(2)), and nitrate/nitrite (NOx). The AUC was calculated for each variable and results were compared using a t test. Effect-size calculations were performed using Cohen's d.

RESULTS

Samples from 10 men and 10 women, aged 18 to 47 years (17 subjects aged <37 years), were compared. AUC data were not significantly different for TG (mean [SEM] 330 [48] vs 354 [34] mg · dL(-1) · 6h(-1) for men and women, respectively; effect size = 0.09) or NOx (165 [25] vs 152 [17] μmol · L(-1) · 6h(-1) for men and women; effect size = 0.09). However, significant differences were noted for MDA (10.7 [1.3] vs 6.1 [0.5] μmol · L(-1) · 6h(-1) for men and women, respectively; P = 0.002; effect size = 0.61) and H(2)O(2) (154 [23] vs 86 [8] μmol · L(-1) · 6h(-1) for men and women; P = 0.013; effect size = 0.53).

CONCLUSIONS

These data indicate that women experience lower oxidative stress than do men, with regard to MDA and H(2)O(2), after ingestion of a lipid load in the form of heavy whipping cream. Considering the strong association between oxidative stress and cardiovascular disease, lower postprandial oxidative stress may be one mechanism associated with decreased risk of cardiovascular disease in women compared with men. Further research is needed to confirm this hypothesis.

Postprandial oxidative stress in response to dextrose and lipid meals of differing size

We have recently noted that ingestion of dietary lipid (in the form of heavy whipping cream) leads to greater oxidative stress than dietary carbohydrate (in the form of dextrose), when consumed in isocaloric amounts.

Objective

In the present investigation we attempted to replicate our work and also to determine the oxidative stress response to dextrose and lipid meals of two different kilocalorie (kcal) amounts.

Design

Nine young (22 ± 2 years), healthy men consumed in a random order, cross-over design one of four meals/drinks: dextrose at 75 g (300 kcals), dextrose at 150 g (600 kcals), lipid at 33 g (300 kcals), lipid at 66 g (600 kcals). Blood samples were collected Pre meal, and at 30 min, 60 min, 120 min, and 180 min post meal. Samples were assayed for glucose, triglycerides (TAG), malondialdehyde (MDA), and hydrogen peroxide (H₂O₂). Area under the curve (AUC) was calculated for each variable, and a 4 × 5 ANOVA was utilized to further analyze data.

Results

A meal × time effect (p = 0.0002) and a time effect was noted for glucose (p < 0.0001; 30 min > Pre, 1 hr, 2 hr, and 3 hr). The dextrose meals primarily contributed to this time effect. No other effects were noted for glucose (p > 0.05). A meal effect was noted for TAG (p = 0.01; 66 g lipid meal > 75 g and 150 g dextrose meals). No other effects were noted for TAG (p > 0.05). An AUC effect was noted for MDA (p = 0.04; 66 g lipid meal > 75 g and 150 g dextrose meals). A meal × time effect (p = 0.02) and a meal effect was noted for MDA (p = 0.004; 66 g lipid meal > 75 g and 150 g dextrose meals). No time effect was noted for MDA (p = 0.72). An AUC effect was noted for H₂O₂ (p = 0.0001; 66 g lipid meal > 33 g lipid meal and 75 g and 150 g dextrose meals). A meal × time effect (p = 0.0002), a meal effect (p < 0.0001; 66 g lipid meal > 33 g lipid meal and 75 g and 150 g dextrose meals), and a time effect was noted for H₂O₂ (p < 0.0001; 2 hr > Pre, 30 min, and 1 hr; 3 hr > Pre). The time effect for H₂O₂ was primarily influenced by the 66 g lipid meal.

Conclusions

These data indicate that 1) minimal oxidative stress is observed following ingestion of dextrose loads of either 75 g or 150 g, or a lipid load of 33 g and 2) lipid ingestion at 66 g leads to greater oxidative stress than lipid at 33 g or dextrose at either 75 g or 150 g. Hence, in a sample of young and healthy men, only 66 g of lipid (taken in the form of heavy whipping cream) leads to a significant increase in blood oxidative stress, as measured by MDA and H₂O₂.

Impact of serum estradiol on postprandial lipemia, oxidative stress, and inflammation across a single menstrual cycle

BACKGROUND

An abrupt rise in circulating lipids, oxidative stress, and inflammatory biomarkers is a common finding after ingestion of a high-fat meal. Estradiol, typically provided via hormone replacement therapy to postmenopausal women, has been reported to possess lipidemic, antioxidant, and antiinflammatory properties, all of which may minimize postprandial oxidative stress.

OBJECTIVE

The purpose of this study was to compare the postprandial triglyceride (TG), oxidative stress, and inflammatory responses after a lipid meal in menstruating women during the early follicular (days 1-3) and preovulatory (day 14) phases of the menstrual cycle.

METHODS

Healthy normolipidemic women (fasting blood TG, <200 mg/dL) with regular menstrual cycles reported to the Cardiorespiratory/Metabolic Laboratory at the University of Memphis, Memphis, Tennessee (October-December 2008) and consumed an identical lipid meal (heavy whipping cream and water) on 2 separate days during the menstrual cycle. Blood samples were collected premeal and 1, 2, 4, and 6 hours postmeal, then assayed for TG, malondialdehyde (MDA), hydrogen peroxide, Trolox equivalent antioxidant capacity (TEAL), nitrate/nitrite, and C-reactive protein (CRP). The AUC was calculated for each variable, and a 2 (menstrual cycle phase) x 5 (time) ANOVA with Tukey post hoc testing was also conducted. Estradiol concentration was measured in premeal samples for verification of cycle phase.

RESULTS

Ten women (mean [SD] age, 29 [11] years; 8 white, 2 black; body mass index, 22 [3] kg/m(2)) participated in the study. Despite a higher serum estradiol concentration on day 14 (113 [56] pg/mL) compared with the early follicular phase (61 [34] pg/mL), the TG, oxidative stress, and inflammatory AUC responses to feeding were not significantly different. TG (P = 0.03), MDA (P = 0.02), and hydrogen peroxide (P < 0.001) were significantly increased in response to feeding (time effect), whereas nitrate/nitrite was decreased (P = 0.01). TEAC and CRP were not significantly affected.

CONCLUSIONS

These data indicate that estradiol, at the concentrations noted in the present study, had no significant effect on postprandial TG or biomarkers of oxidative stress or inflammation in a sample of young, healthy women. It is possible that a greater divergence in circulating estradiol may be needed for significant differences to be detected, as may be the case with chronic hormone replacement therapy in postmenopausal women.

The effect of long-term, high-volume aerobic exercise training on postprandial lipemia and oxidative stress

AIMS

We have previously found no effect of moderate-volume aerobic exercise training (approximately 3 hrs*wk(-1)) on postprandial oxidative stress. It is possible that a higher volume of exercise is needed to impact postprandial oxidative stress in young, otherwise healthy individuals. Our purpose was to compare blood triglycerides (TAGs) and oxidative stress biomarkers in 10 healthy untrained and 10 healthy highly aerobically trained (eg, >or= 40 miles running*wk(-1) or >or= 150 miles cycling*wk(-1)) men and women following ingestion of a lipid meal.

METHODS

Blood samples were collected before (in a 10-hour fasted state), and 1, 2, 4, and 6 hours after ingestion of a lipid load (heavy whipping cream at 1 g*kg(-1)). Blood samples were analyzed for TAGs, malondialdehyde (MDA), hydrogen peroxide (H(2)O(2)), and nitrate/nitrite (NOx).

RESULTS

No training status or interaction effects were noted for TAGs, MDA, H2O2, or NOx (P > 0.05). However, a time effect was noted for TAGs (P = 0.01), with values higher at 2 hours (67 +/- 6 mg*dL(-1)) compared with premeal (41 +/- 6 mg*dL(-1)). A time effect was also noted for H2O2 (P = 0.0001), with values higher at 2 hours (24 +/- 3 micromol*L(-1)), 4 hours (23 +/- 3 micromol*L(-1)), and 6 hours (21 +/- 3 mumol.L(-1)) compared with premeal (7 +/- 2 micromol*L(-1)). The time effect for MDA approached significance (P = 0.07), with values peaking at 4 hours post-meal (1.59 +/- 0.16 micromol*L(-1)) compared with premeal (0.99 +/- 0.15 micromol*L(-1)).

CONCLUSION

These data indicate that aerobic exercise training (even when performed at a relatively high volume) does not attenuate postprandial lipemia or oxidative stress as compared with no exercise when healthy men and women consume a lipid load in the form of heavy whipping cream. Fasting TAG values may be most important in this regard. It is possible that long-term exercise may be capable of attenuating postprandial lipemia or oxidative stress in older individuals, those with chronic disease, or those with elevated fasting TAG values. Future work is needed to confirm these hypotheses.

Postprandial oxidative stress: influence of sex and exercise training status

An individual's sex and exercise training status may influence oxidative stress. No study has compared postprandial oxidative stress in exercise-trained and untrained men and women.

PURPOSE

To compare oxidative stress biomarkers and triglycerides (TAG) in 16 trained and 16 untrained men and women after ingestion of a high-fat meal.

METHODS

Blood samples were collected before, and at 1, 2, 4, and 6 h after intake of a high-fat meal and analyzed for Trolox-equivalent antioxidant capacity (TEAC), malondialdehyde, hydrogen peroxide, xanthine oxidase activity, protein carbonyls (PC), and TAG. Area under the curve was calculated for each variable.

RESULTS

Sex main effects were noted for all variables (P < 0.01), except for PC and TEAC (P > 0.05), with higher values for men compared with women. A training status main effect was noted for TEAC (P = 0.02), with higher values for trained compared with untrained subjects. No interaction effects were noted (P > 0.05). Regression analysis indicated that TAG explained the greatest degree of variability for oxidative stress variables, and premeal TAG best predicted the TAG response to feeding (R(2) = 0.50).

CONCLUSIONS

With the exception of TEAC, for which higher values were noted for trained compared with untrained subjects, our findings indicate that sex, not exercise training status, influences postprandial oxidative stress. Specifically, women experience a significantly lower oxidative stress response to feeding compared with men. This seems mediated in part by the TAG response to feeding.

Effect of oral acetyl L-carnitine arginate on resting and postprandial blood biomarkers in pre-diabetics

Background

Resting and postprandial oxidative stress is elevated in those with metabolic disorders such as diabetes. Antioxidant supplementation may attenuate the rise in oxidative stress following feeding. Therefore we sought to determine the effects of acetyl L-carnitine arginate (ALCA) on resting and postprandial biomarkers of glucose and lipid metabolism, as well as oxidative stress.

Methods

Twenty-nine pre-diabetic men and women were randomly assigned to either 3 g·day^-1 of ALCA (n = 14; 31 ± 3 yrs) or placebo (n = 15; 35 ± 3 yrs) in a double-blind design, to consume for eight weeks. Fasting blood samples were taken from subjects both pre and post intervention. After each fasting sample was obtained, subjects consumed a high fat, high carbohydrate meal and additional blood samples were taken at 1, 2, 4, and 6 hours post meal. Samples were analyzed for a variety of metabolic variables (e.g., glucose, HbA1c, lipid panel, C-reactive protein, nitrate/nitrite, and several markers of oxidative stress). Area under the curve (AUC) was calculated for each variable measured post meal, both pre and post intervention.

Results

ALCA, but not placebo, resulted in an increase in nitrate/nitrite (25.4 ± 1.9 to 30.1 ± 2.8 μmol·L^-1) from pre to post intervention, with post intervention values greater compared to placebo (p = 0.01). No other changes of statistical significance were noted (p > 0.05), although ALCA resulted in slight improvements in glucose (109 ± 5 to 103 ± 5 mg·dL^-1), HbA1c (6.6 ± 1.1 to 6.2 ± 1.2%), and HOMA-IR (3.3 ± 1.3 to 2.9 ± 1.2). AUC postprandial data were not statistically different between ALCA and placebo for any variable (p > 0.05). However, nitrate/nitrite demonstrated a moderate effect size (r = 0.35) for increase from pre (139.50 ± 18.35 μmol·L^-1·6 hr^-1) to post (172.40 ± 21.75 μmol·L^-1·6 hr^-1) intervention with ALCA, and the magnitude of decrease following feeding was not as pronounced as with placebo.

Conclusion

Supplementation with ALCA results in an increase in resting nitrate/nitrite in pre-diabetics, without any statistically significant change in other metabolic or oxidative stress variables measured at rest or post meal.

The role of exercise in minimizing postprandial oxidative stress in cigarette smokers

Cigarette smoking continues to pose a significant health burden on society. Two well-described mechanistic links associating smoking with morbidity and mortality include elevated blood lipids and increased oxidative stress. These variables have traditionally been measured while an individual is fasting, but evidence suggests that postprandial lipemia and oxidative stress provide more important information concerning susceptibility to disease, in particular cardiovascular disease. Cigarette smokers have elevated levels of biomarkers of oxidative stress at rest and experience impaired postprandial lipid and glucose metabolism. We have confirmed these findings while noting an exaggerated oxidative stress response to high-fat feeding. Smoking cessation is without question the best approach to minimizing smoking-induced ill health and disease, but success rates among those who attempt to quit are dismal. Other means to decrease a smoker's susceptibility to oxidative stress-related disease are needed. We propose that exercise may aid in attenuating postprandial oxidative stress, and we do so in 3 distinct ways. First, exercise stimulates an increase in endogenous antioxidant enzyme activity. Second, exercise improves blood triglyceride clearance via a reduced chylomicron-triglyceride half-life and an enhanced lipoprotein lipase activity. Third, exercise improves blood glucose clearance via an enhanced glucose 4 transport protein translocation and protein content, as well as insulin-insulin receptor binding and postreceptor signaling. Improvements in antioxidant status, as well as lipid and glucose processing, may aid greatly in minimizing feeding-induced oxidative stress in smokers. If so, and in accordance with the recent joint initiative of the American College of Sports Medicine and the American Medical Association, exercise may be viewed as a "medicine" for cigarette smokers at increased risk for postprandial oxidative stress. Research into this area may provide insight into the potential benefits of exercise for this purpose.