Exercise training and impaired glucose tolerance in obese humans

The Benefits of Physical Activity for People with Obesity, Independent of Weight Loss: A Systematic Review

Purposeful weight loss continues to be the primary focus for treating obesity. However, this strategy appears to be inadequate as obesity rates continue to rise and a myriad of benefits of physical activity that affect multiple health outcomes related to obesity and associated comorbidities are not integrated into treatment strategies. There are emerging correlational data in individuals with obesity that demonstrate physical activity can be beneficial to many critical health markers, independent of weight loss or changes in BMI. This systematic review investigates interventional studies that examine health markers, independent of weight loss, in individuals with obesity. Fourteen studies were identified that utilized a variety of physical activity interventions with primary endpoints that included cellular, metabolic, systemic and brain health outcomes. The review of the literature demonstrates that for individuals with obesity, there are both small-scale and large-scale physiologic benefits that occur with increased physical activity of various modalities. Focusing on these benefits, rather than a narrow focus of weight loss alone, may increase physical activity behavior and health for individuals with obesity.

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.

Improvement of anti-Müllerian hormone and oxidative stress through regular exercise in Chinese women with polycystic ovary syndrome

PURPOSE

Structured exercise is shown to be one of the most effective lifestyle interventions for women with polycystic ovary syndrome (PCOS). Anti-Müllerian hormone (AMH) has been proposed as a marker of ovarian dysfunction, and oxidative stress plays an important role in the development of PCOS. We sought to investigate whether there was any effect of aerobic exercise on AMH levels and oxidative stress in Chinese PCOS women.

METHODS

Thirty-eight PCOS women were enrolled and divided into two groups. The exercise group carried out a 12-week exercise program, while the control group maintained their normal lifestyle. All women underwent blood tests and cardiopulmonary exercise tests (CPETs) at enrollment and at 12-week follow-up.

RESULTS

At baseline, there was no statistically significant difference between the two groups in clinical characteristics, AMH, oxidative biomarkers, and CPET parameters. After 12 weeks, body mass index (BMI) and cardiovascular fitness indexes of the exercise group were improved. We also found a decrease in AMH (P = 0.021) and malondialdehyde (MDA) (P = 0.002) and an increase in superoxide dismutase (SOD) (P = 0.009) and total antioxidant capacity (TAC) (P = 0.012) in the exercise group, while there was no change in the control group. Moreover, the change of AMH was positively associated with the change of MDA (r = 0.23, P = 0.003) in the exercise group.

CONCLUSIONS

Our findings demonstrated that 12 weeks of aerobic exercise produced beneficial effects on BMI, cardiovascular fitness, AMH, and oxidative stress in PCOS women. Favorable modification of oxidative stress might thus be an effective method for improvement of AMH in these women, which deserves further exploration in the future.

Two-year-supervised resistance training prevented diabetes incidence in people with prediabetes: A randomised control trial

AIM

The purpose of this study is to explore the long-term effects of aerobic training (AT), resistance training (RT), and combined training (AT + RT) on the prevention of T2D incidence in patients with prediabetes.

MATERIALS AND METHODS

In this randomised controlled trial, people with prediabetes (fasting glucose ≥5.6 and <7.0 mmol/L and/or 2-h glucose ≥7.8 and <11.1 mmol/L on the 75-g oral glucose tolerance test and/or haemoglobin A_1c ≥5.7% and <6.4%) were randomly assigned to the control group, AT group, RT group, or AT + RT group. Supervised exercise programmes, including AT, RT, and AT + RT, were completed for 60 minutes per day, three non-consecutive days per week for 24 months. The primary outcome was the incidence of T2D; secondary outcomes were blood glucose and lipid levels, including total cholesterol (TC) and standard 2-hour oral glucose tolerance (2hPG).

RESULTS

A total of 137 (80%) subjects with a mean age of 59 years (45 men, 92 women) entered the final analysis. After 24 months of intervention, the incidences of T2D adjusted by sex and age were significantly decreased by 74% (95% CI, 38-89), 65% (95% CI, 21-85), and 72% (95% CI, 36-87) in the AT + RT, RT, and AT groups compared with the control group (HR: AT + RT 0.26 [95% CI, 0.11-0.62], RT 0.35 [95% CI, 0.15-0.79], and AT 0.28 [95% CI, 0.13-0.64]). The cumulative T2D incidences were significantly lower in the AT + RT, RT, and AT groups than in the control group (21%, 26%, and 22% vs 69%). The blood glucose and lipid profiles improved more in the AT, RT, and AT + RT groups than in the control group.

CONCLUSION

RT and RT plus AT were as effective as isolated AT in preventing progression to T2D.

Does obesity attenuate the beneficial cardiovascular effects of cardiorespiratory fitness?

BACKGROUND AND AIMS

Higher cardiorespiratory fitness is associated with lower pulse wave velocity and arterial stiffness in normal weight individuals, and this has not been examined in obese individuals. It is unclear whether an altered body composition acts as a modifier of the association between cardiorespiratory fitness and arterial stiffness. We examined the association between peak oxygen uptake and brachial-ankle pulse wave velocity and analysed whether body composition attenuates this association in obese middle-aged individuals.

METHODS

Bio-impedance analysis-derived body composition assessment in 212 healthy and sedentary either overweight or obese individuals was followed by measurement of brachial-ankle pulse wave velocity and spiroergometric peak oxygen uptake. Multivariate analysis was performed to analyse the association between peak oxygen uptake and brachial-ankle pulse wave velocity and to assess the moderating effect of several body composition-related interaction terms (BMI, total body mass, body fat mass, waist circumference, waist-to-height ratio) on this association.

RESULTS

Peak oxygen uptake was inversely associated with brachial-ankle pulse wave velocity (β = -0.059, 95% CI = -0.099; -0.018, p = 0.005). Testing for the impact of different body composition-related interaction terms on this association showed no significance, 95% CI lateralized towards positivity.

CONCLUSIONS

This study shows an inverse association between cardiorespiratory fitness and arterial stiffness in middle-aged obese individuals. We also found a tendency towards an attenuating impact of an obese body composition on this association. Physical fitness seems to be a stronger modulator of cardiovascular risk than body composition but the success of training efforts may be compromised by obesity.

The effects of coconut oil supplementation on the body composition and lipid profile of rats submitted to physical exercise

This study aims to verify the effects of coconut oil supplementation (COS) in the body composition and lipid profile of rats submitted to physical exercise. The animals (n=6 per group) were randomly assigned to: G1=Sedentary and Non-supplemented (Control Group), G2=Sedentary and Supplemented, G3=Exercised and Non-supplemented and G4=Exercised and Supplemented. The COS protocol used was 3 mL/Kg of body mass by gavage for 28 days. The physical exercise was the vertical jumping training for 28 days. It was determined the body mass parameters, Lee Index, blood glucose and lipid profile. The COS did not interfere with body mass, but the lean body mass was lower in G3 compared to G2. The final Lee Index classified G1 and G2 as obese (>30g/cm). The lipid profile showed total cholesterol was decreased in G3, LDL-c concentration was decreased in G2, triglycerides, VLDL-c and HDL-c concentrations were increased in G2 and G4 in relation to G1 and G3. The COS decreased LDL-c/HDL-c ratio. In conclusion, the COS associated or not to physical exercise worsen others lipid parameters, like triglycerides and VLDL-c level, showing the care with the use of lipid supplements.

The Janus Head of Oxidative Stress in Metabolic Diseases and During Physical Exercise

PURPOSE OF REVIEW

Oxidative stress describes an imbalance between production and degradation of reactive oxygen species (ROS), which can damage macromolecules. However, ROS may also serve as signaling molecules activating cellular pathways involved in cell proliferation and adaptation. This review describes alterations in metabolic diseases including obesity, insulin resistance, and/or diabetes mellitus as well as responses to acute and chronic physical exercise.

RECENT FINDINGS

Chronic upregulation of oxidative stress associates with the development of insulin resistance and type 2 diabetes (T2D). While single bouts of exercise can transiently induce oxidative stress, chronic exercise promotes favorable oxidative adaptations with improvements in muscle mitochondrial biogenesis and glucose uptake. Although impaired antioxidant defense fails to scavenge ROS in metabolic diseases, chronic exercising can restore this abnormality. The different metabolic effects are likely due to variability of reactive species and discrepancies in temporal (acute vs. chronic) and local (subcellular distribution) patterns of production.

Association between aerobic exercise training effects of serum adropin level, arterial stiffness, and adiposity in obese elderly adults

Serum levels of adropin, which enhances endothelial cell release of nitric oxide (NO), are lower in obese patients. Although habitual aerobic exercise reduces arterial stiffness and adiposity, the relationship between these effects and circulating levels of adropin remains unclear. The purpose of this study was to determine if serum adropin level is associated with the effects of aerobic exercise training on arterial stiffness and adiposity in obese adults. In Experiment 1, we examined whether serum adropin levels are associated with cardiorespiratory fitness, carotid β-stiffness, plasma nitrite/nitrate (NOx) level, and abdominal visceral fat in 27 normal, 20 overweight, and 25 obese adults (age, 41-79 years). In Experiment 2, we examined the effects of an 8-week aerobic exercise training program on the relationship between serum adropin level and arterial stiffness or adiposity in 13 obese adults (age, 54-76 years). Serum adropin levels in normal, overweight, and obese adults negatively correlated with carotid β-stiffness and abdominal visceral fat, and positively correlated with plasma NOx level and cardiorespiratory fitness. After the 8-week exercise program, serum adropin levels in obese adults were elevated, and correlated with training-induced changes in carotid β-stiffness (r = -0.573, P < 0.05), plasma NOx level (r = 0.671, P < 0.05), and abdominal visceral fat (r = -0.585, P < 0.05). These findings suggest that the exercise training-induced increase in serum adropin may be related to the training effects of arterial stiffness and adiposity in obese adults.

Oxidative stress and nitric oxide are increased in obese children and correlate with cardiometabolic risk and renal function

Oxidative stress and nitric oxide (NO) appear to represent important links between obesity and cardiovascular, metabolic and/or renal disease. We investigated whether oxidative stress and NO production/metabolism are increased in overweight and obese prepubertal children and correlate with cardiometabolic risk and renal function. We performed a cross-sectional evaluation of 313 children aged 8-9 years. Anthropometrics, 24-h ambulatory blood pressure, pulse wave velocity (PWV), insulin resistance (homoeostasis model assessment index (HOMA-IR)), inflammatory/metabolic biomarkers, estimated glomerular filtration rate (eGFR), plasma total antioxidant status (TAS), plasma and urinary isoprostanes (P-Isop, U-Isop), urinary hydrogen peroxide (U-H2O2), and plasma and urinary nitrates and nitrites (P-NOx, U-NOx) were compared among normal weight, overweight and obese groups, according to WHO BMI z-score reference. U-Isop were increased in the obese group, whereas U-NOx were increased in both overweight and obese children. U-Isop were positively correlated with U-H2O2, myeloperoxidase (MPO), high-sensitivity C-reactive protein, HOMA-IR and TAG. TAS correlated negatively with U-Isop and MPO and positively with PWV. HOMA-IR and U-H2O2 were associated with higher U-Isop, independently of BMI and eGFR, and total cholesterol and U-H2O2 were associated with U-NOx, independently of BMI, eGFR values and P-NOx concentration. In overweight and obese children, eGFR decreased across P-NOx tertiles (median: 139·3 (25th, 75th percentile 128·0, 146·5), 128·0 (25th, 75th percentile 121·5, 140·4), 129·5 (25th, 75th percentile 119·4, 138·3), P for linear trend=0·003). We conclude that oxidant status and NO are increased in relation to fat accumulation and, even in young children, they translate into higher values of cardiometabolic risk markers and affect renal function.

Low Physical Activity Is Associated With Increased Arterial Stiffness in Patients Recently Diagnosed With Type 2 Diabetes

AIMS

Several studies have indicated that low physical activity is associated with increased risk of cardiovascular disease (CVD) and all-cause mortality among patients with diabetes. The association between physical activity and subclinical cardiovascular changes preceding clinical events remains to be elucidated. We investigated the relationship between physical activity and arterial stiffness, an independent predictor of CVD, in patients with type 2 diabetes and controls.

METHODS

We included 100 patients with type 2 diabetes and 100 sex- and age-matched controls in a cross-sectional study. Arterial stiffness (carotid-femoral pulse wave velocity, cfPWV) was measured using the SphygmoCor device (AtCor Medical, Sydney, Australia). Physical activity was assessed by an accelerometer (counts per minute (cpm), Actiheart (CamNtech, Cambridge, UK)) worn by the participants for up to 6 days. High vs. low levels of physical activity was defined according to the median level of activity (cpm = 31).

RESULTS

Sixty-five patients and 65 controls were included in the final analysis (median age 59 years, 55% men, median diabetes duration 1.9 years). Participants with low physical activity had higher cfPWV compared to participants with high physical activity: (i) Patients and controls combined: 9.3±1.7 m/s vs. 7.8±1.5 m/s, P < 0.001; (ii) Patients with diabetes: 9.5±1.8 m/s vs. 8.3±1.6 m/s, P = 0.02 and C) Controls: 9.0±1.4 m/s vs. 7.7±1.4 m/s, P < 0.01). The difference remained significant after adjustment for other determinants of cfPWV including whole body fat percentage (P < 0.01). No significant interaction between diabetes and the effect of low activity was seen.

CONCLUSIONS

Low physical activity is associated with increased arterial stiffness in patients recently diagnosed with type 2 diabetes and in healthy controls.

CLINICAL TRIALS REGISTRATION

Trial Number NCT00674271.

Effects of aerobic exercise on the resting heart rate, physical fitness, and arterial stiffness of female patients with metabolic syndrome

[Purpose] The purpose of this study was to investigate the effects of aerobic exercise on the resting heart rate, physical fitness, and arterial stiffness or female patients with metabolic syndrome. [Subjects and Methods] Subjects were randomly assigned to an exercise group (n=12) or a control group (n=11). Subjects in the exercise group performed aerobic exercise at 60-80% of maximum heart rate for 40 min 5 times a week for 12 weeks. The changes in metabolic syndrome risk factors, resting heart rate, physical fitness, and arterial stiffness were measured and analyzed before and after initiation of the exercise program to determine the effect of exercise. Arterial stiffness was assessed based on brachial-ankle pulse wave velocity (ba-PWV). [Results] Compared to the control group; The metabolic syndrome risk factors (weight, % body fat, waist circumference, systolic blood pressure, diastolic blood pressure, and HDL-Cholesterol) were significantly improved in the exercise: resting heart rate was significantly decreased; VO2max, muscle strength and muscle endurance were significantly increased; and ba-PWV was significantly decreased. [Conclusion] Aerobic exercise had beneficial effects on the resting heart rate, physical fitness, and arterial stiffness of patients with metabolic syndrome.

Effects of walking on low-grade inflammation and their implications for Type 2 Diabetes

Objective

Inflammatory cytokines released by hypertrophic adipocytes contribute to low-grade inflammation, a characteristic of Type 2 Diabetes. Skeletal muscle contraction during physical activity stimulates the secretion of anti-inflammatory cytokines able to counteract this inflammatory status. The aim of this study was to review the evidence of the effectiveness of walking as a physical activity intervention to reduce inflammation. The interplay between adipose tissue and skeletal muscle contributions was also investigated.

Method

A structured literature review of papers available up to December 2014 was carried out within the PubMed, Scopus and ISI Web of Science databases using the keywords “walking” and “inflammation” in order to identify the studies involving healthy subjects and subjects diagnosed with, or at increased risk of, Type 2 Diabetes.

Results

Thirty-two studies were reviewed, five investigating the acute effects of walking and twenty-seven its chronic effects (n = 21 interventional and n = 6 observational). Acute effects of walking bouts led to an increase of interleukin-6 in one study, although without any increase in the concentration of the anti-inflammatory marker interleukin-1 receptor antagonist. Eight interventional studies showed a significant reduction of inflammation. A reduction in tumour necrosis factor-α concentration was often associated with an adiposity reduction. The observational studies showed that individuals who walk more present a lower inflammatory status.

Conclusion

There is no consensus regarding the efficacy of walking in the reduction of low-grade systemic inflammation, even though a relationship cannot be excluded. In each walking bout, no anti-inflammatory effect due to the IL-6-stimulated myokine cascade can be demonstrated.

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Efficacy of walking in the reduction of inflammation is controversial.

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Walking efficacy in reducing inflammation is mediated by duration and intensity.

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People accustomed to regular walking have lower inflammatory marker concentrations.

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No anti-inflammatory effect mediated by muscular IL-6 can be demonstrated.

Effect of aerobic exercise training on arterial stiffness in obese populations : a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

Controversy exists as to whether aerobic exercise training decreases arterial stiffness in obese subjects. The aim of this study was to systematically review and quantify the effect of aerobic exercise training on arterial stiffness in obese populations.

METHODS

MEDLINE, Cochrane, Scopus, and Web of Science were searched up until May 2013 for trials assessing the effect of aerobic training interventions lasting 8 weeks or more on arterial stiffness in obese populations (body mass index ≥30 kg/m(2)). Standardized mean difference (SMD) in arterial stiffness parameters (augmentation index, β-stiffness, distensibility, pulse wave velocity, arterial waveforms) was calculated using a random-effects model. Subgroup and meta-regression analyses were used to study potential moderating factors.

RESULTS

Eight trials, comprising a total of 235 subjects with an age range of 49-70 years, met the inclusion criteria. Arterial stiffness was not significantly reduced by aerobic training (SMD -0.17; 95 % confidence interval (CI) -0.39, 0.06, P = 0.14). Similarly, post-intervention arterial stiffness was similar between the aerobic-trained and control obese groups (SMD 0.02; 95 % CI -0.28, 0.32, P = 0.88). Neither heterogeneity nor publication bias were detected in these analyses. In subgroup analyses, arterial stiffness was significantly reduced in aerobic-trained subgroups having below median values in post- minus pre-intervention systolic blood pressure (SBP) (P < 0.01), exercise intensity rating score (P < 0.01), and methodological quality score (P < 0.01). Equivalent results were obtained in meta-regression analyses.

CONCLUSION

Based on current published trials, arterial stiffness is generally not reduced in middle-aged and older obese populations in response to aerobic training. However, in studies using low-intensity aerobic training and yielding a decrease in SBP, arterial stiffness may decrease. Long-term studies are needed to assess the prognostic value of these findings.

The diabetic vasculature: physiological mechanisms of dysfunction and influence of aerobic exercise training in animal models

Diabetes mellitus (DM) is associated with a number of complications of which chronic vascular complications are undoubtedly the most complex and significant consequence. With a significant impact on health care, 50-80% of people with diabetes die of cardiovascular disease (including coronary artery disease, stroke, peripheral vascular disease and other vascular disease), making it the major cause of morbidity and mortality in diabetic patients. A healthy lifestyle is essential in the management of DM, especially the inclusion of aerobic exercise, which has been shown effective in reducing the deleterious effects in vasculature. Interest in exercise studies has increased significantly with promising results that demonstrate a future for investigation. Considering the importance of this emerging field, the aim of this mini-review is to summarize and integrate animal studies investigating physiological mechanisms of vascular dysfunction and remodeling in type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) and how these are influenced by chronic aerobic exercise training.

12 weeks' aerobic and resistance training without dietary intervention did not influence oxidative stress but aerobic training decreased atherogenic index in middle-aged men with impaired glucose regulation

Our aim was to determine whether 12 weeks' aerobic Nordic walking (NW) or resistance exercise training (RT) without diet-induced weight loss could decrease oxidative stress and atherogenic index of plasma (AIP), prevalence of metabolic syndrome (MetS) and MetS score in middle-aged men with impaired glucose regulation (IGR) (n=144. 54.5 ± 6.5 years). In addition, we compared effects of intervention between overweight and obese subgroups. Prevalence of MetS and AIP index decreased only in NW group and MetS score in both NW and RT groups but not in control group. The changes in AIP index correlated inversely with changes in plasma antioxidant capacity. The change in AIP index remained a significant independent predictor of the changes in MetS score after the model was adjusted for age, BMI and volume of exercise (MET h/week) in NW group. There were no changes in the other measured markers of oxidative stress and related cytokines (e.g. osteopontin and osteoprotegerin) in any of the groups. Nordic walking decreased prevalence of MetS and MetS score. Improved lipid profile remained a predictor of decreased MetS score only in NW group and it seems that Nordic walking has more beneficial effects on cardiovascular disease risks than RT training.