The effect of different training programs on antioxidant status, oxidative stress, and metabolic control in type 2 diabetes

Skeletal muscle mitochondrial H2 O2 emission increases with immobilization and decreases after aerobic training in young and older men

Currently, it is not known whether impaired mitochondrial function contributes to human ageing or whether potential impairments in mitochondrial function with age are secondary to physical inactivity. The present study investigated mitochondrial respiratory function and reactive oxygen species emission at a predefined membrane potential in young and older men subjected to 2 weeks of one-leg immobilization followed by 6 weeks of aerobic cycle training. Immobilization increased reactive oxygen species emission and decreased ATP generating respiration. Subsequent aerobic training reversed these effects. By contrast, age had no effect on the measured variables. The results of the present study support the notion that increased mitochondrial reactive oxygen species production mediates the detrimental effects seen after physical inactivity and that ageing per se does not cause mitochondrial dysfunction. Mitochondrial dysfunction, defined as increased oxidative stress and lower capacity for energy production, may be seen with ageing and may cause frailty, or it could be that it is secondary to physical inactivity. We studied the effect of 2 weeks of one-leg immobilization followed by 6 weeks of supervised cycle training on mitochondrial function in 17 young (mean ± SEM: 23 ± 1 years) and 15 older (68 ± 1 years) healthy men. Submaximal H2 O2 emission and respiration were measured simultaneously at a predefined membrane potential in isolated mitochondria from skeletal muscle using two protocols: pyruvate + malate (PM) and succinate + rotenone (SR). This allowed measurement of leak and ATP generating respiration from which the coupling efficiency can be calculated. The protein content of the anti-oxidants manganese superoxide dismuthase (MnSOD), CuZn superoxide dismuthase, catalase and gluthathione peroxidase 1 was measured by western blotting. Immobilization decreased ATP generating respiration using PM and increased H2 O2 emission using both PM and SR similarly in young and older men. Both were restored to baseline after the training period. Furthermore, MnSOD and catalase content increased with endurance training. The young men had a higher leak respiration at inclusion using PM and a higher membrane potential in State 3 using both substrate combinations. Collectively, the findings of the present study support the notion that increased mitochondrial reactive oxygen species mediates the detrimental effects seen after physical inactivity. Age, on the other hand, was not associated with impairments in anti-oxidant protein levels, mitochondrial respiration or H2 O2 emission using either protocol.

A novel method for determining human ex vivo submaximal skeletal muscle mitochondrial function

The present study utilized a novel method aiming to investigate mitochondrial function in human skeletal muscle at submaximal levels and at a predefined membrane potential. The effect of age and training status was investigated using a cross-sectional design. Ageing was found to be related to decreased leak regardless of training status. Increased training status was associated with increased mitochondrial hydrogen peroxide emission. Despite numerous studies, there is no consensus about whether mitochondrial function is altered with increased age. The novelty of the present study is the determination of mitochondrial function at submaximal activity rates, which is more physiologically relevant than the ex vivo functionality protocols used previously. Muscle biopsies were taken from 64 old or young male subjects (aged 60-70 or 20-30 years). Aged subjects were recruited as trained or untrained. Muscle biopsies were used for the isolation of mitochondria and subsequent measurements of DNA repair, anti-oxidant capacity and mitochondrial protein levels (complexes I-V). Mitochondrial function was determined by simultaneous measurement of oxygen consumption, membrane potential and hydrogen peroxide emission using pyruvate + malate (PM) or succinate + rotenone (SR) as substrates. Proton leak was lower in aged subjects when determined at the same membrane potential and was unaffected by training status. State 3 respiration was lower in aged untrained subjects. This effect, however, was alleviated in aged trained subjects. H2 O2 emission with PM was higher in aged subjects, and was exacerbated by training, although it was not changed when using SR. However, with a higher manganese superoxide dismuthase content, the trained aged subjects may actually have lower or similar mitochondrial superoxide emission compared to the untrained subjects. We conclude that ageing and the physical activity level in aged subjects are both related to changes in the intrinsic functionality of the mitochondrion in skeletal muscle. Both of these changes could be important factors in determining the metabolic health of the aged skeletal muscle cell.

Response of oxidative stress and inflammatory biomarkers to a 12-week aerobic exercise training in women with metabolic syndrome

BACKGROUND

Evidences have been highlighted the relationship among metabolic syndrome, chronic low-grade inflammation, oxidative stress and several diseases. In this sense, the aim of this study was to investigate the effects of aerobic exercise training on oxidative stress and inflammatory parameters on women with metabolic syndrome (MS).

METHODS

Twenty-three untrained women (51.86 ± 6.58 years old, BMI 30.8 ± 4.3 kg/m2) completed a 12-week treadmill exercise training, without modifications on dietary pattern. Advanced oxidation protein products (AOPP), thiobarbituric acid-reactive substances (TBARS), total thiol content (T-SH) and nitrite and nitrate (NOx) levels were assessed in plasma while the levels of interleukin-1 beta (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-α) and interferon-gamma (IFN-γ) were evaluated in the serum. The RNA expression (mRNA) of IL-1β, IL-10, TNF-α, IFN-γ, insulin receptor substrate 2 (IRS-2) and matrix metalloproteinase-9 (MMP-9) were performed inperipheral blood mononuclear cells (PBMC) of a subset with eight women with MS using real real-time polymerase chain reaction (qPCR).

RESULTS

The intervention resulted in decreased serum levels of IL-1β, IL-6, TNF-α, IFN-γ, AOPP and TBARS, besides increased levels of IL-10 and T-SH (P < 0.001). NOx concentrations were unchanged, similarly to mRNA expressions quantified in PBMC.

CONCLUSIONS

Twelve weeks of AT improved systemic oxidative stress and inflammatory biomarkers in women with MS, although PBMC mRNA expression for inflammatory pathways appeared to be unchanged. This may indicate that AT induced beneficial effects not only in physical fitness but also on health promotion through decreased oxidative damage and proinflammatory status.

Exercise interventions and peripheral arterial function: implications for cardio-metabolic disease

Physical inactivity is a major risk factor for the development of obesity and other cardiovascular (CV) disease (CVD). Vascular endothelial dysfunction is a key event in the development of CVD and is associated with a sedentary lifestyle in otherwise healthy adults. In addition, vascular endothelial dysfunction may be exacerbated in sedentary individuals who are obese and insulin resistant, since excess body fat is associated with elevated levels of pro-atherogenic inflammatory adipokines and cytokines that reduce the nitric oxide (NO) and other upstream paracrine signaling substances which reduces vascular health. Since blood flow-related shear stress is a major stimulus to NO release from the endothelium, disturbed flow or low shear stress is the likely mechanism by which vascular endothelial function is altered with inactivity. Evidence shows that regular physical exercise has beneficial effects on CVD and the risk factors that promote peripheral arterial function and health. Both aerobic and resistance exercise training are generally believed to improve endothelial function and are commonly recommended for CV health, including the management of obesity, hypertension, and insulin resistance. However, many factors including age, disease status, and race appear to influence these outcomes. Although evidence supporting the health benefits of exercise is compelling, the optimum prescription (volume and intensity) and the exact mechanism underlying the effects of exercise training on arterial function and cardiometabolic risk has yet to be identified. The focus of this review will be on the evidence supporting exercise interventions for peripheral arterial function.

Resistance exercise versus aerobic exercise for type 2 diabetes: a systematic review and meta-analysis

BACKGROUND

Resistance and aerobic exercises are both recommended as effective treatments for people with type 2 diabetes. However, the optimum type of exercise for the disease remains to be determined to inform clinical decision-making and facilitate personalized exercise prescription.

OBJECTIVES

Our objective was to investigate whether resistance exercise is comparable to aerobic exercise in terms of effectiveness and safety in people with type 2 diabetes.

DATA SOURCES

PubMed, EMBASE, CENTRAL, CINAHL, and SPORTdiscus were systematically searched up to March 2013. The reference lists of eligible studies and relevant reviews were also checked.

STUDY SELECTION

We used the following criteria to select studies for inclusion in the review: (i) the study was a randomized controlled trial; (ii) the participants were people with type 2 diabetes aged 18 years or more; (iii) the trial compared resistance exercise with aerobic exercise for a duration of at least 8 weeks, with pre-determined frequency, intensity, and duration; and (iv) the trial provided relevant data on at least one of the following: glycaemic control, blood lipids, anthropometric measures, blood pressure, fitness, health status, and adverse events.

STUDY APPRAISAL AND SYNTHESIS METHODS

The assessment of study quality was based on the Cochrane Risk of Bias tool. For effectiveness measures, differences (resistance group minus aerobic group) in the changes from baseline with the two exercises were combined, using a random-effects model wherever possible. For adverse events, the relative risks (resistance group vs. aerobic group) were combined.

RESULTS

Twelve trials (n = 626) were included. Following the exercise interventions, there was a greater reduction of glycosylated hemoglobin with aerobic exercise than with resistance exercise (difference 0.18% (1.97 mmol/mol), 95% confidence interval (CI) 0.01, 0.36). This difference became non-significant with sensitivity analysis (p = 0.14). The differences in changes from baseline were also statistically significant for body mass index (difference 0.22, 95% CI 0.06, 0.39), peak oxygen consumption (difference -1.84 mL/kg/min, 95% CI -3.07, -0.62), and maximum heart rate (difference 3.44 beats per minute, 95% CI 2.49, 4.39). Relative risks for adverse events (all) and serious adverse events were 1.17 (95% CI 0.77, 1.79) and 0.89 (95% CI 0.18, 4.39), respectively.

LIMITATIONS

Most included trials were short term (8 weeks to 6 months), and seven had important methodological limitations. Additionally, the meta-analyses for some of the secondary outcomes had a small number of participants or substantial statistical heterogeneity.

CONCLUSIONS

Although differences in some diabetic control and physical fitness measures between resistance exercise and aerobic exercise groups reached statistical significance, there is no evidence that they are of clinical importance. There is also no evidence that resistance exercise differs from aerobic exercise in impact on cardiovascular risk markers or safety. Using one or the other type of exercise for type 2 diabetes may be less important than doing some form of physical activity. Future long-term studies focusing on patient-relevant outcomes are warranted.

Home-based treadmill training improved seminal quality in adults with type 2 diabetes

OBJECTIVE

This was the first study conducted to determine the influence of home-based treadmill training on seminal quality in adults with type 2 diabetes.

MATERIAL AND METHODS

Sixty sedentary adults with type 2 diabetes volunteered for the current study. Thirty were randomly allocated to the intervention group and performed a a 14-week, home-based, treadmill training program, 3 sessions per week, consisting of a warm-up (10-15min), 40min treadmill exercise at a work intensity of 55-70% of peak heart rate (increasing by 2.5% each two weeks) measured during a maximal treadmill test, and cooling-down (5-10min). The control group included 30, age and BMI matched adults with type 2 diabetes who did not take part in any training program. Seminal quality analysis included semen volume, sperm concentration, motility and normal morphologic features. Furthermore, total antioxidant status (TAS) as well as glutathione peroxidase (GPX) activity were assessed in seminal plasma. This protocol was approved by an Institutional Ethics Committee.

RESULTS

The home-based treadmill training significantly increased sperm concentration as well as percentages of total sperm motility and normal spermatozoa. Furthermore, TAS and GPX activity were increased after the completion of the training program. No significant changes in any of the measured variables were found in the control group.

CONCLUSIONS

Home-based treadmill training improved seminal quality in adults with type 2 diabetes. A secondary finding was that seminal antioxidant defense system was significantly increased after being exercised.

Impact of different training modalities on glycaemic control and blood lipids in patients with type 2 diabetes: a systematic review and network meta-analysis

AIMS/HYPOTHESIS

This study aimed to systematically review randomised controlled trials comparing the effects of aerobic exercise training (AET), resistance training (RT) and combined training (CT) on glycaemic control and blood lipids in patients with type 2 diabetes mellitus.

METHODS

Searches were performed in MEDLINE, EMBASE and the Cochrane Library. Inclusion criteria were: type 2 diabetes mellitus, adult, supervised training and a minimum intervention period of 8 weeks. Pooled effects were calculated by fixed/random effect pairwise and Bayesian fixed/random effects network meta-analyses.

RESULTS

A total of 14 trials enrolling 915 participants were included. AET was more effective than RT in improving HbA1c levels (mean difference [MD] -0.20% [-2.2 mmol/mol]; 95% CI -0.32, -0.08; p = 0.0007, 10 trials/515 participants) and fasting glucose (MD -0.9 mmol/l; 95% CI -1.71, -0.09; p = 0.03, 8 trials/245 participants). Compared with AET, CT resulted in a significantly more pronounced reduction in HbA1c (MD -0.17% [-1.87 mmol/mol]; 95% CI -0.31, -0.03; p = 0.02, 9 trials/493 participants). Compared with RT, the MD of the change in HbA1c (MD -0.62%, [-6.82 mmol/mol]; 95% CI -0.95, -0.30; p = 0.0002, 5 trials/362 participants], fasting glucose (MD -1.99 mmol/l; 95% CI -3.07, -0.90; p = 0.0003, 3 trials/99 participants) and triacylglycerols (MD -0.28 mmol/l; 95% CI -0.46, -0.10; p = 0.003, 4 trials/213 participants) were all in favour of CT. The exclusion of trials with a high risk of bias yielded only non-significant results.

CONCLUSIONS/INTERPRETATION

The present data suggest that CT might be the most efficacious exercise modality to improve glycaemic control and blood lipids. Interpretation with respect to clinical relevance is limited by the low quality of the studies included and the limited information on the clinically important outcomes or adverse effects of exercise.

Influência do exercício físico na cognição: uma atualização sobre mecanismos fisiológicos

Embora um crescente corpo de literatura corrobore o papel benéfico do exercício sobre a cognição, não há consenso sobre os mecanismos que norteiam as adaptações cerebrais agudas e crônicas ao exercício. A presente revisão narrativa tem como objetivo apresentar e discutir os mecanismos pelos quais o exercício afeta o desempenho cognitivo. Agudamente, especula-se que os efeitos do exercício sobre a resposta cognitiva sejam mediados por aumentos no fluxo sanguíneo cerebral e, por conseguinte, no aporte de nutrientes, ou por um aumento na atividade de neurotransmissores. Cronicamente, especula-se que o exercício possa promover adaptações em estruturas cerebrais e plasticidade sináptica que culminariam com melhoras cognitivas. Tais hipóteses são discutidas à luz das evidências científicas disponíveis, tanto em modelos animais quanto em humanos.

A Case–Control Study Examining the Effects of Active Versus Sedentary Lifestyles on Measures of Body Iron Burden and Oxidative Stress in Postmenopausal Women

Approximately half of the Canadian adults have sedentary lifestyles that increase their risk of developing cardiovascular disease (CVD). Women are 10 times more likely to die from CVD than from any other disease. Their risk almost doubles with the onset of menopause, which may result in increased body iron burden and oxidative stress in sedentary women. Body iron burden may catalyze the production of cytotoxic oxygen species in vivo. We hypothesized that postmenopausal women who engage in moderate forms of aerobic exercise for at least 30 min three or more times per week would have significantly (i) lower levels of body iron burden, (ii) increased glutathione peroxidase (GPx) activity, and (iii) decreased oxidative stress in comparison to sedentary controls. An age-matched, case–control study was employed to examine the effects of active ( N = 25) versus sedentary ( N = 25) lifestyles in women aged 55–65 years on measures of body iron burden as quantified by total serum iron, transferrin saturation, and serum ferritin levels; GPx activity; and oxidative stress as quantified by 4-hydroxynonenal, malondialdehyde, and hexanal. Measures of body iron burden were significantly elevated in sedentary women in comparison to active women ( p < .001). Red cell GPx activity was higher in active women compared to sedentary women ( p < .001). Measures of oxidative stress were significantly higher in sedentary versus active women ( p < .001). These findings suggest that aerobic forms of exercise may mitigate the risk of developing CVD in postmenopausal women by improving antioxidant capacity and decreasing body iron burden.

Recent advances in obesity-induced inflammation and insulin resistance

It has been demonstrated in rodents and humans that chronic inflammation characterized by macrophage infiltration occurs mainly in adipose tissue or liver during obesity, in which activation of immune cells is closely associated with insulin sensitivity. Macrophages can be classified as classically activated (M1) macrophages that support microbicidal activity or alternatively activated (M2) macrophages that support allergic and antiparasitic responses. In the context of insulin action, M2 macrophages sustain insulin sensitivity by secreting IL-4 and IL-10, while M1 macrophages induce insulin resistance through the secretion of proinflammatory cytokines, such as TNFα. Polarization of M1/M2 is controlled by various dynamic functions of other immune cells. It has been demonstrated that, in a lean state, TH2 cells, Treg cells, natural killer T cells, or eosinophils contribute to the M2 activation of macrophages by secreting IL-4 or IL-10. In contrast, obesity causes alteration of the constituent immune cells, in which TH1 cells, B cells, neutrophils, or mast cells induce M1 activation of macrophages by the elevated secretion of TNFα and IFNγ. Increased secretion of TNFα and free fatty acids from hypertrophied adipocytes also contributes to the M1 activation of macrophages. Since obesity-induced insulin resistance is established by macrophage infiltration and the activation of immune cells inside tissues, identification of the factors that regulate accumulation and the intracellular signaling cascades that define polarization of M1/M2 would be indispensable. Regulation of these factors would lead to the pharmacological inhibition of obesity-induced insulin resistance. In this review, we introduce molecular mechanisms relevant to the pathophysiology and review the most recent studies of clinical applications targeting chronic inflammation.

Regular physical exercise as a strategy to improve antioxidant and anti-inflammatory status: benefits in type 2 diabetes mellitus

Over the last 30 years the combination of both a sedentary lifestyle and excessive food availability has led to a significant increase in the prevalence of obesity and aggravation of rates of metabolic syndrome and type 2 diabetes mellitus (T2DM). Several lines of scientific evidence have been demonstrating that a low level of physical activity and decreased daily energy expenditure leads to the accumulation of visceral fat and, consequently, the activation of the oxidative stress/inflammation cascade, which underlies the development of insulin resistant T2DM and evolution of micro, and macrovascular complications. This paper focuses on the pathophysiological pathways associated with the involvement of oxidative stress and inflammation in the development of T2DM and the impact of regular physical exercise (training) as a natural antioxidant and anti-inflammatory strategy to prevent evolution of T2DM and its serious complications.