Exercise-induced oxidative stress: past, present and future

Exercise, redox homeostasis and the epigenetic landscape

Physical exercise represents one of the strongest physiological stimuli capable to induce functional and structural modifications in all biological systems. Indeed, beside the traditional genetic mechanisms, physical exercise can modulate gene expression through epigenetic modifications, namely DNA methylation, post-translational histone modification and non-coding RNA transcripts.

Initially considered as merely damaging molecules, it is now well recognized that both reactive oxygen (ROS) and nitrogen species (RNS) produced under voluntary exercise play an important role as regulatory mediators in signaling processes. While robust scientific evidences highlight the role of exercise-associated redox modifications in modulating gene expression through the genetic machinery, the understanding of their specific impact on epigenomic profile is still at an early stage. This review will provide an overview of the role of ROS and RNS in modulating the epigenetic landscape in the context of exercise-related adaptations.

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Physical exercise can modulate gene expression through epigenetic modifications.

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Epigenetic regulation of ROS/RNS generating, sensing and neutralizing enzymes can impact the cellular levels of ROS and RNS.

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ROS might act as modulators of epigenetic machinery, interfering with DNA methylation, hPTMs and ncRNAs expression.

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Redox homeostasis might hold a relevant role in the epigenetic landscape modulating exercise-related adaptations.

Chronic administration of plasma from exercised rats to sedentary rats does not induce redox and metabolic adaptations

The present study aimed to investigate whether endurance exercise-induced changes in blood plasma composition may lead to adaptations in erythrocytes, skeletal muscle and liver. Forty sedentary rats were randomly distributed into two groups: a group that was injected with pooled plasma from rats that swam until exhaustion and a group that was injected with the pooled plasma from resting rats (intravenous administration at a dose of 2 mL/kg body weight for 21 days). Total antioxidant capacity, malondialdehyde and protein carbonyls were higher in the plasma collected from the exercised rats compared to the plasma from the resting rats. Νo significant difference was found in blood and tissue redox biomarkers and in tissue metabolic markers between rats that received the "exercised" or the "non-exercised" plasma (P > 0.05). Our results demonstrate that plasma injections from exercised rats to sedentary rats do not induce redox or metabolic adaptations in erythrocytes, skeletal muscle and liver.

The Emerging Roles of Nicotinamide Adenine Dinucleotide Phosphate Oxidase 2 in Skeletal Muscle Redox Signaling and Metabolism

Significance: Skeletal muscle is a crucial tissue to whole-body locomotion and metabolic health. Reactive oxygen species (ROS) have emerged as intracellular messengers participating in both physiological and pathological adaptations in skeletal muscle. A complex interplay between ROS-producing enzymes and antioxidant networks exists in different subcellular compartments of mature skeletal muscle. Recent evidence suggests that nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) are a major source of contraction- and insulin-stimulated oxidants production, but they may paradoxically also contribute to muscle insulin resistance and atrophy. Recent Advances: Pharmacological and molecular biological tools, including redox-sensitive probes and transgenic mouse models, have generated novel insights into compartmentalized redox signaling and suggested that NOX2 contributes to redox control of skeletal muscle metabolism. Critical Issues: Major outstanding questions in skeletal muscle include where NOX2 activation occurs under different conditions in health and disease, how NOX2 activation is regulated, how superoxide/hydrogen peroxide generated by NOX2 reaches the cytosol, what the signaling mediators are downstream of NOX2, and the role of NOX2 for different physiological and pathophysiological processes. Future Directions: Future research should utilize and expand the current redox-signaling toolbox to clarify the NOX2-dependent mechanisms in skeletal muscle and determine whether the proposed functions of NOX2 in cells and animal models are conserved into humans.

Association between redox state of human serum albumin and exercise capacity in older women: A cross-sectional study

AIM

Oxidative stress plays a key role in declining exercise capacity, which is one of the major health problems in old age. The redox state of human serum albumin (HSA) has been considered a biomarker reflecting oxidative stress; however, its relationship to exercise capacity in older people remains to be examined. We aimed to examine the redox state of HSA as a potential biomarker of exercise capacity in community-dwelling older women.

METHODS

We analyzed 125 women aged ≥75 years. Exercise capacity was evaluated using 6-min walk distance (6MWD). The redox state of HSA was analyzed using the high-performance liquid chromatography post-column bromocresol green reaction method. The fraction of human mercaptalbumin in HSA (f[HMA]) was considered the redox state of HSA. Pearson's correlation coefficient (r) or Spearman's correlation coefficient (ρ) was used to assess correlations between 6MWD, f(HMA) and HSA. The association between 6MWD and f(HMA) was further examined using multivariate linear regression analysis adjusted for age, diabetes mellitus, renal function, number of medications, HSA and knee extensor isometric strength.

RESULTS

The 6MWD was significantly correlated with f(HMA; ρ = 0.44, P < 0.001), but not with HSA (r = 0.05, P = 0.562). The f(HMA) was not significantly correlated with HSA (ρ = 0.03, P = 0.769). Multivariate linear regression analysis showed that f(HMA) was independently associated with 6MWD (standardized β = 0.27, P = 0.004).

CONCLUSIONS

The findings of this study suggest that f(HMA) might serve as a novel biomarker for exercise capacity in community-dwelling older women. Geriatr Gerontol Int 2019; ••: ••-••.

Cardioprotective effects of high-intensity interval training are mediated through microRNA regulation of mitochondrial and oxidative stress pathways

Human studies have shown high-intensity interval training (HIIT) has beneficial cardiovascular effects and is typically more time-efficient compared with traditional endurance exercise. The main goal of this study is to show the potential molecular and functional cardiovascular benefits of HIIT compared with endurance training (ET). Three groups of mice were used including sedentary-control, ET mice, and HIIT mice groups. Results indicated ejection fraction was increased in HIIT compared with ET while fractional shortening was increased in the HIIT group compared with both groups. Blood flow of the abdominal aorta was increased in both exercise groups compared with control. Increases in cross-sectional area and mitochondrial and antioxidative markers in HIIT compared with control were observed, along with several microRNAs. These findings indicate HIIT has specific cardiac-protective effects and may be a viable alternative to traditional ET as a cardiovascular preventative medicine intervention.

NADPH oxidase 4 mediates the protective effects of physical activity against obesity-induced vascular dysfunction

Aims

Physical activity is one of the most potent strategies to prevent endothelial dysfunction. Recent evidence suggests vaso-protective properties of hydrogen peroxide (H2O2) produced by main endothelial NADPH oxidase isoform 4 (Nox4) in the vasculature. Therefore, we hypothesized that Nox4 connects physical activity with vaso-protective effects.

Methods and results

Analysis of the endothelial function using Mulvany Myograph showed endothelial dysfunction in wild-type (WT) as well as in C57BL/6J/ Nox4−/− (Nox4−/−) mice after 20 weeks on high-fat diet (HFD). Access to running wheels during the HFD prevented endothelial dysfunction in WT but not in Nox4−/− mice. Mechanistically, exercise led to an increased H2O2 release in the aorta of WT mice with increased phosphorylation of eNOS pathway member AKT serine/threonine kinase 1 (AKT1). Both H2O2 release and phosphorylation of AKT1 were diminished in aortas of Nox4−/− mice. Deletion of Nox4 also resulted in lower intracellular calcium release proven by reduced phenylephrine-mediated contraction, whilst potassium-induced contraction was not affected. H2O2 scavenger catalase reduced phenylephrine-induced contraction in WT mice. Supplementing H2O2 increased phenylephrine-induced contraction in Nox4−/− mice. Exercise-induced peroxisome proliferative-activated receptor gamma, coactivator 1 alpha (Ppargc1a), as key regulator of mitochondria biogenesis in WT but not Nox4−/− mice. Furthermore, exercise-induced citrate synthase activity and mitochondria mass were reduced in the absence of Nox4. Thus, Nox4−/− mice became less active and ran less compared with WT mice.

Conclusions

Nox4 derived H2O2 plays a key role in exercise-induced adaptations of eNOS and Ppargc1a pathway and intracellular calcium release. Hence, loss of Nox4 diminished physical activity performance and vascular protective effects of exercise.

Is 3 Weeks of Exercise Enough to Change Blood Pressure and Cardiac Redox State in Hypertensive Rats?

The investigation was aimed to evaluate the effects of 3-weeks swimming exercise on blood pressure and redox status in high-salt-induced hypertensive rats. Male Wistar albino rats (n=40, 6 weeks old) were divided into 4 groups: 1. hypertensive rats that swam for 3 weeks; 2. sedentary hypertensive control rats; 3. normotensive rats that swam for 3 weeks; 4. sedentary normotensive control rats. Hypertensive animals were on high concentrated sodium (8% NaCl) solution for 4 weeks (period of induction of hypertension). After sacrificing, hearts were isolated and perfused according to Langendorff technique at gradually increased coronary per-fusion pressure from 40–120 cmH2O. The oxidative stress markers were determined in coronary venous effluent: the index of lipid peroxidation (measured as TBARS), nitrites (NO2 −), superoxide anion radical (O2 −) and hydrogen peroxide (H2O2). Swimming did not lead to significant changes in levels of TBARS, NO2 −, O2 − in any of compared groups while levels of H2O2 were significantly higher in swimming hyper-tensive group comparing to swimming normotensive group at coronary perfusion pressure of 80–120 cmH2O. Our results indicate that the short-term swimming start to reduce blood pressure. In addition it seems that this type of swimming duration does not promote cardiac oxidative stress damages.

High intensity interval training and molecular adaptive response of skeletal muscle

Increased cardiovascular fitness, V˙O_2max, is associated with enhanced endurance capacity and a decreased rate of mortality. High intensity interval training (HIIT) is one of the best methods to increase V˙O_2max and endurance capacity for top athletes and for the general public as well. Because of the high intensity of this type of training, the adaptive response is not restricted to Type I fibers, as found for moderate intensity exercise of long duration. Even with a short exercise duration, HIIT can induce activation of AMPK, PGC-1α, SIRT1 and ROS pathway as well as by the modulation of Ca²⁺ homeostasis, leading to enhanced mitochondrial biogenesis, and angiogenesis. The present review summarizes the current knowledge of the adaptive response of HIIT.

Perioperative Oxidative Stress: The Unseen Enemy

Reactive oxygen species (ROS) are essential for cellular signaling and physiological function. An imbalance between ROS production and antioxidant protection results in a state of oxidative stress (OS), which is associated with perturbations in reduction/oxidation (redox) regulation, cellular dysfunction, organ failure, and disease. The pathophysiology of OS is closely interlinked with inflammation, mitochondrial dysfunction, and, in the case of surgery, ischemia/reperfusion injury (IRI). Perioperative OS is a complex response that involves patient, surgical, and anesthetic factors. The magnitude of tissue injury inflicted by the surgery affects the degree of OS, and both duration and nature of the anesthetic procedure applied can modify this. Moreover, the interindividual susceptibility to the impact of OS is likely to be highly variable and potentially linked to underlying comorbidities. The pathological link between OS and postoperative complications remains unclear, in part due to the complexities of measuring ROS- and OS-mediated damage. Exogenous antioxidant use and exercise have been shown to modulate OS and may have potential as countermeasures to improve postoperative recovery. A better understanding of the underlying mechanisms of OS, redox signaling, and regulation can provide an opportunity for patient-specific phenotyping and development of targeted interventions to reduce the disruption that surgery can cause to our physiology. Anesthesiologists are in a unique position to deliver countermeasures to OS and improve physiological resilience. To shy away from a process so fundamental to the welfare of these patients would be foolhardy and negligent, thus calling for an improved understanding of this complex facet of human biology.

Exercise training in ad libitum and food-restricted old rats: effects on metabolic and physiological parameters

Aging is accompanied by a decline in the healthy function of multiple organs, leading to increased incidence and mortality from diseases such as cancer and inflammatory, cardiovascular and neurodegenerative diseases. Dietary restriction is the most effective experimental intervention known to consistently slow the aging process and with positive effects on health span in different organisms, from invertebrates to mammals. Age is also associated with progressive decline in physical activity levels in a wide range of animal species: therefore, regular physical exercise could represent a safe intervention to antagonize aging. In this research we explore the effects of exercise training initiated in late middle aged rats fed with different lifelong dietary regimens: one group was fed ad libitum and the second group was subjected to every-other-day fasting. These two groups might represent examples of "normal" aging and "successful" aging. The study shows the effects of exercise and food restriction and their interaction on plasma levels of total antioxidant capacity, lactate, amino acids, and on products of protein oxidation in soleus and tibialis anterior muscles. In addition, we evaluated body composition measurement by bioelectrical impedance analysis and muscle strength by grasping test. Results show that late-onset exercise training has the potential to improve some metabolic and physiological parameters in rats with the same "chronological age" but different "biological age", without negative effects, and highlight the relevance of a personalised and selected exercise protocol, since the responsiveness to exercise may depend on the individual's "biological age".

Cytosolic ROS production by NADPH oxidase 2 regulates muscle glucose uptake during exercise

Reactive oxygen species (ROS) act as intracellular compartmentalized second messengers, mediating metabolic stress-adaptation. In skeletal muscle fibers, ROS have been suggested to stimulate glucose transporter 4 (GLUT4)-dependent glucose transport during artificially evoked contraction ex vivo, but whether myocellular ROS production is stimulated by in vivo exercise to control metabolism is unclear. Here, we combined exercise in humans and mice with fluorescent dyes, genetically-encoded biosensors, and NADPH oxidase 2 (NOX2) loss-of-function models to demonstrate that NOX2 is the main source of cytosolic ROS during moderate-intensity exercise in skeletal muscle. Furthermore, two NOX2 loss-of-function mouse models lacking either p47phox or Rac1 presented striking phenotypic similarities, including greatly reduced exercise-stimulated glucose uptake and GLUT4 translocation. These findings indicate that NOX2 is a major myocellular ROS source, regulating glucose transport capacity during moderate-intensity exercise.

The use of site-specific suppressors to measure the relative contributions of different mitochondrial sites to skeletal muscle superoxide and hydrogen peroxide production

Reactive oxygen species are important signaling molecules crucial for muscle differentiation and adaptation to exercise. However, their uncontrolled generation is associated with an array of pathological conditions. To identify and quantify the sources of superoxide and hydrogen peroxide in skeletal muscle we used site-specific suppressors (S1QELs, S3QELs and NADPH oxidase inhibitors). We measured the rates of hydrogen peroxide release from isolated rat muscle mitochondria incubated in media mimicking the cytosol of intact muscle. By measuring the extent of inhibition caused by the addition of different site-specific suppressors of mitochondrial superoxide/hydrogen peroxide production (S1QELs for site I_Q and S3QELs for site III_Qo), we determined the contributions of these sites to the total signal. In media mimicking resting muscle, their contributions were each 12–18%, consistent with a previous method. In C2C12 myoblasts, site I_Q contributed 12% of cellular hydrogen peroxide production and site III_Qo contributed about 30%. When C2C12 myoblasts were differentiated to myotubes, hydrogen peroxide release increased five-fold, and the proportional contribution of site I_Q doubled. The use of S1QELs and S3QELs is a powerful new way to measure the relative contributions of different mitochondrial sites to muscle hydrogen peroxide production under different conditions. Our results show that mitochondrial sites I_Q and III_Qo make a substantial contribution to superoxide/hydrogen peroxide production in muscle mitochondria and C2C12 myoblasts. The total hydrogen peroxide release rate and the relative contribution of site I_Q both increase substantially upon differentiation to myotubes.

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S1QELs, S3QELs and NOX inhibitors report sites of superoxide/H₂O₂ generation.

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Mitochondria and NOXs are the major sources of H₂O₂ in C2C12 cells.

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H₂O₂ release increases 5-fold during differentiation of C2C12 myoblasts to myotubes.

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The relative contribution of site I_Q doubles during differentiation.

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The relative contributions of site III_Qo and NOXs remain the same.

The metabolic face of migraine - from pathophysiology to treatment

Migraine can be regarded as a conserved, adaptive response that occurs in genetically predisposed individuals with a mismatch between the brain's energy reserve and workload. Given the high prevalence of migraine, genotypes associated with the condition seem likely to have conferred an evolutionary advantage. Technological advances have enabled the examination of different aspects of cerebral metabolism in patients with migraine, and complementary animal research has highlighted possible metabolic mechanisms in migraine pathophysiology. An increasing amount of evidence - much of it clinical - suggests that migraine is a response to cerebral energy deficiency or oxidative stress levels that exceed antioxidant capacity and that the attack itself helps to restore brain energy homeostasis and reduces harmful oxidative stress levels. Greater understanding of metabolism in migraine offers novel therapeutic opportunities. In this Review, we describe the evidence for abnormalities in energy metabolism and mitochondrial function in migraine, with a focus on clinical data (including neuroimaging, biochemical, genetic and therapeutic studies), and consider the relationship of these abnormalities with the abnormal sensory processing and cerebral hyper-responsivity observed in migraine. We discuss experimental data to consider potential mechanisms by which metabolic abnormalities could generate attacks. Finally, we highlight potential treatments that target cerebral metabolism, such as nutraceuticals, ketone bodies and dietary interventions.

Electrical stimulation prevents doxorubicin-induced atrophy and mitochondrial loss in cultured myotubes

Muscle contraction may protect against the effects of chemotherapy to cause skeletal muscle atrophy, but the mechanisms underlying these benefits are unclear. To address this question, we utilized in vitro modeling of contraction and mechanotransduction in C2C12 myotubes treated with doxorubicin (DOX; 0.2 μM for 3 days). Myotubes expressed contractile proteins and organized these into functional myofilaments, as electrical field stimulation (STIM) induced intracellular calcium (Ca²⁺) transients and contractions, both of which were prevented by inhibition of membrane depolarization. DOX treatment reduced myotube myosin content, protein synthesis, and Akt (S308) and forkhead box O3a (FoxO3a; S253) phosphorylation and increased muscle RING finger 1 (MuRF1) expression. STIM (1 h/day) prevented DOX-induced reductions in myotube myosin content and Akt and FoxO3a phosphorylation, as well as increases in MuRF1 expression, but did not prevent DOX-induced reductions in protein synthesis. Inhibition of myosin-actin interaction during STIM prevented contraction and the antiatrophic effects of STIM without affecting Ca²⁺ cycling, suggesting that the beneficial effect of STIM derives from mechanotransductive pathways. Further supporting this conclusion, mechanical stretch of myotubes recapitulated the effects of STIM to prevent DOX suppression of FoxO3a phosphorylation and upregulation of MuRF1. DOX also increased reactive oxygen species (ROS) production, which led to a decrease in mitochondrial content. Although STIM did not alter DOX-induced ROS production, peroxisome proliferator-activated receptor-γ coactivator-1α and antioxidant enzyme expression were upregulated, and mitochondrial loss was prevented. Our results suggest that the activation of mechanotransductive pathways that downregulate proteolysis and preserve mitochondrial content protects against the atrophic effects of chemotherapeutics.

Histological changes of female reproductive organs subjected to different jumping exercise intensities and honey supplementation in rats

Background

We assessed histopathological changes of ovaries and uterus in female rats subjected to different jumping exercise intensities combined with honey supplementation at one g/kg body weight/day.

Methods

A total of 72 rats were divided into six groups, 12 rats in each: control (C), 20 and 80 jumps (20E, 80E), honey (H), and 20 and 80 jump with honey (20EH, 80EH).

Results

The endometrium was significantly thicker in the rats in H, 20EH and 80EH groups compared to C, 20E, and 80E. The myometrium thickness was significantly lower in 80E and significantly higher in 80EH compared to C, respectively. There was significantly higher myometrium thickness in 20EH and 80EH compared to 20E and 80E and H. The number of glands of the uterus in 20E and 80E was significantly lower than C. However, there was a significantly higher number of glands in H, 20EH, and 80EH compared to 20E and 80E. The numbers of uterus vessels were significantly lower in 80E compared to 20E. However, the numbers of vessels were significantly higher in H, 20EH, and 80EH compared to 80E. The number of ovarian haemorregia was significantly lower in 20E, 80E, H, 20EH, and 80EH compared to C. The number of corpora lutea was significantly lower in 80EH, H, 80E, and 20E compared to C. However, the number of corpora lutea was significantly higher in 20EH compared to J20 and H.

Conclusion

This study suggested that jumping exercises in particularly high-intensity exercise may induce histopathological changes in uterus and ovary in rats, and honey supplementation may ameliorate these effects.

Multi-Day Prolonged Low- to Moderate-Intensity Endurance Exercise Mimics Training Improvements in Metabolic and Oxidative Profiles Without Concurrent Chromosomal Changes in Healthy Adults

Background

Oxidative stress results in lipid, protein, and DNA oxidation, resulting in telomere erosion, chromosomal damage, and accelerated cellular aging. Training promotes healthy metabolic and oxidative profiles whereas the effects of multi-day, prolonged, and continuous exercise are unknown. This study investigated the effects of multi-day prolonged exercise on metabolic and oxidative stress as well as telomere integrity in healthy adults.

Methods

Fifteen participants performed a 14-day, 260-km, wilderness canoeing expedition (12 males) (EXP) (24 ± 7 years, 72 ± 6 kg, 178 ± 8.0 cm, 18.4 ± 8.4% BF, 47.5 ± 9.3 mlO₂ kg^–1 min^–1), requiring 6–9 h of low- to moderate-intensity exercise daily. Ten controls participated locally (seven males) (CON) (31 ± 11 years, 72 ± 15 kg, 174 ± 10 cm, 22.8 ± 10.0% BF, 47.1 ± 9.0 mlO₂ kg^–1 min^–1). Blood plasma, serum, and mononuclear cells were sampled before and after the expedition to assess hormonal, metabolic, and oxidative changes.

Results

Serum cholesterol, high- and low-density lipoprotein, testosterone, insulin, sodium, potassium, urea, and chloride concentrations were not different between groups, whereas triglycerides, glucose, and creatinine levels were lower following the expedition (p < 0.001). Malondialdehyde and relative telomere length (TL) were unaffected (EXP: 4.2 ± 1.3 vs. CON: 4.1 ± 0.7 μM; p > 0.05; EXP: 1.00 ± 0.48 vs. CON: 0.89 ± 0.28 TS ratio; p = 0.77, respectively); however, superoxidase dismutase activity was greater in the expedition group (3.1 ± 0.4 vs. 0.8 ± 0.5 U ml^–1; p < 0.001).

Conclusion

These results indicate a modest improvement in metabolic and oxidative profiles with increased superoxidase dismutase levels, suggesting an antioxidative response to counteract the exercise-associated production of free radicals and reactive oxygen species during prolonged exercise, mimicking the effects from long-term training. Although improved antioxidant activity may lead to increased TL, the present exercise stimulus was insufficient to promote a positive cellular aging profile with concordant chromosomal changes in our healthy and young participants.

Alterations of redox dynamics and desmin post-translational modifications in skeletal muscle models of desminopathies

Desminopathies are a type of myofibrillar myopathy resulting from mutations in DES, encoding the intermediate filament protein desmin. They display heterogeneous phenotypes, suggesting environment influences. Patient muscle proteins show oxidative features linking oxidative stress, protein aggregation, and abnormal protein deposition. To improve understanding of redox balance in desminopathies, we further developed cellular models of four pathological mutants localized in 2B helical domain (the most important region for desmin polymerization) to explore desmin behavior upon oxidative stress. We show that the mutations desQ389P and desD399Y share common stress-induced aggregates, desR406W presents more scattered cytoplasmic aggregative pattern, and pretreatment with N-acetyl-l-cysteine (NAC), an antioxidant molecule, prevents all type of aggregation. Mutants desD399Y and desR406W had delayed oxidation kinetics following H₂O₂ stress prevented by NAC pretreatment. Further, we used AAV-injected mouse models to confirm in vivo effects of N-acetyl-l-cysteine. AAV-desD399Y-injected muscles displayed similar physio-pathological characteristics as observed in patients. However, after 2 months of NAC treatment, they did not have reduced aggregates. Finally, in both models, stress induced some post-translational modifications changing Isoelectric Point, such as potential hyperphosphorylations, and/or molecular weight of human desmin by proteolysis. However, each mutant presented its own pattern that seemed to be post-aggregative. In conclusion, our results indicate that individual desmin mutations have unique pathological molecular mechanisms partly linked to alteration of redox homeostasis. Integrating these mutant-specific behaviors will be important when considering future therapeutics.

Tissue-Specific Oxidative Stress Modulation by Exercise: A Comparison between MICT and HIIT in an Obese Rat Model

Background and Aim

Exercise is an effective strategy to reduce obesity-induced oxidative stress. The purpose of this study was to compare the effects of two training modalities (moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT)) on the pro/antioxidant status of different tissues in obese Zucker rats.

Methods

Eight-week-old male Zucker rats (fa/fa, n = 36) were subdivided in three groups: MICT, HIIT, and control (no exercise) groups. Trained animals ran on a treadmill (0° slope), 5 days/week for 10 weeks (MICT: 51 min at 12 m·min^-1; HIIT: 6 sets of 3 min at 10 m·min^-1 followed by 4 min at 18 m·min^-1). Epididymal (visceral) and subcutaneous adipose tissue, gastrocnemius muscle, and plasma samples were collected to measure oxidative stress markers (advanced oxidation protein products (AOPP), oxidized low-density lipoprotein (oxLDL)), antioxidant system markers (ferric-reducing ability of plasma (FRAP), superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx) activities), and prooxidant enzymes (NADPH oxidase and xanthine oxidase (XO) activities, myeloperoxidase content).

Results

Compared with the control, MICT increased GPx and catalase activities and the FRAP level in epididymal adipose tissue. HIIT increased the AOPP level in subcutaneous adipose tissue. In the muscle, HIIT increased both SOD and GPx activities and reduced the AOPP level, whereas MICT increased only SOD activity. Finally, plasma myeloperoxidase content was similarly decreased by both training modalities, whereas oxLDL was reduced only in the MICT group.

Conclusion

Both HIIT and MICT improved the pro/antioxidant status. However, HIIT was more efficient than MICT in the skeletal muscle, whereas MICT was more efficient in epididymal adipose tissue. This suggests that oxidative stress responses to HIIT and MICT are tissue-specific. This could result in ROS generation via different pathways in these tissues. From a practical point of view, the two training modalities should be combined to obtain a global response in people with obesity.

Independent and Combined Effects of All-Out Sprint and Low-Intensity Continuous Exercise on Plasma Oxidative Stress Biomarkers in Trained Judokas

The purpose of this study was to assess oxidative stress biomarkers prior to and following different forms of exercise. Ten elite male judokas (age: 18.1 ± 1.7 years, athletic experience: 6 years with a training frequency of 6 Judo-sessions/week) performed three cycle ergometry sessions comprising a 30 s Wingate test (MAX), 30 min at 60% maximal-aerobic-power-output (LOW) or these two exercise protocols combined (COMBINED) in a repeated-measures design. Venous blood-samples were collected before, and 0(P0), 5(P5), 10(P10) and 20(P20) min after each exercise protocol and assessed for malondialdehyde concentration ([MDA]), glutathione peroxidase (GPX), superoxide dismutase (SOD) and glutathione reductase (GR) content, and total-antioxidant-status (TAS). Plasma [MDA] was found to be increased above baseline at P0 and P5 in the MAX, LOW and COMBINED conditions (p < 0.05), but was greater at P10 and P20 in the LOW condition compared to MAX and COMBINED conditions (p < 0.05). Blood GPX and SOD content increased above baseline at P0 in MAX and COMBINED and at P5 in LOW (p < 0.05), with GR content being similar between groups at P0 and P5 (p > 0.05). 20 min post-exercise, GPX, SOD, GR content and TAS were lower in the MAX compared to the LOW and COMBINED conditions (p < 0.05). In conclusion, the findings from this study reveal that redox-related biomarkers exhibited divergent response dynamics following different forms of exercise, which might have implications for understanding the mechanisms of exercise-induced skeletal muscle fatigue and adaptive remodeling.

The Effect of Exhaustive Exercise on Plasma Metabolic Profiles of Male and Female Rats

The objective of the study was to evaluate the alteration in biochemical composition and gender difference within exhaustive exercise in male and female rats using a metabolomics strategy. Sixty male and female rats were randomly assigned to control, exhaustive exercise and one-week recovery groups, respectively. The metabolic profiles of plasma were investigated by gas chromatograph-mass spectrometry (GC-MS) and data further underwent orthogonal partial least-squares (OPLS) analysis. The current study found that gender was a significant determinant of the effects of exhaustive exercise on the cortisol, blood urea nitrogen, creatine kinase, and the ratio of reduced glutathione to oxidized glutathione, whereas, no significant interaction effects between gender and exhaustive exercise were found on the levels of testosterone, malonaldehyde, reduced glutathione, oxidized glutathione and lactic dehydrogenase. In male rats, the altered metabolites within exhaustive exercise included increased tricarboxylic acid cycle intermediates (citric acid, fumaric acid, butanedioic acid), branch-chain amino acids (valine, leucine), fatty acids and metabolite (oleic acid, linoleic acid, 3-hydroxybutyric acid), phosphate and decreased glucose, lactic acid, serine, and glutamic acid. In female rats, the levels of fatty acids and metabolite (linoleic acid, oleic acid, arachidonic acid, 3-hydroxybutyric acid), amino acids (valine, leucine, glutamic acid, 5-oxo-proline, methionine, ornithine), other metabolites urea, myo-inositol and phosphate were increased. The results indicated that exhaustive exercise increased the rates of energy metabolism, glucose metabolism, amino acid catabolism and fatty acid metabolism in male rats, whereas, female rats showed an increased propensity to oxidize lipid and conserve carbohydrate and protein metabolism against physical stress. Disordered urea cycle and inositol metabolism also occurred in female rats with exhaustive exercise. Exhaustive exercise affected the balance of hormone adjustment and caused oxidative stress, subsequent cell membrane damage both in male and female rats. A significant gender-related difference in the metabolic profiles was also found between male and female rats within exhaustive exercise.

Effects of pre- or post-exercise whey protein supplementation on oxidative stress and antioxidant enzymes in older women

BACKGROUND

Oxidative stress is an imbalance between antioxidant system and production of free radicals and has been associated with the age-related deleterious changes. The defense system can be modulated by exercise and nutrition.

OBJECTIVE

The purpose of this investigation was to evaluate the effect of whey protein supplementation pre- or post-resistance training on oxidative stress and antioxidant enzyme activity in pre-conditioned older women.

METHODS

In a randomized, double-blind, and placebo-controlled design, 70 older women (≥60 years) were randomly assigned to one of the following three groups: whey protein-placebo (WP-PLA, n = 24), placebo-whey protein (PLA-WP, n = 23), and placebo-placebo (PLA-PLA, n = 23). Each group received 35 g of whey product or placebo pre- and post-training. The RT program was carried out over 12 weeks (3x/week; 3x 8-12 repetitions maximal). Oxidative stress and blood markers were assessed before and after intervention period. ANOVA for repeated measures was used for data analysis.

RESULTS

There was a significant time effect (P < 0.05), with all groups showing improvements in all oxidative stress markers and antioxidant enzyme activity. A significant (P < 0.001) interaction time vs group was observed for uric acid, with both WP-PLA and PLA-WP presenting greater reductions compared with the PLA-PLA, without differences between the timing of protein intake (WP-PLA: -8.3%; PLA-WP: -11.0%; PLA-PLA:-2.0%).

CONCLUSION

In already pre-conditioned older women, whey protein supplementation reduces plasma uric acid concentration with no further effect on antioxidant enzyme activity and oxidative stress markers. ClinicalTrials.gov: NCT03247192.

Oxidative stress in biological systems and its relation with pathophysiological functions: the effect of physical activity on cellular redox homeostasis

The body of evidence from the past three decades demonstrates that oxidative stress can be involved in several diseases. This study aims to summarise the current state of knowledge on the association between oxidative stress and the pathogenesis of some characteristic to the biological systems diseases and aging process. This review also presents the effect of physical activity on redox homeostasis. There is strong evidence from studies for participation of reactive oxygen and nitrogen species in pathogenesis of acute and chronic diseases based on animal models and human studies. Elevated levels of pro-oxidants and various markers of the oxidative stress and cells and tissues damage linked with pathogenesis of cancer, atherosclerosis, neurodegenerative diseases hypertension, diabetes mellitus, cardiovascular disease, atherosclerosis, reproductive system diseases, and aging were reported. Evidence confirmed that inflammation contributes widely to multiple chronic diseases and is closely linked with oxidative stress. Regular moderate physical activity regulates oxidative stress enhancing cellular antioxidant defence mechanisms, whereas acute exercise not preceded by training can alter cellular redox homeostasis towards higher level of oxidative stress. Future studies are needed to clarify the multifaceted effects of reactive oxygen/nitrogen species on cells and tissues and to continue study on the biochemical roles of antioxidants and physical activity in prevention of oxidative stress-related tissue injury.

Vascular Nitric Oxide-Superoxide Balance and Thrombus Formation after Acute Exercise

INTRODUCTION

An acute bout of strenuous exercise in humans results in transient impairment of nitric oxide (NO)-dependent function, but it remains unknown whether this phenomenon is associated with increased risk of thrombotic events after exercise. This study aimed to evaluate effects of a single bout of exhaustive running in mice on the balance of vascular NO/reactive oxygen species production, and on thrombogenicity.

METHODS

At different time points (0, 2, and 4 h) after exercise and in sedentary C57BL/6 mice, the production of NO and superoxide (O2) in aorta was measured by electron paramagnetic resonance spin trapping and by dihydroethidium/high-performance liquid chromatography-based method, respectively, whereas collagen-induced thrombus formation was analyzed in a microchip-based flow-chamber system (total thrombus-formation analysis system). We also measured pre- and postexercise plasma concentration of nitrite/nitrate and 6-keto-PGF1α.

RESULTS

An acute bout of exhaustive running in mice resulted in decreased production of NO and increased production of O2 in aorta, with maximum changes 2 h after completion of exercise when compared with sedentary mice. However, platelet thrombus formation was not changed by exercise as evidenced by unaltered time to start of thrombus formation, capillary occlusion time, and total thrombogenicity (area under the flow pressure curve) as measured in a flow-chamber system. Strenuous exercise increased the plasma concentration of nitrite but did not affect nitrate and 6-keto-PGF1α concentrations.

CONCLUSION

An acute bout of strenuous exercise in mice reduced NO and in parallel increased O2 production in aorta. This response was most pronounced 2 h after exercise. Surprisingly, the reduced NO and increased O2 production in mice after exercise did not result in increased platelet-dependent thrombogenicity. These results show that transient reduction in NO bioavailability does not modify thromboresistance in healthy mice after exercise.

Sport Nutrigenomics: Personalized Nutrition for Athletic Performance

An individual's dietary and supplement strategies can influence markedly their physical performance. Personalized nutrition in athletic populations aims to optimize health, body composition, and exercise performance by targeting dietary recommendations to an individual's genetic profile. Sport dietitians and nutritionists have long been adept at placing additional scrutiny on the one-size-fits-all general population dietary guidelines to accommodate various sporting populations. However, generic "one-size-fits-all" recommendations still remain. Genetic differences are known to impact absorption, metabolism, uptake, utilization and excretion of nutrients and food bioactives, which ultimately affects a number of metabolic pathways. Nutrigenomics and nutrigenetics are experimental approaches that use genomic information and genetic testing technologies to examine the role of individual genetic differences in modifying an athlete's response to nutrients and other food components. Although there have been few randomized, controlled trials examining the effects of genetic variation on performance in response to an ergogenic aid, there is a growing foundation of research linking gene-diet interactions on biomarkers of nutritional status, which impact exercise and sport performance. This foundation forms the basis from which the field of sport nutrigenomics continues to develop. We review the science of genetic modifiers of various dietary factors that impact an athlete's nutritional status, body composition and, ultimately athletic performance.

Conserving wildlife in a changing world: Understanding capture myopathy-a malignant outcome of stress during capture and translocation

The number of species that merit conservation interventions is increasing daily with ongoing habitat destruction, increased fragmentation and loss of population connectivity. Desertification and climate change reduce suitable conservation areas. Physiological stress is an inevitable part of the capture and translocation process of wild animals. Globally, capture myopathy-a malignant outcome of stress during capture operations-accounts for the highest number of deaths associated with wildlife translocation. These deaths may not only have considerable impacts on conservation efforts but also have direct and indirect financial implications. Such deaths usually are indicative of how well animal welfare was considered and addressed during a translocation exercise. Importantly, devastating consequences on the continued existence of threatened and endangered species succumbing to this known risk during capture and movement may result. Since first recorded in 1964 in Kenya, many cases of capture myopathy have been described, but the exact causes, pathophysiological mechanisms and treatment for this condition remain to be adequately studied and fully elucidated. Capture myopathy is a condition with marked morbidity and mortality that occur predominantly in wild animals around the globe. It arises from inflicted stress and physical exertion that would typically occur with prolonged or short intense pursuit, capture, restraint or transportation of wild animals. The condition carries a grave prognosis, and despite intensive extended and largely non-specific supportive treatment, the success rate is poor. Although not as common as in wildlife, domestic animals and humans are also affected by conditions with similar pathophysiology. This review aims to highlight the current state of knowledge related to the clinical and pathophysiological presentation, potential treatments, preventative measures and, importantly, the hypothetical causes and proposed pathomechanisms by comparing conditions found in domestic animals and humans. Future comparative strategies and research directions are proposed to help better understand the pathophysiology of capture myopathy.

Cocoa Flavanol Supplementation and Exercise: A Systematic Review

BACKGROUND

Cocoa flavanols (CFs) have antioxidant and anti-inflammatory capacities and can improve vascular function. It has recently been suggested that CF intake may improve exercise performance and recovery. This systematic review aimed to evaluate the literature on the effects of CF intake on exercise performance and recovery and exercise-induced changes in vascular function, cognitive function, oxidative stress, inflammation, and metabolic parameters.

METHODS

Two electronic databases (Pubmed and Web of Science) were searched for studies examining the combination of CF intake and exercise in humans (up to 28 March 2017). Articles were included if the exact amount of CFs was mentioned. The methodological quality and level of bias of the 13 included studies was assessed according to the checklist for randomized controlled trials from the Dutch Cochrane center.

RESULTS

Acute, sub-chronic (2 weeks) and chronic (3 months) CF intake reduced exercise-induced oxidative stress. Evidence on the effect of CF on exercise-induced inflammation and platelet activation was scarce. Acute CF intake reduced and tempered the exercise-induced increase in blood pressure in obese participants. Acute and sub-chronic CF intake altered fat and carbohydrate metabolism during exercise. Acute and sub-chronic CF intake did not have ergogenic effects in athletes, while chronic CF intake improved mitochondrial efficiency in untrained participants. While combining sub-chronic CF intake and exercise training improved cardiovascular risk factors and vascular function, evidence on the synergistic effects of CF and exercise training on oxidative stress, inflammation, and fat and glucose metabolism was lacking.

CONCLUSION

CF intake may improve vascular function, reduce exercise-induced oxidative stress, and alter fat and carbohydrate utilization during exercise, but without affecting exercise performance. There is a strong need for future studies examining the synergetic effect of chronic CF intake and exercise training.

Antioxidants: Positive or Negative Actors?

The term “antioxidant” is one of the most confusing definitions in biological/medical sciences. In chemistry, “antioxidant” is simply conceived “a compound that removes reactive species, mainly those oxygen-derived”, while in a cell context, the conceptual definition of an antioxidant is poorly understood. Indeed, non-clinically recommended antioxidants are often consumed in large amounts by the global population, based on the belief that cancer, inflammation and degenerative diseases are triggered by high oxygen levels (or reactive oxygen species) and that through blocking reactive species production, organic unbalances/disorders can be prevented and/or even treated. The popularity of these chemicals arises in part from the widespread public mistrust of allopathic medicine. In fact, reactive oxygen species play a dual role in dealing with different disorders, since they may contribute to disease onset and/or progression but may also play a key role in disease prevention. Further, the ability of the most commonly used supplements, such as vitamins C, E, selenium, and herbal supplements to decrease pathologic reactive oxygen species is not clearly established. Hence, the present review aims to provide a nuanced understanding of where current knowledge is and where it should go.

Aerobic training reduces oxidative stress in skeletal muscle of rats exposed to air pollution and supplemented with chromium picolinate

Objective: The purpose of this study was to investigate the effects of chromium picolinate (CrPic) supplementation associated with aerobic exercise using measures of oxidative stress in rats exposed to air pollution.

Methods: Sixty-one male Wistar rats were divided into eight groups: residual oil fly ash (ROFA) exposure and sedentary (ROFA-SED); ROFA exposure, sedentary and supplemented (ROFA-SED-CrPic); ROFA exposure and trained (ROFA-AT); ROFA exposure, supplemented and trained (ROFA-AT-CrPic); sedentary (Sal-SED); sedentary and supplemented (Sal-SED-CrPic); trained (Sal-AT); and supplemented and trained (Sal-AT-CrPic). Rats exposed to ROFA (air pollution) received 50 µg of ROFA daily via intranasal instillation. Supplemented rats received CrPic (1 mg/kg/day) daily by oral gavage. Exercise training was performed on a rat treadmill (5×/week). Oxidative parameters were evaluated at the end of protocols.

Results: Trained groups demonstrated lower gain of body mass (P < .001) and increased exercise tolerance (P < .0001). In the gastrocnemius, trained groups demonstrated increased SOD activity (P < .0001) and decrease levels of TBARS (P = .0014), although CAT activity did not differ among groups (P = .4487).

Conclusion: Air pollution exposure did not lead to alterations in oxidative markers in lungs and heart, and exercise training was responsible for decreasing oxidative stress of the gastrocnemius.

Exercise-Induced Oxidative Stress and the Effects of Antioxidant Intake from a Physiological Viewpoint

It is well established that the increase in reactive oxygen species (ROS) and free radicals production during exercise has both positive and negative physiological effects. Among them, the present review focuses on oxidative stress caused by acute exercise, mainly on evidence in healthy individuals. This review also summarizes findings on the determinants of exercise-induced oxidative stress and sources of free radical production. Moreover, we outline the effects of antioxidant supplementation on exercise-induced oxidative stress, which have been studied extensively. Finally, the following review briefly summarizes future tasks in the field of redox biology of exercise. In principle, this review covers findings for the whole body, and describes human trials and animal experiments separately.

Effect of centrally acting angiotensin converting enzyme inhibitor on the exercise-induced increases in muscle sympathetic nerve activity

KEY POINTS

The arterial baroreflex's operating point pressure is reset upwards and rightwards from rest in direct relation to the increases in dynamic exercise intensity. The intraneural pathways and signalling mechanisms that lead to upwards and rightwards resetting of the operating point pressure, and hence the increases in central sympathetic outflow during exercise, remain to be identified. We tested the hypothesis that the central production of angiotensin II during dynamic exercise mediates the increases in sympathetic outflow and, therefore, the arterial baroreflex operating point pressure resetting during acute and prolonged dynamic exercise. The results identify that perindopril, a centrally acting angiotensin converting enzyme inhibitor, markedly attenuates the central sympathetic outflow during acute and prolonged dynamic exercise.

ABSTRACT

We tested the hypothesis that the signalling mechanisms associated with the dynamic exercise intensity related increases in muscle sympathetic nerve activity (MSNA) and arterial baroreflex resetting during exercise are located within the central nervous system. Participants performed three randomly ordered trials of 70° upright back-supported dynamic leg cycling after ingestion of placebo and two different lipid soluble angiotensin converting enzyme inhibitors (ACEi): perindopril (high lipid solubility), captopril (low lipid solubility). Repeated measurements of whole venous blood (n = 8), MSNA (n = 7) and arterial blood pressures (n = 14) were obtained at rest and during an acute (SS1) and prolonged (SS2) bout of steady state dynamic exercise. Arterial baroreflex function curves were modelled at rest and during exercise. Peripheral venous superoxide concentrations measured by electron spin resonance spectroscopy were elevated during exercise and were not altered by ACEi at rest (P ≥ 0.4) or during exercise (P ≥ 0.3). Baseline MSNA and mean arterial pressure were unchanged at rest (P ≥ 0.1; P ≥ 0.8, respectively). However, during both SS1 and SS2, the centrally acting ACEi perindopril attenuated MSNA compared to captopril and the placebo (P < 0.05). Arterial pressures at the operating point and threshold pressures were decreased with perindopril from baseline to SS1 with no further changes in the operating point pressure during SS2 under all three conditions. These data suggest that centrally acting ACEi is significantly more effective at attenuating the increase in the acute and prolonged exercise-induced increases in MSNA.

Preterm birth and oxidative stress: Effects of acute physical exercise and hypoxia physiological responses

Preterm birth is a global health issue that can induce lifelong medical sequela. Presently, at least one in ten newborns are born prematurely. At birth, preterm newborns exhibit higher levels of oxidative stress (OS) due to the inability to face the oxygen rich environment in which they are born into. Moreover, their immature respiratory, digestive, immune and antioxidant defense systems, as well as the potential numerous medical interventions following a preterm birth, such as oxygen resuscitation, nutrition, phototherapy and blood transfusion further contribute to high levels of OS. Although the acute effects seem well established, little is known regarding the long-term effects of preterm birth on OS. This matter is especially important given that chronically elevated OS levels may persist into adulthood and consequently contribute to the development of numerous non-communicable diseases observed in people born preterm such as diabetes, hypertension or lung disorders. The purpose of this review is to summarize the current knowledge regarding the consequences of preterm birth on OS levels from newborn to adulthood. In addition, the effects of physical activity and hypoxia, both known to disrupt redox balance, on OS modulation in preterm individuals are also explored.

Relationship Between Aerobic Capacity With Oxidative Stress and Inflammation Biomarkers in the Blood of Older Mexican Urban-Dwelling Population

The maximal oxygen uptake (VO2max) constitutes an indicator of an organism’s capacity to integrate oxygen into the metabolism to obtaining energy. The aim of this study was to determine the relationship between VO2max and oxidative stress (OxS) and chronic inflammation in the elderly individuals. A cross-sectional and exploratory study was conducted in a sample of 52 older persons. We measured plasma lipid peroxides (LPO), red blood cell glutathione peroxidase, red blood cell superoxide dismutase, and total antioxidant status. The interleukin 10 and tumor necrosis factor-α (TNF-α) were measured in serum by ELISA. The VO2max was determined by the Rockport aerobic test, and the energy expenditure (caloric expenditure and metabolic equivalence unit (MET) per day) was measured by a 3-day activity record. We observed a positive correlation between VO2 max with IL-10, MET/day•day-1 and kcal•day-1 (r = 0.31, P < .05, r = 0.44, P < .01, and r = 0.29, P < .05, respectively), and a negative correlation with the body mass index, TNF-α, and LPO (r = −0.27, P < .05, r = −0.29, P < .05, and r = −0.40, P < .01 respectively). Our findings suggest that there is an inverse relationship between the aerobic capacity and the OxS and chronic inflammation biomarkers in the blood in older Mexican adults.

Hepatic PHD2/HIF-1α axis is involved in postexercise systemic energy homeostasis

Exercise plays an important role in the prevention and treatment of chronic liver disease and associated metabolic disorders. A single bout of exercise induces tissue blood flow redistribution, which decreases splanchnic circulation and leads to physiologic hypoxia in the gastrointestinal system and liver. The transcription factor, hypoxia inducible factor-1α (HIF-1α), and its regulator, prolylhydroxylase 2 (PHD2), play pivotal roles in the response to oxygen flux by regulating downstream gene expression levels in the liver. We hypothesized that exercise increases the HIF-1α levels in the liver, and that the hepatic PHD2/HIF-1α axis is involved in postexercise restoration of systemic energy homeostasis. Through constant O₂ consumption, CO₂ production, food and water intake, and physical activity detection with metabolic chambers, we observed that one 30-min session of swimming exercise enhances systemic energy metabolism in mice. By using the noninvasive bioluminescence imaging ROSA26 oxygen-dependent domain Luc mouse model, we reveal that exercise increases in vivo HIFα levels in the liver. Intraperitoneal injections of the PHD inhibitor, dimethyloxalylglycine, mimicked exercise-induced HIFα increase, whereas the HIF-1α inhibitor, PX-478, blocked this effect. We next constructed liver-specific knockout (LKO) mouse models with albumin- Cre-mediated, hepatocyte-specific Hif1a and Phd2 deletion. Compared with their controls, Hif1a-LKO and Phd2-LKO mice exhibited distinct patterns of hepatic metabolism-related gene expression profiles. Moreover, Hif1a-LKO mice failed to restore systemic energy homeostasis after exercise. In conclusion, the current study demonstrates that a single bout of exercise disrupts systemic energy homeostasis, increasing the HIF-1α levels in the liver. These findings also provide evidence that the hepatic PHD2/HIF-1α axis is involved in postexercise systemic metabolic homeostasis.-Luo, B., Xiang, D., Wu, D., Liu, C., Fang, Y., Chen, P., Hu, Y.-P. Hepatic PHD2/HIF-1α axis is involved in postexercise systemic energy homeostasis.

Oxidative stress in elite athletes training at moderate altitude and at sea level

Using a controlled parallel group longitudinal trial design, we investigated the effects of different training interventions on the prooxidant/antioxidant status of elite athletes: living and training at moderate altitude for 3 (Hi-Hi3) and 4 weeks (Hi-Hi), and for 4 weeks too, living high and training high and low (Hi-HiLo) and living and training at sea level (Lo-Lo). From 61 swimmers, 54 completed the study. Nitrites, carbonyls, and lipid peroxidation (LPO) levels were assessed in plasma. Enzymatic antioxidants glutathione peroxidase (GPx) and glutathione reductase (GRd), and non-enzymatic antioxidants total glutathione (GST), reduced glutathione (GSH) and oxidized glutathione (GSSG) were analysed in the erythrocyte fraction. At the end of the intervention, nitrites levels were similar in all altitude groups but higher than in the Lo-Lo controls (P = .02). Hi-HiLo had greater GPx activity than Hi-Hi and Hi-Hi3 during most of the intervention (P ≤ .001). GRd activity was higher in Lo-Lo than in Hi-Hi at the end of the training camp (P ≤ .001). All groups showed increased levels of LPO, except Lo-Lo, and carbonyls at the end of the study (P ≤ .001). Training at altitude for 3 or 4 weeks drives oxidative stress leading to cellular damage mainly by worsening the antioxidant capacities. The GSSG/GSH ratio appears to be related to perceived exertion and fatigue. The stronger antioxidant defence showed by the Hi-HiLo group suggests an inverse relationship between redox alterations and performance. Further studies are required to investigate the role of oxidative stress in acclimatization, performance, and health.

One-week cocoa flavanol intake increases prefrontal cortex oxygenation at rest and during moderate-intensity exercise in normoxia and hypoxia

During exercise in hypoxia, O₂ delivery to brain and muscle is compromised, and oxidative stress is elicited. Cocoa flavanols (CF) have antioxidant capacities and can increase blood flow by stimulating endothelial function. We aimed to examine the effects of 7-day CF intake on oxidative stress, nitric oxide production, and tissue oxygenation in response to exercise in normobaric hypoxia (14.3% O₂). In a randomized, double-blind, cross-over study, 14 well-trained male cyclists completed four trials: exercise in normoxia or hypoxia, after 7-day CF or placebo intake. Flow-mediated dilation (FMD) was measured before intake of the last dose CF or placebo. One hundred minutes later, 20-min steady-state (SS; 45% V̇o_2max) and 20-min time trial (TT) (cycling) were performed. Blood samples were taken. Prefrontal and muscular oxygenation was assessed by near-infrared spectroscopy. At baseline, FMD was increased by CF. Hypoxia increased exercise-induced elevations in lipid peroxidation and antioxidant capacity. CF suppressed exercise-induced lipid peroxidation but did not influence antioxidant capacity. At rest and during SS, prefrontal and muscular oxygenation was decreased by hypoxia. CF elevated prefrontal oxygenation but did not impact muscular oxygenation. During TT, hypoxia accelerated the exercise-induced decrease in prefrontal oxygenation, but not in muscular oxygenation. During TT, CF did not alter prefrontal and muscular oxygenation. CF did not change plasma nitrite, nitrate, and arginine:citrulline. During high-intensity exercise, CF improved neither tissue oxygenation nor performance in well-trained athletes. At rest and during moderate-intensity exercise, CF reduced exercise-induced lipid peroxidation and partially restored the hypoxia-induced decline in prefrontal oxygenation. NEW & NOTEWORTHY For the first time, we showed that CF had beneficial effects on endothelial function at rest, as well as on prefrontal oxygenation at rest and during moderate-intensity exercise, both in normoxia and hypoxia. Moreover, we showed that CF intake inhibited oxidative stress during exhaustive exercise in hypoxia.

Exercise training protects against cancer-induced cardiac remodeling in an animal model of urothelial carcinoma

Limiting cancer-induced cardiac damage has become an increasingly important issue to improve survival rates and quality of life. Exercise training has been shown to reduce cardiovascular complications in several diseases; however, its therapeutic role against cardiovascular consequences of cancer is in its infancy. In order to add new insights on the potential therapeutic effect of exercise training on cancer-related cardiac dysfunction, we used an animal model of urothelial carcinoma submitted to 13 weeks of treadmill exercise after 20 weeks of exposure to the carcinogenic N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN). Data showed that 13 weeks of treadmill exercise reverted cancer-induced cardiomyocytes atrophy and fibrosis, improved cardiac oxidative capacity given by citrate synthase activity and MnSOD content, and increased the levels of the mitochondrial biogenesis markers PGC-1α and mtTFA. Moreover, exercise training reverted cancer-induced decrease of cardiac c-kit levels suggesting enhanced regenerative ability of heart. These cardiac adaptations to exercise were related to a lower incidence of malignant urothelial lesions and less signs of inflammation. Taken together, data from the present study support the beneficial effect of exercise training when started after cancer diagnosis, envisioning the improvement of the cardiovascular function.

Oxidative stress biomarkers after a single maximal test in blind and non-blind soccer players

BACKGROUND

The aim of this study was to compare oxidative stress biomarkers, antioxidant capacity, muscle damage and hormone response between vision impaired and non-vision impaired athletes after a single maximal exercise test.

METHODS

Eight vision impaired and fifteen non-vision impaired athletes performed a maximal aerobic test with blood collected before and after.

RESULTS

Non-vision impaired athletes displayed greater aerobic capacity than blind individuals (P<0.05). Lactate increased by four-fold, while creatine kinase and gamma-glutamyltransferase as well as the oxidative stress biomarkers and antioxidants were unchanged. Cortisol increased, but testosterone and their ratio were not altered. Differences were observed for alanine transaminase and aspartate transaminase, which were increased only in non-blind athletes.

CONCLUSIONS

Our data suggest that blind soccer players, in comparison to those with vision, experienced less cellular damage.

Adaptations to endurance training depend on exercise-induced oxidative stress: exploiting redox interindividual variability

AIM

The aim of this study was to reveal the role of reactive oxygen and nitrogen species (RONS) in exercise adaptations under physiological in vivo conditions and without the interference from other exogenous redox agents (e.g. a pro-oxidant or antioxidant).

METHODS

We invented a novel methodological set-up that exploited the large redox interindividual variability in exercise responses. More specifically, we used exercise-induced oxidative stress as the 'classifier' measure (i.e. low, moderate and high) and investigated the physiological and redox adaptations after a 6-week endurance training protocol.

RESULTS

We demonstrated that the group with the low exercise-induced oxidative stress exhibited the lowest improvements in a battery of classic adaptations to endurance training (VO₂ max, time trial and Wingate test) as well as in a set of redox biomarkers (oxidative stress biomarkers and antioxidants), compared to the high and moderate oxidative stress groups.

CONCLUSION

The findings of this study substantiate, for the first time in a human in vivo physiological context, and in the absence of any exogenous redox manipulation, the vital role of RONS produced during exercise in adaptations. The stratification approach, based on a redox phenotype, implemented in this study could be a useful experimental strategy to reveal the role of RONS and antioxidants in other biological manifestations as well.

Interplay between ROS and Antioxidants during Ischemia-Reperfusion Injuries in Cardiac and Skeletal Muscle

Ischemia reperfusion (IR), present in myocardial infarction or extremity injuries, is a major clinical issue and leads to substantial tissue damage. Molecular mechanisms underlying IR injury in striated muscles involve the production of reactive oxygen species (ROS). Excessive ROS accumulation results in cellular oxidative stress, mitochondrial dysfunction, and initiation of cell death by activation of the mitochondrial permeability transition pore. Elevated ROS levels can also decrease myofibrillar Ca²⁺ sensitivity, thereby compromising muscle contractile function. Low levels of ROS can act as signaling molecules involved in the protective pathways of ischemic preconditioning (IPC). By scavenging ROS, antioxidant therapies aim to prevent IR injuries with positive treatment outcomes. Novel therapies such as postconditioning and pharmacological interventions that target IPC pathways hold great potential in attenuating IR injuries. Factors such as aging and diabetes could have a significant impact on the severity of IR injuries. The current paper aims to provide a comprehensive review on the multifaceted roles of ROS in IR injuries, with a focus on cardiac and skeletal muscle, as well as recent advancement in ROS-related therapies.

Changes in oxidative stress severity and antioxidant potential during muscle atrophy and reloading in mice

[Purpose] Changes in oxidative stress severity and antioxidant potential are routinely used as oxidative stress markers. While several studies have reported the relationship between these markers and exercise, little is known about the dynamic nature of these markers during muscle atrophy and reloading. Therefore, we examined changes in oxidative stress severity and antioxidant potential during muscle atrophy and reloading. [Subjects and Methods] Muscle atrophy was induced in mice by casting the limb for 2 weeks. Mice were then subjected to reloading for 2 weeks. The severity of oxidative stress (hydroperoxide) and antioxidant potential (degree of reduction) were quantified. [Results] Muscle atrophy was induced by cast immobilization. The muscle mass of mice recovered to similar levels as the control group following 2 weeks of reloading. The degree of oxidative stress was within the normal range throughout the experimental period. The antioxidant potential decreased to the clinical borderline level 2 weeks after immobilization, further decreased after 1 day of reloading, and then recovered to within the normal range. [Conclusion] Performing d-ROMs and BAP tests may contribute to the understanding to atrophic process of skeletal muscle in clinical practice of physical therapy.