A single session of resistance exercise induces oxidative damage in untrained men

Fast regulation of the NF-κB signalling pathway in human skeletal muscle revealed by high-intensity exercise and ischaemia at exhaustion: Role of oxygenation and metabolite accumulation

The NF-κB signalling pathway plays a critical role in inflammation, immunity, cell proliferation, apoptosis, and muscle metabolism. NF-κB is activated by extracellular signals and intracellular changes in Ca2+, Pi, H+, metabolites and reactive oxygen and nitrogen species (RONS). However, it remains unknown how NF-κB signalling is activated during exercise and how metabolite accumulation and PO2 influence this process. Eleven active men performed incremental exercise to exhaustion (IE) in normoxia and hypoxia (PIO2:73 mmHg). Immediately after IE, the circulation of one leg was instantaneously occluded (300 mmHg). Muscle biopsies from m. vastus lateralis were taken before (Pre), and 10s (Post, occluded leg) and 60s after exercise from the occluded (Oc1m) and free circulation (FC1m) legs simultaneously together with femoral vein blood samples. NF-κB signalling was activated by exercise to exhaustion, with similar responses in normoxia and acute hypoxia, as reflected by the increase of p105, p50, IKKα, IκBβ and glutathione reductase (GR) protein levels, and the activation of the main kinases implicated, particularly IKKα and CaMKII δD, while IKKβ remained unchanged. Postexercise ischaemia maintained and stimulated further NF-κB signalling by impeding muscle reoxygenation. These changes were quickly reverted at the end of exercise when the muscles recovered with open circulation. Finally, we have shown that Thioredoxin 1 (Trx1) protein expression was reduced immediately after IE and after 1 min of occlusion while the protein expression levels of glutathione peroxidase 1 (Gpx1) and thioredoxin reductase 1 (TrxR1) remained unchanged. These novel data demonstrate that exercising to exhaustion activates NF-κB signalling in human skeletal muscle and regulates the expression levels of antioxidant enzymes in human skeletal muscle. The fast regulation of NF-κB at exercise cessation has implications for the interpretation of published studies and the design of new experiments.

The effect of resistance exercise on the immune cell function in humans: A systematic review

BACKGROUND

Resistance exercise is beneficial for the immune system, including decreased susceptibility to infections and improved effectiveness of vaccinations. This review aims to provide a systematic analysis of the literature regarding the impact of resistance exercise on immune cells in the blood circulation.

MATERIALS AND METHODS

The protocol of this review followed the PRISMA guidelines and registered in PROSPERO (ID: CRD42020157834). PubMed and Web-of-Science were systematically searched for relevant articles. Outcomes were divided into two categories: 1) inflammatory gene expression or secretion of inflammation-related cytokines and 2) other aspects such as cell migration, proliferation, apoptosis, phagocytosis, and redox status.

RESULTS

Thirty intervention studies were included in this review, of which 11 articles were randomized controlled trials and six non-randomized controlled trials. Although only resistance exercise interventions were included, there was a high heterogeneity regarding specific exercise modalities. The most frequently studied outcome measures were the gene and protein expression levels in peripheral blood mononuclear cells (PBMC). This review reveals that already one acute exercise bout activates the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway in PBMC. Although resistance exercise induces an acute cytosolic oxidative stress response, the antioxidant enzyme expression is improved after resistance training period. Natural killer cell activity increases in older but decreases in younger adults immediately after a resistance exercise bout. Moreover, resistance exercise improves neutrophil phagocytic activity. Finally, effects on lymphocyte proliferation remain unclear.

CONCLUSIONS

The results of this systematic review demonstrate that resistance exercise has beneficial effects on several aspects of immune cell function both in young and older individuals. Acute changes in immune cell function occur already after a single bout of resistance exercise. However, regular resistance training during several weeks seems necessary to obtain beneficial adaptations that can be related to better immunity and reduced inflammation. The effects documented in this review confirm the beneficial effects of resistance exercise in young as well as older persons on the immune cell function.

Non-Invasive Measurement of Exercise-Induced Oxidative Stress in Response to Physical Activity. A Systematic Review and Meta-Analysis

Physical activity may benefit health by modulating oxidative stress and inflammation. However, the selection of suitable exercise-induced oxidative stress biomarkers is still challenging. This study aimed at systematically summarizing the available evidence on exercise-induced oxidative stress measured in urine and/or saliva. Two meta-analyses including the most frequently quantified biomarkers of oxidative stress, namely, urinary isoprostane and DNA oxidation products, were performed. Three electronic databases (PubMed, EMBASE and Cochrane CENTRAL) were interrogated. Among 4479 records, 43 original articles were included in the systematic review and 11 articles were included in meta-analysis I and II, respectively. We observed a pooled trend of increase of urinary isoprostanes in response to physical activity (+0.95, 95% CI: -0.18; 2.09). In comparison with aerobic exercise, anaerobic training determined a greater induction of isoprostanes (+5.21, 95% CI: 2.76; 7.66, p < 0.0001), which were markedly increased after vigorous physical activity (+6.01, 95% CI: 1.18; 10.84, p < 0.001) and slightly decreased in response to exercise interventions protracted over time (e.g., months) (-1.19, 95% CI: -2.25; -0.12, p < 0.001). We recommend the most integrative approach of oxidative stress multi-marker panels in response to physical activity instead of selecting one preferential biomarker to quantify physical activity-induced oxidative stress in humans.

Vitamins C and E Associated With Cryotherapy in the Recovery of the Inflammatory Response After Resistance Exercise: A Randomized Clinical Trial

de Brito, E, Teixeira, AdO, Righi, NC, Paulitcth, FdS, da Silva, AMV, and Signori, LU. Vitamins C and E associated with cryotherapy in the recovery of the inflammatory response after resistance exercise: A randomized clinical trial. J Strength Cond Res XX(X): 000-000, 2019-The objective of this research was to compare the effects of cryotherapy associated with vitamins (C and E) on the recovery of the inflammatory response from the resistance exercise (RE) session of untrained volunteers. Fourteen subjects (26.2 ± 5 years old, 25.8 ± 3 kg·m) underwent 4 sessions of RE with different forms of recovery. The RE consisted of 4 sets of 10 maximal repetitions for each exercise (extensor bench, squat, and leg press). The recoveries were randomized and comprised the passive (control), with vitamins C (1 g) and E (800 UI) supplementation 40 minutes before exercise, with cryotherapy (immersion in water 15° C for 10 minutes), and the association (vitamins and cryotherapy). Hemogram, inflammatory markers (C-reactive protein and creatine kinase [CK]), and parameters of oxidative stress (lipid peroxidation [LPO] and antioxidant capacity against radical peroxyl) were evaluated before (baseline) and after (0, 30, and 120 minutes) the RE sessions. Muscle pain (primary outcome) was evaluated 24 hours after exercise. C-reactive protein (p = 0.010) and LPO (p < 0.001) increased (120 minutes) only in passive recovery. Recovery with cryotherapy (30 minutes), with vitamins and the association (0 and 30 minutes) delayed increases in CK (p < 0.001). Antioxidant capacity against radical peroxyl increased (30 minutes) only in recovery with the association (p < 0.011). The pain decreased in the recoveries with cryotherapy and association (p < 0.001). The association of vitamins (C and E) with cryotherapy attenuated the inflammatory response and pain, favoring recovery after an acute RE session.

Flavanol-Rich Cacao Mucilage Juice Enhances Recovery of Power but Not Strength from Intensive Exercise in Healthy, Young Men

(1) Background: Mucilage within cacao pods contains high levels of polyphenols. We investigated whether consumption of cacao juice enhances the recovery of muscle function following intensive knee extension exercise. (2) Methods: Ten recreationally active males completed two trials of 10 sets of 10 single leg knee extensions at ~80% one repetition maximum. Participants consumed each supplement (ZumoCacao^® juice, CJ or a dextrose drink, PL) for 7 days prior to and 48 h post exercise. Knee extension maximum voluntary contraction (MVC) and a counter movement jump (CMJ) were performed at baseline, immediately, 24 h, and 48 h post-exercise. Venous blood samples were collected at each time point and analyzed for indices of inflammation, oxidative damage, and muscle damage. (3) Results: CMJ height recovered faster with CJ at 24 h and 48 h post-exercise (p < 0.05), but there was no effect of CJ on recovery of MVC (both p > 0.05). There was also no effect of the trial on any blood markers (all p > 0.05). (4) Conclusions: Supplementation with CJ for 7 days prior to and 2 days after intensive knee extensor exercise improved functional recovery as shown by an improved recovery of CMJ up to 48 h post-exercise. However, the precise mechanism of action is unclear and requires further investigation.

Photobiomodulation Leads to Reduced Oxidative Stress in Rats Submitted to High-Intensity Resistive Exercise

The aim of this study was to determine whether oxidative stress markers are influenced by low-intensity laser therapy (LLLT) in rats subjected to a high-intensity resistive exercise session (RE). Female Wistar rats divided into three experimental groups (Ctr: control, 4J: LLLT, and RE) and subdivided based on the sampling times (instantly or 24 h postexercise) underwent irradiation with LLLT using three-point transcutaneous method on the hind legs, which was applied to the gastrocnemius muscle at the distal, medial, and proximal points. Laser (4J) or placebo (device off) were carried out 60 sec prior to RE that consisted of four climbs bearing the maximum load with a 2 min time interval between each climb. Lipoperoxidation levels and antioxidant capacity were obtained in muscle. Lipoperoxidation levels were increased (4-HNE and CL markers) instantly post-RE. LLLT prior to RE avoided the increase of the lipid peroxidation levels. Similar results were also notified for oxidation protein assays. The GPx and FRAP activities did not reduce instantly or 24 h after RE. SOD increased 24 h after RE, while CAT activity did not change with RE or LLLT. In conclusion, LLLT prior to RE reduced the oxidative stress markers, as well as, avoided reduction, and still increased the antioxidant capacity.

Local Injections of Superoxide Dismutase Attenuate the Exercise Pressor Reflex in Rats with Femoral Artery Occlusion

The exercise pressor reflex is amplified in patients with peripheral artery disease (PAD) and in an experimental PAD model of rats induced by femoral artery occlusion. Heightened blood pressure worsens the restricted blood flow directed to the limbs in this disease. The purpose of this study was to determine the role played by muscle oxidative stress in regulating the augmented pressor response to static exercise in PAD. We hypothesized that limb ischemia impairs muscle superoxide dismutase (SOD) thereby leading to abnormal autonomic responsiveness observed in PAD animals, and a chronic compensation of SOD for anti-oxidation improves the exaggerated exercise pressor reflex. Our data show that femoral occlusion decreased the protein levels of SOD in ischemic muscle as compared with control muscle. Downregulation of SOD appeared to a greater degree in the oxidative (red) muscle than in the glycolytic (white) muscle under the condition of muscle ischemia. In addition, the exercise pressor response was assessed during electrically induced static contraction. The data demonstrates that the enhancement of the exercise pressor reflex was significantly attenuated after tempol (a mimetic of SOD, 30 mg over a period of 72 h) was administered into the occluded hindlimb. In the occluded rats, mean arterial pressure (MAP) response was 26 ± 3 mmHg with no tempol and 12 ± 2 mmHg with tempol application (P < 0.05 vs. group with no tempol; n = 6 in each group). There were no differences in muscle tension development (time-tension index: 12.1 ± 1.2 kgs with no tempol and 13.5 ± 1.1 kgs with tempol; P > 0.05 between groups). In conclusion, SOD is lessened in the ischemic muscles and supplement of SOD improves the amplified exercise pressor reflex, which is likely beneficial to the restricted blood flow to the limbs in PAD.

The level of physical training modulates cytokine levels through P2X7 receptor in healthy subjects

INTRODUCTION

The P2X7 receptor-NLRP3 inflammasome complex (P2X7R-Infl) regulates inflammatory and immune responses. Physical exercise modulates heat-shock proteins (Hsps), influencing cytokine levels and oxidative stress; Hsp72 triggers P2X7R-Infl-dependent responses.

SUBJECTS AND METHODS

We studied the effect of a single bout of maximal exercise on lymphomonocyte expression of P2X7R, NLRP3, caspase-1, NF-kB and Hsp72 and circulating levels of IL-1β, IL-18 and MCP-1, all modulated by P2X7R-Infl, in healthy sedentary (SED), trained (ATH), endurance (END) male individuals.

RESULTS

Baseline P2X7R, NLRP3 and Caspase-1 expression progressively increased from SED to ATH and END; NF-kβ showed the same trend. Hsp72 did not differ among groups. Acute exercise strongly reduced P2X7R in all participants, irrespective of their degree of physical training. Inflammasome responses differed across groups: in SED, NLRP3 and Caspase-1 increased; in ATH, NLRP3 reduced and caspase-1 did not vary; in END, NLRP3 and Caspase-1 declined. Baseline IL-1β, higher in END, was unmodified after exercise; IL-18 decreased; MCP-1 doubled in SED, did not vary in ATH, declined in END. In the whole study population, significant direct relationships emerged between P2X7R expression and IL-1β, IL-18, MCP-1 levels, all P < .001; also Caspase-1 related with these markers. A multivariate analysis showed age, BMI and P2X7R as determinants of postexercise IL-1β levels.

CONCLUSION

Endurance show higher P2X7R-Infl expression and function vs SED and ATH; however, maximal exercise determines prevailing pro-inflammatory vs anti-inflammatory responses in untrained and trained participants, respectively, highlighting a likely cause-effect relationship between degree of physical activity and P2X7R-Infl-mediated responses.

Exercise as a Positive Modulator of Brain Function

Various forms of exercise have been shown to prevent, restore, or ameliorate a variety of brain disorders including dementias, Parkinson's disease, chronic stress, thyroid disorders, and sleep deprivation, some of which are discussed here. In this review, the effects on brain function of various forms of exercise and exercise mimetics in humans and animal experiments are compared and discussed. Possible mechanisms of the beneficial effects of exercise including the role of neurotrophic factors and others are also discussed.

Resistance training to improve type 2 diabetes: working toward a prescription for the future

The prevalence of type 2 diabetes (T2D) is rapidly increasing, and effective strategies to manage and prevent this disease are urgently needed. Resistance training (RT) promotes health benefits through increased skeletal muscle mass and qualitative adaptations, such as enhanced glucose transport and mitochondrial oxidative capacity. In particular, mitochondrial adaptations triggered by RT provide evidence for this type of exercise as a feasible lifestyle recommendation to combat T2D, a disease typically characterized by altered muscle mitochondrial function. Recently, the synergistic and antagonistic effects of combined training and Metformin use have come into question and warrant more in-depth prospective investigations. In the future, clinical intervention studies should elucidate the mechanisms driving RT-mitigated mitochondrial adaptations in muscle and their link to improvements in glycemic control, cholesterol metabolism and other cardiovascular disease risk factors in individuals with T2D.

The effects of 2 weeks of interval vs continuous walking training on glycaemic control and whole-body oxidative stress in individuals with type 2 diabetes: a controlled, randomised, crossover trial

AIMS/HYPOTHESIS

The aim of this study was to evaluate the effects of oxygen consumption-matched short-term interval walking training (IWT) vs continuous walking training (CWT) on glycaemic control, including glycaemic variability, in individuals with type 2 diabetes. We also assessed whether any training-induced improvements in glycaemic control were associated with systemic oxidative stress levels.

METHODS

Participants (n = 14) with type 2 diabetes completed a crossover trial using three interventions (control intervention [CON], CWT and IWT), each lasting 2 weeks. These were performed in a randomised order (computerised generated randomisation) and separated by washout periods of 4 or 8 weeks after CON or training interventions, respectively. Training included ten supervised treadmill sessions, lasting 60 min/session, and was performed at the research facility. CWT was performed at moderate walking speed (75.6% ± 2.5% of walking peak oxygen consumption [[Formula: see text]]), while IWT was performed as alternating 3 min repetitions at slow (58.9% ± 2.0% [Formula: see text]) and fast (90.0% ± 3.6% [Formula: see text]) walking speed. Before and after each intervention, the following was assessed: 24 h continuous glucose monitoring (CGM) and urinary free 8-iso prostaglandin F_2α (8-iso PGF_2α; a marker for oxidative stress), physical fitness and body composition. Neither participants nor assessors were blinded to the interventions.

RESULTS

No intervention-induced changes were seen in physical fitness or body composition. Compared with baseline, IWT reduced mean glucose levels non-significantly (-0.7 ± 0.3 mmol/l, p = 0.08) and significantly reduced maximum glucose levels (-1.8 ± 0.5 mmol/l, p = 0.04) and mean amplitude of glycaemic excursions (MAGE; -1.7 ± 0.4 mmol/l, p = 0.02), whereas no significant within-group changes were seen with CON or CWT. Although 8-iso PGF_2α was associated with minimum glucose levels at baseline, no change in 8-iso PGF_2α was seen with any intervention, nor were there any associations between changes in 8-iso PGF_2α and changes in glycaemic control (p > 0.05 for all). No adverse effects were observed with any of the interventions.

CONCLUSIONS/INTERPRETATION

Short-term IWT, but not CWT, improves CGM-derived measures of glycaemic control independent of changes in physical fitness and body composition in individuals with type 2 diabetes. Systemic oxidative stress levels are unaffected by short-term walking and changes in oxidative stress levels are not associated with changes in glycaemic control.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02320526 FUNDING : The Centre for Physical Activity Research (CFAS) is supported by a grant from TrygFonden. During the study period, the Centre of Inflammation and Metabolism (CIM) was supported by a grant from the Danish National Research Foundation (DNRF55). The study was further supported by grants from Diabetesforeningen, Augustinusfonden and Krista og Viggo Petersens Fond. CIM/CFAS is a member of the Danish Center for Strategic Research in Type 2 Diabetes (DD2; the Danish Council for Strategic Research, grant no. 09-067009 and 09-075724). MR-L was supported by a post-doctoral grant from the Danish Diabetes Academy supported by the Novo Nordisk Foundation.

Repeated Supramaximal Exercise-Induced Oxidative Stress: Effect of β-Alanine Plus Creatine Supplementation

Background:

Carnosine is a dipeptide formed from the β-alanine and histidine amino acids and found in mainly in the brain and muscle, especially fast twitch muscle. Carnosine and creatine has an antioxidant effect and carnosine accounts for about 10% of the muscle's ability to buffer the H⁺ ions produced by exercise.

Objectives:

The aim of the study was to investigate the effects of beta alanine and/or creatine supplementation on oxidant and antioxidant status during repeated Wingate tests (WTs).

Patients and Methods:

Forty four sedentary males participated in the study. Participants performed three 30s WTs with 2 minutes rest between exercise bouts. After the first exercise session, the subjects were assigned to one of four groups: Placebo, Creatine, Beta-alanine and Beta-alanine plus creatine. Participants ingested twice per day for 22 consecutive days, then four times per day for the following 6 days. After the supplementation period the second exercise session was applied. Blood samples were taken before and immediately after the each exercise session for the analysis of oxidative stress and antioxidant markers.

Results:

Malondialdehyde levels and superoxide dismutase activities were affected by neither supplementation nor exercise. During the pre-supplementation session, protein carbonyl reduced and oxidized glutathione (GSH and GSSG) levels increased immediately after the exercise. However, during the post-supplementation session GSH and GSSG levels increased in beta-alanine and beta-alanine plus creatine groups immediately after the exercise compared to pre-exercise. In addition, during the post-supplementation session total antioxidant capacity increased in beta-alanine group immediately after the exercise.

Conclusions:

Beta-alanine supplementation has limited antioxidant effect during the repeated WTs.

Explosive type of moderate-resistance training induces functional, cardiovascular, and molecular adaptations in the elderly

Current recommendations aimed at reducing neuromuscular and functional loss in aged muscle have identified muscle power as a key target for intervention trials, although little is known about the biological and cardiovascular systemic response in the elderly. This study investigated the effects of 12 weeks of low-frequency, moderate-intensity, explosive-type resistance training (EMRT) on muscle strength and power in old community-dwelling people (70-75 years), monitoring functional performance linked to daily living activities (ADL) and cardiovascular response, as well as biomarkers of muscle damage, cardiovascular risk, and cellular stress response. The present study provides the first evidence that EMRT was highly effective in achieving a significant enhancement in muscular strength and power as well as in functional performance without causing any detrimental modification in cardiovascular, inflammatory, and damage parameters. Moreover, trained elderly subjects showed an adaptive response at both systemic and cellular levels by modulation of antioxidant and stress-induced markers such as myeloperoxidase (MPO), heat shock protein 70 (Hsp70) and 27 (Hsp27), and thioredoxin reductase 1 (TrxR1).

Potential role of oxidative protein modification in energy metabolism in exercise

Exercise leads to the production of reactive oxygen species (ROS) via several sources in the skeletal muscle. In particular, the mitochondrial electron transport chain in the muscle cells produces ROS along with an elevation in the oxygen consumption during exercise. Such ROS generated during exercise can cause oxidative modification of proteins and affect their functionality. Many evidences have been suggested that some muscle proteins, i.e., myofiber proteins, metabolic signaling proteins, and sarcoplasmic reticulum proteins can be a targets modified by ROS generated due to exercise. We detected the modification of carnitine palmitoyltransferase I (CPT I) by Nε-(hexanoyl)lysine (HEL), one of the lipid peroxides, in exercised muscles, while the antioxidant astaxanthin reduced this oxidative stress-induced modification. Exercise-induced ROS may diminish CPT I activity caused by HEL modification, leading to a partly limited lipid utilization in the mitochondria. This oxidative protein modification may be useful as a potential biomarker to examine the oxidative stress levels, antioxidant compounds, and their possible benefits in exercise.

Effect of oxidative stress on sympathetic and renal vascular responses to ischemic exercise

Reactive oxygen species (ROS), produced acutely during skeletal muscle contraction, are known to stimulate group IV muscle afferents and accentuate the exercise pressor reflex (EPR) in rodents. The effect of ROS on the EPR in humans is unknown. We conducted a series of studies using ischemic fatiguing rhythmic handgrip to acutely increase ROS within skeletal muscle, ascorbic acid infusion to scavenge free radicals, and hyperoxia inhalation to further increase ROS production. We hypothesized that ascorbic acid would attenuate the EPR and that hyperoxia would accentuate the EPR. Ten young healthy subjects participated in two or three experimental trials on separate days. Beat-by-beat measurements of heart rate (HR), mean arterial pressure (MAP), muscle sympathetic nerve activity (MSNA), and renal vascular resistance index (RVRI) were measured and compared between treatments (saline and ascorbic acid; room air and hyperoxia). At fatigue, the reflex increases in MAP (31 ± 3 versus 29 ± 2 mmHg), HR (19 ± 3 versus 20 ± 3 bpm), MSNA burst rate (21 ± 4 versus 23 ± 4 burst/min), and RVRI (39 ± 12 versus 44 ± 13%) were not different between saline and ascorbic acid. Relative to room air, hyperoxia did not augment the reflex increases in MAP, HR, MSNA, or RVRI in response to exercise. Muscle metaboreflex activation and time/volume control experiments similarly showed no treatment effects. While contrary to our initial hypotheses, these findings suggest that ROS do not play a significant role in the normal reflex adjustments to ischemic exercise in young healthy humans.

The effect of agility exercise on eicosanoid excretion, oxidant status, and plasma lactate in dogs

Background

The objective was to determine the effects of agility exercise on dogs of different skill levels with respect to urinary eicosanoids, urinary 15F_2t-isoprostane (lipid peroxidation marker) and hematological/biochemical changes in plasma. Fifteen adult dogs had blood and urine samples obtained prior to, immediately and 4-hours following an agility exercise.

Results

Hematocrit, red blood cells (RBC), albumin, and hemoglobin increased following exercise, with greatest increases correlating to increased skill group (novice, intermediate, masters); at 4-hours post-exercise, hematocrit, RBC, and hemoglobin were decreased. Phosphorus increased following exercise with the greatest increase in novice and intermediates. Plasma lactate increased 3.6-fold in masters, 3.2-fold in intermediates, and 1.2-fold in novice dogs. Urine thromboxane B₂ (TXB2) more than tripled 4-hours post-exercise while 6-keto prostaglandin F_1α (PGF1α, prostacyclin metabolite), prostaglandin E₂ metabolites (13,14-dihydro-15-keto-prostaglandin A₂ and 13,14-dihydro-15-keto-prostaglandin E₂), and 13,14-dihydro-15-keto prostaglandin F_2α were unaffected as determined by a competitive enzyme immunoassay and standardized by division with urine creatinine. Urine 15F_2t-isoprostane increased insignificantly.

Conclusions

Alterations in the plasma post-exercise were likely due to hemoconcentration from insensible water loss, splenic contraction and sympathetic stimulation while 4-hours later autohemodilution reduced RBC parameters. Elevations in plasma lactate and urinary TXB2 correlated with advanced skill level/speed of the dogs.

Oxidative stress contributes to the augmented exercise pressor reflex in peripheral arterial disease patients

Exaggerated blood pressure (BP) responses to dynamic exercise predict cardiovascular mortality in patients with peripheral arterial disease (PAD). However, the underlying mechanisms are unclear and no attempt has been made to attenuate this response using antioxidants. Three physiological studies were conducted in patients with PAD and controls. In Protocol 1, subjects underwent 4 min of low-intensity (0.5-2.0 kg), rhythmic plantar flexion in the supine posture. In Protocol 2, patients with PAD received high-dose ascorbic acid intravenously before exercise. In Protocol 3, involuntary exercise was conducted via electrical stimulation of the tibial nerve. The primary outcome measure was Δ mean arterial pressure (MAP) during the first 20 s of exercise (i.e. the onset of sympathoexcitation by muscle afferents). Compared to controls, patients with PAD had significantly greater ΔMAP during plantar flexion, particularly at 0.5 kg with the most affected leg (11 ± 2 vs. 2 ± 1 mmHg) as well as the least affected leg (7 ± 1 vs. 1 ± 1 mmHg). This augmented response occurred before the onset of claudication pain and was attenuated by ∼50% with ascorbic acid. Electrically evoked exercise also elicited larger haemodynamic changes in patients with PAD compared to controls. Further, the ΔMAP during 0.5 kg plantar flexion inversely correlated with the ankle-brachial index, indicating that patients with more severe resting limb ischaemia have a larger BP response to exercise. The BP response to low-intensity exercise was enhanced in PAD. Chronic limb ischaemia may sensitize muscle afferents and potentiate the BP response to muscle contraction in a dose-dependent manner.

Adaptive response, evidence of cross-resistance and its potential clinical use

Organisms and their cells are constantly exposed to environmental fluctuations. Among them are stressors, which can induce macromolecular damage that exceeds a set threshold, independent of the underlying cause. Stress responses are mechanisms used by organisms to adapt to and overcome stress stimuli. Different stressors or different intensities of stress trigger different cellular responses, namely induce cell repair mechanisms, induce cell responses that result in temporary adaptation to some stressors, induce autophagy or trigger cell death. Studies have reported life-prolonging effects of a wide variety of so-called stressors, such as oxidants, heat shock, some phytochemicals, ischemia, exercise and dietary energy restriction, hypergravity, etc. These stress responses, which result in enhanced defense and repair and even cross-resistance against multiple stressors, may have clinical use and will be discussed, while the emphasis will be on the effects/cross-effects of oxidants.

Prepubertal children with suitable fitness and physical activity present reduced risk of oxidative stress

To assess the impact of fitness status and physical activity on oxidative stress in prepubertal children, we measured selected biomarkers such as protein carbonyls (PC), lipid peroxidation products, and total nitrites, as well as the antioxidant system: total glutathione (TG), oxidized glutathione (GSSG), reduced glutathione (GSH), superoxide dismutase activity, and glutathione peroxidase. A total of 132 healthy children ages 7-12, at prepubertal stage, were classified into two groups according to their fitness level: low fitness (LF) and high fitness (HF). They were observed while engaged in an after-school exercise program, and a questionnaire was created to obtain information on their physical activity or sedentary habits. Plasma and red blood cells were obtained to analyze biomarkers. Regarding oxidative stress markers, the LF group and the sedentary group showed higher levels of TG and GSSG and a lower GSH/GSSG ratio than the HF group and the children engaged in physical activity. A negative association was found between PC and GSSG and TG and between TG and the GSH/GSSG ratio. Moreover, a negative correlation was found between GSSG and fitness, with a positive correlation with the GSH/GSSG ratio. TG, GSSG, and the GSH/GSSG ratio seem to be reliable markers of oxidative stress in healthy prepubertal children with low fitness or sedentary habits. This research contributes to the recognition that an adequate level of fitness and recreational physical activity in childhood leads to better health and oxidative status.

Chemotherapy-induced weakness and fatigue in skeletal muscle: the role of oxidative stress

SIGNIFICANCE

Fatigue is one of the most common symptoms of cancer and its treatment, manifested in the clinic through weakness and exercise intolerance. These side effects not only compromise patient's quality of life (QOL), but also diminish physical activity, resulting in limited treatment and increased morbidity.

RECENT ADVANCES

Oxidative stress, mediated by cancer or chemotherapeutic agents, is an underlying mechanism of the drug-induced toxicity. Nontargeted tissues, such as striated muscle, are severely affected by oxidative stress during chemotherapy, leading to toxicity and dysfunction.

CRITICAL ISSUES

These findings highlight the importance of investigating clinically applicable interventions to alleviate the debilitating side effects. This article discusses the clinically available chemotherapy drugs that cause fatigue and oxidative stress in cancer patients, with an in-depth focus on the anthracycline doxorubicin. Doxorubicin, an effective anticancer drug, is a primary example of how chemotherapeutic agents disrupt striated muscle function through oxidative stress.

FUTURE DIRECTIONS

Further research investigating antioxidants could provide relief for cancer patients from debilitating muscle weakness, leading to improved quality of life.

Cell-free plasma DNA and purine nucleotide degradation markers following weightlifting exercise

The present study aimed to investigate the acute effects of a single bout of high-intensive strength training on the production of cell-free plasma DNA (cf-DNA), as well as on the degradation of purine nucleotides as assessed by the concentration of xanthine (XA) and hypoxanthine (HX) in urine and serum. Twelve trained weightlifters performed six sets of six lifting exercises with 90-95% of the one repetition maximum. Blood samples and urine were obtained 1 h before training, immediately after finishing the exercise session and following 2 h of recovery. Cf-DNA, HX, and XA (in serum) significantly increased (P < 0.05-P < 0.001) immediately after heavy lifting exercise when compared with baseline levels, and significantly decreased (P < 0.05-P < 0.001) after 2 h of recovery. These results indicate that, cf-DNA and oxypurines might be relevant biomarkers for cellular damage, mechanical, energetic, and/or ischemic stress in context with exercise.

Blood reflects tissue oxidative stress depending on biomarker and tissue studied

This study investigated whether selected oxidative stress markers measured in blood adequately reflect redox status in skeletal muscle, heart, and liver. Several markers were determined after implementing two treatments known to affect redox status, namely exercise and allopurinol administration. Xanthine oxidase, thiobarbituric acid-reactive substances (TBARS), protein carbonyls (PC), reduced glutathione (GSH), oxidized glutathione (GSSG), catalase, and total antioxidant capacity were determined in blood, skeletal muscle, heart, and liver. Correlation between blood and tissues in each marker was performed through the Spearman rank correlation coefficient. GSSG in erythrocytes was correlated with all tissues, ranging in the five experimental groups as follows: skeletal muscle r(s)=0.656-0.874, heart r(s)=0.742-0.981, liver r(s)=0.646-0.855. Xanthine oxidase and TBARS measured in blood satisfactorily described the redox status of the heart (0.753-0.964 and 0.705-1.000, respectively) and liver (0.755-0.902 and 0.656-1.000, respectively). Skeletal muscle and heart redox status can be adequately described by PC (0.652-1.000 and 0.656-0.964, respectively), GSH (0.693-1.000 and 0.656-1.000, respectively), and catalase (0.745-1.000 and 0.656-1.000, respectively) measured in blood. In conclusion, this study suggests that a combination of markers measured in blood provides a reliable indication about the redox status in skeletal muscle, heart, and liver.

Effect of a tart cherry juice blend on exercise-induced muscle damage in horses

OBJECTIVE

To evaluate whether administering a tart cherry juice blend (TCJB) prior to exercise would reduce skeletal and cardiac muscle damage by decreasing the inflammatory and oxidative stress response to exercise in horses.

ANIMALS

6 horses.

PROCEDURES

Horses were randomly allocated into 2 groups in a crossover study with a 2-week washout period and orally administered either TCJB or a placebo solution (1.42 L, twice daily) in a double-masked protocol for 2 weeks prior to a stepwise incremental exercise protocol. Horses were tested for serum activities of creatine kinase and aspartate aminotransferase (AST) and concentrations of cardiac troponin I (cTnI), thiobarbituric acid reactive substances (TBARS; an indicator of oxidative stress), and serum amyloid A (SAA; an indicator of inflammation). To ensure that treatment would not result in positive results of an equine drug-screening protocol, serum samples obtained from each horse prior to and after 2 weeks of administration of TCJB or the placebo solution were tested.

RESULTS

All horses had negative results of drug screening at both sample times. The exercise protocol resulted in a significant increase in TBARS concentration, SAA concentration, and serum AST activity in all horses. Administration of TCJB or placebo solution was not associated with an effect on malondialdehyde or SAA concentrations. However, administration of TCJB was associated with less serum activity of AST, compared with administration of placebo solution.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of TCJB may diminish muscle damage induced by exercise.

Acute exercise and oxidative stress: a 30 year history

The topic of exercise-induced oxidative stress has received considerable attention in recent years, with close to 300 original investigations published since the early work of Dillard and colleagues in 1978. Single bouts of aerobic and anaerobic exercise can induce an acute state of oxidative stress. This is indicated by an increased presence of oxidized molecules in a variety of tissues. Exercise mode, intensity, and duration, as well as the subject population tested, all can impact the extent of oxidation. Moreover, the use of antioxidant supplements can impact the findings. Although a single bout of exercise often leads to an acute oxidative stress, in accordance with the principle of hormesis, such an increase appears necessary to allow for an up-regulation in endogenous antioxidant defenses. This review presents a comprehensive summary of original investigations focused on exercise-induced oxidative stress. This should provide the reader with a well-documented account of the research done within this area of science over the past 30 years.