Lipid peroxidation and antioxidant status in professional American football players during competition

Effects of Particulate Matter Inhalation during Exercise on Oxidative Stress and Mitochondrial Function in Mouse Skeletal Muscle

Particulate matter (PM) has deleterious consequences not only on the respiratory system but also on essential human organs, such as the heart, blood vessels, kidneys, and liver. However, the effects of PM inhalation on skeletal muscles have yet to be sufficiently elucidated. Female C57BL/6 or mt-Keima transgenic mice were randomly assigned to one of the following four groups: control (CON), PM exposure alone (PM), treadmill exercise (EX), or PM exposure and exercise (PME). Mice in the three-treatment group were subjected to treadmill running (20 m/min, 90 min/day for 1 week) and/or exposure to PM (100 μg/m3). The PM was found to exacerbate oxidative stress and inflammation, both at rest and during exercise, as assessed by the levels of proinflammatory cytokines, manganese-superoxide dismutase activity, and the glutathione/oxidized glutathione ratio. Furthermore, we detected significant increases in the levels of in vivo mitophagy, particularly in the PM group. Compared with the EX group, a significant reduction in the level of mitochondrial DNA was recorded in the PME group. Moreover, PM resulted in a reduction in cytochrome c oxidase activity and an increase in hydrogen peroxide generation. However, exposure to PM had no significant effect on mitochondrial respiration. Collectively, our findings in this study indicate that PM has adverse effects concerning both oxidative stress and inflammatory responses in skeletal muscle and mitochondria, both at rest and during exercise.

The Influence of Single Whole-Body Cryostimulation on Cytokine Status and Oxidative Stress Biomarkers during Exhaustive Physical Effort: A Crossover Study

The purpose of the study was to assess the impact of single whole-body cryostimulation (WBC) preceding submaximal exercise on oxidative stress and inflammatory biomarkers in professional, male athletes. The subjects (n = 32, age 25.2 ± 37) were exposed to low temperatures (−130 °C) in a cryochamber and then participated in 40 min of exercise (85% HRmax). Two weeks afterwards, the control exercise (without WBC) was performed. Blood samples were taken before the start of the study, immediately after the WBC procedure, after exercise preceded by WBC (WBC exercise) and after exercise without WBC. It has been shown that catalase activity after WBC exercise is lower in comparison with activity after control exercise. The interleukin 1β (IL-1-1β) level was higher after control exercise than after WBC exercise, after the WBC procedure and before the start of the study (p < 0.01). The WBC procedure interleukin 6 (IL-6) level was compared with the baseline level (p < 0.01). The level of Il-6 was higher both after WBC exercise and after control exercise compared with the level recorded after the WBC procedure (p < 0.05). Several significant correlations between the studied parameters were shown. In conclusion, the changes in the cytokine concentration in the athletes’ blood confirm that body exposition to extremely low temperatures before exercise could regulate the inflammatory reaction course and secretion of cytokines during exercise. A single session of WBC in the case of well-trained, male athletes does not significantly affect the level of oxidative stress indicators.

Seasonal Oxy-Inflammation and Hydration Status in Non-Elite Freeskiing Racer: A Pilot Study by Non-Invasive Analytic Method

Freeskiing is performed in an extreme environment, with significant physical effort that can induce reactive oxygen species (ROS) generation and dehydration. This study aimed to investigate the evolution of the oxy-inflammation and hydration status during a freeskiing training season with non-invasive methods. Eight trained freeskiers were investigated during a season training: T0 (beginning), T1-T3 (training sessions), and T4 (after the end). Urine and saliva were collected at T0, before (A) and after (B) T1-T3, and at T4. ROS, total antioxidant capacity (TAC), interleukin-6 (IL-6), nitric oxide (NO) derivatives, neopterin, and electrolyte balance changes were investigated. We found significant increases in ROS generation (T1A-B +71%; T2A-B +65%; T3A-B +49%; p < 0.05-0.01) and IL-6 (T2A-B +112%; T3A-B +133%; p < 0.01). We did not observe significant variation of TAC and NOx after training sessions. Furthermore, ROS and IL-6 showed statistically significant differences between T0 and T4 (ROS +48%, IL-6 +86%; p < 0.05). Freeskiing induced an increase in ROS production, which can be contained by antioxidant defense activation, and in IL-6, as a consequence of physical activity and skeletal muscular contraction. We did not find deep changes in electrolytes balance, likely because all freeskiers were well-trained and very experienced.

Polyphenol Supplementation and Antioxidant Status in Athletes: A Narrative Review

Antioxidants in sports exercise training remain a debated research topic. Plant-derived polyphenol supplements are frequently used by athletes to reduce the negative effects of exercise-induced oxidative stress, accelerate the recovery of muscular function, and enhance performance. These processes can be efficiently modulated by antioxidant supplementation. The existing literature has failed to provide unequivocal evidence that dietary polyphenols should be promoted specifically among athletes. This narrative review summarizes the current knowledge regarding polyphenols' bioavailability, their role in exercise-induced oxidative stress, antioxidant status, and supplementation strategies in athletes. Overall, we draw attention to the paucity of available evidence suggesting that most antioxidant substances are beneficial to athletes. Additional research is necessary to reveal more fully their impact on exercise-induced oxidative stress and athletes' antioxidant status, as well as optimal dosing methods.

Characterization of Redox Environment and Tryptophan Catabolism through Kynurenine Pathway in Military Divers’ and Swimmers’ Serum Samples

Endurance and resistance exercises, alone or in combination, induce metabolic changes that affect tryptophan (Trp) catabolism. The kynurenine pathway (KP) is the main route of Trp degradation, and it is modulated by the inflammatory and redox environments. Previous studies have shown that KP metabolites work as myokines that mediate the positive systemic effects related to exercise. However, it is poorly understood how different exercise modalities and intensities impact the KP. The aim of this study was to characterize the effect of two different exercise modalities, military diving and swimming, on the KP and the redox environment. A total of 34 healthy men from the Mexican Navy were included in the study, 20 divers and 14 swimmers, who started and stayed in military training consistently during the six months of the study; 12 Mexican men without fitness training were used as the control group. Physical fitness was determined at the beginning and after 6 months of training; criteria included body composition; serum levels of Trp, kynurenine (KYN), kynurenic acid (KYNA) and 3-hydroxykynurenine (3-HK); the glutathione ratio (GSH/GSSG); and malondialdehyde (MDA).. Results showed a significant loss of body fat in both the diver and swimmer groups. Compared with the control group, divers showed a decrease in Trp and 3-HK levels, but no changes were observed in the KYN/Trp, KYNA/Trp or 3-HK/Trp ratios, while swimmers showed a decrease in KYN levels and an increase in the KYNA and 3-HK levels. Additionally, divers showed a decrease in the GSH/GSSG ratio and an increase in MDA levels, in contrast to the swimmers, who showed a decrease in MDA levels and an increase in GSH/GSSG levels. Our findings suggest a differential shift in the KP and redox environment induced by diving and swimming. Swimming promotes an antioxidant environment and a peripheral overactivation of the KP.

Antioxidants Markers of Professional Soccer Players During the Season and their Relationship with Competitive Performance

The aim of this study was to assess antioxidant markers before and after a mid-season of professional soccer players from the 3^rd Spanish Division, and to correlate antioxidant markers with competitive performance. Sixty-five male players (age = 25.3 ± 4.2 yr, body mass = 73.2 ± 6.7 kg, body height = 177.8 ± 5.7 cm) from three soccer clubs from Cádiz (Spain) participated in the study. Body composition, maximal aerobic capacity (VO_2max), and baseline antioxidant blood markers (Total Antioxidant Status (TAS) and Reduced glutathione/Oxidized glutathione ratio) were assessed in the first week of the championship season (pre-test) and after 18 weeks in the mid-season (post-test). Soccer performance was registered according to the official classification ranking at both the mid-season and at the end of the season; ranking positions for Team A were 2^nd and 1^st, for Team B were 5^th and 5^th, while for Team C were 12^th and 14^th, respectively. Regression analyses showed that TAS and VO_2max were able to independently predict (p < 0.05) performance in our participants. Moreover, antioxidant levels showed significant main effects on performance (p < 0.001); where a higher antioxidant capacity was observed in the best performance soccer team, both before and after the mid-season. Notwithstanding, the competitive period compromised the antioxidant status since TAS levels significantly decreased after the 18-week training program and competition compared with baseline values in all soccer teams (p < 0.001). These results suggest the need of monitoring antioxidants in soccer players to prevent excessive oxidative stress and cellular damage which could compromise success in competition, by adjusting the training loads, diet or ergogenic aids, if needed.

Effects of Exercise-Induced ROS on the Pathophysiological Functions of Skeletal Muscle

Oxidative stress is the imbalance of the redox system in the body, which produces excessive reactive oxygen species, leads to multiple cellular damages, and closely relates to some pathological conditions, such as insulin resistance and inflammation. Meanwhile, exercise as an external stimulus of oxidative stress causes the changes of pathophysiological functions in the tissues and organs, including skeletal muscle. Exercise-induced oxidative stress is considered to have different effects on the structure and function of skeletal muscle. Long-term regular or moderate exercise-induced oxidative stress is closely related to the formation of muscle adaptation, while excessive free radicals produced by strenuous or acute exercise can cause muscle oxidative stress fatigue and damage, which impacts exercise capacity and damages the body's health. The present review systematically summarizes the relationship between exercise-induced oxidative stress and the adaptions, damage, and fatigue in skeletal muscle, in order to clarify the effects of exercise-induced oxidative stress on the pathophysiological functions of skeletal muscle.

Work Intensity, Low-Grade Inflammation, and Oxidative Status: A Comparison between Office and Slaughterhouse Workers

Limited knowledge exists about the impact of physical workload on oxidative stress in different occupational categories. Thus, we aimed to investigate the oxidative and inflammatory status in employees with different physical workloads. We enrolled a total of 79 male subjects, 27 office workers (mean age 38.8 ± 9.1 years) and 52 heavy workers, in a slaughterhouse (mean age 40.8 ± 8.2 years). Fasting blood was drawn from an antecubital vein in the morning of the midweek before an 8-hour or 12-hour work shift. The antioxidative capacity was assessed measuring total antioxidant capacity (TAC), uric acid, total polyphenols (PPm), and endogenous peroxidase activity (EPA). Total peroxides (TOC), malondialdehyde (MDA), and myeloperoxidase (MPO) were analyzed as prooxidative biomarkers, and an oxidative stress index (OSI) was calculated. In addition, hsCRP, interleukin-6 (IL-6), MDA-LDL IgM antibodies, galectin-3, adrenocorticotropic hormone (ACTH), and the brain-derived neurotrophic factor (BDNF) were measured as biomarkers of chronic systemic inflammation and emotional stress. TOC (p = 0.032), TAC (p < 0.001), ACTH (p < 0.001), OSI (p = 0.011), and hsCRP (p = 0.019) were significantly increased in the heavy workers group, while EPA, BDNF (p < 0.001), and polyphenols (p = 0.004) were significantly higher in office workers. Comparison between 8 and 12 h shifts showed a worse psychological condition in heavy workers with increased levels for hsCRP (p = 0.001) and reduced concentration of BDNF (p = 0.012) compared to office workers. Oxidative stress and inflammation are induced in heavy workers and are particularly pronounced during long working hours, that is, 12-hour versus 8-hour shifts.

Low-density lipoprotein oxidation biomarkers in human health and disease and effects of bioactive compounds

Based on the significance of oxidized low-density lipoprotein (LDL) in health and disease, this review focuses on human studies addressing oxidation of LDL, including three lines of biomarkers, (i) ex vivo LDL resistance to oxidation, a "challenge test" model, (ii) circulating oxidized LDL, indicating the "current in vivo status", and (iii) autoantibodies against oxidized LDL as fingerprints of an immune response to oxidized LDL, along with circulating oxysterols and 4-hydroxynonenal as biomarkers of lipid peroxidation. Lipid peroxidation and oxidized LDL are hallmarks in the development of various metabolic, cardiovascular and other diseases. Changes further occur across life stages from infancy to older age as well as in athletes and smokers. Given their responsiveness to targeted nutritional interventions, markers of LDL oxidation have been employed in a rapidly growing number of human studies for more than 2 decades. There is growing interest in foods, which, besides providing energy and nutrients, exert beneficial effects on human health, such as protection of DNA, proteins and lipids from oxidative damage. Any health claim, however, needs to be substantiated by supportive evidence derived from human studies, using reliable biomarkers to demonstrate such beneficial effects. A large body of evidence has accumulated, demonstrating protection of LDL from oxidation by bioactive food compounds, including vitamins, other micronutrients and secondary plant ingredients, which will facilitate the selection of oxidation biomarkers for future human intervention studies and health claim support.

Cameroonian professional soccer players and risk of atherosclerosis

Background

Elevated titers of antibodies against oxidized low-density lipoproteins-cholesterol (ox-LDL-Ab) have been reported among professional athletes, paradoxically reflecting an increased risk of developing atherogenic and/or cardiovascular events. This study aimed to determine titers of ox-LDL-Ab in a group of Cameroonian professional soccer players, and evaluate their evolution during part of a competition season as well as the plasmatic antioxidant status to find out if this latter correlates with ox-LDL-Ab .

Methods

We conducted a descriptive cohort study in 2012 including 18 healthy male soccer players. Three samplings were performed in March (T1), May (T2), and July 2012 (T3) to assess the lipid profile, titers of ox-LDL-Ab, and plasmatic concentrations of four antioxidants: the ferric reducing antioxidant power (FRAP), reduced glutathione (GSH), superoxide dismutase (SOD), and uric acid.

Results

Ages ranged from 16 to 28 years with a median (interquartile range) of 19.5 (19–23) years. Total cholesterol, high-density lipoproteins-cholesterol (HDL-C), low-density lipoproteins-cholesterol (LDL-C) and triglycerides varied within normal ranges throughout the three samplings. While total cholesterol and LDL-C titers increased significantly (p = 0.003 and p = 0.006, respectively), triglycerides and HDL-C values varied non-significantly throughout the measurements (p = 0.061 and p = 0.192, respectively). The median ox-LDL-Ab titers were respectively: 653.3 (468.2–838.8) mIU/ml at T1, 777.7 (553.7–1150.7) mIU/ml at T2, and 1037.7 (901.7–1481.5) mIU/ml at T3. Overall, ox-LDL-Ab titers increased significantly from T1 to T3 (p = 0.006). Concomitantly, uric acid and FRAP concentrations decreased significantly (p = 0.001 and p = 0.003, respectively); on the contrary, GSH and SOD values increased, but insignificantly (p = 0.115 and p = 0.110, respectively). There was a positive and significant correlation between ox-LDL-Ab and HDL-C (ρ = 0.519, p = 0.027), and between ox-LDL-Ab and SOD (ρ = 0.504, p = 0.033) at T2. Ox-LDL-Ab values were expected to increase with each new visit (β = 201.1; p = 0.041) and each IU/ml of SOD titers (β = 23.6; p = 0.019).

Conclusion

These Cameroonian professional soccer players exhibited high levels of ox-LDL-Ab reflecting elevated levels of oxidatively-modified LDL-C particles with an increment over time, this being insufficiently counterbalanced by the antioxidant defense mechanisms. As a consequence, they may be at increased atherogenic and cardiovascular risks.

Oxidative Stress in Training, Overtraining and Detraining: from Experimental to Applied Research

According to the hormesis theory, the responses of biological systems to stressors in exercise training may be explained by a U-shaped curve with inactivity and overtraining as the two endpoints. Both of these endpoints decrease physiological functions. Markers of oxidative stress may be important parameters for biological monitoring of athletes. Numerous studies have shown that acute exercise has the potential to induce oxidative stress, but regular exposure to an increased level of prooxidants leads to upregulation of the endogenous antioxidative defence system (ADS) of an athlete. Studies that explored the redox state in athletes during the competitive season showed that the antioxidative status changes depending on the training load and training phase. During the training season, a state of fatigue known as overtraining may occur, which results from an excessive training load. Oxidative stress has been suggested as one of the causes of overtraining syndrome. Based on the existing studies, it can be said that a connection exists, but whether oxidative stress is a cause or a consequence of overtraining is yet to be clarified. Furthermore, detraining (training reduction or cessation) leads to a partial or complete loss of training-induced anatomical, physiological and performance adaptations; therefore, it seems reasonable to assume that changes in ADS are also reversible.

Serum oxidant and antioxidant status following an all-out 21-km run in adolescent runners undergoing professional training--a one-year prospective trial

This study investigated the 1-year longitudinal effect of professional training in adolescent runners on redox balance during intense endurance exercise. Changes in selected serum oxidant and antioxidant status in response to a 21-km running time trial in 10 runners (15.5 ± 1.3 years) undergoing professional training were evaluated twice in 12 months (pre- and post-evaluation). Venous blood samples were collected immediately before and 4-h following the 21-km run for analysis of serum concentrations of thiobarbituric acid-reactive substances (TBARS), xanthine oxidase (XO), catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC). In pre-evaluation trial, serum TBARS and SOD decreased after the 21-km run (p < 0.05) while XO, GSH, CAT and TAOC were unchanged. In post-evaluation trial, serum TBARS and SOD decreased, whereas XO and CAT increased post-exercise (p < 0.05). Furthermore, pre-exercise serum T-AOC, post-exercise serum XO, CAT, T-AOC (p < 0.05), and GSH (p = 0.057) appeared to be higher than the corresponding pre-evaluation values. The current findings suggest that a professional training regime in adolescent runners is not likely to jeopardize the development of their antioxidant defense. However, uncertainties in the maintenance of redox balance in runners facing increased exercise-induced oxidative stress as a consequence of training-induced enhancement of exercise capacity await further elucidation.

The beneficial effects of physical exercise on antioxidant status in asthmatic children

BACKGROUND

The pathogenesis of asthma involves both airway inflammation and an oxidant/antioxidant imbalance. It is demonstrated in asthmatic adults that exercise programmes improve lung function, a mechanism yet to be elucidated. The purpose of this study was to investigate the possible beneficial effects of physical exercise on antioxidant status in asthmatic children which may lead to ameliorated lung function.

METHODS

The study enrolled thirteen control and thirty asthmatic children. The asthmatic group was subdivided into two: the first group receiving only pharmacological treatment (n=15) and the second receiving pharmacological treatment with exercise programme (n=15) for 8 weeks. Blood samples were drawn from the subjects before and after treatment periods. As oxidant stress markers blood levels of malondialdehyde (MDA) and total nitric oxide (NO), and as antioxidant status, glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) enzyme activities were assessed.

RESULTS

Before any treatment was initiated, MDA and NO levels in the asthmatic group were significantly higher than the controls (3.40±0.96 nmol/ml vs 2.46±0.58 nmol/ml, and 12.53±2.10 vs 9.40±1.39 micromol/L, respectively). Both SOD (p=0.0001) and GSH-Px (p=0.023) activities were significantly lower in the asthmatic group. Pharmacological treatment and exercise programme together significantly improved lung performance and decreased the levels of oxidant stress markers, in concordance with a significantly increase in antioxidant enzyme activity measures when compared to the pharmacological treatment.

CONCLUSION

Structured exercise programme in asthmatic children resulted in better lung function, which may be attributed to its effect on antioxidant status.

[Oxidative status evaluation in elite karate athletes during training process]

BACKGROUND/AIM

Oxidative stress is a state of disturbed balance between reactive oxygen species (ROS) and reactive nitrogen species (RNS) on the one hand, and antioxidative defense on the other. As a result of oxidative stress we have irreversible changes in cell function leading to pathological tissue changes, development of many diseases and fast aging process. Increased consumption of oxygen during exercise could be the cause of oxidative stress. The aim of the study was to establish oxidative status of elite karate athletes in the state of rest and after the loading, monitoring the parameters of oxidative stress and components of antioxidative defense in a training process.

METHODS

During training process, a group of 30 elite karate athletes was included in the study of prevalence. They were males, from 16 to 30 years of age. The examination was conducted both in resting condition and after the loading. Oxidative status was determined by the level of superoxide anion radical (O2-), hydrogen peroxide (H2O2) as prooxidants, and enzymes of the antioxidant defanse system: superoxide dismutase (SOD) and catalase (CAT).

RESULTS

There was a homogenous group of young athletes of normal weight and fats percentage. A significant decrease of O2- after the load was founded, while the levels of H2O2 was significantly increased. Activity of SOD was not significantly changed after exsercise while that of CAT was significantly increased.

CONCLUSION

In the long run a programmed physical exercise does not lead to oxidative stress, but an excessive physical load may cause its occurrence.

Evolução de biomarcadores de estresse oxidativo e relação com a performance competitiva em dois momentos da temporada de treinamento de natação

Estudos têm demonstrado aumento na formação de espécies reativas de oxigênio após o esforço físico intenso. Esses eventos podem aumentar a suscetibilidade das células musculares a danos oxidativos como a peroxidação lipídica. Assim, variações na intensidade e no volume de treinamento durante a temporada podem modular o metabolismo oxidativo e influenciar a performance dos atletas. OBJETIVO: Estudar a evolução de biomarcadores de peroxidação lipídica em dois momentos de um ciclo periodizado de treinamento e relacionar com a performance competitiva de natação. MÉTODOS: Participaram do presente estudo 16 nadadores (nove do gênero masculino e sete do feminino). Amostras de sangue foram coletadas em dois períodos do ciclo de treinamento: período preparatório específico e período de polimento. Espécies reativas ao ácido tiobarbitúrico (TBARS) e peróxidos totais foram determinados como biomarcadores de peroxidação lípidica. Creatina quinase foi determinada como parâmetro de dano celular muscular. O índice técnico alcançado no estilo de especialidade de cada atleta foi utilizado como parâmetro de performance competitiva. O índice técnico foi determinado na competição preparatória Troféu Electro Bonini realizada no período preparatório específico, e no Campeonato Paulista realizado no final do período de polimento. RESULTADOS: Foi encontrado aumento significativo (p < 0,05) no índice técnico no Campeonato Paulista (769,6 ± 51,1 pontos) em relação ao Troféu Electro Bonini (751,1 ± 55,7 pontos). Significativas reduções na concentração de TBARS (5,7 ± 2,9 vs 3,3 ± 2,2µmol/L) e peróxidos totais (45,1 ± 20,6 vs 29,6 ± 13,0, µmol H2O2/L) foram encontrados no período de polimento com relação ao período preparatório específico. O mesmo não foi encontrado para creatina quinase (123,6 ± 60,1 vs 137,4 ± 74,9U/L). CONCLUSÃO: A significativa diminuição nos biomarcadores de peroxidação lipídica decorrente do decréscimo no volume e intensidade do treinamento após o período de polimento demonstra a influência das variações do treinamento sobre o estresse oxidativo e sua possível relação com a performance.

Antioxidant status, oxidative stress, and damage in elite kayakers after 1 year of training and competition in 2 seasons

The large volume of training performed by elite athletes throughout the season can translate into a chronic oxidative insult. To study the effects that chronically high training loads have on athletes’ redox status, superoxide dismutase (SOD), glutathione reductase, glutathione peroxidase (GPx), and creatine kinase activities; total antioxidant status (TAS); and uric acid, retinol, α-tocopherol, α-carotene, β-carotene, lycopene, lutein + zeaxanthin, vitamin C, thiobarbituric acid reactive substances (TBARS), interleukin-6, and cortisol levels were determined in 9 kayakers (6 men) in a competitive period during the first season (June, T1), and in precompetitive (March, T2) and competitive (June, T3) periods during the following season. TAS decreased from the first to the second season (T1 vs. T2, p < 0.001; T1 vs. T3, p < 0.001). TBARS (p = 0.024) decreased from T1 to T2. The α-tocopherol increase (p = 0.001) from T1 to T2 lost statistical significance after adjustment for total lipids (p = 0.243). GPx (p = 0.003) increased, while SOD (p < 0.001) and uric acid (p = 0.032) decreased from T2 to T3. Cortisol levels decreased significantly throughout the study (T1 vs. T2, p = 0.042; T2 vs. T3, p = 0.018; T1 vs. T3, p = 0.002). No significant differences were observed for any of the other parameters studied. Antioxidant status changed more within the same season than from one season to another. Redox markers should be monitored throughout the season to detect athletes at an increased oxidative risk.

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.

Effect of exercise on oxidative stress biomarkers

Acute bouts of aerobic and anaerobic exercise can induce a state of oxidative stress, as indicated by an increase in oxidized molecules in a variety of tissues and body fluids. The extent of oxidation is dependent on the exercise mode, intensity, and duration, and is specifically related to the degree of oxidant production. Findings of increased oxidative stress have been reported for both healthy and diseased subjects following single bouts of exercise. While acute exercise has the ability to induce an oxidative stress, this same exercise stimulus appears necessary to allow for an upregulation in endogenous antioxidant defenses. This chapter presents a summary of exercise-induced oxidative stress.

Oxidative stress : relationship with exercise and training

Free radicals are reactive compounds that are naturally produced in the human body. They can exert positive effects (e.g. on the immune system) or negative effects (e.g. lipids, proteins or DNA oxidation). To limit these harmful effects, an organism requires complex protection - the antioxidant system. This system consists of antioxidant enzymes (catalase, glutathione peroxidase, superoxide dismutase) and non-enzymatic antioxidants (e.g. vitamin E [tocopherol], vitamin A [retinol], vitamin C [ascorbic acid], glutathione and uric acid). An imbalance between free radical production and antioxidant defence leads to an oxidative stress state, which may be involved in aging processes and even in some pathology (e.g. cancer and Parkinson's disease). Physical exercise also increases oxidative stress and causes disruptions of the homeostasis. Training can have positive or negative effects on oxidative stress depending on training load, training specificity and the basal level of training. Moreover, oxidative stress seems to be involved in muscular fatigue and may lead to overtraining.

Interdependency of the oxidizability of lipoproteins and peroxidase activity with base excess, HCO3, pH and magnesium in human venous and capillary blood

As continuous production of free radicals and reactive oxygen species is a normal metabolic process, increased metabolism during exercise/workload should increase free radical generation and oxidative stress. Oxidative stress intensity should then depend on the intensity of metabolic stress effects. Intensity of stress is usually reflected in norepinephrine (NE) levels, which correlate linearly and significantly with changes in blood gases, blood buffer systems, blood electrolytes, blood glucose and lactate [Porta, S., Leitner, G., Heidinger, D., Lang, T., Weiss, U., Smolle, K.H., Hasiba, K., 1997. Magnesium während der Alpinausbildung bringt um 30% bessere Energieverwertung. Magnesium-Bulletin 19(2), 59-61]. Those parameters were used in an open study design to screen 64 subjects for metabolic stress effects along with their antioxidative capacity using both venous and capillary blood. To compare venous and capillary blood, we took venous blood samples from 12 healthy volunteers and capillary blood from 52 other healthy subjects. To show whether free radical changes indeed go along with metabolic stress effects, we tried to quantify relations between metabolic stress effects and oxidative stress by linear correlations. In conclusion, both venous and capillary blood are suitable for determining at least those parameters of the oxidative state that we used. All significant correlations of peroxidase activity and oxidation lag time (OLT) with pH, bicarbonate (HCO3), base excess (BE) and magnesium (Mg) indicate that free radical production increases with metabolism. Those relationships could help to evaluate the oxidative state more precisely.

Persistent Oxidative Stress after Myocardial Infarction Treated by Percutaneous Coronary Intervention

Acute myocardial infarction causing cardiac ischemia is responsible for the majority of cardiac related deaths. Medical interventions that ensure rapid reperfusion, such as percutaneous coronary intervention, are aimed to allow myocardial re-oxygenation. However, this generates reactive oxygen species, resembling ischemia-reperfusion type of injury based on oxidative stress. In the present study we monitored dynamic changes of total serum peroxides, total antioxidant capacity and soluble intercellular adhesion molecule-1 as well as the titer of antibodies against oxidized low-density lipoproteins in the blood during the convalescence period of 32 patients with acute myocardial infarction treated by percutaneous coronary intervention. Samples were taken at admittance and at two hours, four hours, three days and seven days following percutaneous coronary intervention. Total antioxidant capacity dropped to 82% (p < 0.05). The titer of antibodies against oxidized low-density lipoproteins transiently decreased within the first three days, and increased afterwards. The values of serum peroxides and soluble intercellular adhesion molecule-1 increased continuously in respect to the initial levels reaching the maximum at the time of release from hospital. These findings indicate a persistent oxidative stress that might be associated with intravascular inflammation in patients during convalescence and release from hospital.

Plasma oxidative stress biomarkers, nitric oxide and heat shock protein 70 in trained elite soccer players

The physiological response to the physical exercise involves a number of changes in the oxidative balance and in the metabolism of some important biological molecules, including nitric oxide (NO) and heat shock proteins (Hsp 70). With the aim to optimise previous laboratory diagnostic panels, we measured the plasma concentration of reactive oxygen metabolites (ROMs), total antioxidant status (TAS), glutathione reductase (GR) activity, and NO and Hsp 70 levels in 44 elite, antioxidant-supplemented and trained soccer players and in 15 sedentary controls. Although no statistically significant difference between athletes and controls was detected in the plasma level of ROMs and TAS, soccer players showed a significantly higher plasma GR activity, NO and Hst 70 levels than those of sedentary controls. These findings suggest that the measuring of relatively novel biomarkers in sport medicine, like GR, NO and Hsp 70, in addition to the well-known and reliable assays (d-ROMs test and TAS) may be useful to a clinician to better assess and evaluate the benefits of training and/or supplementation programs.

A new automated colorimetric method for measuring total oxidant status

OBJECTIVES

To develop a new, colorimetric and automated method for measuring total oxidation status (TOS).

DESIGN AND METHODS

The assay is based on the oxidation of ferrous ion to ferric ion in the presence of various oxidant species in acidic medium and the measurement of the ferric ion by xylenol orange. The oxidation reaction of the assay was enhanced and precipitation of proteins was prevented. In addition, autoxidation of ferrous ion present in the reagent was prevented during storage. The method was applied to an automated analyzer, which was calibrated with hydrogen peroxide and the analytical performance characteristics of the assay were determined.

RESULTS

There were important correlations with hydrogen peroxide, tert-butyl hydroperoxide and cumene hydroperoxide solutions (r=0.99, P<0.001 for all). In addition, the new assay presented a typical sigmoidal reaction pattern in copper-induced lipoprotein autoxidation. The novel assay is linear up to 200 micromol H2O2 Equiv./L and its precision value is lower than 3%. The lower detection limit is 1.13 micromol H2O2 Equiv./L. The reagents are stable for at least 6 months on the automated analyzer. Serum TOS level was significantly higher in patients with osteoarthritis (21.23+/-3.11 micromol H2O2 Equiv./L) than in healthy subjects (14.19+/-3.16 micromol H2O2 Equiv./L, P<0.001) and the results showed a significant negative correlation with total antioxidant capacity (TAC) (r=-0.66 P<0.01).

CONCLUSIONS

This easy, stable, reliable, sensitive, inexpensive and fully automated method that is described can be used to measure total oxidant status.

Soy versus whey protein bars: effects on exercise training impact on lean body mass and antioxidant status

Background

Although soy protein may have many health benefits derived from its associated antioxidants, many male exercisers avoid soy protein. This is due partly to a popular, but untested notion that in males, soy is inferior to whey in promoting muscle weight gain. This study provided a direct comparison between a soy product and a whey product.

Methods

Lean body mass gain was examined in males from a university weight training class given daily servings of micronutrient-fortified protein bars containing soy or whey protein (33 g protein/day, 9 weeks, n = 9 for each protein treatment group). Training used workouts with fairly low repetition numbers per set. A control group from the class (N = 9) did the training, but did not consume either type protein bar.

Results

Both the soy and whey treatment groups showed a gain in lean body mass, but the training-only group did not. The whey and training only groups, but not the soy group, showed a potentially deleterious post-training effect on two antioxidant-related related parameters.

Conclusions

Soy and whey protein bar products both promoted exercise training-induced lean body mass gain, but the soy had the added benefit of preserving two aspects of antioxidant function.

The relationship between potency of oxidative stress and severity of depression

BACKGROUND

Oxidative stress is one of the suggested mechanisms in major depression.

OBJECTIVE

To determine the oxidative and antioxidative status of plasma of patients with major depression and to investigate whether there is a relationship between the potency of oxidative stress and the severity of depression.

METHODS

To determine the antioxidative status of plasma, total and individual antioxidant levels which are total antioxidant potential (TAOP), total protein, albumin, uric acid, vitamin C and total bilirubin were measured. To determine the oxidative status, total peroxide level of plasma was measured in patients with drug-free depressive patients and compared with those of controls. Per cent ratio of total peroxide to TAOP was evaluated as oxidative stress index (OSI).

RESULTS

Plasma TAOP and individual antioxidant levels were found to be lower in patients with depression than those of controls. On the contrary, the patients had high total plasma peroxide levels. OSI values of the patients were significantly higher than those of controls (P = 0.002), and a significant positive correlation between Hamilton Depression Rating Scale (HDRS) and OSI values was found (r = 0.54, P = 0.01).

CONCLUSIONS

The patients with major depression are exposed to oxidative stress, and OSI may be useful to reflect the severity of the disease.

Oxidative stress: potential of distinct peroxide determination systems

When reactive oxygen species attack biological structures, peroxides, which are short-lived oxidative intermediates, are generated. We evaluated the potential of two different, commercially available peroxide activity assays (Pox-Act and d-ROMS) to see whether the results were associated with the clinical condition of subjects who were participating in a routine health care program. Furthermore, we determined the total antioxidant status (TAS) and the titer of autoantibodies against oxidized low-density lipoprotein (oLAb) to verify the hydroperoxide measurements.

Subjects with medical conditions (hereafter referred to as patients) had significantly increased serum peroxide levels compared to healthy subjects. The d-ROMS kit indicated that 86% of subjects had an increased level of total peroxides. Although the assays had a significant correlation (p < 0.001), 34% of the subjects had an increased total peroxide concentration in the Pox-Act assay that was clearly associated with clinical symptoms. Furthermore, the sensitivity of the Pox-Act assay was 35 times higher than that of the d-ROMS kit. In subjects with medical conditions, there was a trend toward a decreased TAS and a slightly increased oLAb titer in comparison to healthy subjects, but this was not statistically significant. The Pox-Act assay seems to be a valuable tool for the determination of total peroxides, while the results from the d-ROMS kit should be considered with caution.