Characterization of the Sideritis scardica Extract SidTea+TM and Its Effect on Physiological Profile, Metabolic Health and Redox Biomarkers in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Study.

This study aimed to characterize a Sideritis scardica extract (SidTea+TM) and investigate its effect on the physiological profile, metabolic health and redox status in healthy individuals. The chemical profile and antioxidant potential of the SidTea+TM extract were evaluated by UPLC-HRMS analysis and in vitro cell-free methods. Twenty-eight healthy adults participated in this randomized, double-blind, placebo-controlled study. Participants consumed 1500 mg/day of SidTea+TM or a placebo for 4 weeks. At baseline and post-supplementation, participants were assessed for their anthropometric and physiological profile and provided a resting blood sample. SidTea+TM decreased (p < 0.05) systolic blood pressure (-10.8 mmHg), mean arterial pressure (-4.5 mmHg), resting heart rate (-3.1 bpm) and handgrip strength of the non-dominant limb (-0.8 kg) whereas the placebo decreased (p < 0.05) handgrip strength of the dominant (-5.8 kg) and non-dominant (-3.2 kg) limb. SidTea+TM also resulted in an increase (p < 0.05) in estimated VO2max (+1.1 mL/kg/min) and a reduction (p < 0.05) in γ-GT and SGPT enzymatic activity in serum (-3.7 and -3.3 U/L, respectively). Finally, SidTea+TM increased (p < 0.001) total antioxidant capacity and decreased (p < 0.05) lipid peroxidation levels in plasma. These results indicate that SidTea+TM is a potent and safe to use antioxidant that can elicit positive changes in indices of blood pressure, cardiorespiratory capacity, liver metabolism, and redox status in healthy adults over a 4-week supplementation period.

Inter-individual variability in redox and performance responses after antioxidant supplementation: A randomized double blind crossover study.

AIM: We aimed to investigate the inter-individual variability in redox and physiological responses of antioxidant-deficient subjects after antioxidant supplementation. METHODS: Two hundred individuals were sorted by plasma vitamin C levels. A low vitamin C group (n = 22) and a control group (n = 22) were compared in terms of oxidative stress and performance. Subsequently, the low vitamin C group received for 30 days vitamin C (1 g) or placebo, in randomized, double-blind, crossover fashion, and the effects were examined through a mixed-effects model, while individual responses were calculated. RESULTS: The low vitamin C group exhibited lower vitamin C (-25 µmol/L; 95%CI[-31.7, -18.3]; p < 0.001), higher F2 -isoprostanes (+17.1 pg/mL; 95%CI[6.5, 27.7]; p = 0.002), impaired VO2max (-8.2 mL/kg/min; 95%CI[-12.8, -3.6]; p < 0.001) and lower isometric peak torque (-41.5 Nm; 95%CI[-61.8, -21.2]; p < 0.001) compared to the control group. Regarding antioxidant supplementation, a significant treatment effect was found in vitamin C (+11.6 µmol/L; 95%CI[6.8, 17.1], p < 0.001), F2 -isoprostanes (-13.7 pg/mL; 95%CI[-18.9, -8.4], p < 0.001), VO2max (+5.4 mL/kg/min; 95%CI[2.7, 8.2], p = 0.001) and isometric peak torque (+18.7; 95%CI[11.8, 25.7 Nm], p < 0.001). The standard deviation for individual responses (SDir) was greater than the smallest worthwhile change (SWC) for all variables indicating meaningful inter-individual variability. When a minimal clinically important difference (MCID) was set, inter-individual variability remained for VO2max , but not for isometric peak torque. CONCLUSION: The proportion of response was generally high after supplementation (82.9%-95.3%); however, a few participants did not benefit from the treatment. This underlines the potential need for personalized nutritional interventions in an exercise physiology context.

The Effects of Spirulina Supplementation on Redox Status and Performance Following a Muscle Damaging Protocol.

Spirulina plantensis is a popular supplement which has been shown to have antioxidant and performance enhancing properties. The purpose of this study was to evaluate the effects of spirulina supplementation on (a) redox status (b) muscle performance and (c) muscle damage following an eccentric bout of exercise that would induce muscle damage. Twenty-four healthy, recreationally trained males participated in the study and were randomly separated into two groups: a spirulina supplementation (6 g per day) and a placebo group. Both groups performed an eccentric bout of exercise consisting of 5 sets and 15 maximum reps per set. Blood was collected at 24, 48, 72 and 96 h after the bout and total antioxidant capacity (TAC) and protein carbonyls (PC) were assessed in plasma. Delayed onset muscle soreness (DOMS) was also assessed at the same aforementioned time points. Eccentric peak torque (EPT) was evaluated immediately after exercise, as well as at 24, 48, 72 and 96 h post exercise. Redox status indices (TAC and PC) did not change significantly at any time point post exercise. DOMS increased significantly 24 h post exercise and remained elevated until 72 h and 96 h post exercise for the placebo and spirulina group, respectively. EPT decreased significantly and immediately post exercise and remained significantly lower compared to baseline until 72 h post exercise. No significant differences between groups were found for DOMS and EPT. These results indicate that spirulina supplementation following a muscle damaging protocol does not confer beneficial effects on redox status, muscle performance or damage.

Effect of whey vs. soy protein supplementation on recovery kinetics following speed endurance training in competitive male soccer players: a randomized controlled trial.

BACKGROUND: Soccer-specific speed-endurance training induces short-term neuromuscular fatigue and performance deterioration over a 72-h recovery period, associated with elevated markers of exercise-induced muscle damage. We compared the effects of whey vs. soy protein supplementation on field activity, performance, muscle damage and redox responses following speed-endurance training in soccer players. METHODS: Ten well-trained, male soccer players completed three speed-endurance training trials, receiving whey protein (WP), soy protein (SP) or an isoenergetic placebo (PL; maltodextrin) according to a randomized, double-blind, crossover, repeated-measures design. A pre-loading period was applied in each trial during which protein supplementation was individually adjusted to reach a total protein intake of 1.5 g/kg/day, whereas in PL protein intake was adjusted at 0.8-1 g/kg/day. Following pre-loading, two speed-endurance training sessions (1 and 2) were performed 1 day apart, over a 3-day experimental period. During each session, field activity and heart rate were continuously monitored using global positioning system and heart rate monitors, respectively. Performance (isokinetic strength of knee extensors and flexors, maximal voluntary isometric contraction, speed, repeated sprint ability, countermovement jump), muscle damage (delayed-onset of muscle soreness, creatine kinase activity) and redox status (glutathione, total antioxidant capacity, protein carbonyls) were evaluated at baseline (pre), following pre-loading (post-load), and during recovery from speed-endurance training. RESULTS: High-intensity and high-speed running decreased (P ≤ 0.05) during speed-endurance training in all trials, but WP and SP mitigated this response. Isokinetic strength, maximal voluntary isometric contraction, 30-m speed, repeated sprint ability and countermovement jump performance were similarly deteriorated during recovery following speed-endurance training in all trials (P ≤ 0.05). 10 m speed was impaired at 24 h only in PL. Delayed-onset of muscle soreness, creatine kinase, total antioxidant capacity and protein carbonyls increased and glutathione decreased equally among trials following speed-endurance training (P ≤ 0.05), with SP inducing a faster recovery of protein carbonyls only at 48 h (P ≤ 0.05) compared to WP and PL. CONCLUSIONS: In conclusion, increasing daily protein intake to 1.5 g/kg through ingestion of either whey or soy protein supplements mitigates field performance deterioration during successive speed-endurance training sessions without affecting exercise-induced muscle damage and redox status markers. TRIAL REGISTRATION: Name of the registry: clinicaltrials.gov. TRIAL REGISTRATION: NCT03753321 . Date of registration: 12/10/2018.

Fibroblast Growth Factor 23 (FGF23) and Klotho Protein in Beta-Thalassemia.

Derangements in phosphate and calcium homeostasis are common in patients with beta-thalassemia. Fibroblast growth factor 23 (FGF23) is among the main hormones regulating phosphate levels, while several studies underline an interplay between iron (Fe) and FGF23. Herein, we investigated, for the first time, the serum intact molecule (iFGF23) and the carboxyl-terminal fragment (C-FGF23) and Klotho levels simultaneously in patients with beta-thalassemia major receiving iron chelation regimens in comparison to healthy control subjects. We also correlated them with the body iron burden. The observational case-control study included 81 subjects (40 thalassemic patients and 41 healthy controls). Serum iFGF23, C-FGF23 and Κlotho were measured by ELISA. Parathormone, 25-hydroxycholecalciferol, calcium, and phosphorus were measured in blood and/or urine. The degree of hemosiderosis was evaluated by assessing the serum ferritin levels and performing T2* MRI measurements. Serum C-FGF23 levels were significantly lower in patients compared to control subjects (p=0.04), while iFGF23 and Klotho levels did not differ. Serum C-FGF23 levels were negatively correlated with ferritin (r=-0,421, p=0.018), whereas there were no significant correlations of each of the three factors with the iron chelation therapy. Decreased serum C-FGF23 levels were found in ßTh patients which may be attributed to inhibition of proteolytic cleavage of iFGF23. Further studies in a greater number of patients will shed more light on the disturbances of the iFGF23, Klotho and C-FGF23 in thalassemia and their possible role in bone disease of such patients.

Protein-Based Supplementation to Enhance Recovery in Team Sports: What is the Evidence?

Protein supplementation is a major nutritional practice among professional and amateur team-sport athletes representing a market of $5 billion in the USA alone. This practice, however, may not be supported by evidence-based science. Our objective as to present a thorough review of literature investigating the effects of protein supplementation on performance recovery and exercise-induced muscle damage following team-sport activity. PubMed-derived, full English language articles investigating the effects of protein-based supplementation/feeding on skeletal muscle performance, muscle damage and inflammatory status during recovery following team-sport activity were included. Studies investigated professional or amateur team-sport athletes participating in regular training and competition as well as examining the impact of protein supplementation on performance, muscle damage/soreness and inflammatory markers after team-sport activity. Finally, ten articles (150 participants) met the inclusion criteria. Experimental designs were evaluated for confounders. All protocols employing team-sport activity increased systemic muscle damage indicators and inflammatory markers and deteriorated performance during recovery. Protein-based supplementation attenuated the rise in muscle damage markers and enhanced performance recovery in six (60% of the studies included) and three (30% of the studies included) out of 10 studies, respectively. In contrast, immunity and muscle soreness remained unaffected by protein ingestion, independent of dosage and distribution pattern. In conclusion, there are limited and inconsistent data showing that protein supplementation may enhance performance recovery following team-sport activity despite an attenuation of indirect markers of muscle damage. Interpretation of results is limited by small sample sizes, high variability in tested supplements, participants' training level, length of recovery periods, absence of direct measurement of myofibrillar disruption, protein turnover and protein metabolism, and lack of dietary monitoring during experimentation.

Exercise in Glucose-6-Phosphate Dehydrogenase Deficiency: Harmful or Harmless? A Narrative Review.

OBJECTIVES: Glucose-6-phosphate dehydrogenase (G6PD) deficiency, theoretically, renders red blood cells (RBC) susceptible to oxidative stress. G6PD deficiency has also been found in other types of cells than RBC, such as leukocytes and myocytes, where an inefficient protection against oxidative stress may occur too. Glutathione (GSH), a significant antioxidant molecule, levels are lower in G6PD individuals, and theoretically, the probability of oxidative stress and haemolysis due to exercise in individuals with G6PD deficiency is increased, whereas dietary supplementation with antioxidants may have beneficial effects on various aspects of this enzymopathy. METHODS: A search of the available literature was conducted using the keywords glucose-6-phosphate dehydrogenase (G6PD), deficiency, disease, exercise, muscle, antioxidant, vitamin, supplement, and supplementation. The search was limited to publications in English, conducted on humans, and published until August 2018. After screening, only relevant articles were included. RESULTS: There is little evidence indicating that G6PD deficiency can cause perturbations in redox status, haemolysis, and clinical symptoms such as fatigability and myoglobinuria, especially after intense exercise, compared to individuals with normal enzyme levels. CONCLUSIONS: Exercise could be used by G6PD-deficient individuals as a tool to improve their quality of life. However, there is a lack of training studies, and assessment of the effects of regular and systematic exercise in G6PD-deficient individuals is warranted. Finally, since GSH levels are lower in G6PD deficiency, it would be interesting to examine the effects of antioxidant or cysteine donor supplements on redox status after exercise in these individuals.

Exercise and Redox Status Responses Following Alpha-Lipoic Acid Supplementation in G6PD Deficient Individuals.

G6PD deficiency renders cells more susceptible to oxidative insults, while antioxidant dietary supplementation could restore redox balance and ameliorate exercise-induced oxidative stress. To examine the effects of alpha-lipoic acid (ALA) supplementation on redox status indices in G6PD deficient individuals, eight male adults with G6PD deficiency (D) participated in this randomized double-blind placebo-controlled crossover trial. Participants were randomly assigned to receive ALA (600 mg/day) or placebo for 4 weeks separated by a 4-week washout period. Before and at the end of each treatment period, participants exercised following an exhaustive treadmill exercise protocol. Blood samples were obtained before (at rest), immediately after and 1h after exercise for later analysis of total antioxidant capacity (TAC), uric acid, bilirubin, thiobarbituric acid reactive substances (TBARS) and protein carbonyls (PC). ALA resulted in significantly increased resting TAC and bilirubin concentrations. Moreover, TAC increased immediately and 1h after exercise following both treatment periods, whereas bilirubin increased immediately after and 1h after exercise following only ALA. No significant change in uric acid, TBARS or PC was observed at any time point. ALA supplementation for 4 weeks may enhance antioxidant status in G6PD individuals; however, it does not affect redox responses to acute exercise until exhaustion or exercise performance.

Post-Game High Protein Intake May Improve Recovery of Football-Specific Performance during a Congested Game Fixture: Results from the PRO-FOOTBALL Study.

The effects of protein supplementation on performance recovery and inflammatory responses during a simulated one-week in-season microcycle with two games (G1, G2) performed three days apart were examined. Twenty football players participated in two trials, receiving either milk protein concentrate (1.15 and 0.26 g/kg on game and training days, respectively) (PRO) or an energy-matched placebo (1.37 and 0.31 g/kg of carbohydrate on game and training days, respectively) (PLA) according to a randomized, repeated-measures, crossover, double-blind design. Each trial included two games and four daily practices. Speed, jump height, isokinetic peak torque, and muscle soreness of knee flexors (KF) and extensors (KE) were measured before G1 and daily thereafter for six days. Blood was drawn before G1 and daily thereafter. Football-specific locomotor activity and heart rate were monitored using GPS technology during games and practices. The two games resulted in reduced speed (by 3-17%), strength of knee flexors (by 12-23%), and jumping performance (by 3-10%) throughout recovery, in both trials. Average heart rate and total distance covered during games remained unchanged in PRO but not in PLA. Moreover, PRO resulted in a change of smaller magnitude in high-intensity running at the end of G2 (75-90 min vs. 0-15 min) compared to PLA (P = 0.012). KE concentric strength demonstrated a more prolonged decline in PLA (days 1 and 2 after G1, P = 0.014-0.018; days 1, 2 and 3 after G2, P = 0.016-0.037) compared to PRO (days 1 after G1, P = 0.013; days 1 and 2 after G2, P = 0.014-0.033) following both games. KF eccentric strength decreased throughout recovery after G1 (PLA: P=0.001-0.047-PRO: P =0.004-0.22) in both trials, whereas after G2 it declined throughout recovery in PLA (P = 0.000-0.013) but only during the first two days (P = 0.000-0.014) in PRO. No treatment effect was observed for delayed onset of muscle soreness, leukocyte counts, and creatine kinase activity. PRO resulted in a faster recovery of protein and lipid peroxidation markers after both games. Reduced glutathione demonstrated a more short-lived reduction after G2 in PRO compared to PLA. In summary, these results provide evidence that protein feeding may more efficiently restore football-specific performance and strength and provide antioxidant protection during a congested game fixture.

Chronic Eccentric Exercise and Antioxidant Supplementation: Effects on Lipid Profile and Insulin Sensitivity.

Eccentric exercise has been shown to exert beneficial effects in both lipid profile and insulin sensitivity. Antioxidant supplementation during chronic exercise is controversial as it may prevent the physiological training-induced adaptations. The aim of this study was to investigate: 1) the minimum duration of the eccentric exercise training required before changes on metabolic parameters are observed and 2) whether antioxidant supplementation during training would interfere with these adaptations. Sixteen young healthy men were randomized into the Vit group (1 g of vitamin C and 400 IU vitamin E daily) and the placebo (PL) group. Subjects received the supplementation for 9 weeks. During weeks 5-9 all participants went through an eccentric exercise training protocol consisting of two exercise sessions (5 sets of 15 eccentric maximal voluntary contractions) per week. Plasma triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), apolipoproteins (Apo A1, Apo B and Lpa) and insulin sensitivity (HOMA) were assessed before the supplementation (week 0), at weeks 5, 6, 7, 8 and 9. TG, TC and LDL were significantly lower compared to pre supplementation at both weeks 8 and 9 (P<0.05) in both groups. HDL was significantly elevated after 4 weeks of training (p < 0.005) in both groups. There was no effect of the antioxidant supplementation in any of the variables. There was no effect of either the training or the supplementation protocol in apolipoproteins levels and insulin sensitivity. A minimum duration of 3 weeks of eccentric exercise training is required before beneficial effects in lipid profile can be observed in healthy young men. Concomitant antioxidant supplementation does not interfere with the training-induced adaptations.

Protein ingestion preserves proteasome activity during intense aseptic inflammation and facilitates skeletal muscle recovery in humans.

The ubiquitin-proteasome system (UPS) is the main cellular proteolytic system responsible for the degradation of normal and abnormal (e.g. oxidised) proteins. Under catabolic conditions characterised by chronic inflammation, the UPS is activated resulting in proteolysis, muscle wasting and impaired muscle function. Milk proteins provide sulphur-containing amino acid and have been proposed to affect muscle inflammation. However, the response of the UPS to aseptic inflammation and protein supplementation is largely unknown. The aim of this study was to investigate how milk protein supplementation affects UPS activity and skeletal muscle function under conditions of aseptic injury induced by intense, eccentric exercise. In a double-blind, cross-over, repeated measures design, eleven men received either placebo (PLA) or milk protein concentrate (PRO, 4×20 g on exercise day and 20 g/d for the following 8 days), following an acute bout of eccentric exercise (twenty sets of fifteen eccentric contractions at 30°/s) on an isokinetic dynamometer. In each trial, muscle biopsies were obtained from the vastus lateralis muscle at baseline, as well as at 2 and 8 d post exercise, whereas blood samples were collected before exercise and at 6 h, 1 d, 2 d and 8 d post exercise. Muscle strength and soreness were assessed before exercise, 6 h post exercise and then daily for 8 consecutive days. PRO preserved chymotrypsin-like activity and attenuated the decrease of strength, facilitating its recovery. PRO also prevented the increase of NF-κB phosphorylation and HSP70 expression throughout recovery. We conclude that milk PRO supplementation following exercise-induced muscle trauma preserves proteasome activity and attenuates strength decline during the pro-inflammatory phase.

Iron Supplementation Effects on Redox Status following Aseptic Skeletal Muscle Trauma in Adults and Children.

Exercise-induced skeletal muscle microtrauma is characterized by loss of muscle cell integrity, marked aseptic inflammatory response, and oxidative stress. We examined if iron supplementation would alter redox status after eccentric exercise. In a randomized, double blind crossover study, that was conducted in two cycles, healthy adults (n = 14) and children (n = 11) received daily either 37 mg of elemental iron or placebo for 3 weeks prior to and up to 72 h after an acute eccentric exercise bout. Blood was drawn at baseline, before exercise, and 72 h after exercise for the assessment of iron status, creatine kinase activity (CK), and redox status. Iron supplementation at rest increased iron concentration and transferrin saturation (p < 0.01). In adults, CK activity increased at 72 h after exercise, while no changes occurred in children. Iron supplementation increased TBARS at 72 h after exercise in both adults and children; no changes occurred under placebo condition. Eccentric exercise decreased bilirubin concentration at 72 h in all groups. Iron supplementation can alter redox responses after muscle-damaging exercise in both adults and children. This could be of great importance not only for healthy exercising individuals, but also in clinical conditions which are characterized by skeletal muscle injury and inflammation, yet iron supplementation is crucial for maintaining iron homeostasis. This study was registered at Clinicaltrials.gov Identifier: NCT02374619.

Inflammaging and Skeletal Muscle: Can Protein Intake Make a Difference?

Inflammaging is the chronic low-grade inflammatory state present in the elderly, characterized by increased systemic concentrations of proinflammatory cytokines. It has been shown that inflammaging increases the risk of pathologic conditions and age-related diseases, and that it also has been associated with increased skeletal muscle wasting, strength loss, and functional impairments. Experimental evidence suggests that the increased concentrations of proinflammatory cytokines and primary tumor necrosis factor α observed in chronic inflammation lead to protein degradation through proteasome activation and reduced skeletal muscle protein synthesis (MPS) via protein kinase B/Akt downregulation. Dairy and soy proteins contain all the essential amino acids, demonstrate sufficient absorption kinetics, and include other bioactive peptides that may offer nutritional benefits, in addition to those of stimulating MPS. Whey protein has antioxidative effects, primarily because of its ability to enhance the availability of reduced glutathione and the activity of the endogenous antioxidative enzyme system. Soy protein and isoflavone-enriched soy protein, meanwhile, may counteract chronic inflammation through regulation of the nuclear transcription factor κB signaling pathway and cytokine production. Although evidence suggests that whey protein, soy protein, and isoflavone-enriched soy proteins may be promising nutritional interventions against the oxidative stress and chronic inflammation present in pathologic conditions and aging (inflammaging), there is a lack of information about the anabolic potential of dietary protein intake and protein supplementation in elderly people with increased systemic inflammation. The antioxidative and anti-inflammatory effects, as well as the anabolic potential of protein supplementation, should be further investigated in the future with well-designed clinical trials focusing on inflammaging and its associated skeletal muscle loss.

Thiol-based antioxidant supplementation alters human skeletal muscle signaling and attenuates its inflammatory response and recovery after intense eccentric exercise.

BACKGROUND: The major thiol-disulfide couple of reduced glutathione (GSH) and oxidized glutathione is a key regulator of major transcriptional pathways regulating aseptic inflammation and recovery of skeletal muscle after aseptic injury. Antioxidant supplementation may hamper exercise-induced cellular adaptations. OBJECTIVE: The objective was to examine how thiol-based antioxidant supplementation affects skeletal muscle's performance and redox-sensitive signaling during the inflammatory and repair phases associated with exercise-induced microtrauma. DESIGN: In a double-blind, crossover design, 10 men received placebo or N-acetylcysteine (NAC; 20 mg · kg(-1) · d(-1)) after muscle-damaging exercise (300 eccentric contractions). In each trial, muscle performance was measured at baseline, after exercise, 2 h after exercise, and daily for 8 consecutive days. Muscle biopsy samples from vastus lateralis and blood samples were collected before exercise and 2 h, 2 d, and 8 d after exercise. RESULTS: NAC attenuated the elevation of inflammatory markers of muscle damage (creatine kinase activity, C-reactive protein, proinflammatory cytokines), nuclear factor κB phosphorylation, and the decrease in strength during the first 2 d of recovery. NAC also blunted the increase in phosphorylation of protein kinase B, mammalian target of rapamycin, p70 ribosomal S6 kinase, ribosomal protein S6, and mitogen activated protein kinase p38 at 2 and 8 d after exercise. NAC also abolished the increase in myogenic determination factor and reduced tumor necrosis factor-α 8 d after exercise. Performance was completely recovered only in the placebo group. CONCLUSION: Although thiol-based antioxidant supplementation enhances GSH availability in skeletal muscle, it disrupts the skeletal muscle inflammatory response and repair capability, potentially because of a blunted activation of redox-sensitive signaling pathways. This trial was registered at clinicaltrials.gov as NCT01778309.

Α-lipoic acid supplementation up-regulates antioxidant capacity in adults with G6PD deficiency.

The purpose of this study was to examine the effect of α-lipoic acid (LA) supplementation on blood redox status in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Eight adults with G6PD deficiency (D group) and eight controls with normal G6PD levels (N group) participated in this study. Participants received LA (600 mg/day) for 28 days. At baseline, 2 and 4 weeks after supplementation, venous blood was collected for analysis of reduced glutathione (GSH), catalase, protein carbonyls (PC), thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC), bilirubin, uric acid (UA) and hemoglobin (Hb) levels. Baseline GSH was lower (P<0.05) in D compared to N group whereas LA supplementation for 2 and 4 weeks increased significantly (P<0.05) GSH levels in both groups. Catalase and TAC increased (P<0.05) in both groups following 2 and 4 weeks of supplementation. Baseline TBARS values were higher (P<0.05) in D compared to N group while LA supplementation reduced (P<0.05) TBARS and PC in both groups. There were no differences for UA at baseline between the two groups but LA supplementation increased significantly UA levels only in the D group. Bilirubin and Hb were unchanged. These results indicate that LA supplementation may modulate redox status regardless G6PD deficiency.

No effect of antioxidant supplementation on muscle performance and blood redox status adaptations to eccentric training.

BACKGROUND: It was recently reported that antioxidant supplementation decreases training efficiency and prevents cellular adaptations to chronic exercise. OBJECTIVE: This study aimed to investigate the effects of vitamin C and vitamin E supplementation on muscle performance, blood and muscle redox status biomarkers, and hemolysis in trained and untrained men after acute and chronic exercise. A specific type of exercise was applied (eccentric) to produce long-lasting and extensive changes in redox status biomarkers and to examine more easily the potential effects of antioxidant supplementation. DESIGN: In a double-blinded fashion, men received either a daily oral supplement of vitamin C and vitamin E (n = 14) or placebo (n = 14) for 11 wk (started 4 wk before the pretraining exercise testing and continued until the posttraining exercise testing). After baseline testing, the subjects performed an eccentric exercise session 2 times/wk for 4 wk. Before and after the chronic eccentric exercise, the subjects underwent one session of acute eccentric exercise, physiologic measurements were performed, and blood samples and muscle biopsy samples (from 4 men) were collected. RESULTS: The results failed to support any effect of antioxidant supplementation. Eccentric exercise similarly modified muscle damage and performance, blood redox status biomarkers, and hemolysis in both the supplemented and nonsupplemented groups. This occurred despite the fact that eccentric exercise induced marked changes in muscle damage and performance and in redox status after exercise. CONCLUSION: The complete lack of any effect on the physiologic and biochemical outcome measures used raises questions about the validity of using oral antioxidant supplementation as a redox modulator of muscle and redox status in healthy humans.

Effects of L-carnitine on oxidative stress responses in patients with renal disease.

PURPOSE: Hemodialyzed patients demonstrate elevated oxidative stress and reduced functional status. Exercise induces health benefits, but acute exertion up-regulates oxidative stress responses in patients undergoing hemodialysis. Therefore, the aim of the present study was to examine the effect of L-carnitine supplementation on i) exercise performance and ii) blood redox status both at rest and after exercise. METHODS: Twelve hemodialysis patients received either L-carnitine (20 mg kg(-1) i.v.) or placebo in a double-blind, placebo-controlled, counterbalanced, and crossover design for 8 wk. Participants performed an exercise test to exhaustion before and after supplementation. During the test, V˙O2, respiratory quotient, heart rate, and time to exhaustion were monitored. Blood samples, collected before and after exercise, were analyzed for lactate, malondialdehyde, protein carbonyls, reduced and oxidized glutathione, antioxidant capacity, catalase, and glutathione peroxidase activity. RESULTS: Blood carnitine increased by L-carnitine supplementation proportionately at rest and after exercise. L-carnitine supplementation increased time to fatigue (22%) and decreased postexercise lactate (37%), submaximal heart rate, and respiratory quotient but did not affect V˙O2peak. L-carnitine supplementation increased reduced/oxidized glutathione (2.7-fold at rest, 4-fold postexercise) and glutathione peroxidase activity (4.5% at rest, 10% postexercise) and decreased malondialdehyde (19% at rest and postexercise) and protein carbonyl (27% at rest, 40% postexercise) concentration. CONCLUSIONS: Data suggest that a 2-month L-carnitine supplementation may be effective in attenuating oxidative stress responses, enhancing antioxidant status, and improving performance of patients with end-stage renal disease.

Dose-related effects of prolonged NaHCO3 ingestion during high-intensity exercise.

PURPOSE: Sodium bicarbonate (NaHCO3) ingestion may prevent exercise-induced perturbations in acid-base balance, thus resulting in performance enhancement. This study aimed to determine whether different levels of NaHCO3 intake influences acid-base balance and performance during high-intensity exercise after 5 d of supplementation. METHODS: Twenty-four men (22 +/- 1.7 yr) were randomly assigned to one of three groups (eight subjects per group): control (C, placebo), moderate NaHCO3 intake (MI, 0.3 g x kg(-1) x d(-1)), and high NaHCO3 intake (HI, 0.5 g x kg(-1) x d(-1)). Arterial pH, HCO3(-), PO2, PCO2, K+, Na, base excess (BE), lactate, and mean power (MP) were measured before and after a Wingate test pre- and postsupplementation. RESULTS: HCO3(-) increased proportionately to the dosage level. No differences were detected in C. Supplementation increased MP (W x kg(-)) in MI (7.36 +/- 0.7 vs 6.73 +/- 1.0) and HI (7.72 +/- 0.9 vs 6.69 +/- 0.6), with HI being more effective than MI. NaHCO3 ingestion resulted postexercise in increased lactate (mmol x L(-1)) (12.3 +/- 1.8 vs 10.3 +/- 1.9 and 12.4 +/- 1.2 vs 10.4 +/- 1.5 in MI and HI, respectively), reduced exercise-induced drop of pH (7.305 +/- 0.04 vs 7.198 +/- 0.02 and 7.343 +/- 0.05 vs 7.2 +/- 0.01 in MI and HI, respectively) and HCO3(-) (mmol x L(-1)) (13.1 +/- 2.4 vs 17.5 +/- 2.8 and 13.2 +/- 2.7 vs 19.8 +/- 3.2 for HCO3 in MI and HI, respectively), and reduced K (3.875 +/- 0.2 vs 3.625 +/- 0.3 mmol x L(-1) in MI and HI, respectively). CONCLUSION: NaHCO3 administration for 5 d may prevent acid-base balance disturbances and improve performance during anaerobic exercise in a dose-dependent manner.