Short term creatine loading improves strength endurance even without changing maximal strength, RPE, fatigue index, blood lactate, and mode state.

Creatine is consumed by athletes to increase strength and gain muscle. The aim of this study was to evaluate the effects of creatine supplementation on maximal strength and strength endurance. Twelve strength-trained men (25.2 ± 3.4 years) supplemented with 20 g Creatina + 10g maltodextrin or placebo (20g starch + 10g maltodextrin) for five days in randomized order. Maximal strength and strength endurance (4 sets 70% 1RM until concentric failure) were determined in the bench press. In addition, blood lactate, rate of perceived effort, fatigue index, and mood state were evaluated. All measurements were performed before and after the supplementation period. There were no significant changing in maximal strength, blood lactate, RPE, fatigue index, and mood state in either treatment. However, the creatine group performed more repetitions after the supplementation (Cr: Δ = +3.4 reps, p = 0.036, g = 0.53; PLA: Δ = +0.3reps, p = 0.414, g = 0.06), and higher total work (Cr: Δ = +199.5au, p = 0.038, g = 0.52; PLA: Δ = +26.7au, p = 0.402, g = 0.07). Creatine loading for five days allowed the subjects to perform more repetitions, resulting in greater total work, but failed to change the maximum strength.

Effects of a Low Dose of Orally Administered Creatine Monohydrate on Post-Fatigue Muscle Power in Young Soccer Players.

The use of creatine monohydrate (Cr) in professional soccer is widely documented. However, the effect of low doses of Cr on the physical performance of young soccer players is unknown. This study determined the effect of a low dose of orally administered Cr on muscle power after acute intra-session fatigue in young soccer players. Twenty-eight young soccer players (mean age = 17.1 ± 0.9 years) were randomly assigned to either a Cr (n = 14, 0.3 g·kg-1·day-1 for 14 days) or placebo group (n = 14), using a two-group matched, double-blind, placebo-controlled design. Before and after supplementation, participants performed 21 repetitions of 30 m (fatigue induction), and then, to measure muscle power, they performed four repetitions in half back squat (HBS) at 65% of 1RM. Statistical analysis included a two-factor ANOVA (p ˂ 0.05). Bar velocity at HBS, time: p = 0.0006, ŋp2 = 0.22; group: p = 0.0431, ŋp2 = 0.12, time × group p = 0.0744, ŋp2 = 0.02. Power at HBS, time: p = 0.0006, ŋp2 = 0.12; group: p = 0.16, ŋp2 = 0.06, time × group: p = 0.17, ŋp2 = 0.009. At the end of the study, it was found that, after the induction of acute intra-session fatigue, a low dose of Cr administered orally increases muscle power in young soccer players.

Study of anti-fatigue activity of polysaccharide from fruiting bodies of Armillaria gallica.

Fatigue is a common physiological response that is closely related to energy metabolism. Polysaccharides, as excellent dietary supplements, have been proven to have a variety of pharmacological activities. In this study, A 23.007 kDa polysaccharide from Armillaria gallica (AGP) was purified and performed structural characterization, including analysis of homogeneity, molecular weight and monosaccharide composition. Methylation analysis is used to analyze the glycosidic bond composition of AGP. The mouse model of acute fatigue was used to evaluate the anti-fatigue effect of AGP. AGP-treatment improved exercise endurance in mice and reduced fatigue symptoms caused by acute exercise. AGP regulated the levels of adenosine triphosphate, lactic acid, blood urea nitrogen and lactate dehydrogenase, muscle glycogen and liver glycogen of acute fatigue mice. AGP affected the composition of intestinal microbiota, the changes of some intestinal microorganisms are correlated with fatigue and oxidative stress indicators. Meanwhile, AGP reduced oxidative stress levels, increased antioxidant enzyme activity and regulated the AMP-dependent protein kinase/nuclear factor erythroid 2-related factor 2 signaling pathway. AGP exerted an anti-fatigue effect through modulation of oxidative stress, which is related to intestinal microbiota.

Anti-fatigue effects of enzyme-hydrolyzed okara in C2C12 myotubes and Sprague-Dawley rats.

Okara is a by-product of tofu or soymilk production processes. The disposal of huge quantities of okara is a significant issue. Based on previous reports, protein hydrolysis can release excess free amino acids and small peptides from okara and exhibit anti-fatigue function. We aimed to investigate the anti-fatigue effect of okara protein hydrolysate (OPH) in vitro and in vivo. In the first phase, we treated C2C12 myotubes with different processed OPHs to detect mitochondrial functions. The results revealed that OPH hydrolyzed with alcalase containing 2% E/S for 2 h increased the mitochondrial mRNA level (cytochrome b and cytochrome c oxidase I) and enzyme activity (citrate synthase and cytochrome c oxidase) most efficiently. In the second phase, we conducted animal studies to assess the anti-fatigue function of OPH. After acclimatization, 8 week-old male Sprague-Dawley (SD) rats were randomly classified into four groups: (1) control group, (2) 1X-OPH, (3) 2X-OPH, and (4) 5X-OPH (8 rats per group, treated for 28 days). The results indicated that the intake of OPH for 28 days increased the exhaustive swimming time of rats and lowered the increment of the lactate ratio, as well as the activity of lactate dehydrogenase and creatine kinase. These results indicated that OPH improves exercise performance and anti-fatigue function in male SD rats. Therefore, OPH could be a potential health supplement for anti-fatigue function.

Effectiveness of Nitrate Intake on Recovery from Exercise-Related Fatigue: A Systematic Review.

BACKGROUND: Recovery between efforts is critical to achieving optimal physical and sports performance. In this sense, many nutritional supplements that have been proven to improve recovery and physical and physiological performance are widely used. Supplements such as nitrates (NO3-), including organic foods such as beets, promote muscle recovery and relieve fatigue. This study aimed to comprehensively summarise the available literature on the effect of NO3- consumption on exercise-related fatigue and muscle damage. METHODS: A systematic search was carried out based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) using electronic databases (e.g., PubMed, Scopus, and Web of Science). From a total of 1634 studies identified, 15 studies were included in this review. RESULTS: Based on the review, NO3- intake provokes physiological and metabolic responses that could potentially boost exercise-related recovery. NO3- could improve recovery indicators related to strength, pain, inflammation, and muscle damage. CONCLUSIONS: Despite the relative proven effectiveness of NO3- on recovery after aerobic and anaerobic efforts, based on the heterogeneity of the procedures (e.g., dosage, chronic vs. acute intake, participants' characteristics, variables and outcomes), it could be premature to suggest its extended use in sports.

Capsaicin and Its Effect on Exercise Performance, Fatigue and Inflammation after Exercise.

Capsaicin (CAP) activates the transient receptor potential vanilloid 1 (TRPV1) channel on sensory neurons, improving ATP production, vascular function, fatigue resistance, and thus exercise performance. However, the underlying mechanisms of CAP-induced ergogenic effects and fatigue-resistance, remain elusive. To evaluate the potential anti-fatigue effects of CAP, 10 young healthy males performed constant-load cycling exercise time to exhaustion (TTE) trials (85% maximal work rate) after ingestion of placebo (PL; fiber) or CAP capsules in a blinded, counterbalanced, crossover design, while cardiorespiratory responses were monitored. Fatigue was assessed with the interpolated twitch technique, pre-post exercise, during isometric maximal voluntary contractions (MVC). No significant differences (p > 0.05) were detected in cardiorespiratory responses and self-reported fatigue (RPE scale) during the time trial or in TTE (375 ± 26 and 327 ± 36 s, respectively). CAP attenuated the reduction in potentiated twitch (PL: -52 ± 6 vs. CAP: -42 ± 11%, p = 0.037), and tended to attenuate the decline in maximal relaxation rate (PL: -47 ± 33 vs. CAP: -29 ± 68%, p = 0.057), but not maximal rate of force development, MVC, or voluntary muscle activation. Thus, CAP might attenuate neuromuscular fatigue through alterations in afferent signaling or neuromuscular relaxation kinetics, perhaps mediated via the sarco-endoplasmic reticulum Ca2+ ATPase (SERCA) pumps, thereby increasing the rate of Ca2+ reuptake and relaxation.

The anti-fatigue effect of the Auxis thazard oligopeptide via modulation of the AMPK/PGC-1α pathway in mice.

The Auxis thazard oligopeptide (ATO) was obtained by papain digestion and ultrafiltration membrane separation, and its anti-fatigue effects and mechanisms were evaluated using animal experiments on Kunming mice. Compared with the negative control group, the ATO extended the time to exhaustion in mice in a forced swim test by 0.81-1.62 times. Liver glycogen levels were significantly increased by 0.6-1.63 times and muscle glycogen levels were increased by 9.52-10.02%; the levels of lactic acid (16.46-17.21%) and urea nitrogen (34.88-41.91%) decreased. The ATO also increased antioxidant activity, reduced malondialdehyde levels (18.00-35.79%) in the liver and myocardium, and increased the gene and protein expression of AMPK and PGC-1α in fatigued mice. These results indicate that the ATO exerts an anti-fatigue effect via improving energy metabolism and decreasing oxidative stress.

Blockade of 5-HT2 receptors suppresses rate of torque development and motor unit discharge rate during rapid contractions.

Serotonin (5-HT) is a neuromodulator that is critical for regulating the excitability of spinal motoneurons and the generation of muscle torque. However, the role of 5-HT in modulating human motor unit activity during rapid contractions has yet to be assessed. Nine healthy participants (23.7 ± 2.2 yr) ingested 8 mg of the competitive 5-HT2 antagonist cyproheptadine in a double-blinded, placebo-controlled, repeated-measures experiment. Rapid dorsiflexion contractions were performed at 30%, 50%, and 70% of maximal voluntary contraction (MVC), where motor unit activity was assessed by high-density surface electromyographic decomposition. A second protocol was performed where a sustained, fatigue-inducing dorsiflexion contraction was completed before undertaking the same 30%, 50%, and 70% MVC rapid contractions and motor unit analysis. Motor unit discharge rate (P < 0.001) and rate of torque development (RTD; P = 0.019) for the unfatigued muscle were both significantly lower for the cyproheptadine condition. Following the fatigue inducing contraction, cyproheptadine reduced motor unit discharge rate (P < 0.001) and RTD (P = 0.024), whereas the effects of cyproheptadine on motor unit discharge rate and RTD increased with increasing contraction intensity. Overall, these results support the viewpoint that serotonergic effects in the central nervous system occur fast enough to regulate motor unit discharge rate during rapid powerful contractions.NEW & NOTEWORTHY We have shown that serotonin activity in the central nervous system plays a role in regulating human motor unit discharge rate during rapid contractions. Our findings support the viewpoint that serotonergic effects in the central nervous system are fast and are most prominent during contractions that are characterized by high motor unit discharge rates and large amounts of torque development.

Anti-fatigue effect of phlorizin on exhaustive exercise-induced oxidative injury mediated by Nrf2/ARE signaling pathway in mice.

Oxidative stress plays a crucial role in fatigue, thus it is of significance to develop safe and efficient antioxidant to prevent fatigue. Phlorizin (PHZ) is a major active ingredient of dihydrochalcone from Lithocarpus polystachyus Rehd., which has already been approved as a new food material in China since 2017. The current study was designed to investigate the effect of PHZ on fatigue, and further to elucidate its possible underlying mechanism. Our results revealed that PHZ exerted beneficial effect on exhaustive exercise-induced fatigue in mice, as reflected by rotarod test and exhaustive swimming test. Moreover, PHZ also effectively decreased the levels of blood urea nitrogen, creatine kinase and plasma lactic acid, increased the liver glycogen and skeletal muscle glycogen of fatigued mice, as evidenced by enzyme linked immunosorbent assay. PHZ balanced the redox status through reducing generation of reactive oxygen species, enhancing the activities of antioxidative enzymes. Furthermore, PHZ not only increased the ratio of Bcl2/Bax, but also decreased the level of cleaved-caspase 3. Notably, PHZ facilitated nuclear factor erythroid 2-related factor 2 (Nrf2) translocated from cytoplasm to nucleus, and up-regulated its downstream antioxidant response element including heme oxygenase-1 and NADPH quinone oxidoreductase-1. Intriguingly, PHZ directly bound to Nrf2, as evidenced by molecular docking, and the anti-fatigue effects of PHZ were almost abolished in Nrf2 deficient mice. In summary, our findings suggest that PHZ might be a natural occurring antioxidant with safety profile to relieve fatigue via targeting Nrf2 to inhibit apoptosis.

Physiological tremor is suppressed and force steadiness is enhanced with increased availability of serotonin regardless of muscle fatigue.

Although there is evidence that 5-HT acts as an excitatory neuromodulator to enhance maximal force generation, it is largely unknown how 5-HT activity influences the ability to sustain a constant force during steady-state contractions. A total of 22 healthy individuals participated in the study, where elbow flexion force was assessed during brief isometric contractions at 10% maximal voluntary contraction (MVC), 60% MVC, MVC, and during a sustained MVC. The selective serotonin reuptake inhibitor, paroxetine, suppressed physiological tremor and increased force steadiness when performing the isometric contractions. In particular, a main effect of drug was detected for peak power of force within the 8-12 Hz range (P = 0.004) and the coefficient of variation (CV) of force (P < 0.001). A second experiment was performed where intermittent isometric elbow flexions (20% MVC sustained for 2 min) were repeatedly performed so that serotonergic effects on physiological tremor and force steadiness could be assessed during the development of fatigue. Main effects of drug were once again detected for peak power of force in the 8-12 Hz range (P = 0.002) and CV of force (P = 0.003), where paroxetine suppressed physiological tremor and increased force steadiness when the elbow flexors were fatigued. The findings of this study suggest that enhanced availability of 5-HT in humans has a profound influence of maintaining constant force during steady-state contractions. The action of 5-HT appears to suppress fluctuations in force regardless of the fatigue state of the muscle.NEW & NOTEWORTHY Converging lines of research indicate that enhanced serotonin availability increases maximal force generation. However, it is largely unknown how serotonin influences the ability to sustain a constant force. We performed two experiments to assess physiological tremor and force steadiness in unfatigued and fatigued muscle when serotonin availability was enhanced in the central nervous system. Enhanced availability of serotonin reduced physiological tremor amplitude and improved steadiness regardless of muscle fatigue.

Molecular Mechanisms of Muscle Fatigue.

Muscle fatigue (MF) declines the capacity of muscles to complete a task over time at a constant load. MF is usually short-lasting, reversible, and is experienced as a feeling of tiredness or lack of energy. The leading causes of short-lasting fatigue are related to overtraining, undertraining/deconditioning, or physical injury. Conversely, MF can be persistent and more serious when associated with pathological states or following chronic exposure to certain medication or toxic composites. In conjunction with chronic fatigue, the muscle feels floppy, and the force generated by muscles is always low, causing the individual to feel frail constantly. The leading cause underpinning the development of chronic fatigue is related to muscle wasting mediated by aging, immobilization, insulin resistance (through high-fat dietary intake or pharmacologically mediated Peroxisome Proliferator-Activated Receptor (PPAR) agonism), diseases associated with systemic inflammation (arthritis, sepsis, infections, trauma, cardiovascular and respiratory disorders (heart failure, chronic obstructive pulmonary disease (COPD))), chronic kidney failure, muscle dystrophies, muscle myopathies, multiple sclerosis, and, more recently, coronavirus disease 2019 (COVID-19). The primary outcome of displaying chronic muscle fatigue is a poor quality of life. This type of fatigue represents a significant daily challenge for those affected and for the national health authorities through the financial burden attached to patient support. Although the origin of chronic fatigue is multifactorial, the MF in illness conditions is intrinsically linked to the occurrence of muscle loss. The sequence of events leading to chronic fatigue can be schematically denoted as: trigger (genetic or pathological) -> molecular outcome within the muscle cell -> muscle wasting -> loss of muscle function -> occurrence of chronic muscle fatigue. The present review will only highlight and discuss current knowledge on the molecular mechanisms that contribute to the upregulation of muscle wasting, thereby helping us understand how we could prevent or treat this debilitating condition.

Antifatigue effects of Hechong (Tylorrhynchus heterochaetus) through modulation of Nrf2/ARE- mediated antioxidant signaling pathway.

This study was to evaluate the antifatigue effect of T. heterochaetus and explore the underlying mechanism of action. T. heterochaetus extract was treated to mice for 28 days. On the 28th day, after weight loaded swimming test. The levels of antioxidant enzymes and levels of pro- and anti-inflammatory cytokines in the liver and muscles of exercised mice were evaluated. mRNA and protein expression levels of Nrf2, SOD, HO-1, and Keap-1 were evaluated using RT-PCR and western blot analysis. The low (2.70 mg/0.5 ml/20 g) and medium (5.41 mg/0.5 ml/20 g) dose enhanced the activities of antioxidant enzymes like SOD, CAT and GPx in the liver and skeletal muscle thereby enhancing the antifatigue effect. The low and medium doses showed good anti-inflammatory effects by evaluating the levels of pro and anti-inflammatory cytokines such as TNF-α, IL-1ß, IL-6, and IL-10 both in the liver and skeletal muscle. Furthermore, RT-PCR and western blot analysis showed increased expression of HO-1, SOD, Nrf2, and decreased expression of Keap-1 gene and proteins in liver and skeletal muscle of T. heterochaetus treated group mice. The current results indicate that T. heterochaetus exert the antifatigue effect through attenuating oxidative stress injury and inflammatory responses through the Nrf2/ARE-mediated signaling pathway.

Mitochondria and Antibiotics: For Good or for Evil?

The discovery and application of antibiotics in the common clinical practice has undeniably been one of the major medical advances in our times. Their use meant a drastic drop in infectious diseases-related mortality and contributed to prolonging human life expectancy worldwide. Nevertheless, antibiotics are considered by many a double-edged sword. Their extensive use in the past few years has given rise to a global problem: antibiotic resistance. This factor and the increasing evidence that a wide range of antibiotics can damage mammalian mitochondria, have driven a significant sector of the medical and scientific communities to advise against the use of antibiotics for purposes other to treating severe infections. Notwithstanding, a notorious number of recent studies support the use of these drugs to treat very diverse conditions, ranging from cancer to neurodegenerative or mitochondrial diseases. In this context, there is great controversy on whether the risks associated to antibiotics outweigh their promising beneficial features. The aim of this review is to provide insight in the topic, purpose for which the most relevant findings regarding antibiotic therapies have been discussed.

The Effect of a Multi-Ingredient Pre-Workout Supplement on Time to Fatigue in NCAA Division I Cross-Country Athletes.

This investigation aimed to determine the effect of a multi-ingredient pre-workout supplement (MIPS) on heart rate (HR), perceived exertion (RPE), lactate concentration, and time to fatigue (TTF) during a running task to volitional exhaustion. Eleven NCAA Division I cross-country runners (20 ± 2 year; height: 171 ± 14 cm; weight: 63.5 ± 9.1 kg) participated in this randomized, double-blind, placebo-controlled cross-over study. Bayesian statistical methods were utilized, and parameter estimates were interpreted as statistically significant if the 95% highest-density intervals (HDIs) did not include zero. TTF was increased in the MIPS condition with a posterior Meandiff = 154 ± 4.2 s (95% HDI: -167, 465) and a 0.84 posterior probability that the supplement would increase TTF relative to PL. Blood lactate concentration immediately post-exercise was also higher in the MIPS condition compared to PL with an estimated posterior Meandiff = 3.99 ± 2.1 mmol (95% HDI: -0.16, 7.68). There were no differences in HR or RPE between trials. These findings suggest that a MIPS ingested prior to sustained running at lactate threshold has an 84% chance of increasing TTF in highly trained runners and may allow athletes to handle a higher level of circulating lactate before reaching exhaustion.

A single oral glucose load decreases arterial plasma [K+ ] during exercise and recovery.

AIM: We investigated whether acute carbohydrate ingestion reduced arterial potassium concentration ([K+ ]) during and after intense exercise and delayed fatigue. METHODS: In a randomized, double-blind crossover design, eight males ingested 300 ml water containing 75 g glucose (CHO) or placebo (CON); rested for 60 min, then performed high-intensity intermittent cycling (HIIC) at 130% V˙O2peak , comprising three 45-s exercise bouts (EB), then a fourth EB until fatigue. Radial arterial (a) and antecubital venous (v) blood was sampled at rest, before, during and after HIIC and analyzed for plasma ions and metabolites, with forearm arteriovenous differences (a-v diff) calculated to assess inactive forearm muscle effects. RESULTS: Glucose ingestion elevated [glucose]a and [insulin]a above CON (p = .001), being, respectively, ~2- and ~5-fold higher during CHO at 60 min after ingestion (p = .001). Plasma [K+ ]a rose during and declined following each exercise bout in HIIC (p = .001), falling below baseline at 5 min post-exercise (p = .007). Both [K+ ]a and [K+ ]v were lower during CHO (p = .036, p = .001, respectively, treatment main effect). The [K+ ]a-v diff across the forearm widened during exercise (p = .001), returned to baseline during recovery, and was greater in CHO than CON during EB1, EB2 (p = .001) and EB3 (p = .005). Time to fatigue did not differ between trials. CONCLUSION: Acute oral glucose ingestion, as used in a glucose tolerance test, induced a small, systemic K+ -lowering effect before, during, and after HIIC, that was detectable in both arterial and venous plasma. This likely reflects insulin-mediated, increased Na+ ,K+ -ATPase induced K+ uptake into non-contracting muscles. However, glucose ingestion did not delay fatigue.

The use of a pre-workout supplement containing an amphetamine derivative and its effects on physical performance / Uso de suplemento pre-entrenamiento que contiene un derivado anfetamínico y sus efectos sobre el desempeño físico / Uso de suplemento pré-treino que contém um derivado anfetaminico e seus efeitos sobre o desempenho físico

ABSTRACT Introduction: The quest for better sports performance or simply for esthetic ends has led individuals to seek ergogenic resources indiscriminately to attain their goals. It is believed that nutritional supplements promote better strength, power, focus and better reaction time. Nutritional supplements are used to delay fatigue and increase athletic performance. Also, the anorectics, drugs derived from amphetamines and commonly sought for weight loss, act on the central nervous system by releasing substances that transmit the sensation of not being hungry. Supplements that promise quick solutions to these goals may have compounds in their formulas that compromise health. Objectives: In this study, the potential of creatine and Jack 3D® to boost physical performance and delay muscle fatigue was evaluated in animals that were given the supplements. Methods: The animals underwent 10 weeks of swim training at 80% of the maximum load and received creatine and/or Jack 3D. The muscle contractions were recorded by an electrophysiograph for analysis of muscle fatigue. Results: It was observed that the SED+CR group had significantly different values compared to the SED group and NAT+CR group showed significant differences between groups for the SED, SED+JACK, JACK, NAT and NAT+JACK groups (p <0.05). For the two last parameters, the SED group showed a significant difference in relation to the SED+CR, NAT and NAT+CR groups (p <0.05). Conclusions: These results demonstrate a possible positive influence of physical exercise associated with the use of creatine, delaying muscle fatigue and making an increase in sports performance possible. Level of Evidence III; Development of diagnostic criteria in consecutive patients (with "gold" reference standard applied) .

RESUMEN Introducción: La búsqueda por el mejor desempeño deportivo o simplemente para fines estéticos ha inducido a los individuos a buscar indiscriminadamente recursos ergogénicos para alcanzar el éxito. Se cree que la ingestión de suplementos nutricionales puede proporcionar mayor resistencia, potencia, enfoque y mejor tiempo de reacción. Los suplementos nutricionales son empleados para retardar el surgimiento de la fatiga y aumentar el desempeño atlético. También comúnmente buscados para adelgazamiento están los anorexígenos, medicamentos a base de drogas anfetamínicas, que actúan sobre el sistema nervioso central liberando sustancias que transmiten la sensación de ausencia de hambre. Los suplementos que prometen soluciones rápidas para estos objetivos pueden presentar en sus fórmulas, compuestos que comprometen la salud. Objetivo: En este estudio fue evaluado el potencial de la creatina y del Jack3D® para el desempeño físico y la fatiga muscular de los animales que recibieron la suplementación. Métodos: Los animales fueron sometidos a 10 semanas de entrenamiento de natación a 80% de la carga máxima y recibieron creatina y/o Jack3D. Las contracciones musculares fueron registradas por un electrofisiógrafo para análisis de la fatiga muscular. Resultados: Se observó que el grupo SED+CR presentó valores significativamente diferentes en comparación con el grupo SED y el grupo NAT+CR presentó diferencias significativas con relación a los grupos SED, SED+JACK, NAT y NAT+JACK (p < 0,05). En los dos últimos parámetros, el grupo SED presentó diferencia significativa con relación a los grupos SED+CR, NAT y NAT+CR (p < 0,05). Conclusión: Esos resultados demuestran una posible influencia positiva del ejercicio físico asociado al uso de la creatina, retardando la fatiga muscular y posibilitando un aumento en el desempeño deportivo. Nivel de evidencia III; Desarrollo de criterios diagnósticos en pacientes consecutivos (con estándar de referencia "oro" aplicado) .

RESUMO Introdução: A busca pelo melhor rendimento esportivo ou simplesmente para fins estéticos tem induzido indivíduos a procurarem indiscriminadamente recursos ergogênicos para atingir o êxito. Acredita-se que a ingestão de suplementos nutricionais pode proporcionar maior resistência, potência, foco e melhor tempo de reação. Os suplementos nutricionais são empregados afim de retardar o surgimento da fadiga e aumentar o desempenho atlético. Também comumente procuradas para emagrecimento estão os anorexígenos, medicamentos à base de drogas anfetamínicas, que agem sobre o sistema nervoso central liberando substâncias que transmitem a sensação de ausência de fome. Suplementos que prometem soluções rápidas para estes objetivos podem conter em suas fórmulas compostos que comprometem a saúde. Objetivos: Neste estudo foi avaliado o potencial da creatina e do Jack 3D®para o desempenho físico e fadiga muscular dos animais que receberam a suplementação. Métodos: Os animais foram submetidos a 10 semanas de treinamento de natação a 80% da carga máxima e receberam creatina e/ou Jack 3D. As contrações musculares foram registradas por um eletrofisiógrafo para análise da fadiga muscular. Resultados: Observou-se que o grupo SED+CR apresentou valores significativamente diferentes em comparação com o Grupo SED e o Grupo NAT+CR apresentou diferenças significativas com relação aos grupos SED, SED+JACK, NAT e NAT+JACK (p < 0,05). Nos dois últimos parâmetros, o Grupo SED apresentou diferença significativa com relação aos grupos SED+CR, NAT e NAT+CR (p < 0,05). Conclusão: Esses resultados demonstram uma possível influência positiva do exercício físico associado ao uso da creatina, retardando a fadiga muscular e possibilitando um aumento no desempenho esportivo. Nível de Evidência III; Desenvolvimento de critérios diagnósticos em pacientes consecutivos (com padrão de referência "ouro" aplicado) .

Effect of creatine and sildenafil citrate on the physical performance of mice / Efecto de la creatina y del citrato de sildenafil sobre el desempeño físico de ratones / Efeito da creatina e do citrato de sildenafila sobre o desempenho físico de camundongos

ABSTRACT Introduction: The use of substances to enhance sports performance among professional and amateur athletes is increasing. Such substances may either be included in the group of dietary supplements or fall into pharmacological classes. Every substance used for this purpose is called an ergogenic agent. The number of ergogenic options available increases every day, favoring overuse and use without proper guidance. Among the dietary supplements, we highlight the use of creatine, a substance widespread in sports. Among the pharmacological groups, many drugs are used. Recently the use of sildenafil citrate by professional athletes from various predominantly aerobic sports modalities was reported in the media. Objective: To compare and demonstrate the responses caused by physical training associated with the use of creatine and sildenafil citrate in mice. Methods: A swim training protocol was applied and then an electrophysiograph was used in order to obtain parameters related to contraction intensity, the area under the curve and the percentage drop. Results: The responses obtained demonstrated the ergogenic action of creatine because it altered the parameters used for measurement. The use of sildenafil citrate did not yield satisfactory results to frame the drug as an ergogenic agent. Conclusion: Creatine has an ergogenic effect, reducing the percentage drop after 10 seconds, while sildenafil demonstrated no ergogenic potential and, interestingly, resulted in weaker responses when compared to the exercise groups. Evidence level II; Comparative prospective study .

RESUMEN Introducción: El uso de sustancias con el objetivo de aumentar el rendimiento deportivo entre atletas profesionales y amateurs es creciente. Tales sustancias pueden formar parte del grupo de suplementos alimentarios o integrar clases farmacológicas. Toda sustancia empleada para ese fin es denominada agente ergogénico. El número de opciones entre los agentes ergogénicos aumenta cada día, favoreciendo así su uso excesivo y sin la debida orientación. Entre los suplementos alimentarios, se destaca el uso de creatina, sustancia muy difundida en el medio deportivo. Ya entre los grupos farmacológicos, muchas sustancias son usadas. Recientemente, fue divulgado entre los medios de comunicación el uso de citrato de sildenafil por atletas profesionales, de varias modalidades deportivas, predominantemente las aeróbicas. Objetivos: Comparar y demostrar las respuestas ocasionadas por el entrenamiento físico, asociadas al uso de creatina y citrato de sildenafil en ratones. Métodos: Se aplicó un protocolo de entrenamiento de natación y, a continuación, se usó un electrofisiógrafo con el objetivo de obtener parámetros referentes a la intensidad de contracción, al área bajo la curva y a la caída porcentual. Resultados: Las respuestas obtenidas demuestran acción ergogénica de la creatina, visto que alteraron los parámetros empleados para la medición. Ya el uso de citrato de sildenafil no presentó resultados satisfactorios para encuadrar al fármaco como agente ergogénico. Conclusión: La creatina presenta efecto ergogénico porque reduce la caída porcentual después de 10 segundos, mientras que el sildenafil no presentó potencial ergogénico y, curiosamente, demostró respuestas inferiores cuando comparado a los grupos de ejercicio. Nivel de evidencia II; Estudio prospectivo comparativo .

RESUMO Introdução: O uso de substâncias com o objetivo de aumentar o rendimento esportivo entre atletas profissionais e amadores é crescente. Tais substâncias podem fazer parte do grupo de suplementos alimentares ou integrar classes farmacológicas. Toda substância empregada para esse fim é denominada de agente ergogênico. O número de opções entre os agentes ergogênicos aumenta a cada dia, favorecendo assim o uso em demasia e sem a devida orientação. Entre os suplementos alimentares, salientamos a utilização de creatina, substância muito difundida no meio esportivo. Já entre os grupos farmacológicos, muitas substâncias são utilizadas. Recentemente, foi divulgado entre os meios de comunicação o uso de citrato de sildenafila por atletas profissionais de várias modalidades esportivas, predominantemente as aeróbicas. Objetivos: Comparar e demonstrar as repostas ocasionadas pelo treinamento físico, associadas ao uso de creatina e citrato de sildenafila em camundongos. Métodos: Aplicou-se um protocolo de treinamento de natação e, a seguir, empregou-se um eletrofisiógrafo com objetivo de obter parâmetros referentes à intensidade de contração, à área sob a curva e à queda percentual. Resultados: As respostas obtidas demonstram ação ergogênica da creatina, visto que alteraram os parâmetros empregados para a mensuração. Já a utilização de citrato de sildenafila não apresentou resultados satisfatórios para enquadrar o fármaco como agente ergogênico. Conclusão: A creatina apresenta efeito ergogênico porque reduz a queda percentual após 10 segundos, já a sildenafila não apresentou potencial ergogênico e, curiosamente, demonstrou respostas inferiores quando comparado aos grupos de exercício. Nível de evidência II; Estudo prospectivo comparativo .

The relieving effect of sun-dried protein tonic on sports fatigue / O efeito calmante na fadiga esportiva da proteína tônica secada ao sol / El efecto calmante en la fatiga deportiva de la proteína tónica secada al sol

ABSTRACT Fatigue is a comprehensive process that involves many physiological and biochemical factors. It is a normal physiological reaction when human physical or mental activities reach a certain level. In recent years, it has been verified that free radicals are closely related to exercise-induced fatigue. Cardamine bursa purified selenoprotein has good oxygen-free radical scavenging ability and anti-lipid peroxide. It could protect mitochondria, liver, and red blood cells from peroxide injury. Therefore, it was speculated that the purification of selenoprotein Cardamine may play an active role in attenuating exercise-induced fatigue by scavenging free radicals. This study cleared the selenite protein Capsella bursa (SPC) as a research object, and evaluated its structural characteristics in relieving exercise-induced fatigue. The selenoprotein index system for exercise-induced fatigue was constructed by combining two AHP methods, principal component analysis and factor analysis. Purity, subunit composition, amino acid composition and RCM content were evaluated. The corresponding RCM protein was preliminarily predicted. The results showed that SPCH could significantly prolong the swimming time (P <0.01), improve the lactate clearance capacity (P <0.01), increase the glycogen content of the liver (P <0.01), and reduce the level of the BUN (P <0.05). SPCH has a good effect in relieving exercise-induced fatigue in mice, so it can be considered for development as a nutritional supplement to alleviate exercise-induced fatigue.

RESUMO Fadiga é um processo abrangente envolvendo muitos fatores fisiológicos e bioquímicos. É uma reação fisiológica normal quando as atividades físicas ou mentais humanas atingem um certo nível. Nos últimos anos, verificou-se que os radicais livres estão intimamente relacionados com a fadiga induzida pelo exercício. A selenoproteina purificada de Cardamina bursa tem boa capacidade de depuração de radicais sem oxigénio e de peróxido anti-lípido. Poderia proteger as mitocôndrias, fígado e glóbulos vermelhos de lesões por peróxido. Por conseguinte, especulou-se que a purificação da selenoproteina de Cardamina pode desempenhar um papel activo na atenuação da fadiga induzida pelo exercício por meio de radicais livres de scavenging. Este estudo depurou a proteína selenita Capsella bursa (SPC) como objeto de pesquisa, e avaliou as suas características estruturais no alívio da fadiga induzida pelo exercício. O sistema de índice de selenoproteinas para a fadiga induzida pelo exercício foi construído por meio da combinação dos métodos de AHP, análise principal de componentes e a análise de fatores. Foram avaliados a pureza, a composição sub-unitária, a composição de aminoácidos e o conteúdo do RCM. A proteína correspondente do RCM foi prevista preliminarmente. Os resultados mostraram que o SPCH poderia prolongar significativamente o tempo de natação (P < 0.01), melhorar a capacidade de depuração do lactato (P< 0.01), aumentar o conteúdo do glicogênio do fígado (P < 0.01), e reduzir o nível do BUN (P< 0.05). o SPCH tem um bom efeito em aliviar a fadiga induzida pelo exercício em ratos, de modo que pode ser considerado para desenvolvê-lo como um suplemento nutricional para aliviar a fadiga induzida pelo exercício.

RESUMEN La fatiga es un proceso abarcador que envuelve muchos factores fisiológicos y bioquímicos. Es una reacción fisiológica normal cuando las actividades físicas o mentales humanas alcanzan un cierto nivel. En los últimos anos, se verificó que los radicales libres están íntimamente relacionados con la fatiga inducida por el ejercicio. La selenoproteína purificada de Cardamina bursa tiene buena capacidad de depuración de radicales sin oxígeno y de peróxido antilipídico. Podría proteger las mitocondrias, el hígado y los glóbulos rojos de lesiones por peróxido. Por consiguiente, se especuló que la purificación de la selenoproteína de Cardamina puede desempeñar un papel activo en la atenuación de la fatiga inducida por el ejercicio por medio de radicales libres de scavenging. Este estudio depuró la proteína selenita Capsella bursa (SPC) como objeto de investigación, y evaluó sus características estructurales en el alivio de la fatiga inducida por el ejercicio. El sistema de índice de selenoproteínas para a fatiga inducida por el ejercicio fue construido por medio de la combinación dos métodos de AHP, el análisis principal de componentes y el análisis de factores. Fueron evaluados la pureza, la composición sub-unitaria, la composición de aminoácidos y el contenido del RCM. La proteína correspondiente del RCM fue prevista preliminarmente. Los resultados mostraron que el SPCH podría prolongar significativamente el tiempo de natación (P < 0.01), mejorar la capacidad de depuración del lactato (P< 0.01), aumentar el contenido del glicógeno del hígado (P < 0.01), y reducir el nivel del BUN (P< 0.05). el SPCH tiene un buen efecto en aliviar la fatiga inducida por el ejercicio en ratones, de modo que puede ser considerado para desarrollarlo como un suplemento nutricional para aliviar la fatiga inducida por el ejercicio.

Lycopene increases the proportion of slow-twitch muscle fiber by AMPK signaling to improve muscle anti-fatigue ability.

Lycopene has a wide range of biological functions, especially its antioxidant capacity. However, effects of lycopene on muscle fatigue resistant and muscle fiber type conversion are unknown. In this study, we found that lycopene significantly prolonged the swimming time to exhaustion in mice. We also showed that lycopene increased the proportion of slow-twitch muscle fiber by promoting muscle fiber type conversion from fast-twitch to slow-twitch in mice and in C2C12 myotubes. The AMP-activated protein kinase (AMPK) signaling was activated by lycopene. AMPK upstream and downstream regulators including nuclear respiratory factor 1, calcium calmodulin-dependent protein kinase kinase-ß, sirtuin 1 and peroxisome proliferator activated receptor-γ coactivator-1ɑ were also increased by lycopene. AMPK inhibitor compound C markedly attenuated the lycopene-induced skeletal muscle fiber type conversion in C2C12 myotubes. Taken together, we provided the first evidence that lycopene increases the proportion of slow-twitch muscle fiber through AMPK signaling pathway to improve fatigue resistant of skeletal muscle.

Ganoderic acid alleviates chemotherapy-induced fatigue in mice bearing colon tumor.

Chemotherapy-related fatigue (CRF) is increasingly being recognized as one of the severe symptoms in patients undergoing chemotherapy, which not only largely reduces the quality of life in patients, but also diminishes their physical and social function. At present, there is no effective drug for preventing and treating CRF. Ganoderic acid (GA), isolated from traditional Chinese medicine Ganoderma lucidum, has shown a variety of pharmacological activities such as anti-tumor, anti-inflammation, immunoregulation, etc. In this study, we investigated whether GA possessed anti-fatigue activity against CRF. CT26 tumor-bearing mice were treated with 5-fluorouracil (5-FU, 30 mg/kg) and GA (50 mg/kg) alone or in combination for 18 days. Peripheral and central fatigue-related behaviors, energy metabolism and inflammatory factors were assessed. We demonstrated that co-administration of GA ameliorated 5-FU-induced peripheral muscle fatigue-like behavior via improving muscle quality and mitochondria function, increasing glycogen content and ATP production, reducing lactic acid content and LDH activity, and inhibiting p-AMPK, IL-6 and TNF-α expression in skeletal muscle. Co-administration of GA also retarded the 5-FU-induced central fatigue-like behavior accompanied by down-regulating the expression of IL-6, iNOS and COX2 in the hippocampus through inhibiting TLR4/Myd88/NF-κB pathway. These results suggest that GA could attenuate 5-FU-induced peripheral and central fatigue in tumor-bearing mice, which provides evidence for GA as a potential drug for treatment of CRF in clinic.