جستجوی مقالات مرتبط با کلیدواژه « کراتین » در نشریات گروه « پزشکی »

Several studies have investigated the effect of creatine supplementation on indirect markers of muscular damage and sports performance of athletes. However, pooled data from several studies suggest that the benefits of creatine on recovery of athletes are limited. The aim of this study was to investigate the effect of creatine supplementation on post-exercise recovery and muscle injury factors in healthy subjects.

A systematic search of articles published in English and Persian databases until November 2023 was conducted to investigate the effect of creatine supplementation on muscle injury markers creatine kinase (CK) and lactate dehydrogenase (LDH) and muscle soreness in healthy subjects. Weighted mean difference (WMD) and standardized mean difference (SMD) and 95% confidence interval were calculated using random effect model.

A total of 20 studies including 458 subjects were included in the present meta-analysis. The results showed that creatine did not cause a significant change in muscle soreness in any of 24, 48, 72, and 96 hours after exercise compared to the control group. Also, creatine did not cause a significant change in CK in any time spectrum compared to the control group. In addition, creatine did not cause a significant change in LDH in different time ranges after exercise compared to the control group in athletes and non-athletes.

The results of the present study show that creatine supplementation is not effective in reducing muscle soreness and muscle injury factors after exercise.

Studies have shown that participation in intense and increasing exercise causes delayed damage to the muscle fiber membrane. Because the best type of recycling is not known between training sessions, using methods such as active recycling or creatine supplementation may have beneficial effects through faster removal of fatigue-related factors or the availability of energy sources such as creatine phosphate. On the other hand, the processes of anemia - re-injection of blood, autoxidation of catecholamines, induction of the activity of inflammatory cells as well as neutrophils due to tissue damage in this active species, intensify this activity. Continuation of this process increases free radicals and consequently oxidative stress, and the body of living organisms needs an antioxidant system to limit the harmful effects of free radicals. The range of active antioxidants in the body includes endogenous enzymatic antioxidants and non-enzymatic antioxidants present in meals. Studies have shown that the production of free radicals during strenuous exercise stimulates the production of heat shock proteins (HSPs). Research shows that under physiological conditions, such as strenuous exercise, in which athletes at competitive levels experience excessive training, such as frequent repetitions of competitions throughout the day, to achieve high levels of performance, endogenous antioxidants cannot be completely eliminated. Prevent oxidative damage. For this reason, in recent years, researchers have been looking for strategies to reduce fatigue and maintain performance for athletes by reducing the factors that affect physical performance during and after intense intermittent exercise. Creatine supplementation is one of the most commonly used strategies by athletes. Therefore, the aim of the present study was to investigate the effect of high-intensity interval training with creatine supplementation and two types of active in-water and out-of-water recovery on heat shock protein in men and women swimmers.

 In this quasi-experimental study, 32 non-professional swimmers (16 men and 16 women) with at least 6 months of swimming experience and position in the city with an average anaerobic power of 497 watts per kg participated. Men and women were each randomly divided into two subgroups: in-water recovery (8 men and 8 women) and out-of-water recovery (8 men and 8 women). All groups performed 6 50-meter sprints with a 120-second rest interval (depending on the type of recovery in and out of the water) before and after 6 days of creatine supplementation (4 servings of 5 g per day for 6 days). Data were analyzed by two-way analysis of variance with repeated measures.

 The findings of the combined analysis of variance test showed that the main effect of measurement time was significant. The main effect of recovery was also significant. In addition, the interaction of measurement time with recovery was significant. The interactive effect (measurement time وری recovery × gender) was not significant. In addition, the results of intragroup analysis of variance test with repeated measures on the measurement factor showed that complementary intervention improves HSP72 in both sexes. Also, differences between groups using two-way analysis of variance test showed that the amount of HSP72 after rest, the third and sixth repetition without creatine was not significant. Also at rest and after the third repetition with creatine was not significant but after the sixth Recurrence with creatine supplementation was significant in both sexes.

 The results of the present study show that despite the relative decrease in the mean HSP of the groups after the supplementation period, this difference is not significant and there is no interaction between the independent variables in relation to HSP. Regarding the better condition of the in-water group than the out-of-water group, the present study on further reduction of HSP72 also pointed to the possibility of better regulation of body temperature in water during methionine recycling, which leads to removing or reducing the excitatory effect of heat as a production stimulus. HSP70 caused a drop in the group average after recycling. The lack of significant HSP adjustment among research groups after recovery probably led to the indirect inference that HSP was not highly adjusted in athletes following exercise. The researchers explain why HSP decreases in people who train with high repetition. When a muscle trains better progressively, there is a decrease in HSP due to cellular regulatory mechanisms. Also, when people who have not exercised begin to exercise, there is a false increase in their HSP, which will decrease over time and as the exercise progresses. The researchers said that the higher the amount of exercise, the thinner the amount of HSP. Researchers believe that HSP has a negative self-regulatory mechanism that is regulated by its own synthesis. It can probably be said that HSP does not change as much in trained people as it does in the untrained ones. However, in terms of the type of recycling, the in-water group was in a better position than the out-of-water group. In the present study, supplementation had no significant effect on HSP compared to the period without supplementation, and its interaction with the type of recycling did not make a significant difference in HSP. Studies show that 95% of creatine is stored in skeletal muscle, and creatine supplementation also increases muscle creatine content. Research on the effects of creatine supplementation on muscle phosphocreatine has provided evidence of increased creatine vigor. Another issue addressed in this study was the difference in HSP72 response between men and women to exercise, and the issue of gender impact was raised. In this study, it was concluded that the level of HSP72 in male and female athletes is similar on average and there is no significant difference. Although exercise increased HSP72, it was similar in male and female athletes and was not affected by gender. Also, in this study, the positive effects of specialized recovery in the mentioned indicators following high-intensity intermittent swimming were not found.

Billions of chickens are consumed annually in the world and about billions of tons of chicken feathers are produced. About 5 to 7 percent of the chickenchr('39')s weight is feather and about 90 percent of the feathers are keratin. Feather is a pure keratin protein that is highly insoluble and difficult to break down. Some bacteria have the ability to produce the keratinase enzyme to break down keratin. The aim of this study was to determine the factors affecting the growth of SKH14-isolated bacilli megatrium strain SKH14 and to measure the enzymatic activity of keratinase.

Soil samples were collected in sterile plastic containers. Seven bacterial isolates were grown on a specific environment, of which 5 showed clear decomposition and were selected for biochemical tests, 16S rRNA sequencing and keratin measurement activity. These five bacteria were then sequenced and GeneBank accession number was assigned for each of them as a new strain. Five bacteria were tested for keratinase production and the strongest strain was optimized for keratinase production.

Five isolates were belonged to different strains of bacilli, and all five isolates were feather decomposer at different times. The highest enzymatic activity was reported in Bacillus megaterium SKH14 with 18.01 units per ml and the lowest in Bacillus felexus SKH4 with 10.81 units per ml.

The complete decomposition of Bacillus megaterium SKH14 isolate showed that this bacterium has high protease activity and is able to decompose complete keratin.

One of the consequences of intense exercise is muscle injury, pain and muscle sorenes. Symptoms of muscle injury include the appearance of intramuscular proteins in the blood and long-term decline in muscle function, decrease in strength and power, flexibility and dynamic muscle speed (1). Muscle damage is associated with the release of creatine kinase and lactate dehydrogenase enzymes and can be measured by the release of these enzymes into the blood. Creatine kinase (CK) is a key enzyme involved in muscle cell metabolism that accelerates the conversion of creatine to phosphate or inverse. increase in this substance in the blood may be sign of muscle damage and inflammation (3). Lactate dehydrogenase (LDH) is an enzyme that is found in large quantities in the cytoplasm of all body tissues at different concentrations and in the conversion of pyruvic acid to lactic acid or inverse in the anaerobic glycolysis pathway accelerates this reaction (3). studies have reported muscle damage by measuring CK and LDH levels during the interval between sets (4), high-intensity training (5), muscle contractions (6, 7), speed training (8) and aerobic training (9). On the other hand, exercise increases the concentration of lactate in the blood. It has been shown that nutritional interventions and the use of antioxidant supplements can be one of the best ways to protect against muscle damage caused by exercise (1). Creatine, an unnecessary dietary compound, can either come from exogenous sources such as fish or meat, or it can be produced endogenously by the body primarily in the liver. Creatine was produced by two-step process from the three amino acids arginine, glycine and methionine (15). In addition to creatine, the amino acid β-alanine is a newer supplement for those interested in professional sports. Beta-Alanine is a precursor of carnosine (β-alanine -histidine); Which can increase the concentration of carnosine in muscles (13,17). Studies have reported the benefits of beta-alanine supplementation in variety of laboratory protocols (19). Researchers are looking for ways to improve performance, prevent unwanted changes in muscle injury indexes, or at least minimize them. Therefore, the present study aims to investigate the effect of three weeks of β-alanine and creatine supplementation on the response of creatine kinase, lactate dehydrogenase and lactate to an exhausting swimming session in elite swimmers.

In this semi-experimental study, 21 elite boy swimmers 15 to 20 years were selected as sample and divided into three groups: 1) supplementation of beta-allanine (daily dose of 2 tablets 1500 mg))2), supplementation of creatine (4 and 2 servings of creatine monohydrate 5 g) (3) placebo (the amount of 2 capsules containing wheat flour). During supplementation, the subjects performed their daily workouts for three days a week (1.5 hours of swimming at distance of 1200 meters) (22). The exhausting exercise protocol was performed in three stages: warming, progressive and lactate tolerance training. Blood samples were collected before, immediately, 15 and 30 minutes after training. Data were analyzed by repeated measures ANOVA and Bonferroni post hoc test at the P<0.05. 

Three weeks the supplementation of β-alanine (P=0.007) and creatine (P=0.001) significant increase LDH levels in response to exhausting swimming session. No significant difference was observed in the CPK changes in the supplemented groups of beta-alanine, creatine and placebo. The use of creatine supplementation significantly decreases LDH in elite swimmers (P=0.02). Significant increase in lactate levels was observed after three weeks of supplementation of creatine in response to exhausting swimming session (P=0.001).

The findings of this study were consistent with the results of Previous research (23,25,26). According to previous studies, beta-alanine supplementation is responsible for the buffer system, carnosine, antioxidant role, enzymatic regulator and calcium control in the sarcoplasmic reticulum (13,17,19). Mechanism and pattern of changes (increase) of serum total creatine kinase enzyme following aerobic training is mainly due to leakage due to energy loss and instability or damage due to peroxidation of cell membrane phospholipids (30). decreased muscle strength and dysfunction due to decreased sarcoplasmic calcium is due to continued muscle contraction and intracellular calcium accumulation and its inability to return to sarcoplasmic cells (27). increasing muscle carnosine with positive effect on muscle cell calcium increases the function of muscle contraction protein and consequently, increases the efficiency of contractile motor units (13,17,19). Therefore, due to metabolic adaptations and increased buffering capacity which is caused by the consumption of beta alanine, no significant changes in creatine kinase enzyme were observed after beta-alanine consumption. Beta-alanine is one of the supplements that athletes use to increase performance and reduce fatigue (13). Beta-alanine supplementation affects aerobic and anaerobic capacity, increases exercise intensity, improves performance, increases carnosine and histidine, changes in hydrogen ion levels in blood and reduces fatigue (13). It seems that taking beta-alanine supplementation increases ability of athletes to exercise more intensely. In general, several factors such as the period and amount of supplementation before the activity, the size and speed of absorption of supplements during the activity, the diet of the subjects before and during the study and the training status of the participants and a combination of the above factors can affect the response of the muscle injury indicators. According to the results, it seems creatine have a greater effect on cell membrane consolidation, and the use of beta-allanine supplements, increases the individual's ability to perform a more intense exercise.