Background and Purpose
In many sports activities and at the end of training and competition, the athlete enters the fatigue phase. Fatigue disrupts the rate of muscle production and shortening, causing a continuous and repetitive activity that depends on the intensity and duration of the activity. Therefore, the athlete's performance decreases and his performance is affected. Some supplements and sports drinks claim to delay or reduce the perception of fatigue. Beta-alanine can have beneficial effects on sports performance variables, blood lactate and fatigue index. The present study was conducted to investigate the effect of beta-alanine consumption on lactate and anaerobic performance of female swimmers.
Materials and Methods
In this semi-experimental study, 30 female swimmers aged 17-25 from Tehran province participated. Initially, all subjects completed health status questionnaires and informed consent by the athlete. The inclusion criteria for the present study were having at least three years of experience in swimming, not participating in other sports, being at least 17 and not more than 25 years old, not having any pathological symptoms, history of fractures, surgeries, or joint diseases in the lower limbs or spine in the past 7 years. Also, in order to eliminate the effect of previous training on the levels of research variables, the swimmers were given a 48-hour rest before implementing the training protocol and supplement consumption. At the beginning of the research protocol, the demographic characteristics of the subjects, such as height, weight, and body mass index, were measured. Then, the subjects were randomly assigned to two placebo and beta-alanine groups. The beta-alanine group took two 400 mg capsules daily and the placebo group took 500 mg dextrose capsules one hour before training for four weeks. The subjects performed their daily training for three days a week, swimming 1.5 hours every other day for a distance of about 2.5 km. The 100 and 200 m breaststroke swimming records were taken in the first and last sessions. The SAST test was used to measure anaerobic power. Immediately after the last training session and beta-alanine supplementation, lactate and pH were measured. Blood lactic acid concentration was measured using a lactometer. Data were evaluated using analysis of variance with repeated measures.

Results
The results of the repeated measures analysis of variance test showed that four weeks of beta-alanine consumption had a significant effect on blood lactate (P=0.009, F=7.79), and it can be said that the lactate level in the beta-alanine group was significantly reduced compared to the placebo group. Beta-alanine has a significant effect on the 100-meter swimming record (P=0.001, F=37.59) and 200-meter swimming record (P=0.001, F=28.63) of swimmers. After four weeks of beta-alanine consumption, the 100-meter and 200-meter swimming records improved significantly. Beta-alanine consumption had a significant effect on the anaerobic power of the first (P=0.001, F=42.54), second (P=0.001, F=42.53), third (P=0.001, F=1.87), fourth (P=0.001, F=139.57), and fifth (P=0.001, F=82.99) female swimmers, and it can be said that the time in the beta-alanine group was significantly reduced compared to the placebo group. In other words, beta-alanine consumption improved the anaerobic power of the female swimmers. However, it did not have a significant effect on pH (P=0.747, F=106) and the anaerobic power of the sixth (P=0.249, F=1.38).

Conclusion
The results of the present study showed that beta-alanine supplementation for four weeks in female amateur swimmers significantly reduced blood lactate, improved 100- and 200-meter breaststroke records, and increased anaerobic power compared to the placebo group; while no significant change was observed in blood pH levels. More specifically, the mean blood lactate decreased after the intervention in the beta-alanine group, the 100-meter and 200-meter swimming records improved significantly, and anaerobic power also showed a significant increase.Beta-alanine supplementation affects aerobic and anaerobic capacity, increased exercise intensity, improved performance, increased carnosine and histidine, changes in plasma hydrogen ion levels, and reduced fatigue (16). Beta-alanine plays a prominent role in regulating muscle buffering capacity, and changes in blood lactate have been observed with its consumption. It seems that beta-alanine consumption increases an individual’s ability to perform more intense exercise. Beta-alanine has a buffering effect due to the imidazole ring in its structure and its high concentration in human skeletal muscle (17). Physiologically, the main mechanism of action of beta-alanine is related to the increase in muscle carnosine levels. Carnosine acts as an intracellular buffer and prevents the decrease in muscle pH by inhibiting the excessive increase in H⁺ ions (produced during intense exercise) (18). This leads to a delay in the onset of muscle fatigue, increased exercise tolerance, and improved anaerobic performance. Although blood pH did not change significantly in the present study, the reduction in lactate and improvement in anaerobic power are likely due to this buffering effect of carnosine in the intracellular environment of the muscle, which may not be clearly reflected in the blood.

Article Message
The results showed that daily consumption of two 400 mg beta-alanine capsules per day for four weeks can improve performance and anaerobic capacity in athletes, therefore, taking into account the precautions, it can be suggested to swimmers to use beta-alanine supplementation to improve their records and anaerobic capacity.

Ethical Considerations
The present study was conducted in accordance with the ethical principles of Semnan University of Medical Sciences with ethical considerations with the approved code (IR.SEMUMS.REC.1403.330).

Authors’ Contributions
All authors contributed equally to the design, implementation, data analysis, and writing of the article.

Conflict of Interest
The authors of this article have no vested interest in its publication.

Acknowledgments
The researchers express their gratitude to the subjects who helped us in this project.