Effects of l-tyrosine amino acid on competitive performance of 17-19 years old academic table tennis players

Dr.Biol., Professor Yu.N. Romanov1
Associate Professor, PhD L.A. Romanova1
S.A. Knyazev1
A.L. Lyapina1
1South Ural State University (National Research University), Chelyabinsk

Keywords: L-tyrosine, table tennis, students, short-term memory.

Introduction. Modern sports insists upon complete refusal from the drugs prohibited by the World Anti-Doping Agency. A number of studies have been conducted on the effects on the human body of various kinds of amino acids, and in particular tyrosine, which improves mental concentration and exercise performance, well-being and mood [4], cognitive abilities during exercise and heat stress [5, 9]. L-tyrosine administration may affect the level of stress during prolonged wakefulness, which results in a slower decrease in cognitive functions with a lack of sleep as compared to the reference group [7]. It has been found that L-tyrosine helps athletes avoid overtraining owing to its ability to eliminate fatigue and increase endurance [8].

The above experiments are undoubtedly important and interesting enough, however, they do not give an answer to the following question: is it possible to improve sports results, in particular, in situational sports by means of L-tyrosine treatment.

Objective of the study was to analyze benefits of aromatic amino acid L-tyrosine administration for competitive performance and psychophysiology test rates of academic table tennis players.

Methods and structure of the study. Subjects. Sampled for the study were the South Ural State University students (n=20) aged 18.83±0.10 years, weighing 69.75±1.90 kg and 180.20±1.72 cm tall, trained twice a week under the academic Physical Education and Sport curriculum and split up into two groups (EG and RG) of 10 people each. Competitive performance of the sample was tested in a daily table tennis Olympics-modeling tournament.

Organization of the study. The Olympics-modeling table tennis tournament lasted one day. Each tennis play lasted 3 minutes. Upon the competition, each player took his place on the ranking list (from 1st to 20th). The game rating data enabled to split the group of 20 students into two groups of 10 people on the following principle: students with the odd numbers of points in the rating scale formed the 1st group, and those with the even - the 2nd. We conducted a preliminary survey of the subjects, which revealed the absence of thyroid disease, mental disorders, and the presence of contraindications for taking amino acid L-tyrosine (at the time of the experiment, all the examined students were 18 years old). One hour prior to the tournament the EG administered L-tyrosine pills (5g, made by Twinlab, USA); and the RG took placebo of microcrystal cellulose (5g, made by Evalar, Russia); with both agents taken with 400ml of fresh orange juice. Prior and 1 hour after administration of the agents the sample was tested to obtain the WAM, attention focusing, short-term memorizing and thinking abilities and nervous reactivity test rates. Both of the groups competed in the academic table tennis tournament 1 hour after administration of the agents. The players were paired randomly by drawing lots. Each pair played one 4-min-long game.

The WAM (Well-being-Activity-Mood) test was aimed to analyze such important mental state indicators as well-being, activity and mood [6].

The short-term memorizing test consisted in auditory memorization of five numbers and performance of a series of mental operations: adding the first number to the second, the second to the third, the third to the fourth, and the fourth to the fifth [3].

During the thinking abilities and nervous reactivity test, the students were to fill in the missing letters to 19 words. The test lasted 2 minutes in total [1].

Attention focusing was determined using the dot cancellation test (Bourdon test). The results were assessed by the number of correct answers [2].

Statistical analysis. The statistical data processing was made using the Statistica 10.0 and SPSS 17 software and implied the key methods. The significance of inter-group differences was assessed using the Mann-Whitney test.

Results and discussion. Prior to administration of amino acid L-tyrosine and microcrystal cellulose, the students did not have any statistically significant inter-group differences, which confirmed the homogeneity of the sample. In the second survey conducted using the WAM test, the groups were found to differ significantly in the "Activity" indicator only. The activity index in the 1st group was 5.62±0.31 c.u., and in the 2nd - 4.63±0.22 (p<0.05).

In the second test for attention focusing, the indicator improved considerably in both groups (p<0.001). The groups did not differ statistically significantly in terms of attention focusing in the second test (in the 1st group it was equal to 37.52±2.81 points, in the 2nd - to 37.51±2.09, р>0.05). Short-term memorizing test rates increased significantly in the 1st group upon L-tyrosine administration (p<0.01). In the 2nd group, we observed only an upward trend. The athletes of the 1st group who took the agent were tested to obtain the short-term memorizing test rates as compared to the 2nd group (p<0.001). The amino acid administration did not affect the thinking abilities and nervous reactivity test rates (p>0.05). The table tennis match between the two groups revealed a significant advantage of the 1st group after the intake of amino acid tyrosine. The total score of the game was 6:4 in favor of the 1st group students, and averaged for the 1st group to 22.3±1.99, for the 2nd – to 17.6±1.86 (p≤0.001), which testifies to fact that the 1st group demonstrated the best result.

Conclusions:

  • Single administration of L-tyrosine led to the statistically significant changes in the psychophysiological indicators of the 1st group subjects: according to the WAM and short-term memorizing tests.
  • Changes in the hormonal status of the students due to the intake of amino acid L-tyrosine contributed to the significant improvement in sports results in table tennis.
  • The students participating in this experiment did not have any experience in table tennis competitions, therefore, it cannot be reliably predicted without additional research how L-tyrosine administration may affect performance of elite athletes in this sport.

The article was supported by the Government of the Russian Federation (Act No. 211 of 03/16/2013), Contract No. 02.A03.21.0011.

References

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Corresponding author: romanovla@susu.ru

Abstract

Objective of the study was to analyze benefits of aromatic amino acid L-tyrosine administration for competitive performance and psychophysiology test rates of the 17-19 year old academic table tennis players. Sampled for the study were the South Ural State University students (n=20) aged 18.83±0.10 years, weighing 69.75±1.90 kg and 180.20±1.72 cm tall, trained twice a week under the academic Physical Education and Sport curricula and split up into two groups (EG and RG) of 10 people each. Competitive performance of the sample was tested in a daily table tennis Olympics-modeling tournament. One hour prior to the tournament the EG administered L-tyrosine pills (5g, made by Twinlab, USA); and the RG took placebo of microcrystal cellulose (5g, made by Evalar, Russia); with both agents taken with 400ml of fresh orange juice. Prior and 1 hour after administration of the agents the sample was tested to obtain the WAM, attention focusing, short-term memorizing and thinking abilities and nervous reactivity test rates. Both of the groups competed in the academic table tennis tournament 1 hour after administration of the agents. The tests found a significant growth of the WAM (p<0.05) and short-term memorizing ability (р<0.01) in the EG upon administration of L-tyrosine; that could be one of the reasons for the EG win in the tournament. The test data and competitive success may be interpreted as indicative of the L-tyrosine administration being beneficial for the competitive performance.