Effects of supplement L-theanine on cognitive anxiety, salivary alpha-amylase, and cortisol in archery competition
Article information
Abstract
[Purpose]
Archery is a representative sport requiring high levels of concentration. Accordingly, assessing participants’ physiological and psychological factors related to tension, anxiety, and stress represents a valuable resource for enhancing performance. This study examines the impact of L-theanine administration on archers' cognitive anxiety levels, salivary alpha-amylase (sAA), and salivary cortisol (sC) in archery competition.
[Methods]
The study included 18 athletes from women's colleges who participated in the 50-meter individual competition at the 40th president's cup national archery competition in June 2023. Athletes’ anxiety levels were assessed on a Likert scale, ranging from 1 “not at all” to 10 “extremely anxious.” Saliva samples were collected 30, 20, and 10 minutes before and 20 minutes after the game. Repeated measures of the general linear model ANOVA were performed to compare the mean values of sAA and anxiety level.
[Results]
Cognitive anxiety levels were significantly reduced in the treatment compared to the placebo group at 10 minutes before the game (p<.05); sAA levels were significantly reduced in the treatment group compared to the placebo group at 20 and 10 minutes before the game (pre-20 and pre-10, respectively); and sC levels were significantly reduced in the treatment compared to the placebo group at 10 minutes before the game (p<.05).
[Conclusion]
The findings demonstrate that L-theanine treatment is an efficacious intervention for reducing cognitive anxiety, sAA, and sC levels in sports. Therefore, it is recommended to alleviate competitive anxiety in sports requiring high concentration levels such as archery.
INTRODUCTION
Archery is a representative sport requiring a high level of concentration. Compared to other sports, archers are significantly influenced by psychological factors. The assessment of physiological and psychological factors related to tension, anxiety, and stress in archery competitions represents a valuable resource for enhancing performance. A related study revealed a correlation between elevated heart rate and competition anxiety with diminished performance in archery [1]. A study examining the relationship between cognitive anxiety and performance in 106 athletes revealed a robust negative correlation between these variables [2]. In general, stress activates the hypothalamic-pituitary-adrenal (HPA) axis and the sympatho-adrenal medulla (SAM). The activity of the HPA axis has been demonstrated to elevate cortisol levels, while SAM has been shown to increase catecholamine levels. In competitive settings, anxiety and stress levels in athletes are typically assessed through the measurement of blood cortisol and catecholamine levels. However, in real-life sporting scenarios, the use of a simpler salivary method is often recommended. Salivary alpha-amylase (sAA) and salivary cortisol (sC) are used as biomarkers to assess anxiety, tension, and stress levels owing to their increased activity in situations of physical and psychological anxiety, which is attributed to the activation of the sympathetic nervous system [3,4]. Previous studies have reported that acute stress is associated with a significant increase in sAA levels and that patients with chronic stress exhibit elevated sAA levels [5,6,7]. L-theanine, a functional food that has demonstrated efficacy in reducing anxiety, tension, and stress, has recently garnered considerable attention. It is biosynthesized from glutamine and ethylamine in the roots of green tea by enzymatic activity and is degraded in the presence of sunlight to ultimately convert to catechins, a polyphenol [8]. L-theanine has been shown to cross the blood-brain barrier to reach the brain and reduce stress and anxiety [9]. In particular, L-theanine affects the release of neurotransmitters in brain neurons, increasing levels of gamma-aminobutyric acid, serotonin, and dopamine, thereby reducing anxiety and stress hormone secretion in stressful situations [10]. L-theanine has been demonstrated to induce a decrease in beta waves and an increase in alpha waves in the electroencephalogram, as well as a reduction in heart rate and blood pressure [11]. White et al. determined that 200 mg of L-theanine resulted in a notable reduction in the subjective stress response one hour after administration, as well as a significant reduction in cortisol levels three hours after administration [12]. In a related study, four weeks of L-theanine administration resulted in a reduction in anxiety levels [13], and curling players reported improvements in performance and a significant decrease in cognitive anxiety levels [14]. Nevertheless, the physiological mechanisms underlying anxiety in real archery competitions remain poorly understood, and the efficacy of L-theanine for anxiety reduction in athletic contexts is particularly uncertain. This study examined whether theanine intake could reduce anxiety levels and biomarkers of anxiety during archery competition. Accordingly, this study aims to analyze the effects of L-theanine administration on cognitive anxiety levels, sAA, and cortisol during official archery competitions, a sport where performance is highly dependent on psychological factors such as concentration, tension, anxiety, and stress.
METHODS
Participants
This study included 18 athletes from women’s colleges who participated in the 50-meter individual competition of the 40th President’s Cup National Archery Competition in June 2023. The participants were randomized into the L-theanine treatment (n=9) and placebo groups (n=9). The participants were archers with a career spanning more than 10 years, were not taking any substance or medication, and did not report any clinical disease, especially intra oral disease or inflammation. The mean age of the participants was 21.21 ± 1.67 years, their mean height was 165.3 ± 3.15 cm, and their mean body weight was 65.13 ± 3.34 kg.
Assessment of anxiety
The anxiety levels of athletes in an archery competition were assessed on a Likert scale based on the scale of Beck et al., ranging from 1 “not at all” to 10 “extremely anxious.” With respect to the evaluation method, the cognitive anxiety of the participants was measured 30 minutes before archery performance (pre-30), 20, and 10 minutes before performance (pre-20, pre-10), and 10 minutes after performance (post-10).
L-theanine intake
The recommended daily intake of L-theanine is 150 mg to 250 mg. Although L-theanine is not known to cause drug interactions, it is recommended that the maximum dosage not exceed 600 mg in a six-hour period or 1,200 mg in a 24-hour period. L-theanine, also known as sun theanine, was approved by the U.S. Food and Drug Administration in 2007 as a safe substance for use in food and beverages and is currently available as a supplement. The supplement used in this study is a capsule of L-theanine manufactured by Company B, which is a 100% extract of theanine found in the tea plant, having 0 kcal and weighing 200 g. The main component of L-theanine is green tea, with small amounts of cellulose, magnesium, and dioxide. The placebo tablet of lactose was in a similar color to a theamine tablet. The participants were instructed to ingest a single capsule following their evening meal for four weeks.
Saliva collection and analysis
The participants were instructed to fasted for at least 40 minutes before collecting saliva because food and drinks affect the saliva components. After the participants washed their mouths 5 minutes before sample collection, saliva was collected 30, 20, 10 minutes before the game, and 20 minutes after the game by asking the participants to chew the absorbent swab in the mouth. Saliva samples were contained in collection tubes and stored in the refrigerator. Kinetic colormetric method was conducted for sAA activity. The competitive immune enzymatic colorimetric method was performed for cortisol concentration. The sAA and sC analysis was performed using the ELISA(enzyme-linked immunosorbent assay) method with the VersaMax™ Microplate Reader manufactured by Molecular Devices, LLC in the USA. For reagents, the Salimetrics™ sAA assay kit was used.
Statistical analysis
The data were analyzed using SPSS ver. 23 software. The values of all the variables were presented as mean and standard deviation. Repeated measures of two-way ANOVA were performed to compare the mean values of sAA and anxiety levels. The statistical significance of the results was determined with a significance level of 0.05 except for correction for multiple testing.
RESULTS
The results of the analysis of changes in cognitive anxiety, sC, and sAA at pre-30, pre-20, and pre-10 and 20 minutes after the match (post-20) are presented in Table 1. As the game drew nearer, there was a notable rise in cognitive anxiety levels among participants in both groups. A significant reduction in cognitive anxiety levels was observed in the treatment group compared to the placebo group at pre-10, indicating that L-theanine administration was effective in reducing cognitive anxiety during archery competition (p<.05). As the game time drew nearer, sAA levels rose considerably in both groups, with an interaction effect being observed. In between-group comparisons, a significant decrease was observed in the treatment group relative to the placebo group at pre-20 and pre-10 (p<.05). Additionally, sC levels demonstrated a notable increase as the game drew nearer, a phenomenon that was observed in both groups and exhibited an interaction effect. A significant reduction was observed in the treatment compared to the placebo group at pre-10 (p<.05). In particular, sC levels were markedly elevated in the treatment group in comparison to the placebo group, specifically at post-20. The findings indicate that L-theanine supplementation in archery practice may attenuate sAA and sC levels, which are indicative of competitive anxiety.
Changes of the anxiety, sAA, and sC in the archery competition
Comparison of the cognitive anxiety level during pre-30, pre-3, and post-30 between Theanine and Placebo group.
pre-30 : 30 min before competition; pre-20 : 20 min before competition; pre-10 : 10 min before competition; post-20 : 20 min after competition; *: p<.05.
Comparison of the sAA level during pre-30, pre- 3, and post-30 between theanine and placebo group.
sAA : salivary alpha amylase. pre-30 : 30 min before competition; pre-20 : 20 min before competition; pre-10 : 10 min before competition; post-20 : 20 min after competition; *: p<.05.
Comparison of the sC level during pre-30, pre-20, pre-10 and post-30 between theanine and placebo group.
sC : salivary cortisol; pre-30 : 30 min before competition; pre-20 : 20 min before competition; pre-10 : 10 min before competition; post-20 : 20 min after competition; *: p<.05.
DISCUSSION
The study revealed that as the game approached, there was a notable increase in cognitive anxiety levels. The placebo group exhibited a notable decline in cognitive anxiety levels compared to the treatment group. In particular, the placebo group exhibited a statistically significant increase in cognitive anxiety levels, with a three-fold increase in cognitive anxiety levels at pre-10 compared to pre-30. In a study on archery and anxiety, Salleh et al. (2020) reported that archery performance was associated with higher heart rate and competition anxiety, and lower performance was associated with higher pressure to compete [1,15]. In particular, the study demonstrated a statistically significant reduction in cognitive anxiety in the treatment group compared to the placebo group in the 10 minutes preceding the competition, suggesting that L-theanine was effective in reducing cognitive anxiety. These findings corroborate those of prior research [16], which has demonstrated that L-theanine is efficacious in mitigating stress, heart rate, and sympathetic ner-vousness. Furthermore, it has been documented that acute stress is associated with elevated sAA levels [7]. The findings of this study indicated that sAA and sC levels exhibited an increase as the game time approached, with a notable decline observed in the treatment group in comparison to the placebo group. The findings indicate that L-theanine may have a notable impact on anxiety reduction in archery. However, there was no difference in game performance between the two groups. This is believed to be due to individual differences in game skills and game rankings. At pre-10, the treatment group exhibited a notable reduction in cognitive anxiety, sAA, and sC levels in comparison to the placebo group. The results indicated that cognitive anxiety reached its peak just before the game, as evidenced by the data from pre-10 compared to pre-30 and pre-20, which was also reflected in the results for sAA and sC levels. A related study demonstrated that the secretion of sAA was markedly elevated in response to chronic stress and stress-related pathologies [17]. A significant elevation in stress assessments was observed in the L-theanine treatment group relative to the placebo group [18]. Additionally, a study examining sC, sAA, and anxiety levels in wushu athletes reported increases as the competition season drew near and notable reductions with mindfulness as an intervention [19]. The collective findings of this study and related studies indicate that anxiety scales and sC and sAA levels are reliable indicators of physiological and psychological assessment in athletes during competition. Additionally, the administration of L-theanine has been demonstrated to be an effective intervention for alleviating competitive anxiety in sports requiring a high level of concentration, such as archery.
In between-group comparisons, cognitive anxiety levels were significantly reduced in the treatment group compared to the placebo group at pre-10; sAA levels were significantly reduced in the treatment group compared to the placebo group at pre-20 and pre-10; and sC levels were significantly reduced in the treatment group compared to the placebo group at pre-10. These findings indicate that L-theanine administration may be an efficacious intervention for the alleviation of competitive anxiety in sports requiring a high level of concentration, such as archery.
Acknowledgements
This research was supported by the Changwon National University in 2023~2024.