L-theanine and competition anxiety in archery: Lim 2024

Eighteen Korean women university archers competing in the 50-metre individual event of the 40th President's Cup national competition in June 2023 were randomly split into two groups of nine: one took a capsule of L-theanine, the other a lactose placebo, once a day after the evening meal for four weeks. On competition day cognitive anxiety was rated on a 1 to 10 scale, and salivary alpha-amylase and cortisol were measured, at 30, 20 and 10 minutes before shooting and after the event.

In both groups all three values rose as shooting approached. Ten minutes before, anxiety was 6.9 in the theanine group and 8.7 with placebo; alpha-amylase was lower in the theanine group at 20 minutes (42.7 against 58.3) and at 10 minutes (81.3 against 102.5), and cortisol at 10 minutes (10.7 against 14.6) and after the event (13.5 against 18.9). All these differences are reported as significant. According to the author, competition results did not differ between groups, but the scores are not reported. The paper ends by recommending theanine against competition anxiety in precision sports.

The athletes had careers of more than ten years, a mean age of 21.21 and no current illness or medication. The randomisation method is not described, nor is it said whether athletes and researchers knew who was taking theanine; the placebo was of a similar colour. The capsule is described as pure theanine extract "of 200 g", almost certainly 200 mg. The time between the last dose and the competition is not given.

Cognitive anxiety was rated on a Likert scale based on Beck's, where 1 meant "not at all" and 10 "extremely anxious". For saliva, athletes had to avoid food and drink for at least 40 minutes and rinse their mouths 5 minutes beforehand; samples were collected by chewing a swab and analysed in the laboratory, with a Salimetrics kit for alpha-amylase. The groups were compared with a repeated-measures analysis of variance, group by time, without correction for multiple comparisons. The bow type is not stated.

Nine athletes per group is a small number, and the paper leaves important points open: how allocation was done, whether the trial was blinded, when the last dose was taken. There is no measurement at the start of the four weeks, so it is unknown whether the two groups began alike in anxiety and stress response; values 30 minutes before competition are similar, but that is the only point of comparison.

Several passages of the text do not match the table. The methods say anxiety was measured 10 minutes after competition, the table 20 minutes after, with identical values in both groups (4.56 ± 0.8). The results text says cortisol after competition was much higher in the theanine group, while the table shows it lower. The discussion states that it was the placebo group that showed a fall in anxiety, and, citing another study, mentions increased stress in the theanine group: statements that contradict the conclusion, or at least make it ambiguous. Cortisol is given in u/ml, an unusual unit for this measure. For anxiety the group-by-time interaction is not significant (F 1.25), and the difference at 10 minutes comes from a single-point comparison. Finally, the one figure an archer would want is missing: the competition scores, mentioned only as not different.

For archers, the study does not show that theanine improves shooting: scores are mentioned but not reported and, according to the author, did not differ between groups. What it does report is that in nine archers who had taken it for a month, self-rated anxiety and two salivary stress markers were slightly lower in the minutes before shooting than in nine team-mates on placebo. Given the mismatches between text and table, the doubts about blinding and the missing scores, this is a preliminary finding, not a basis for the recommendation the paper ends with.

Theanine is a supplement, and the study gives no clear information on dose or on timing relative to competition. In the registry it counts as evidence on pre-competition anxiety and stress, not on performance.