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Matcha extract effects on simple and complex reaction time
ŠKOPEK, M., LOUN, J.
University of J. E. Purkyně, Faculty of Education, Ústí nad Labem, Czech Republic
ABSTRACT
This study analysis the effect of a food supplement – Matcha tea extract, its effects on
simple and complex reaction time. The main objective of the analysis was to verify the
positive effect of this product on organism mainly in the area of the speed of organism
reaction to a visual stimuli after the extract was applied.
After the test substance was applied, selected individuals (n=31) were tested for simple
and complex reaction time performance. Double blind experiment method with added
placebo was used in order to find satisfactory results.
Statistical analysis then followed in which the recorded data sample went through the
Wilcoxon test to analyse the substance effect. Majority of probands manifested
significant difference practically and statistically in measured variables of both complex
and reaction time.
The study results proved the influence of Matcha extract effect on the reaction time of
the observed individuals and thus suggest that this nutrition supplement is suitable for
lowering the time response after a visual stimuli occurring either for simple and
complex reaction.
Key words: Simple reaction, complex reaction, matcha, Wilcoxon test
ÚVOD INTRODUCTION
The matcha (抹茶 in jap.) extract has been known for more than a millennium, first
recorded traces of which date back to the 12th century China and Japan. In Japanese
then such type of extract is called Tencha (てんちゃ, 点茶) and is commonly used
during traditional tea ceremonies. Matt (抹) in Japaneese means crushed into a powder,
which preserves all the active substances (Thoma, 2014). Depending on the batch the
amount of the active substance can differ up to 10%. Main reason for this is the
collection of the tea during harvest. Such composition is typical for matcha which has
enough „delicacy“, which means that the more delicacy the higher quality of matcha
tea. Matcha contains twice as much caffeine and 4 times more amount of L-theanine
amino acid than any other green tea known to mankind (Standard Tables of Food
Composition, 2012). Negative effects of matcha have not yet been described, however
there are 35 mg of active substance
One gram of tea including the daily recommended dose should not exceed 400mg of the
active substance. That is equal to 12 cups of tea (Haskell, Kennedy, Milne, Wesnes, &
Scholey, 2008; Weiss & Anderton, 2003).
Haskell (Haskell et al., 2008) states that L-theanine can be found mainly in tea and as
well as caffeine. In his study he analysed cognitive effects of this amino acid in
combination with caffeine. The results showed that caffeine leads to faster reaction in
terms of number perception, better RVIP (Rapid visual information processing) and the
reduction of the fatigue effect. Combination of RVIP and decrease of psychological
fatigue leads towards faster reaction time, faster working memory and better sentence
verification accuracy. According to the results of Haskell’s study, the intensity of
headaches also decreased. Such facts suggest that beverages containing caffeine and L-
theanine at the same time can have different pharmacological profile than such
substances which contain only caffeine. Caffeine itself helped increase the reaction
speed, information processing accuracy, simple reaction time and RVIP, numeric
definition of the reaction time of the working memory, reaction time of the delayed
word recognition. Sentence recognition was then more accurate when both substances
were used at the same time.
One study concerning the catechin amounts in green tea using electronic
chromatography, pointed out that green tea contains high amounts of Epigallocatechin
gallate (EGCG). This catechin is one of the most effective antioxidants and its effects
can prevent cancer. EGCG levels in matcha exceed several times the amount of the
same substance in ordinary green tea (Weiss & Anderton, 2003). Quinlan, King, Hanna
and Ghazziudin (1997) came with a finding, that tea containing 100mg of caffeine had
significantly stronger effects than coffee with the same amount of caffeine. Steptoe,
Hamer a Chida (2007) found, that tea is able to decrease the activation of platelets and
cortisol levels during stress reaction and also that tea helps increase feeling of relaxation
and body control.
Kakuda (2000) during his animal testing proved that is capable of stimulation inhibition
caused by caffeine during EEG scan of spontaneous animal activity.
Lu, Guarnieri and Simon (2004) studies the subjective mood effects of L-theanine and
found that 200mg of the substance can increase the feeling of “peace in mind”.
Kobayashi, Heck, Nomura, Horiuchi (1998) found, that 200 mg of L-theanine leads to
increase of alpha brain waves, which suggests that this substance is good for relaxation
without fatigue and may decrease reaction time to a specific degree. From available
sources we then may conclude that matcha tea contains beneficial substances which
have positive effect on human body. The beneficial substances are amino acids, anti-
oxidants, vitamins (C, B1, B2…) and minerals (potassium, sodium, calcium, etc.).
Matcha tea has many good effects on overall health, such as helps lower the cholesterol
and sugar levels in bloodstream, supports blood vessel structure, as well heart and
overall blood circulation. Matcha contains high amount of polyphenol catechin which
are very effective against many diseases and this effect does not only include EGCF.
Study conducted by Weiss and Andertona (2003) found, that it is matcha tea, which had
several times higher amount of EGCG than in regular types of green tea. The study also
pointed to the fact, that caffeine as itself can lead to reaction time decrease, however
combined with L-thiamine, supporting good mood, alpha waves and anxiety relief, can
thus decrease the overall reaction time possibly even more (Haskell et al., 2008).
On the other hand the effects of matcha tea have been verified in terms of fragile
hypotheses based on specific analyses, method and factors which in some cases assured
positive or negative effect of this extract. That is why we decided to contribute to the
canon of research to add more to the solution of the extract effect.
Test subject group description
This study is concerned with the possible increase of individual’s reaction skills while
using nutrition supplements – in this case, matcha extract. The main objective it to find,
whether after its consumption reaction skills get better, as sources regarding this subject
suggest. This study is then an additional contribution to the already existing canon of
nutrition supplement studies, and thus verify that matcha extract functions as a
stimulant, which can prepare human organism for faster responses to a selected
stimulus. The study was attended by 31 probands (15 women, 16 men) ages 20 – 45
(table 1.), based on two measurements during one week. All probands were in good
physical shape and healthy during testing without any subjective issues, however
kinesiology analysis of test subjects was not included in the study. The overall data
sample was done via purposeful selection.
Table 1. Basic description of the test subject group
Characteristics
Age/SD
(years)
height/SD
(m)
weight/SD
(kg)
34,4/15
171,1/10
69,7/10
Legend: SD - standard deviation
Methods
The testing procedure has been done twice, always a week in between each testing
taking place. Each individual had to abstain from drinking or using any substances
which may cause any cognitive arousal (e.g. caffeine etc.) for 48 hours and were
advised not to engage in any difficult physical activity before testing as well. The
testing then involved double blind test. Each probands randomly took prepared sample
(capsule) of substances labelled A, or B. Sample A contained 35 mg.kg-1 of matcha and
sample B contained the same amount of placebo (starch). The amount of substance dose
had to be adjusted according to test subject’s weight. After 50 minutes from the
swallowing of the capsule each subject was tested via reactimeter to measure simple and
subsequently complex reaction time. After a week, second testing took place, during
which probands took an opposite label capsule than previous week. All measurements
took place in a standard environment in KTVS UJEP laboratories in Ústí nad Labem
based on recommendation of a study conducted by Balkó (Balkó, Wasik, Chytrý,
Dunajová a Škopek, 2017).
In order to measure simple reaction time to a visual stimulus, test subjects were seated
in an immobile chair opposite a chair (eyes positioned 60cm horizontally from the
computer screen). The plate for reaction time testing was placed under either right, or
left hand depending on the preference of the test subject. The hand was placed 4 cm
above the touch-sensitive plate. Test subjects were facing the computer screen and
observed a green circle symbol in the middle of the screen on a white background which
appeared in different intervals. Each appearance of the symbol meant that test subject
had to react to it by touching the sensitive plate 20 times in row. For complex reaction
time measurement we used four different plates and four symbols on the screen, Test
subject had to react to a specific symbol by pressing the related plate, again, 20 times in
a row. The plates were positioned in a square setting with a 4 cm gap in between each
plate. The first plate was for the red square, second one dot green circle, third plate
represented blue triangle and the fourth yellow cross. Like in the previous testing of
simple reaction time, the stimulus always appeared in the centre of the screen. This test
regarded the use of both hands with the default positioning of hand, which was 4cm
above the workspace, left hand 3cm away front he left plates and right hand 3 cm away
from the right plates.
For the purpose of reaction skill measurement, special reactimeter and Fitro Agility
Check & Reaction 2.0 (Fitronic, s. r. o.) software was used. The software is able to
generate stimuli in a range between 500-3000 Ms, project them on a computer screen
and recorded the reaction time of a test subject (plate press). Error attempts were not
included in the analysis. Simple reaction time threshold range of correct attempt was
calculated to be spectrum between 100-1500 Ms, complex reaction time then has
threshold range of 150-2000 Ms. All participants were not disturbed by any external
stimuli during testing.
Data normality was tested via Shapiro-Wilks test. The results of simple and complex
reaction time do not have normal data distribution and that is why nonparametric
Pic. 1 Simple reaction time
Statistical methods have to be applied in the analysis.
In order to statistically process the nonparametric data set, Wilcoxon test is suitable,
because it compares dependent selections. The effect size threshold was set to p < 0, 05.
In order to calculate the effect size, Rosenthal coefficient r (Rosenthal, 1994) was used,
which sets effect intervals in a following spectrum:
small effect (r > 0,1)
Moderate effect (r > 0,3)
Significant effect (r > 0,5)
Results
This chapter describes the outcomes and results of the reactimeter testing showed via
software tools described above. Picture 1.shows measurements of simple reaction times
(medians) of individual probands after matcha extract and placebo consumption. Picture
2. Than shows reaction time levels of each test subject.
Pic. 2 Complex reaction time
Out of all measured samples of SRT (simple reaction time) after matcha extract and
placebo, the analysis showed (Tab. 3) there exists a significant difference (p´0, 00; r=0,
56). The analysis of CRT (complex reaction time) found, that there is also a significant
difference between matcha tea extract and placebo (p = 0, 00; r = 0, 34). The effect size
of SRT (56%) is higher than within complex reaction time (34%)
Tab. 1 Reaction time after placebo and matcha tea extract consumption
Placebo
(med)
Matcha
(med)
p
r
SRT
327,2
293,0
0,00
0,56
CRT
729,1
696,2
0,00
0,34
SRT – simple reaction time, CRT – complex reaction time, p –error probability after
zero hypothesis rejection, r – effect size
The following picture (Pic. 3) shows differences in SRT after matcha extract, after
placebo consumption. Such differences can be seen also in CRT, after the consumption
of placebo (Picture 4.).
Pic. 3 Simple reaction time after matcha extract and placebo consumption
Pic. 4 Complex reaction time after matcha extract and placebo consumption
The results shown above describe the difference between SRT and CRT, the effect of
the analysed substance, which proved to manifest significant differences in reaction
time levels.
DISCUSSION
After the data processing, the analysis showed that statistically significant change can
be spotted among both of the observed variables of reaction time. Thus we may
conclude that among both simple and complex reaction time have been influenced by
decreasing the speed of reaction to 56%simple and 34 % of complex reaction time. For
this particular reason it is possible to induct, that matcha extract is able to decrease the
response time period to a visual stimuli for both simple and complex reaction time. The
analysis was however unsuccessful to be comparable with other studies in terms of its
results. It was, however, possible to compare similar articles regarding similar issues,
e.g. study conducted in 2003 testing the caffeine influence (Jensen et al., 2005), and
another study article written in 2010 which tested the taurine effects on RT (Škopek,
Hnízdil, 2010). Interesting to point out, is that among all of the previously mentioned
substances have no, proven effect, as the one showed in our study concerning matcha
extract, even though some manufacturers of supplements including the previously
mentioned substances say that caffeine and taurine have similar effects as matcha. We
are, of course, aware that our study results have to be read with a certain amount of
caution. The better reaction time levels may have been also caused by other variables
which influence performance such as individual psychological fitness etc. In order to
verify the results presented in our study, additional control (repeated) testing on the
same sample of probands would be required which may increase the reliability and
validity. Nevertheless, the findings in this study a\re more than impressive.
COCNLUSION
This article contribution set its objective to find out whether it is possible to influence
the reaction time of a person depending on the reaction to a visual stimulus after matcha
tea extract consumption. The results of the data analysis have shown that this nutrition
supplement has manifested signs of a stimulant during the testing of simple and
complex reaction time. After the consumption of the extract, in majority of cases the
predicted decrease of reaction time truly occurred. That is the main reason why we may
recommend the matcha extract as a suitable supplement for better and faster reactions to
visual stimuli, which can be of course used within a wide range of sport activities, or
also suitable for maintaining better reactions in every day, e.g. driving a vehicle etc.
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