Journal of Digital Life 2021, 1, 2

ArticleEffect of positive and negative ions in esports
performance and arousal levels
Goichi Hagiwara1*, Takehiro Iwatsuki2, Hirokazu Funamori3, Masaru Matsumoto3, Yukihiro
Kubo3, Seiji Takami3, Hiroaki Okano3, Daisuke Akiyama 1
1

Department of Human Science, Kyushu Sangyo University, y, 2-3-1 Matsukadai, Higasgi-ku, Fukuoka-shi, Fukuoka 813-8503, Japan
Department of Kinesiology, The Pennsylvania State University, Altoona College, 3000 Ivyside Park, Altoona, PA 16601, USA
3
Sharp Corporation, 3-1-72 Kitakamei-cho, Yao-shi, Osaka 581-8585, Japan
2*Correspondence: hagi-g@ip.kyusan-u.ac.jp; Tel.: +81-92-673-5878

Abstract
The purpose of this study was to investigate the psychological effects of arousal levels in esports players
during a racing-game under positive and negative ion environments. Participants (10 male) who belonged tothe collegiate esports team were recruited. The influences of positive and negative ions were evaluated in arandomized, crossover, and placebo-controlled double-blind design. Each participant completed two
experiments within a 4-week interval. Two experimental environments were used: positive and negative ionsfilled up the atmosphere (PNI), and a control (CON) condition. For the performance task, a car-racing game
was adopted. Arousal state was measured by the Two-Dimensional Mood Scale (TDMS) and anelectroencephalogram (EEG). Results indicated that the EEG level was significantly higher in PNI than CON
condition. Also, the PNI had a significantly higher performance on the gaming task than the CON condition.
The present study demonstrated the beneficial effects of positive and negative ion environments on esports
players.
Keywords: electronic sports, athlete, game, car race, driving, EEG.

1. Introduction
Esports involves the enactment of video games as spectator-driven sport, carried out through promotional activities;
broadcasting infrastructures; the socioeconomic organization of teams, tournaments, and leagues; and the embodied
performances of players themselves (Taylor, 2016; Reitmen et al., 2020), and it is phenomenon that has grown
dramatically over the past decade (Toth et al., 2019). Sport involves the display of elite athletes' physical andpsychological skill in sports competition for entertainment aims in general (Campbell, et al., 2018). On the other hand,esports' athletes seem to rely more on psychological or emotional skills for success rather than motor skills thattraditional sports athletes rely on (Himmelstein et al., 2017). Thus, training of psychological or emotional skills foresports is significant to promote its entertainment and it is necessary to pursue whether to improve psychological oremotional skills for esports athletes. Therefore, research on training method and environment to improve more
psychological and emotional skills would be necessary in esports filed. However, currently, there is no esports training
method that was established in the sports science filed, and further research would be needed. Furthermore, in thefield of sports science, the training environment is also important in addition to the establishment of training methods.
Hence, it is necessary to examine the training environment related to esports in the field of sports science.
Arousal is a human psychological state and defined as being "worked up" or energized (Perkins et al., 2001). Highlevels of arousal would benefit or be essential for maximal performance (Oxendine, 1970); thus, several studies
investigated the relationships between arousal and sports performance (e.g., Gould & Krane, 1992; Hagiwara et al.,2019; Perkins et al., 2001). Athletes with higher arousal levels, assessed by a questionnaire, had a significantly higher
Received: 20 August 2021, Accepted: 7 September Published: 24 September 2021
* Correspondence: hagi-g@ip.kyusan-u.ac.jp;
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Effect of positive and negative ions in esports performance and arousal levels
Hagiwara et al.
success rates of shots in badminton (Yamazaki & Sugiyama, 2009). Subjective assessments (i.e., questionnaire) havebeen mostly used to understand the relationship between the arousal levels and performance (Nagao & Sugiyama,
2013; Perkins et al., 2001; Yamazaki & Sugiyama, 2009); however, a few studies have been conducted using EEG(Fronso et al., 2016; Hagiwara et al., 2019; Hagiwara et al., 2020). The higher EEG was associated with increased
performance in Olympic athletes in air-pistol shooting (Fronso et al., 2016). Hagiwara et al. (2019) then examined therelationship between the arousal levels and swimming performance though both questionnaire and EEG before andafter watching a motivational video. Hagiwara and colleagues demonstrated that athletes with higher arousal levels
tended to perform better. However, it is important more work to understand the relationship between the two,
especially by using EEG.
Various training environments have been used for facilitating sports performance, and an altitude environment hasoften been adapted (Berglund, 1992). Training in a hyperoxic or hypoxic environment found to enhance sports
performance (Cardinale & Ekblom, 2018; Roels et al., 2007). Recently, training in an air-ionic environment has been
considered to have positive impacts on athletes’ emotional states, which might relate to their sport performance(Hagiwara et al., 2020; Nimmericher et al., 2014; Ryushi et al., 1998). Physical training under positive and negative
ion environments among elite swimmers might enhance both (questionnaires, EEG) arousal levels and training
performance (Hagiwara et al., 2020). However, research on the environmental contributions to sports performance
was limited (Davids & Baker, 2007), and effective environments for esports performers are currently unknown. The
current study examined this matter using positive and negative iron environments.
Air ions are small particles that exist in nature and are positively or negatively charged molecules or atoms in the air(Jiang & Ma, 2018). Positively charged ions are positive ions and vice-versa (Yamamoto et al., 2015). In addition, airions containing positive and negative ions have certain abilities such as purification of the atmosphere anddeodorization (Nishikawa, 2013). The relationship between air ion and emotions have been conducted (Flory et al.,2010; Perez et al., 2013). For instance, a high-density negative ion environment was found to reduce depression. In
addition, other studies that examined the relationship between negative ions and depression (Goel & Etwaroo, 2006;
Terman & Terman, 2006; Terman et al., 1998), lower stress (Malik et al., 2010), and increased well-being (Lips et al.,1987) have been conducted. Several studies also suggest that the relationships exist between positive ion environmentand human emotions (Perez et al., 2013). For instance, Gianinni et al. (1986) examined the correlation between
positive air ion and emotion. Results showed anxiety and excitement significantly increased under this condition. In
addition, the relationship between positive ions and feelings of unpleasantness, irritation and anxiety has been verified(Giannini et al., 1986; Charry & Hawkinshire, 1981).
Although research findings have been mixed, environments that induce ions and emotions have been connected. To
our knowledge, little research has been conducted to understand a better relationship among, environments, arousal
states, and performance in esports. The purpose of the present study was to examine the arousal level and performancein esports under positive and negative ion environments.
2. Methods
2.1. Participants
Ten male participants who belonged to the collegiate esports team (age: M = 21.22 ± 1.59) were recruited. They were
informed the purpose of the study and completed an informed consent form prior to participation. The Institutional
review board approval was obtained from the research institute, National Institute of Fitness and Sports in Kanoya.
2.2. Experimental Protocol
The influence of plasmacluster ions was evaluated in a randomized, crossover, placebo-controlled double-blind trail.
Each participant completed two experiments within a four-week interval. Two experimental conditions were prepared(Figure 1): positive and negative ions were filled up the atmosphere in the experimental tent (PNI) and ions were notgenerated (CON) condition. The PNI condition was delivered by a PlasmaclusterTM ionizer (Sharp Corporation,
Japan) and exposed to positive and negative ions (147,000-164,000 PNI/cm3) with air wind from the ionizer. In the
CON condition, air wind from the ionizer without ions at the same air wind velocity was adapted (wind velocity: 0.29
m/sec). This method to generate positive and negative ions was previous used (Yamamoto et al., 2015). First,
molecules in the air were decomposed by applying positive and negative high voltages to each discharge brushelectrode of the ion generation devices, and the devices generated positive ions and negative ions (Nishikawa &Nojima, 2001). The ion concentrations were determined by an ion counter (MY1210S, Asahi System Inc. Japan) bymeans of the double concentric circle tube method (Nishikawa & Nojima, 2001). The room temperature and humidity
were 23.5 ℃±0.5 and 60% ± 2.0, respectively.

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Effect of positive and negative ions in esports performance and arousal levels
Hagiwara et al.

Figure 1 Bauhutte single-person gaming tent (be-s Co., Ltd., Japan)
The details of the experimental procedure were as follows (Figure 2). First, the participants were asked to put on an
EEG device for 2 minutes for their baseline assessment of arousal level. The participants then completed aquestionnaire to assess arousal level before performing a racing-type action game. They completed the 3 times aspractice trials prior to performing in the experimental setting in the tent. They also performed 3 times as final trials.
For the performance task, the participants completed MARIOKART Deluxe 8. The driving course was Mario Kart
Stadium, and the race-mode setting was Time Attack, which involved driving 3 laps around the same course. The
class of the vehicle was set to 150cc, and the participants choose the character of the driver. During the completion,
EEG was assessed to measure their arousal level. After the task, participants completed the questionnaire

Figure 2 Flow diagram of the study design
2.3. Evaluation of Arousal
The arousal level was assessed by a questionnaire and EEG. A Two-Dimensional Mood Scale (TDMS) (Sakairi et al.,2013) was used to evaluate arousal level. The TDMS is composed of 8 items and 4 factors: activity, stability, comfort,
and arousal. We adopted a simple band-type EEG device (NeuroSky Co., Ltd., Tokyo, Japan) that only measures thefront polar area 1 (Fp1) lobe as defined by the international 10–20 system (Figure 3). The EEG obtained from Fp1 has

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Effect of positive and negative ions in esports performance and arousal levels
Hagiwara et al.
been found to be suitable for obtaining data on psychological condition (Mitsukura, 2016; Hotta et al., 2017).
Therefore, we used Fp1 to estimate the arousal level.

Figure 3 Measurement points of the international 10-20 system
Brainwaves were classified into 4 types according to their frequency range: 0.5–4 Hz: delta waves, 4–8 Hz: theta
waves, 8–13 Hz: alpha waves, 13–40 Hz: beta waves. Psychological states were associated with each type (Okubo etal., 2018) (Table 1).

Table 1. Type of brain wave and psychological state

Type of brain wave
Delta wave
Theta wave
Alpha wave
Beta wave

Frequency(Hz)
0.5 ~ 4 Hz
4 ~ 8 Hz
8 ~ 13 Hz
13 ~ 40 Hz

Psychological state
Non-REM sleep, unconscious
Sleep onset, illusion
Relaxed mental state
ArousalThis present study examined the beta wave band. The EEG data were recorded on a smartphone in the Kansei Module
Logger (Littlesoftware Inc., Japan). This produced the data output in the most sensitive manner. The occurrence ratioof the beta wave band was defined as the arousal level, and the value was displayed from 0 to 100. The arousal levelby the Kansei Module Logger correlated with the subjective arousal level, measured by a questionnaire (Hagiwara etal., 2019). The basic concept of the Kansei Module Logger is that it calculates the power ratio between the beta wave
bands. The potential difference obtained from the electrodes on the forehead and earlobe of the left Fp1 is amplified
by the circuit inside the measuring instrument, digitized at 512 samples/sec, and subjected to the Hanning window
processing. The power spectral analysis was then conducted using the fast Fourier transform. EEG data are analyzed
every second, and the amplitude spectra can be obtained at 1-64 Hz. Thus, this study obtained delta, theta, alpha andbeta waves. From the obtained power spectrum, the sum of each power in each frequency band was calculated after,
and the ratio included in the total power is shown as a relative numerical value. However, the sum of the power of
each frequency cannot be used because the amplitude of each frequency band is different. Therefore, the average valueof the power of each frequency band was obtained. The calculation method used the following formula as a standard
for analysis.
The average Px of the x-wave power was calculated by formula (1), where Vf is the power of the EEG at the frequency
f [Hz]. Since the beta wave band (13 Hz to 40 Hz) was handled, when x = β, it became (13, 40) [Hz], and the numericalvalue was applied to (Fxmax − Fxmin) in formula (1). Next, the sum of power averages (Psum) in each frequency
band was calculated by formula (2). The ratio (Rx) included in the total power of the beta wave band was calculated
in formula (3). With these calculations below, the beta band were normalized to provide the value of 0-100.

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Effect of positive and negative ions in esports performance and arousal levels
Hagiwara et al.

Px 

x
F max

V

x
f  F minfxx/( F max
 F min 1)(1)

Psum  P  P  P  P(2)

R x  P x / Psum

(3)

2.4. Analysis
The TDMS scores before and after completing the task and EEG during the task were averaged. A t-test was used to
examine the difference between the PNI and CON conditions on the TDMS and EEG. For the task performance, the3 trials prior between the PNI and CON conditions were averaged. A t-test was also performed to examine thedifference between the two conditions. The IBM SPSS Statistics 25.0 software was used for the analysis, and p value
was set at 0.05.
3. Results
3.1. TDMS
There was no significant difference between the PNI condition (M = 6.44, SD = 5.10) and CON condition (M = 4.78,
SD = 4.63) on TDMS (p > .05) (Figure 4).

Figure 4 Arousal level by TDMS
3.2. EEG
The PNI condition (M = 28.47, SD = 9.79) had significantly higher value (p < .05) than the CON condition (M = 18.35,
SD = 8.03) on the brain activation – β-band power ratio – via EEG (Figure 5).

Figure 5 β-band power ratio

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Effect of positive and negative ions in esports performance and arousal levels
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3.3. Racing Performance
Racing performance is shown in Figure 6. The PNI condition (M = -3.64, SD = 2.53) significantly outperformed the
CON condition (M = -1.18, SD = 2.25) on racing performance, measured by racing speed (p < .05).

Figure 6 Racing performance
4. Discussion
The purpose of this study was to investigate the psychophysiological effects of arousal in esports during a racinggame under positive and negative ion environments. Although no difference was found between the PNI and CON
condition on TDMS, the PNI condition had the higher values than the CON condition on the EEG – the brain activation.
Importantly, the PNI condition outperformed the CON condition on the racing or esports performance, assessed by
racing speed. How esports performance can be enhanced is interesting for researchers and esports players, and ourstudy showed that changing an environment using positive and negative ions enhanced esports performance, alongwith increasing brain activation.
One of the research questions was whether simultaneously using both positive and negative ions influenced esports
performance. Although the esports task was not used, training under combined positive and negative ions mightsuggest increasing the beta wave power ratio with increased performance relative to a nutral environment in a recent
study (Hagiwara et al., 2020). Whether use of higher concentrations of both ions differed from lower concentrations
on cognitive performance and physiological measurements was examined (Wallner et al., 2015). Results showed that,
although there was no difference on lung function and well-being, the higher concentrations outperformed the lower
concentrations on cognitive performance. Specifically, reasoning ability and perceptual speed were measured ascognitive performance, which are closely related to esports performance. Wallner and collogues (2015) concluded that
increasing air ions concertation enhanced one’s psychological and physiological performance.
Currently, how using both ions affect esports performance has not been examined in the literature. However, the metaanalysis performed by Pereza and colleagues (2013) examined how positive and/or negative ions has been used toevaluate mood outcomes. For instance, negative ions generally reduced depressed symptoms. Although the effect ofnegative ions expressed various advantages including higher ratings of alertness, freshness, and environmental warmth,
the effects of positive ions were not explicitly discussed (Harkins, 1981). In fact, the same meta-analysis showed that
positive ions have not been demonstrated any meaningful positive outcomes on one’s psychological states. However,
one study demonstrated the positive contribution in increasing levels of arousal though positive ions (Charry &Hawkinshire, 1981). Future studies are encouraged to examine how positive or negative ions, or a combination ofboth ions influence esports performance, along with the underlying mechanism of the performance outcomes.
How arousal influence performance allowed us to examine the underlining mechanics of increased esports
performance in this study, and the relationships between the arousal and sports performances have been assessed (e.g.,
Perkins et al., 2001; Gould & Krane, 1992; Hagiwara et al., 2020). Badminton players with higher arousal levels hada significantly higher success rate of shots (Yamazaki & Sugiyama, 2009). Additionally, high EEG was associatedwith shooting performance in air-pistol shooting athletes at the Olympic level (Fronso et al., 2016). Among elitecollegiate swimmers, those who had high arousal levels measured by EEG and questionnaire tended to have effective
performance. Thus, arousal level positively impacted on sports performance. This study suggested that positive ionsmight enhance the arousal level of esports players, in turn, enhanced esports performance.
Some limitation should be acknowledged. First, future studies are encouraged to increase the sample size. Although
the effect of negative ions offers various advantages than positive ions on psychological and performance outcomes,

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Effect of positive and negative ions in esports performance and arousal levels
Hagiwara et al.
our study found that a combined both positive and negative ions enhanced esports performance than the natural (i.e.,
CON) condition. We were not exactly sure how each (e.g., positive, or negative) iron influenced the participant’s
psychological function, the brain activation, and the esports performance. Future studies should examine alongitudinal experiment to evaluate how the brain activation has been sifted from the beginning to the end of theperformance, instead of simply taking the average of each trial, to provide rich understanding on this matter.
In sum, the purpose of the research was to examine whether using combination of positive and negative ions influenced
psychophysiological measures of arousal and esports performance. Our research demonstrated that esports
performance – measured by racing-game performance – was enhanced by the experimental environment, along withhigher EEG values. Esports have currently been one of the most growing sports in the world and how performance
could be enhanced is attractive from various angles. Interestingly, a recent review focused on how instructors canprovide practice conditions to players to enhance esports performance from instructors’ perspective as coaching
application (Iwatsuki et al., 2021). Various research line in esports has been emerged in this past five years, and we
expect to see more research on how environmental factors such as using positive or/and negative ions influence esports
performance as researchers, instructors, and players look for ways to enhance esports performance like traditional
sports.

Author Contributions
Conceptualization, G.H.; methodology, G.H., H.F., M.M., Y.K., S.T., H.O., D.A.; software, G.H.; validation, G.H.,
M.M. and D.A.; formal analysis, G.H.; investigation, G.H., H.F, M.M., Y.K., S.T., H.O., D.A.; resources, D.A.; data
curation, D.A.; writing—original draft preparation, G.H.; writing—review and editing, T.I.; visualization, T.I.;
supervision, G.H., T.I.; project administration, G.H.; funding acquisition, H.F., M.M., Y.K., S.T., H.O.; All authors
have read and agreed to the published version of the manuscript.
Funding
This research was funded by Sharp Corporation.
Conflicts of interest
This study was funded by Sharp Corporation. M.M., H.F. Y.K., S.T. and H.O. are employees of Sharp Corporation.
Institutional Review Board Statement
The study was conducted according to the Declaration of Helsinki, and approved by the Institutional Review Boardof the National Institute of Fitness and Sports in Kanoya (No.5-1, 22 April 2020).
Informed Consent Statement
Informed consent was obtained from all participants involved in the study.
Data Availability Statement
Not applicable
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