Converging Evidence Supporting the Cognitive Link between Exercise and Esport Performance: A Dual Systematic Review

Comparing the cognitive performance of action video game players and age-matched controls following a cognitively fatiguing task: A stage 2 registered report

Recent work demonstrates that those who regularly play action video games (AVGs) consistently outperform non-gamer (NG) controls on tests of various cognitive abilities. AVGs place high demands on several cognitive functions and are often engaged with for long periods of time (e.g., over 2 h), predisposing players to experiencing cognitive fatigue. The detrimental effects of cognitive fatigue have been widely studied in various contexts where accurate performance is crucial, including aviation, military, and sport. Even though AVG players may be prone to experiencing cognitive fatigue, this topic has received little research attention to date. In this study, we compared the effect of a cognitively fatiguing task on the subsequent cognitive performance of action video game players and NG control participants. Our results indicated AVGs showed superior spatial working memory and complex attention abilities while showing no difference from NGs on simple attention performance. Additionally, we found that our cognitive fatigue and control interventions did not differentially affect the cognitive performance of AVGs and NGs in this study. This pre-registered study provides evidence that AVGs show superior cognitive abilities in comparison to a non-gaming population, but do not appear more resilient to cognitive fatigue.

Caffeine improves the shooting performance and reaction time of first-person shooter esports players: a dose-response study

Caffeine is recognized as one of the most effective dietary ergogenic aids in sports, yet its evidence-based effectiveness in esports is unclear. This study investigated the effects of two different doses of caffeine on the shooting performance and reaction time of 24 first-person shooter (FPS) esports players (22 men, 2 women; age = 22.29 ± 2.91 years). Participants completed three experimental trials in which they consumed either a water control (CON), a 1 mg·kg-1 BM (CAF1) or a 3 mg·kg-1 BM (CAF3) dose of caffeine. Performance measures (e.g., score, accuracy (%), hit rate (hits/sec), and shots fired) were assessed in a static clicking and reactive tracking style task on the KovaaK's FPS aim trainer. Reaction time was used to assess vigilance on the psychomotor vigilance test (PVT). Performance was measured at four time points in each trial: pre-treatment (PRE), 60 min (POST1), 80 min (POST2), and 100 min (POST3) post-treatment. Significant differences were identified using repeated-measures analysis of variances. Caffeine, irrespective of dose, significantly improved performance compared to CON for static clicking score and hit rate, reactive tracking accuracy, and reaction time on the PVT. Significant interactions between treatment and time were identified and post hoc analyses showed that compared to CON, CAF1 significantly improved static clicking score at POST1 and POST3, static clicking hit rate at POST1, reactive tracking accuracy at POST1, POST2, and POST3, and reaction time on the PVT at POST1 and POST2. Post hoc analysis also showed that compared to CON, CAF3 significantly improved static clicking score, reactive tracking accuracy, and reaction time on the PVT at all time points, in addition to static clicking hit rate at POST1 and POST3. In summary, caffeine supplementation enhances the shooting performance and reaction time of FPS esports players.

From "online brains" to "online lives": understanding the individualized impacts of Internet use across psychological, cognitive and social dimensions

In response to the mass adoption and extensive usage of Internet-enabled devices across the world, a major review published in this journal in 2019 examined the impact of Internet on human cognition, discussing the concepts and ideas behind the "online brain". Since then, the online world has become further entwined with the fabric of society, and the extent to which we use such technologies has continued to grow. Furthermore, the research evidence on the ways in which Internet usage affects the human mind has advanced considerably. In this paper, we sought to draw upon the latest data from large-scale epidemiological studies and systematic reviews, along with randomized controlled trials and qualitative research recently emerging on this topic, in order to now provide a multi-dimensional overview of the impacts of Internet usage across psychological, cognitive and societal outcomes. Within this, we detail the empirical evidence on how effects differ according to various factors such as age, gender, and usage types. We also draw from new research examining more experiential aspects of individuals' online lives, to understand how the specifics of their interactions with the Internet, and the impact on their lifestyle, determine the benefits or drawbacks of online time. Additionally, we explore how the nascent but intriguing areas of culturomics, artificial intelligence, virtual reality, and augmented reality are changing our understanding of how the Internet can interact with brain and behavior. Overall, the importance of taking an individualized and multi-dimensional approach to how the Internet affects mental health, cognition and social functioning is clear. Furthermore, we emphasize the need for guidelines, policies and initiatives around Internet usage to make full use of the evidence available from neuroscientific, behavioral and societal levels of research presented herein.

Playing for keeps or just playing with emotion? Studying tilt and emotion regulation in video games

Introduction

In video gaming, tilt is thought to relate to poor emotional control and game performance. Despite widespread recognition of tilt in video gaming, there is a lack of research examining tilt empirically.

Methods

One thousand and seven gamers took part in our online study examining gamers experience of tilt, the factors which contribute to and protect against tilt, and the emotion regulation strategies gamers employ to deal with tilt.

Results

Gamers who reported playing for more competitive reasons, were at higher risk of experiencing tilt. Additional factors associated with an increased risk of experiencing tilt were increased anger and more hours spent playing. Protective factors against experiencing tilt were also identified, inclusive of a greater number of years gaming experience and engagement in adaptive emotion regulation strategies.

Discussion

This study provides an important starting point for creating a better understanding of tilt in gaming, equipping us with new knowledge to better support gamers to improve their emotion regulation during game play performance.

Changes in concentration performance and alternating attention after short-term virtual reality training in E-athletes: a pilot study

In the dynamic landscape of e-sports, where intense competitive gaming demands high cognitive abilities, concentration performance and alternating attention play a pivotal role. E-sports encompass diverse genres, each requiring specific cognitive functions. Maintaining unwavering focus is crucial, as split-second decisions can determine victory. The study explores the potential of Virtual Reality (VR) training to enhance concentration performance and alternating attention, shedding light on the importance and possibilities of optimizing cognitive abilities for e-athletes. VR training emerges as a promising intervention, offering immersive environments for cognitive exercises. The study investigates the impact of VR training on concentration performance and alternating attention in amateur e-athletes, utilizing standardized tests. A randomized controlled trial with 66 participants reveals significant improvements in the VR training group, highlighting the adaptability and plasticity of cognitive processes. The findings suggest that VR training can enhance concentration abilities, providing valuable insights for e-sports and potentially extending to other fields requiring sustained attention and rapid task-switching. The study underscores the convergence of cognitive psychology, neuroscience, and VR technology, paving the way for innovative training methodologies and advancements in e-sports performance.

Nutrition, lifestyle, and cognitive performance in esport athletes

Introduction

Electronic sports, termed esports, is a growing athletic activity in which high levels of attention and cognitive performance are required. With its increasing popularity and competitiveness, interest in strategies to improve performance have emerged. Improving esports athlete performance, namely cognitive endurance, and resilience, may lie in nutritional or lifestyle factors. The Nutrition, Vision, and Cognition in Sport Studies (IONSport) investigated nutritional and behavioral factors that can influence cognition via 3-dimensional multiple objects tracking test (3DMOT) via Neurotracker X (NTx) software. The purpose of this study was to characterize the lifestyle of high level esports athletes with detailed nutrition, sleep, and physical activity assessments, and their association to gaming related cognitive performance.

Methods

103 male and 16 elite female esports athletes aged 16 to 35 years old completed surveys, food records, and cognitive testing sessions over 10 days. Participants were instructed to maintain their normal dietary and lifestyle habits.

Results

There were positive significant associations between average NTx scores and the following nutrients: magnesium, phosphorous, potassium, sodium, zinc, selenium, thiamin, niacin, vitamins B6 and B12, folate, cholesterol, saturated, polyunsaturated, and monounsaturated fats, omega-6 and omega-3 fatty acids, and choline. Majority of participants did not meet recommended dietary allowances (RDAs) for these micronutrients nor the recommended intakes for dairy, fruit, and vegetables. There was a significant (p = 0.003) positive (r = 0.272) association between total vegetable intake and average NTx score. There was a significant negative association (p = 0.015) with our final sustain session, which measured cognitive resilience, and the Stanford Sleepiness Scale score. Repeated measures analysis was done with these groups over the 18 core NTx sessions. There were significant (p = 0.018) differences between the two groups with those who consumed the recommended amount of protein or more performing significantly better on NTx over the 18 sessions than those that did not consume enough protein. Those who consumed the recommended intakes for riboflavin, phosphorous, vitamin B12, and selenium performed significantly better over the 18 core NTx sessions than those that did not meet the recommended amounts.

Discussion

The need for a nutrition intervention that is rich in protein, vitamins, and minerals is warranted in this population.

Normative Performance Profiles of College Aged Esport Athletes in a Pilot Study

Aims

This study aimed to holistically assess the physical and cognitive attributes of esport athletes.

Methods and Results

Forty-six adults between 18 and 32 years old with experience playing videogames were enrolled in this study. Participants completed assessments in five areas: demographics, self-report questionnaires, cognitive performance, physical performance, and gaming performance. Participants self-reported Overwatch ranking and physical activity participation (Pediatric Physical Activity Measure), and grip strength was measured with a handheld dynamometer. Seven domains of physical, mental, and social health and well-being were measured with the Patient Reported Outcomes Measurement Information System (PROMIS-29). The List Sorting Working Memory Test and Picture Sequence Memory Test from the National Institutes of Health (NIH) Toolbox Cognition Batteries were used to measure cognitive performance. Finally, esports performance was measured using a series of tasks through Alienware Academy and AIM Booster to record accuracy, reaction time, and targets hit. Participants were separated into high and low ranking groups for comparisons. This sample of esport athletes was similar to the general population for grip strength, each of the PROMIS-29 metrics, the List Sorting Working Memory Test, and the Picture Sequence Memory Test. Reaction time was the variable with the only significant difference between ranking groups.

Conclusion

This study represents a primary investigation of esport athletes using a holistic approach. By incorporating physical and cognitive components, the most important factors to esport athletes' health and performance can be better understood and applied.

Can Intelligence Affect Alcohol-, Smoking-, and Physical Activity-Related Behaviors? A Mendelian Randomization Study

People with high levels of intelligence are more aware of risk factors, therefore choosing a healthier lifestyle. This assumption seems reasonable, but is it true? Previous studies appear to agree and disagree. To cope with the uncertainty, we designed a mendelian randomization (MR) study to examine the causal effects of genetically proxied intelligence on alcohol-, smoking-, and physical activity (PA)-related behaviors. We obtained genome-wide association study (GWAS) datasets concerning these variables from separate studies or biobanks and used inverse-variance weighted (IVW) or MR-Egger estimator to evaluate the causal effects according to an MR protocol. The MR-Egger intercept test, MR-PRESSO, and funnel plots were employed for horizontal pleiotropy diagnosis. The Steiger test (with reliability test), Cochran's Q test, MR-PRESSO, and leave-one-out method were employed for sensitivity analysis. We found significant or potential effects of intelligence on alcohol dependence (OR = 0.749, p = 0.003), mental and behavioral disorders due to alcohol (OR = 0.814, p = 0.009), smoking (OR = 0.585, p = 0.005), and smoking cessation (OR = 1.334, p = 0.001). Meanwhile, we found significant or potential effects on walking duration (B = -0.066, p < 0.001), walking frequency (B = -0.055, p = 0.031), moderate PA frequency (B = -0.131, p < 0.001), and vigorous PA frequency (B = -0.070, p = 0.001), but all in a negative direction. In conclusion, our findings reinforce some existing knowledge, indicate the complexity of the health impacts of human intelligence, and underline the value of smoking and alcohol prevention in less intelligent populations. Given the existing limitations in this study, particularly the potential reverse causality in some estimations, re-examinations are warranted in future research.

Co-Transformation of Digital Health and eSport in Metaverse: Moderating Effects of Digital Personality on Mental Health in Multiplayer Online Battle Arena (MOBA)

Mental health issues (e.g., social exclusion, depression, anxiety, and burnout) became highly prevalent in the global eSport industry. Likewise, the eSport trend in China also dramatically increased, while the attitudes and behaviours of the players also impacted their intentions to utilize video gaming. As China became the epicentre of the online video gaming industry, especially MOBA, it primarily influenced young athletes to adopt video gaming strategies for training purposes. Still, preventive measures are needed for video gaming addictions by athletes to improve their overall eSport performance. To conduct this study, self-administered questionnaires were distributed to 400 athletes aged 18-27 years; the response rate was adequate after screening, out of which 345 were finalized for the data analysis. The results indicate that metaverse-based digital healthcare significantly impacts eSport performance. Moreover, mental health significantly mediated the relationship between metaverse-based digital health and eSport performance. In addition, the digital personality also significantly moderated the relationship between metaverse-based digital healthcare and eSport performance. This research holds tremendous significance both from theoretical and practical perspectives. The study adds valuable insights to the growing body of literature regarding eSport gaming and mental health. The beneficial and constructive intuitions regarding eSport from a psychological perspective can be gained from this study, along with its pros and cons on the mental health of young Chinese athletes.

Videogaming Frequency and Executive Skills in Young Adults

Many studies have shown that "action" videogames (VG) training can improve various cognitive aspects (such as attention, enumeration skill, problem solving, vigilance, inhibitory control and decision making). Unfortunately, independently by VG genre, little research has been conducted on the relevance of videogaming frequency to modulate cognitive performance. In the present study, we investigated the differences between two groups of young adults (Experienced Gamers and Casual Gamers, respectively, EGs and CGs) in some attentional and executive abilities. To this end, 19 EGs (age 23.21 ± 1.68 years; gaming frequency 46.42 ± 11.15 h/week) and 19 CGs (age 23.10 ± 2.28 years; gaming frequency 1.31 ± 1.76 h/week) were selected and asked to complete a computer-based and customized version of an executive battery (i.e., Attention Network Task, Game of Dice task, Go/NoGo task and Task Switching). The results showed better basic attentional abilities and alertness level (i.e., as indicated by faster reaction times (RTs) and greater accuracy) in EGs compared to CGs. Moreover, EGs showed a more efficient decision making than CGs, particularly evident in risky decisions. Taken together, such results show that an executive functioning improvement can be observed as a consequence of continuous and constant exposure to VG, independently by the specific genre played. These data can be a useful starting point to develop new and innovative executive training protocols, based and inspired to videogames to be applied in clinical populations suffering, for example, from dysexecutive impairment.

Associations Between Esports Participation and Health: A Scoping Review

Esports are a contemporary phenomenon, with millions of people involved. Still, scientific literature on the topic is scarce. Anecdotal reports, mostly based on what is known from videogames practice, have associated esports with unhealthy lifestyles and health-related problems. The present scoping review aimed to provide an overview of findings from studies regarding the health and well-being in adult esports players, while identifying the most studied topics in the field and those still lacking scientific research.The search was conducted in MEDLINE, Scopus, Web of Science, B-on, and ESCBO databases. Studies regarding health consequences of esports practice conducted with adult esports players were included. No exclusion criteria concerning age, sex, esports modality, or esports level were applied, but articles related to other forms of video gaming or gambling were excluded. The search was limited to peer-reviewed articles. Opinion and review articles were excluded.There were 1416 articles retrieved from which 33 met the inclusion criteria. Lifestyle habits, sleep, exercise and physical health (including musculoskeletal health), physiological demands, and mental health were the main topics of investigation. Several gaps in the literature were identified, namely studies on cardiovascular, respiratory, or metabolic health, or consuming-related risks. Also, the lack of homogeneous methodologies and definitions used in esports-related studies was identified.Esports practice has been associated with different health-related symptoms, but more studies using more robust methodologies and appropriate research design are needed. Topics such as cardiovascular health or the use of performance-enhancing drugs are lacking.

Motivators and Barriers to Physical Activity among Youth with Sickle Cell Disease: Brief Review

Purpose: Health disparities for minority groups include a low rate of physical activity and underserved urban minority youth with chronic disease are among the least active population segments, as exemplified by sickle cell disease (SCD). “Exercise prescriptions” for youth with chronic diseases need to be evidence based and align with psychologic motivators and barriers. This scoping review sought evidence for psychosocial motivators or barriers to physical activity (PA) in youth with SCD and other chronic disease that could be relevant to SCD. Methods: Five databases were searched for studies on urban minority youth published between 2009 and 2022. Results: Keyword searching yielded no papers on SCD and PA motivation and barriers. Adding health-related quality of life (HRQL) in SCD found eleven relevant papers. Widening the search to chronic disease in minority youth resulted in a total of 49 papers. Three thematic categories and seven sub-themes emerged. PA barriers added by chronic disease include fear of triggering disease complications, negative relationships due to disease limitations on performance in sports, and lack of suitable environment for PA that accommodates the chronic disease. PA motivators are similar for youth without chronic disease: self-efficacy, autonomy, positive relationships with peers and parents and coach/teacher. Conclusion: Direct descriptions of PA motivations and barriers to PA in SCD are limited to fatigue and fear of sickle vaso-occlusive pain. The PA barriers and motivators found for urban youth with chronic disease overlap with themes in healthy adolescents from underserved minorities. Community-based interventions could strengthen PA motivators (self-efficacy, autonomy, positive relationships with peers and parents and coach/teacher) but need disease accommodations to overcome the barriers (fear of triggering disease complications, environmental limitations, and negative relationships). Evidence-based exercise prescriptions might incorporate educational modules to overcome disease stigma and misconceptions. Prospective studies of PA motivators and barriers could improve HRQL in SCD.

Professional Esports Players: Motivation and Physical Activity Levels

The professionalisation of esports has increased in recent years, generating the need for further study. Its evolution and continuous development have led the consideration of esports as a profession, increasing the number of players, practice modalities, and hours of play dedicated to this field. The aim of this study was to analyse the relationship between physical activity levels and motivational orientations in an international sample of professional esports players. A cross-sectional and observational study was conducted in European and Latin American countries. The sample was non-probabilistic by convenience, and 260 male professional esports players were recruited. A survey was used that included demographic data, body composition, physical activity (International Physical Activity Questionnaire), and motivation (Sport Motivation Scale). The results show that 92.7% of professional esports players have moderate and high levels of physical activity and that players with low levels of physical activity have positive values in all dimensions of motivation. It is concluded that extrinsic and intrinsic motivation correlates inversely with energy expenditure.

Can Nutrients and Dietary Supplements Potentially Improve Cognitive Performance Also in Esports?

Factors influencing brain function and cognitive performance can be critical to athletic performance of esports athletes. This review aims to discuss the potential beneficial effects of micronutrients, i.e., vitamins, minerals and biologically active substances on cognitive functions of e-athletes. Minerals (iodine, zinc, iron, magnesium) and vitamins (B vitamins, vitamins E, D, and C) are significant factors that positively influence cognitive functions. Prevention of deficiencies of the listed ingredients and regular examinations can support cognitive processes. The beneficial effects of caffeine, creatine, and probiotics have been documented so far. There are many plant products, herbal extracts, or phytonutrients that have been shown to affect precognitive activity, but more research is needed. Beetroot juice and nootropics can also be essential nutrients for cognitive performance. For the sake of players’ eyesight, it would be useful to use lutein, which, in addition to improving vision and protecting against eye diseases, can also affect cognitive functions. In supporting the physical and mental abilities of e-athletes the base is a well-balanced diet with adequate hydration. There is a lack of sufficient evidence that has investigated the relationship between dietary effects and improved performance in esports. Therefore, there is a need for randomized controlled trials involving esports players.

Physical Activity and Health Promotion in Esports and Gaming-Discussing Unique Opportunities for an Unprecedented Cultural Phenomenon

Due to long periods of sedentary behavior, and unhealthy diets gamers and esports players are at risk for numerous chronic diseases and all-cause mortality. Health research has started addressing the public health implications of the esports phenomenon, drawing a bleak picture of this megatrend. However, instead of just highlighting adverse public health implications of this trend, it is recommended to become involved in this phenomenon and positively influence it. Esports has an enormous potential for physical activity and health-promoting efforts, provides a context for broadly disseminating interventions, and offers new ways of gaining access to an often-neglected population. This paper presents: the potential of the esports phenomenon to promote physical activity, health, and well-being in gamers and esports players; the strategic and preventive solutions to ameliorate esports possible adverse health impacts; and the utilization of esports technology (streams, media platforms, exergames, etc.) as an innovative health promotion tool, especially reaching gamers and esports players with attractive and interactive interventions. This is to encourage systematic scientific research so that evidence-based guidelines and intervention strategies involving regular physical activity, healthy diet, and sleep hygiene for esports will be developed. The goal is to promote public health approaches that move toward a better integration of esports and gaming.

Breaking up prolonged sitting with a 6 min walk improves executive function in women and men esports players: a randomised trial

Objective

The effect of prolonged sitting on executive function and performance in competitive esports players are unknown. This study aimed to evaluate executive function following a 6 min bout of walking or rest during prolonged gaming in competitive esports players.

Methods

12 men and 9 women completed three separate 2-hour gaming session days assigned in randomised order consisting of a 6 min walk break, 6 min rest break and continuous before and after each session. Postintervention participant exit survey data were also collected.

Results

The walk condition produced a significantly faster mean solution time (7613.6±3060.5 min, p=0.02) and planning time (5369.0±2802.09, p=0.04) compared with the resting condition (9477±3547.4; 6924±3247.7) and continuous play (8200.0±3031.6; 5862.7±2860.7). The rest condition resulted in the slowest mean solution time (9477.0±3547.4) and planning time (6924.0±3247.7), with the continuous play resulting in a faster mean solution time (8200.1±3031.6) and planning time (5862.7±2860.7) than the rest condition. There was no impact on game performance in any of the conditions. However, over 70% of participants felt that the walk break improved esports performance.

Conclusions

Reducing sit time and breaking up prolonged sitting have acute and chronic health benefits. This study provides evidence that a 6 min walking break in the middle of 2 hours of gameplay allows gamers to have these health benefits while improving processing speed and executive function.

Trial registration number

NCT04674436.

Gaming Your Mental Health: A Narrative Review on Mitigating Symptoms of Depression and Anxiety Using Commercial Video Games

Globally, depression and anxiety are the two most prevalent mental health disorders. They occur both acutely and chronically, with various symptoms commonly expressed subclinically. The treatment gap and stigma associated with such mental health disorders are common issues encountered worldwide. Given the economic and health care service burden of mental illnesses, there is a heightened demand for accessible and cost-effective methods that prevent occurrence of mental health illnesses and facilitate coping with mental health illnesses. This demand has been exacerbated post the advent of the COVID-19 pandemic and the subsequent increase in incidence of mental health disorders. To address these demands, a growing body of research is exploring alternative solutions to traditional mental health treatment methods. Commercial video games have been shown to impart cognitive benefits to those playing regularly (ie, attention control, cognitive flexibility, and information processing). In this paper, we specifically focus on the mental health benefits associated with playing commercial video games to address symptoms of depression and anxiety. In light of the current research, we conclude that commercial video games show great promise as inexpensive, readily accessible, internationally available, effective, and stigma-free resources for the mitigation of some mental health issues in the absence of, or in addition to, traditional therapeutic treatments.

To be or not to be (e)sports? That is not the question! Why and how sport and exercise psychology could research esports

Whether esports can be considered a sport is highly debated. The German Olympic Sport Federation (DOSB) and the German Society for Sport Sciences (DVS) recently stated that esports should not be integrated into the canon of sport. Our aim is not to further fuel this debate but rather to argue that to be or not to be sport is not the most important question from a scientific perspective. After summarizing the current discussion on whether esports constitute a sport, this paper discusses why and how sport and exercise psychology (SEP), in particular, could research esports. To exploit research opportunities in esports, such as adapting validated methods and testing existing models, scholars in SEP could examine the aspects arising from its positional stance. We argue that the potential of SEP approaches, models, and methods, positions it well to play an important role in research on esports. The present perspective provides a starting point for a constructive discourse on the development of SEP and the potential for its role in esports research.

Physical Activity Levels of Adult Virtual Football Players

Esports, including virtual football, are a worldwide phenomenon. Yet, little is known about the physical activity levels of individuals engaged in virtual football game play. Therefore, we aimed to perform a preliminary evaluation of the levels of physical activity, sedentarism, and habits of physical training of adults engaged with virtual football in Portugal. This was a cross-sectional investigation based on a structured online survey using the International Physical Activity Questionnaire (IPAQ) and a set of questions regarding habits of physical training. The participants (n = 433) reported spending a median of 5,625 MET-min⋅week⁻¹ being physically active. Still, the participants spent 320 min/day sitting, and 150 min/day practicing virtual football. According to the IPAQ scores, high physical activity levels were reported by 84.5% of the participants, and 87.1% were considered physically active considering the WHO guidelines on physical activity and sedentary behavior. Overall, 60.0% of the participants reported planning their own physical training. Maintaining or improving overall physical health was one of the main reasons for doing physical training (66.7%), with only 6.1% responding being active to improve virtual football performance. Overall, the results showed that virtual football players accomplished the standard recommendations for physical activity, with high levels of physical activity, and encompassing regular physical training focused mostly on health promotion, rather than improved virtual football performance.