Currently, there are about 70,000 adolescent athletes in the Republic of Korea (Korean Sport & Olympic Committee, 2015). However, the probability of becoming a professional athlete is low, at about 3.2% among adolescent soccer players and 4.1% among baseball players (Yoo, 2009). This suggests that adolescents must overcome numerous challenges to become professional athletes.

Especially, adolescent athletes, above all, have a lot of worries about the future and are likely to be affected by many psychological factors (Hill, Hall & Appleton, 2010). Therefore, they need a firm will to strive constantly for their goals and succeed as athletes. Indeed, athletes’ attitudes towards playing a sport is a key aspect of psychological preparation for achieving peak performance (i.e., “a state in which the person performs to the maximum of their ability, characterized by subjective feelings of confidence, effortlessness and total concentration on the task”), and is an exceedingly important concern of both coaches and athletes themselves (Kwon, Moon, & Ahn, 2015). The athletes who seek to succeed in competitive situations that can greatly affect their lives, such as tournaments, the Olympic Games, or World Championships, tend to have different attitudes towards achieving success. While researchers have attempted to understand the relations of various psychological factors with the peak performance of athletes, such as concentration (Wilson, 2012), self-confidence (Fahiminezhad, Khani, & Ghasemi, 2014), and flow (Koehn & Morris, 2012), they have not yet explored the potential driving force or attitude underlying these factors.

In Korea, becoming the champion in professional boxing or earning a medal in the Olympics became an instrument for success among many athletes, raising their economic and social status (Ha & Mangan, 2002). To this end, many athletes began to devote themselves towards achieving success, even under the worst of conditions (Kim, 2011). The “Hungry Spirit,”¹⁾ which is mainly applied to combat sports athletes, at some point in the 1970s and 80s became a factor associated with peak performance among Korean athletes. As South Korea’s national economy grew, “Hungry Spirit” was replaced with the term “Julsil (切實).” These two terms were connected by their emphasis on strong motivation. In the backdrop of these improved economic conditions, Korean athletes continued to attain achievements in the Olympics and other global competitions, and these achievements were attributed to their Julsil (Ha & Mangan, 2002).

Julsil is not a term used in academia, but it is often used by the Korean media and in everyday life, even outside of sports. Much like the concept of han²⁾, Julsil is a concept specific to Korean culture that is difficult to express as a single English word. Generally, it can be defined as intense feelings or thoughts, or an exceedingly urgent and critical state (National Institute of Korean Language). It is also considered a psychological factor that can enhance mental strength (Kim, 2018; Kwon et al., 2015). For athletes, Julsil can be defined as a state of urgent and critical feelings or thoughts about peak performance (Kwon et al., 2015). More specifically, for athletes competing in a match, Julsil refers to the adoption of a serious attitude towards engaging in the match; strong psychological skills, which refer to the techniques that allow individuals to maximize their skills in the game or situations of extreme tension through adjustment of their thoughts and emotions in order to overcome stress; and a strong aspiration towards appropriate preparation and competition (Kwon et al., 2015). Thus, Julsil not only enables athletes to devote themselves to practice before the match, but also helps them engage in self-management when they are not playing the sport. Furthermore, it enables athletes to apply various psychological skills to their benefit during matches, in particular increasing their interest and aspiration for success in the match (Kwon et al., 2015). Kwon et al. (2015) found that most athletes, including world-renowned Korean Ladies Professional Golf Association (LGPA) athletes, are in close proximity to their peak performance when they reach a state of Julsil.

To directly determine whether Julsil is related to athletes’ peak performance, researchers (e.g., Kwon et al., 2015) have measured actual athletes’ performance in their chosen sport. However, this is problematic because performance will vary according to the athlete’s athletic ability. To correct this problem, in the present study, we used the concept of flow as an index of peak performance.

Flow can be defined as a feeling of mind-body unity that occurs when one is completely immersed in an activity (Csikszentmihalyi, 1988). In athletics, flow seems to be a factor of peak performance and the relation of flow wtih peak performance has been observed globally, including South Korea (e.g., Kwon, Lee, & Lee, 2011). Athletic flow can be sequential—progressing from antecedent factors to threshold, experience, and then consequence factors—or simultaneous (Csikszentmihalyi, 1988). In this study, we focused on the experience factor of athletic flow—namely, flow in actual game situations, which is characterized by a sense of control, loss of self-consciousness, and altered feelings of time (Csikszentmihalyi, 1990). Specifically, we referred to Kwon’s (2008) concept of flow experience, which is determined by the interaction of behaviors and perceptions in Korean athletes. Researchers have also found that flow directly leads to higher performance and more positive experiences (Stavrou, Jackson, Zervas & Kateroliotis, 2007), and that the peak performance of athletes is related to the characteristics of flow (Jackson & Roberts, 1992). In fact, peak performance in athletes can be considered as an indicator of flow (Csikszentmihalyi & Massimini, 1985), given that the higher the likelihood of flow, the higher the likelihood of reaching peak performance. As a result, many athletes strive to reach a state of flow. Flow is also a major variable of interest among sports psychologists (Stavrou et al., 2007).

Prior to beginning this study, Kwon et al. (2015) conducted preliminary interviews with professional and national sports team athletes currently active in South Korea to predict the relationship between athlete Julsil and flow. We were able to determine that athlete Julsil might play an important role in athletic flow during the actual game, as evidenced by comments such as, “when feeling Julsil, I don’t know how time passes while exercising,” and “when feeling Julsil, I become so immersed in the game that I can hardly hear even if people are talking loudly outside.” However, athlete Julsil alone is not likely to increase flow—psychological variables are rarely, if ever, explained by a single factor—and thus we expected that there are variables that mediate this relationship.

In general, athletes’ ability to engage in flow during a game is the result of a gradual improvement, possibly in relation to the development of their self-regulation (Pintrich, 2004). Self-regulation is defined as an individual’s ability to change him/herself by controlling various internal impulses, including cognition, emotion, and behavior, in order to achieve his or her goals (Zimmerman, 2000). We set self-regulation as a potential mediating variable in the relationship between athlete Julsil and flow. In particular, we predicted that self-regulation would be strongly related to flow. At present, there are few studies involving athletes that indicate a direct relationship between these two constructs (or even between self-regulation and adolescent athletes’ performance; [Toering, Elferink-Gemser, Jordet & Visscher, 2009]); nevertheless, a correlation between the two can be predicted from the findings of previous studies in the field of learning. Specifically, self-​regulated learning ability was found to influence academic satisfaction through the mediating variable of learning flow (Cho & Do, 2013). Furthermore, one study demonstrated that self-regulated learning ability set their learning goals through processes exploring the basic conditions required to perform the task through concentrating on that task (Pintrich & Groot, 1990; Schunk & Zimmerman, 1994). Csikszentmihalyi (1997) argues that having a clear goal is a condition of flow, which suggests that flow does not occur when the individual’s goal is ambiguous. We might infer, then, that athletes with good self-regulation are better able to set firm goals, which in turn would increase their likelihood of experiencing athletic flow. Self-regulation, as a complex psychological process involving cognitive and emotional regulation (Fernyhough, 2010), also has been found to play an important role in psychological function (Schmeichel & Baumeister, 2004). Self-regulation is more important for adolescent athletes because it allows them to learn effectively in practice situations (Kitsantas & Zimmerman, 2006). In a previous study on self-​regulation in athletes, researchers found that athletes with good self-regulation tended to practice more than did those without (Cleary & Zimmerman, 2001; Toering et al., 2009). Furthermore, among adolescent soccer players, elite athletes tended to have better self-regulation than did non-elite athletes (Toering et al., 2009). In other words, it seems that skilled athletes have better self-​regulation than do those who are less skilled, and the more self-regulated athletes are, the more likely they will be to maximize their potential (Toering, 2011) and reach peak performance.

Nevertheless, the psychological structure of athletes’ self-regulation is still unclear, suggesting the need for a clearer explanation. In the preliminary interviews conducted prior to this study, we found that athlete Julsil appeared to be closely related to self-regulation, as with athletic flow. For example, athletes made comments in Kwon et al. (2015) study, such as, “if there is Julsil, I do not consume things that harm my body like junk food, alcohol, etc.,” and “when there is Julsil, I practice the areas I am lacking in by myself outside of practice time.” These comments seem to reflect how the planning, self-monitoring, and effort sub-factors of self-​regulation can be influenced by athlete Julsil.

Therefore, in this study, we examined the effects of athlete Julsil and self-regulation on the formation of the athletic flow in Korean adolescent athletes, and examined the relationships among all three variables using a structural model. Through this study, we will be able to explain one of the psychological and cultural factors (i.e., Julsil) that lead athletes to employ psychological techniques (i.e., self-regulation) and thereby experience flow in actual matches. Furthermore, we will provide the information on the psychological preparation stage of achieving peak performance.

Hypothesis 1. Self-regulation will mediate the relation between Athlete Julsil and Flow of adolescent athletes.

Hypothesis 2. Self-regulation will remain a significant mediator of the relationship between Athlete Julsil and Flow even after consideration of group differences (gender, school).

The path for adolescent athletes to become a member of a national team is very narrow (Yoo, 2009); they must endure strenuous training in order to enter into international competitions, colleges, and commercial teams (Han, Chung, & Seo, 2010). Famous South Korean athletes have described that Julsil was the psychological state most contributed to setting goals, and also has operated as a motivation since their adolescence that has perpetuated them to achieve their current positions as athletes (Sung, 2012). Based on these athletes’ statements, we sought to identify whether the Julsil of adolescent athletes can contribute to athlete flow. In addition, we found in the preliminary interviews of professional and national team athletes that excellent performance was achieved not only by Julsil but also by adequate self-regulation in actual practice and training situations. Thus, we sought to predict the relationship among athlete Julsil, self-regulation, and flow, in order to provide information on the psychological factors that help adolescent athletes achieve peak performance.

The results showed that the relationships among athlete Julsil, self-regulation, and flow were all positive. In other words, athlete Julsil is associated with increased self-regulation and flow, and self-regulation is associated with increased flow. In addition, self-​regulation ability of adolescent athletes during practice and training is an important factor, which is applied to flow and peak performance in actual competition. Our findings show consistent results to that of Aherne, Moran, and Lonsdale (2011) related to the association between self-regulation and increased flow, which highlight how mindfulness training is a catalyst to increase athletes’ self-regulation ability, later allowing athletes to experience flow. Furthermore, Kee and Wang (2008) explained the dimension of flow in relation to self-regulation. Thus, with heightened self-​regulation, athletes can experience the flow state. Therefore, self-regulation might be interpreted as one method of achieving peak performance among adolescent athletes (Toering, Elferink-Gemser, Jordet, Pepping, & Visscher, 2012). Our study is meaningful in that it identified the influence of athlete Julsil, which has received little attention in past research on flow in adolescent athletes. The results suggest that athletes with Julsil l cannot be easily dissuaded from their goals, which in turn may lead to improved self-regulation, thus allowing athletes to better control their emotions, feelings, and behaviors in practice and training situations.

In summary, athletes with Julsil tend to exercise greater self-regulation in their practice and training situations, which in turn may help them to reach flow. This flow, in turn, increases their likelihood of achieving peak performance. Therefore, athletes must be able to secure their own mindsets (Julsil) to ensure optimal performance, although they require further qualities that motivate them to act (i.e., self-regulation). In addition, coaches who are directing adolescent athletes should also consider what situations will increase athlete Julsil—which is highly likely to be caused by external circumstances—as well as instruct athletes on how to develop a habit of self-regulation in actual practice and training situations. In other words, we expect that athletes’ own efforts and the aid of the coach together will have a positive effect on baseline peak performance.