Communication plays the most basic role in shaping human relationships. Communication refers to the face-to-face interaction between two or more people and can be largely classified into verbal and nonverbal communication. A study by Birdwhistell (1970) reported that more than 65 percent of nonverbal elements are communicated while communicating with others, while linguistic elements convey the remaining 35 percent [1]. This result indicated that nonverbal communication could convey various meanings and emotions through body behaviors, gestures, postures, facial expressions, voice changes, and various body aspects [2]. Thus, nonverbal communication may be more effective or as effective as verbal communication in education.

One educational exercise where nonverbal communication can be meaningful is sports education. In sports, there is that vital interaction of sports leaders or coaches with their students wherein the leader can motivate the learners to have the right attitude and skills in sports. As Kim (2007) pointed out, the method and quality of the leader's communication behavior play an important role in the interaction between the sports leader and the students [3]. Sports communication among the adolescents of a country is important if one wants to have a healthy and socially adaptable generation.

In addition, adolescence is a period in which students' self-identity is established due to various mental, social, and physical changes in the developmental stage from childhood to adulthood. For example, sports develop their physical, intellectual, emotional, social, creative, and practical talents among adolescents. So, physical activities during childhood or school develop the student's thinking process, which also affects their beliefs and behaviors as they become adults. People's exercise habits or lifestyles can be important in making decisions [4]. Further, participation in sports activities is recognized as a useful cultural form that has social, mental, and cultural values.

A sport that is steadily gaining ground in Korea is golf. Golf used to be regarded as a high-end sport enjoyed by only a small number of wealthy people. However, it is now being popularized as a lifelong sport that can be enjoyed by all ages and sexes [5]. The main reasons for the popularization of golf are the increase in leisure time due to the economic growth of Korea, the improvement of public perception of the golf culture, the good performance of players at home and abroad, and the improving value of golf as a sports industry [6]. Today, teenagers are trying to make golfing a future career. As a result, the number of elementary, middle, and high school students registering as golf players continues to increase, especially with the establishment of golfing in schools [7].

In recent years, professional golf groups based in foreign countries have started to establish branches in Korea and train professionals. Golf leaders who guide teenagers in playing golf, especially for the first time, must play various roles and gain special qualities as life sports leaders. Golf has physical, psychological, and mental demands. Physically, it requires energy metabolism related to accurate technical skills and momentary movements for physical fitness. Psychologically, it is an exercise that emphasizes the desire to achieve. Mentally, it demands strong mental strength, high concentration, and sharp judgment. Hence, the first prerequisites in teaching golf are the sports leader's philosophy, attitude, and a firm awareness of their role and mission. The sports leader's professionalism, attitude, and consciousness are vital to participants [8, 9].

Golf is an exercise where mutual communication and emotional exchange between leaders and participants is more important than any other sport. Furthermore, a lot of physical contact and demonstration with the participants is needed due to the nature of golf lessons. Hence, golfers need guidance from effective golf leaders [10, 11]. Furthermore, in most golf cases, education is conducted one to one, so golf leaders need proper and effective communication to guide the students in the technical and psychological aspects of the game [12].

The communication ability of the leader is particularly important compared to other events [13, 14]. To motivate the youth to learn sports, including golf, sports leaders use various methods and strategies, specifically nonverbal communication. Lee (2009) found that nonverbal communication of sports leaders resulted in the active participation of students in physical education classes and various activities, harmonious growth development, and improved attitudes and satisfaction with physical education classes. Park (2009) pointed out that non-verbal communication can reduce language anxiety between sports leaders and students. However, much research on youth golf in Korea has been focused on the performance and psychological aspects of the youth golf participants.

There have also been studies on the influence of sports leaders on youth golf players, but more on their leadership qualities and verbal skills [15, 16]. Sports leaders must motivate students to participate in golf activities actively and enhance their positive attitude and satisfaction towards golfing. To do this, sports leaders should have good communication skills and knowledge of the technical aspects of golf to maintain a smooth human relationship with their students. Several studies have already recognized the importance of verbal communication in sports. Therefore, this study examined the nonverbal communication skills of the golf leaders and their effects on participation satisfaction, positive emotion, exercise adherence, and recommendation of golf leaders among youth participants.

The specific research question for this study is:

RQ: What are the nonverbal communication behavior of sports leaders that influence the participation satisfaction, positive emotion, exercise adherence, and recommendation of golf leaders among youth participants [17-34]?

Humans can communicate through nonverbal messages without using verbal messages and exchange various meanings and emotions through facial expressions, gestures, postures, gaze behaviors, changes in voice, and various aspects of the body [35]. Non-verbal communication is performed with verbal expressions and sometimes has a stronger meaning than verbal content [36]. Accordingly, nonverbal communication is more than simple communication and maximizes its efficiency. The meaning can differ depending on the non-verbal elements involved when delivering verbal messages of the same content [37].

According to Knapp (1980), nonverbal communication comprises seven factors: kinesics, physical appearance, contact behavior, paralanguage, temporal behavior, proxemics, and environmental factors related to artifacts. For example, Dodd (1998) showed that body movement had five factors: eye movement, gaze, physical contact, proxemics, and temporal behavior. On the other hand, Sundaram and Webster (2000) pointed to four elements: kinesics, proxemics, paralanguage, and physical appearance. Based on the research of Sundaram and Webster (2000), studies in Korea on the nonverbal communication of leaders in sports showed that it comprises paralanguage, proxemics, physical appearance, and kinesics [38].

Firstly, paralanguage refers to expressing emotion through voice, tone, and speed of speech, even when the same word is used [39]. It is also related to voice characteristics and use, called voice or voice action. Since paralanguage conveys people's emotions, they elicit greater trust than the meaning of words, and sometimes they more accurately reflect an individual's psychological state than actual language [40]. Woo Ryong Kim and Ji Won Won (2004) divided paralanguage into tone, tone, and speech elements. The meaning of language can be clearly understood through paralanguage, such as pronunciation, tone of voice, speed of speech, loudness of speech, and tone of speech [41]. In addition, since the speaker's emotional state and the person's personality can be grasped through paralanguage, paralanguage is an important factor in determining communication skills [23]. In conversation, people consciously and unconsciously grasp the degree of confidence in the content of the conversation and the importance of the content through similar languages.

Secondly,proxemics is a method of expressing intimacy or politeness by maintaining a distance from or contacting one another in an interactive situation [39]. As it relates to an individual's space use and physical distance, it means the distance or relative position between the interactors. In relation to human space usage, Kim Woo-ryong and Place Won (2004) viewed the physical distance between the receiver and the sender as a nonverbal element in a communication situation. Generally, it was argued that people seek psychological stability by pursuing adequate physical space [41]. Woo Ryong Kim and Ji Won Won (2004) and Sundaram and Webster (2000) pointed out that maintaining contact distance was a sign of intimacy. Therefore, securing the most important space was regarded as the most important part of proxemics.

Thirdly,physical appearance refers to the body's external appearance [41]. Physical attractiveness and appearance, such as hairstyle, clothes, and ornaments, influence cognition in the interaction [38]. Physical appearance, which includes physique, physical attractiveness, skin and hair color, hair, health status, and smell, is an important determinant of perception in interpersonal interaction [42, 43]. Based on physical appearance, people perceive a lot of information such as gender, age, personality, physical fitness, and health status; through this, they have stereotypes [44].

Fourth,kinesics is a body movement related to light greetings, nodding heads, facial expressions such as smiles, gaze and eye contact, gestures, and postures [40]. It can include the nod of the head, which is a gesture; the movement of a hand or arm, etc.; and facial expressions such as smile and frown. Tubbs and Moss (2010) say that facial expression is the most important type of nonverbal communication as it enables personal identification and determines personal impressions. Posture can characterize an individual's emotions, such as an aggressive posture, a relaxed posture, etc. Finally, gestures consist of one or several gestures as a concept of continuous movement [15, 39]. Kinesics has the advantage of being able to communicate more delicately [45]. It can also express one's feelings and emotions or give instructions [46].

Prior to the hypothesis testing, the relationships among nonverbal communication, participation satisfaction, positive emotion, exercise adherence, and recommendation intention were analyzed through a review of previous studies. Accordingly, five major research hypotheses and the 18 corresponding sub-hypotheses were established.

The analytical model used in Fig. (1) shows the concepts studied based on the literature, the specific variables, and the relationship between the concepts. The nonverbal communication of sports leaders deemed important to the student-athletes are paralanguage, proxemics, physical appearance, and kinesics. When sports leaders use these effectively, they can elicit satisfaction, positive emotion, and exercise adherence, leading them to recommend golf leaders to their friends or peers.

As the research goal is to develop a theoretical model of what nonverbal factors of the sports leaders affect what response variables among the youth participants in golf, these variables were all subjected to statistical analyses and verification. For this process, structural equation modeling (SEM) was used.

Structural Equation Modelling (SEM) is a powerful technique that estimates the relationship between more than one dependent variable and many independent variables. That is to say that a researcher may be interested in the strength of the relationships between variables in a hypothesis, and SEM is a way to examine those variables.

Fig. (1). Research model showing the variables and hypotheses of the study.

First, the paralanguage (H1-1) and physical appearance (H1-3) of golf leaders significantly affected youth participants' participation satisfaction. The results affirm the findings of Baek (2017) that the dance leader's paralanguage, kinesics, and physical appearance affected students' participation satisfaction [21]. Hyun et al. (2017) also found that leaders' paralanguage and physical appearance significantly affected athletes' life satisfaction [22]. Meanwhile, Chunayoung's (2019) study on college physical education class instructors showed that kinesics significantly affected class satisfaction.

This result implies that golf leaders should be aware of the importance of paralanguage, such as proper speech speed, tone, clear pronunciation, soft speech, and lively voice. It requires personal effort to undergo voice management, pronunciation correction through pronunciation practice, correct communication, and self-development. In addition, they should be conscious and enhance their physical appearance. They should maintain a good and neat image and wear golf attire to look professional.

Second, the physical appearance of the golf leaders (H3-3) had a statistically significant effect on the exercise adherence of the youth participants. This finding is supported by the study of Jeon et al. (2019), who showed that the physical appearance of badminton leaders affected exercise adherence among the players [23]. Meanwhile, the paralanguage and proxemics of golf leaders did not affect participants' exercise commitment and exercise adherence [24], and the paralanguage and kinesics of aerobic leaders did not affect exercise adherence. Kim and Lee (2015) found that the golf leaders' paralanguage, proxemics, auditory language, and physical appearance did not affect the participants' exercise intention [25].

Third, participation satisfaction (H4-2) among youth participants significantly affected their positive emotions, exercise adherence, and recommendations of golf leaders. The effect of participation satisfaction is supported by the study of Yoon and Kim (2017), who showed that the participation satisfaction of a youth basketball club motivated them to adhere to their exercise [26]. As to the significant effect of satisfaction of participation on the intention to recommend sports leaders, this is supported by other studies. For example, Kim and Lee (2018) found that customer satisfaction with the sports event significantly influenced their referral to it [27]. In addition, satisfaction was found to have a significant influence on recommendations and supports the results of this study [28-31].

Results show that the youth satisfied with golf developed positive emotions and exercise adherence and recommended golf leaders to people and social media. In addition, it is necessary to develop and actively implement various detailed golf instruction programs to increase participation satisfaction. Second, increasing the technical leadership capable of specific explanations and demonstrations of golf is necessary. Third, participation satisfaction will be even higher if the interaction is enhanced through personal guidance, counseling, and training journaling.

Fourth, positive emotions about golf leaders (H5-2) significantly affected youth participants' recommendations of golf leaders. Findings support the study of Kim et al. (2018) that the emotional participation of golf participants significantly affected their exercise adherence [32]. Furthermore, according to the study by Won et al. (2019), golf participants' achievement, goal orientation, and emotional responses significantly influenced their intentions to adhere to their exercises [33]. Kim and Yoon (2019) also proved the significant and positive relationship between perceived values, positive emotions, and exercise adherence intentions among exercise participants [34].

For the youth golf participants, having positive feelings about golf did not necessarily mean exercise adherence to golf. However, through positive emotions such as joy, comfort, happiness, and pleasantness, they could recommend sports leaders to neighbors, friends, and social media. Hence, golf leaders must research enjoyable teaching methods and develop specific programs that include interest and fun. If it is possible to evoke fun and positive feelings about golf in youth golf participants, they will likely recommend the golf leader and the sports to others.

The survey showed that the golf leaders' paralanguage (H1-1) and physical appearance (H1-3) significantly affected the participation satisfaction of youth participants. In addition, their physical appearance (H3-3) had a statistically significant effect on the exercise adherence of the youth participants. In turn, the participation satisfaction (H4-2) among the youth participants significantly affected their positive emotions, exercise adherence, and recommendation of golf leaders. In effect, their positive emotion (H5-2) significantly affected their recommendations of golf leaders to others.

The golf leaders' paralanguage (clear and lively voice, appropriate tone and speed, clear pronunciation) and physical appearance (proper hairstyle, neat faces, appropriate clothing such as uniform) significantly affected the participation satisfaction and exercise adherence of the youth participants. This result may be because these non-verbal expressions connote professionalism, expertise, and encouraging or non-threatening messages. If the golf leaders' image can increase the youth's participation satisfaction, the youth participants would also feel positive emotions, adhere to their golf exercises, and recommend the golf leader to others and the media. Hence, golf leaders should learn and share nonverbal communication skills with youth participants. They can do this through continuous self-management, class preparation, and active demonstrations among their students.

This study ventures into the development communication area of sports. Findings can provide sports leaders and schools with principles and strategies to make their sports development programs more effective and develop sports communication programs. As such, findings can enhance the youth's participation in the short run and popularize golf as a sport in the long run.

The study also recognizes that it is necessary to supplement the competence of sports leaders with empirical research. No longer are sports just an art and technique but a matter of communication between sports leaders and their students, especially the youth. Hence, this study can add to the growing body of knowledge on sports development as an interplay among actors in the field of communication.