The impact of shadowboxing on the psychological well-being of professional martial artists

Does martial arts practice contribute to psychological well-being in professional martial artists? If so, what are the specific ways that martial arts practice accomplishes this? It has been a long-standing and widely held belief that martial arts practice can contribute to psychological well-being, however, there has been a lack of empirical research in the psychological literature focused on investigating the details of this hypothesis. The purpose of this research is therefore to investigate the impact of a paradigmatic martial arts practice—shadowboxing—on the psychological well-being of professional martial artists. In this article I present the results from an original empirical study on professional Muay Thai practitioners (n = 14) that reveals how a martial arts practice (shadowboxing) contributes to their overall psychological well-being by contributing to their positive emotions, engagement, relationships, meaning, and accomplishment. I present general results for how shadowboxing contributes to the psychological well-being of these professional martial artists overall, as well as more specific results for how shadowboxing contributes to the psychological well-being of these professional martial artists based on factors such as their gender, fight experience, and training location. This article also provides qualitative first-person reports from professional Muay Thai practitioners (n = 14) about their use of visualization and mental imagery and their experience of flow while shadowboxing, offering unique insight into the minds of professional martial artists as they are actively engaged in their craft. Finally, this article discusses the value and limitations of the present study and outlines suggestions for future research.


Introduction
Muay Thai has been the national sport of Thailand since the 1930s, and with over two dozen training camps across the country, Muay Thai remains a huge draw for tourism from all over the world [9,20,24]. In fact, Thai Fight recently invested over $5.5 million USD (200 million THB) into developing and opening the world's first Muay Thai luxury hotel [15]. Not only is Muay Thai a fun and effective form of exercise that is enjoyed by people of all kinds from all over the world, it is also one of the most popular and effective striking systems in mixed martial arts, as evidenced by the prominent usage of Muay Thai techniques in contemporary MMA [2,34]. Further, at the 138th International Olympic Committee session

Shadowboxing and the psychological well-being of professional martial artists
In the existing literature on martial arts, "shadowboxing" has been characterized by Croom [2] as: The practice of rehearsing and refining martial arts techniques and mentally simulating training or combat-relevant scenarios in order to develop technical mastery and physical capacity. For example, a Muay Thai practitioner may use a shadowboxing session to practice their jab-cross-hook-roundhouse-kick combination, both aiming to improve the mechanics with which this complex movement pattern is executed as well as their energetic ability to execute this complex movement pattern successfully. (p. 13) In other words, when professional martial artists are engaged in intentional shadowboxing practice, they are not simply producing random motor outputs in a thoughtless manner, but are rather intentionally creating different mental scenarios to work through, rehearsing and refining complex motor sequences, and adapting to the energetic and other physical requirements involved in these activities. There are at least two reasons for why shadowboxing is a particularly interesting activity to study among martial artists. First, shadowboxing is a particularly interesting activity to study because martial artists across all the striking arts engage in shadowboxing, including athletes involved in Boxing, Capoeira, Karate, Kickboxing, Krav Maga, Kung-Fu, Sambo, and Taekwondo. Although shadowboxing varies from art to art, all striking arts make important use of shadowboxing (as the individual rehearsal of technical forms) since rehearsal of relevant striking techniques is central to mastering any striking system. As Cynarski [8,9] writes, "Technical forms for centuries have been used as the basic method of conveying the technical knowledge of a given style, about tactics and experiences of masters from previous generations" (p. 48, [10,23]). Accordingly, I use the term shadowboxing in general to include the practice or rehearsal of relevant technical forms at any speed, with any technique, from any striking art. Second, shadowboxing is a particularly interesting activity to study because it is an especially intentional or cognitive activity that involves imagination, mental simulation, planning, and complex and accurate motor execution. Given the large number of individual strikes (variations of punches, kicks, knees, and elbows) and common combinations available in Muay Thai, shadowboxing sessions provide Nak Muays (professional Muay Thai practitioners) with a mentally and physically engaging activity with limitless aspects of their art to practice and improve upon. Finally, given that shadowboxing requires no additional equipment or training partners, it is also an extremely convenient form of martial arts training that can be done almost anywhere and at any time.
Exercise physiologists, sports psychologists, and positive psychologists have not yet investigated the physical and psychological effects of Muay Thai training, making this an exciting area for new research. For example, previous empirical research on Muay Thai largely adopted a semi-structured interview methodology and did not provide quantitative data on the influence of Muay Thai training on the individual elements of psychological well-being, such as positive emotions, flow experience, social relationships, meaning or purpose in life, and accomplishment [2,4,22]. Further, previous 1 3 empirical research did not yet consider how Muay Thai training may benefit people differently based on their gender, martial arts experience, and training location. An important goal of the present research on professional Nak Muays (n = 14) is therefore to address these important research questions and fill this gap in the literature by drawing upon quantitative methods from social psychology and positive psychology. Another important goal of the present research is to gain insight into the use of visualization or mental simulation among these professional and highly decorated martial artists (n = 14). Since no other empirical research on the psychological well-being of professional Muay Thai practitioners (n = 14) exists in the literature, results from this research can offer valuable new insights into the minds and practices of elite martial artists. Further, since the martial artists covered in this study include many professional Muay Thai champions (for example, IKF, Lion Fight, Muay Thai Grand Prix, WBC, and WKA world title holders), this article covers an especially elite population never before covered in the literature on Muay Thai and psychological well-being.
This original research article will focus on providing answers to the following research questions about shadowboxing and psychological well-being among Muay Thai professionals: (1) Does the practice of shadowboxing among professional Muay Thai practitioners contribute to their positive emotions? (2) Does the practice of shadowboxing among professional Muay Thai practitioners contribute to their engagement or flow experience? (3) Does the practice of shadowboxing among professional Muay Thai practitioners contribute to their social relationships? (4) Does the practice of shadowboxing among professional Muay Thai practitioners contribute to their meaning or purpose in life? (5) Does the practice of shadowboxing among professional Muay Thai practitioners contribute to their accomplishment? (6) Which elements of psychological well-being does shadowboxing contribute to the most and the least among professional Muay Thai practitioners? (7) Does shadowboxing contribute to the psychological well-being of professional Muay Thai practitioners differently based on factors such as their gender, fight experience, and training location?

Methods
This section provides details regarding the professional martial artists that participated in this research (n = 14) as well as the PERMA research questions regarding psychological well-being (n = 23). In "Flourish: Positive Psychology and Positive Interventions, " Seligman [27] explains that "Positive psychology is about the concept of well-being. The elements of well-being are PERMA: positive emotion, engagement, relationships, meaning, and accomplishment" (p. 236). For a detailed literature review of the PERMA framework for psychological well-being, especially as it applies to martial artists, see Croom [2,4,5]. This article will focus on a concise presentation of the empirical results about the psychological well-being of professional Muay Thai practitioners.

Participants
Participants were recruited through social media (Instagram) and were provided a link to a website that included a 23-item questionnaire. Since this study is focused on professional martial artists, only professional Muay Thai practitioners that had a record of winning professionally sanctioned fights were eligible to participate (professional events are regulated and sanctioned by official organizations such as the WBC

Questionnaire
13 of the 23 items were free response questions that asked: (Q1) "What is your name?", (Q2) "What is your age, location, and affiliated gym?", (Q3) "Which martial art do you practice?", (Q4) "How long have you been training in martial arts?", (Q5) "How many professional fights do you have?", (Q6) "How frequently do you shadowbox?", (Q7) "With your best guess, how many total shadowboxing sessions have you done in your life?", (Q8) "What is your shadowboxing-to-fighting ratio?", (Q9) "How long are your shadowboxing sessions?", (Q10) "Why do you shadowbox?", (Q11) "What do you think about or visualize when you shadowbox?", (Q12) "What are the benefits of shadowboxing?", and (Q13) "What are the harms of shadowboxing?". The remaining 10 items concerned psychological well-being and were presented with 7-point scales from 1 (strongly disagree) to 7 (strongly agree). The remaining 10 items regarding psychological well-being were adopted from the influential PERMA framework in positive psychology [2][3][4][27][28][29] that characterizes psychological well-being in terms of five elements including positive emotions (P), engagement or flow experience (E), social relationships (R), meaning or purpose in life (M), and accomplishment (A). The PERMA element P for positive emotions was assessed with two sentences: (Q14) and (Q20). (Q14) was positively scored and stated: "On a scale from 1 (strongly disagree) to 7 (strongly agree), rate this sentence: "Shadowboxing contributes to my experience of positive emotions". " (Q20) was negatively scored and stated: "On a scale from 1 (strongly disagree) to 7 (strongly agree), rate this sentence: "Shadowboxing contributes to my experience of negative emotions". " The scores from (Q14) and (Q20) were then combined to form a composite score for the PERMA element P for positive emotions. The PERMA element E for engagement or flow experience was assessed with two sentences: (Q17) and (Q22). (Q17) was positively scored and stated: "On a scale from 1 (strongly disagree) to 7 (strongly agree), rate this sentence: "Shadowboxing contributes to my experience of flow or absorbed engagement in what I'm doing". " (Q22) was negatively scored and stated: "On a scale from 1 (strongly disagree) to 7 (strongly agree), rate this sentence: "Shadowboxing detracts from my experience of flow or absorbed engagement in what I'm doing"." The scores from (Q17) and (Q22) were then combined to form a composite score for the PERMA element E for engagement or flow experience. The PERMA element R for social relationships was assessed with two sentences: (Q18) and (Q15). (Q18) was positively scored and stated: "On a scale from 1 (strongly disagree) to 7 (strongly agree), rate this sentence: "Shadowboxing contributes to my positive relationships with others"." (Q15) was negatively scored and stated: "On a scale from 1 (strongly disagree) to 7 (strongly agree), rate this sentence: "Shadowboxing detracts from my positive relationships with others"." The scores from (Q18) and (Q15) were then combined to form a composite score for the PERMA element R for social relationships. The PERMA element M for meaning or purpose in life was assessed with two sentences: (Q21) and (Q19). (Q21) was positively scored and stated: "On a scale from 1 (strongly disagree) to 7 (strongly agree), rate this sentence: "Shadowboxing contributes to my sense of meaning or purpose in life"." (Q19) was negatively scored and stated: "On a scale from 1 (strongly disagree) 1 3 to 7 (strongly agree), rate this sentence: "Shadowboxing detracts from my sense of meaning or purpose in life"." The scores from (Q21) and (Q19) were then combined to form a composite score for the PERMA element M for meaning or purpose in life. Finally, the PERMA element A for accomplishment was assessed with two sentences: (Q23) and (Q16). (Q23) was positively scored and stated: "On a scale from 1 (strongly disagree) to 7 (strongly agree), rate this sentence: "Shadowboxing contributes to my sense of accomplishment"." (Q16) was negatively scored and stated: "On a scale from 1 (strongly disagree) to 7 (strongly agree), rate this sentence: "Shadowboxing detracts from my sense of accomplishment"." The scores from (Q23) and (Q16) were then combined to form a composite score for the PERMA element A for accomplishment. The scoring method for positive sentences (positively scored) and negative sentences (negatively scored) adopted in this study follow standard scoring conventions in the field such as those adopted in the Oxford Happiness Inventory and the Oxford Happiness Questionnaire [6,11,12,14,18,19,21,33].

Results
This section presents general results for how shadowboxing contributes to the psychological well-being of professional Muay Thai practitioners overall (n = 14), as well as more specific results for how shadowboxing contributes to the psychological well-being of these professional martial artists based on factors such as their gender, fight experience, and training location.
One research question that I raised was whether the practice of shadowboxing among professional martial artists contributes to positive emotions. Results from this study demonstrate that professional Muay Thai practitioners strongly agreed with the statement "Shadowboxing contributes to my experience of positive emotions" (6.32 ± 1.23, CI 5.61-7.03) and strongly disagreed with the statement "Shadowboxing contributes to my experience of negative emotions" (1.14 ± 0.36, CI 0.93-1.35). A composite score of 14 (out of 14) on this dimension indicates the strongest possible agreement that shadowboxing contributes positively to emotions whereas a composite score of 2 (out of 14) indicates the strongest possible agreement that shadowboxing contributes negatively to emotions. A composite score of 8 (out of 14) on this dimension reflects a neutral position on whether shadowboxing contributes positively or negatively to emotions. Results show that the composite score for the influence of shadowboxing on positive emotions was 13.18 out of 14.00 (13.18 ± 1.20, CI 12.48-13.87) confirming our hypothesis that the practice of shadowboxing contributes to positive emotions among professional Muay Thai practitioners (Fig. 1).
A second research question that I raised was whether the practice of shadowboxing among professional martial artists contributes to engagement or flow experience. Results from this study demonstrate that professional Muay Thai practitioners strongly agreed with the statement "Shadowboxing contributes to my experience of flow or absorbed engagement in what I'm doing" (6.36 ± 1.65, CI 5.41-7.31) and strongly disagreed with the statement "Shadowboxing detracts from my experience of flow or absorbed engagement in what I'm doing" (1.00 ± 0.00, CI 1.00-1.00). A composite score of 14 (out of 14) on this dimension indicates the strongest possible agreement that shadowboxing contributes positively to engagement or flow experience whereas a composite score of 2 (out of 14) indicates the strongest possible agreement that shadowboxing contributes negatively to engagement or flow experience. A composite score of 8 (out of 14) on this dimension reflects a neutral position on whether shadowboxing contributes positively or negatively to engagement or flow experience. Results show that the composite score for the influence of shadowboxing on engagement or flow experience was 13.36 out of 14.00 (13.36 ± 1.65, CI 12.41-14.31) confirming our hypothesis that the practice of shadowboxing contributes to engagement or flow experience among professional Muay Thai practitioners (Fig. 1).
A third research question that I raised was whether the practice of shadowboxing among professional martial artists contributes to social relationships. Results from this study demonstrate that professional Muay Thai practitioners strongly agreed with the statement "Shadowboxing contributes to my positive relationships with others" (4.54 ± 2.36, CI 3.17-5.90) and strongly disagreed with the statement "Shadowboxing detracts from my positive relationships with others" (1.00 ± 0.00, CI 1.00-1.00). A composite score of 14 (out of 14) on this dimension indicates the strongest possible agreement that shadowboxing contributes positively to relationships whereas a composite score of 2 (out of 14) indicates the strongest possible agreement that shadowboxing contributes negatively to relationships. A composite score of 8 (out of 14) on this dimension reflects a neutral position on whether shadowboxing contributes positively or negatively to relationships. Results show that the composite score for the influence of shadowboxing on relationships was 11.54 out of 14.00 (11.54 ± 2.36, CI 10.17-12.90) confirming our hypothesis that the practice of shadowboxing contributes to social relationships among professional Muay Thai practitioners (Fig. 1).
A fourth research question that I raised was whether the practice of shadowboxing among professional martial artists contributes to meaning or purpose in life. Results from this study demonstrate that professional Muay Thai practitioners strongly agreed with the statement "Shadowboxing contributes to my sense of meaning or purpose in life" (4.93 ± 2.23, CI 3.64-6.22) and strongly disagreed with the statement "Shadowboxing detracts from my sense of meaning or purpose in life" (1.14 ± 0.53, CI 0.83-1.45). A composite score of 14 (out of 14) on this dimension indicates the strongest possible agreement that shadowboxing contributes positively to meaning or purpose in life whereas a composite score of 2 (out of 14) indicates the strongest possible agreement that shadowboxing contributes negatively to meaning or purpose in life. A composite score of 8 (out of 14) on this dimension reflects a neutral position on whether shadowboxing contributes positively or negatively to meaning or purpose in life. Results show that the composite score for the influence of shadowboxing on meaning or purpose in life was 11.86 out of 14.00 (11.86 ± 2.03, CI 10.68-13.03) confirming our hypothesis that the practice of shadowboxing contributes to meaning or purpose in life among professional Muay Thai practitioners (Fig. 1).
A fifth research question that I raised was whether the practice of shadowboxing among professional martial artists contributes to accomplishment. Results from this study demonstrate that professional Muay Thai practitioners strongly agreed with the statement "Shadowboxing contributes to my sense of accomplishment" (6.00 ± 2.00, CI 4.85-7.15) and strongly disagreed with the statement "Shadowboxing detracts from my sense of accomplishment" (1.00 ± 0.00, CI 1.00-1.00). A composite score of 14 (out of 14) on this dimension indicates the strongest possible agreement that shadowboxing contributes positively to accomplishment whereas a composite score of 2 (out of 14) indicates the strongest possible agreement that shadowboxing contributes negatively to accomplishment. A composite score of 8 (out of 14) on this dimension reflects a neutral position on whether shadowboxing contributes positively or negatively to accomplishment. Results show that the composite score for the influence of shadowboxing on accomplishment was 13.00 out of 14.00 (13.00 ± 2.00, CI 11.85-14.15) confirming our hypothesis that the practice of shadowboxing contributes to accomplishment among professional Muay Thai practitioners (Fig. 1). . For each element of psychological well-being, the lowest possible composite score is 2 representing that professional Nak Muays strongly agree that shadowboxing negatively impacts that element of psychological well-being, whereas the highest possible composite score is 14 representing that professional Nak Muays strongly agree that shadowboxing positively impacts that element of psychological well-being. A composite score of 8 (dotted line) reflects a neutral position on whether shadowboxing contributes positively or negatively to that element. Results in this figure show that professional Nak Muays strongly agree that shadowboxing positively contributes to all elements of their psychological well-being. Further, results in this figure show that shadowboxing contributes to the elements of psychological well-being in the following rank-order for professional Muay Thai fighters overall: engagement (E), positive emotions (P), accomplishment (A), meaning (M), and relationships (R). Statistics were calculated using IBM SPSS Statistics software Given that the composite score for the influence of shadowboxing on positive emotions (P) is 13.18 out of 14.00 (13.18 ± 1.20, CI 12.48-13.87), the composite score for the influence of shadowboxing on engagement or flow experience (E) is 13.36 out of 14.00 (13.36 ± 1.65, CI 12.41-14.31), the composite score for the influence of shadowboxing on social relationships (R) is 11.54 out of 14.00 (11.54 ± 2.36, CI 10.17-12.90), the composite score for the influence of shadowboxing on meaning or purpose in life (M) is 11.86 out of 14.00 (11.86 ± 2.03, CI 10.68-13.03), and the composite score for the influence of shadowboxing on accomplishment (A) is 13.00 out of 14.00 (13.00 ± 2.00, CI 11.85-14.15), the results from this study provide clear empirical support for the hypothesis that shadowboxing significantly contributes to all five elements of psychological well-being in professional Muay Thai practitioners (Fig. 1).
Further, the results from this study provide an answer to a sixth research question that I raised concerning which elements of psychological well-being shadowboxing contributes to the most, and which elements of psychological wellbeing shadowboxing contributes to the least. Figure 1 provides a visualization of the overall results and Table S1 provides relevant descriptive statistics (prepared using IBM SPSS Statistics software). A comparison of composite scores reveals that shadowboxing contributed to the elements of psychological well-being in the following rank-order: (1) Fig. 1), shadowboxing contributes most strongly to engagement or flow experience (1st), followed by positive emotions (2nd), accomplishment (3rd), meaning or purpose in life (4th), and finally, social relationships (5th).
A seventh research question that I raised was whether shadowboxing contributes to the psychological well-being of individuals differently based on factors such as their gender, fight experience, and training location. A comparison of composite scores shows that shadowboxing contributed to the elements of psychological well-being in the following rank-order for men, women, more experienced practitioners, less experienced practitioners, practitioners training in Thailand, and practitioners training outside of Thailand, respectively: For men (n = 10), shadowboxing contributed to the elements of psychological well-being in the following rank-order: In other words, results show that although shadowboxing contributes to all elements of psychological well-being in male Muay Thai practitioners (n = 10), it contributes most strongly to their engagement or flow experience (1st), followed by accomplishment (2nd), positive emotions (3rd), meaning or purpose in life (4th), and finally, social relationships (5th) (Fig. 2).
For practitioners training in Thailand (n = 5), shadowboxing contributed to the elements of psychological well-being in the following rank-order: (1) accomplishment (13.60 ± 0.89, CI 12.49-14.71), (2) engagement (13.40 ± 0.89, CI 12.30-14.51), Fig. 2 This figure provides a bar plot with 95% confidence intervals (CIs) for composite PERMA scores: men (n = 10). For each element of psychological well-being, the lowest possible composite score is 2 representing that professional Nak Muays strongly agree that shadowboxing negatively impacts that element of psychological well-being, whereas the highest possible composite score is 14 representing that professional Nak Muays strongly agree that shadowboxing positively impacts that element of psychological well-being. A composite score of 8 (dotted line) reflects a neutral position on whether shadowboxing contributes positively or negatively to that element. Results in this figure show that male Nak Muays strongly agree that shadowboxing positively contributes to all elements of their psychological well-being. Further, results in this figure show that shadowboxing contributes to the elements of psychological well-being in the following rank-order for men: engagement (E), accomplishment (A), positive emotions (P), meaning (M), and relationships (R) Fig. 3 This figure provides a bar plot with 95% confidence intervals (CIs) for composite PERMA scores: women (n = 4). For each element of psychological well-being, the lowest possible composite score is 2 representing that professional Nak Muays strongly agree that shadowboxing negatively impacts that element of psychological well-being, whereas the highest possible composite score is 14 representing that professional Nak Muays strongly agree that shadowboxing positively impacts that element of psychological well-being. For each element of psychological well-being, the lowest possible composite score is 2 representing that professional Nak Muays strongly agree that shadowboxing negatively impacts that element of psychological well-being, whereas the highest possible composite score is 14 representing that professional Nak Muays strongly agree that shadowboxing positively impacts that element of psychological well-being. For each element of psychological well-being, the lowest possible composite score is 2 representing that professional Nak Muays strongly agree that shadowboxing negatively impacts that element of psychological well-being, whereas the highest possible composite score is 14 representing that professional Nak Muays strongly agree that shadowboxing positively impacts that element of psychological well-being. (3) positive emotions (12.80 ± 1.79, CI 10.58-15.02), (4) meaning (12.00 ± 2.12, CI 9.37-14.63), and (5) relationships (10.40 ± 2.19, CI 7.68-13.12). In other words, results show that although shadowboxing contributes to all elements of psychological well-being in Muay Thai practitioners training in Thailand (n = 5), it contributes most strongly to their accomplishment (1st), followed by engagement or flow experience (2nd), positive emotions (3rd), meaning or purpose in life (4th), and finally, social relationships (5th) (Fig. 6). For practitioners training outside of Thailand (n = 9), shadowboxing contributed to the elements of psychological well-being in the following rank-order: (1) positive emotions (13.39 ± 0.78, CI 12.79-13.99), (2) engagement (13.33 ± 2.00, CI 11.80-14.87), (3) accomplishment (12.67 ± 2.40, CI 10.82-14.51), (4) relationships (12.17 ± 2.32, CI 10.38-13.95), and (5) meaning (11.78 ± 2.11, CI 10. 16-13.40). In other words, results show that although shadowboxing contributes to all elements of psychological well-being in Muay Thai practitioners training outside of Thailand (n = 9), it contributes most strongly to their positive emotions (1st), followed by engagement or flow experience (2nd), accomplishment (3rd), social relationships (4th), and finally, meaning or purpose in life (5th) (Fig. 7).  For each element of psychological well-being, the lowest possible composite score is 2 representing that professional Nak Muays strongly agree that shadowboxing negatively impacts that element of psychological well-being, whereas the highest possible composite score is 14 representing that professional Nak Muays strongly agree that shadowboxing positively impacts that element of psychological well-being. Then as I get a rhythm, like I'm just sort of throwing punches and kicks and knees just to warm and limber up the motions that I'm about to use on the pads or bag or partner or sparring or whatever, but as I start to get limber I then start to channel in a little bit more, like imagining that there's an opponent in front of me and I'm trying to hit in between or around the guard, or knee up the middle, or grab the hands, like I try to visualize someone being there and actually hitting them. If I'm doing it as a real technical thing, then I'll shadowbox with the purpose of trying to perfect a jab, or perfect a cross, I might even sometimes film it, so I'll film my shadowboxing and review the video, film the shadowboxing then review the video, so that's a really slow and long process but I tend to find that I get good results from that". CJ: "When shadowboxing make sure to put yourself in the moment! Don't just do it mindlessly, really create the atmosphere with your mind". How I need to move. Visualization is essential. I also use shadowboxing to visualize my own technique and to repeat techniques over and over again. Slow or fast. Repetition in any sport is crucial, and shadowboxing is a fantastic way to work on your skill and technique development without anyone or any equipment needed. You can make your technique/movement/footwork/defense PERFECT with slow thoughtful shadowboxing. Lastly, shadowboxing can Fig. 7 This figure provides a bar plot with 95% confidence intervals (CIs) for composite PERMA scores: Nak Muays training outside of Thailand (n = 9). For each element of psychological well-being, the lowest possible composite score is 2 representing that professional Nak Muays strongly agree that shadowboxing negatively impacts that element of psychological well-being, whereas the highest possible composite score is 14 representing that professional Nak Muays strongly agree that shadowboxing positively impacts that element of psychological well-being. A composite score of 8 (dotted line) reflects a neutral position on whether shadowboxing contributes positively or negatively to that element. Results in this figure show that Nak Muays training outside of Thailand strongly agree that shadowboxing positively contributes to all elements of their psychological well-being. Further, results in this figure show that shadowboxing contributes to the elements of psychological well-being in the following rank-order for Nak Muays training outside of Thailand: positive emotions (P), engagement (E), accomplishment (A), relationships (R), and meaning (M) be used on a less technical basis to cut weight, to stay active and to improve focus and discipline. I love shadowboxing and believe that many underestimate the benefits". JB: "I visualize different things at different times. Sometimes I focus on good footwork, other times on good balance while performing powerful techniques. Combinations, correct breathing and also putting it all together". MH: "I visualize an opponent to train different fight scenes, for example, attacking and blocking and answering back". MP: "You simulate the process of a fight in your mind. You create mental scenarios of fighting your opponent and where you use all aspects of your fighting skills. Working on attack and defense as well as technique. It's key to be able to freestyle your movement with fluidity and flow of the mind and body [...] The benefits to shadowboxing primarily for me is enabling the mind to be active in a process of fighting without fighting. It allows you to be creative and try movements. To develop better self body awareness". OT: "I think about my opponent's attacks/think about specific defense techniques that I need to improve on. It helps prepare the mind for the techniques that you are trying to improve on before trying them on pads then sparring/helps visualize your opponent's moves". SG: "It depends on the goal of the session. If I for example work on speed and throw 40 jabs as fast as possible, I focus on counting and to explode back and forth. If I do shadow as a warmup, I visualize an opponent and work on attack and defense". One important insight from the first-person reports provided by Muay Thai professionals is that flow experience (in bolded sections) is an important component of their shadowboxing. For example, MP reports that flow and fluidity of movement is a key component of shadowboxing, CJ reports the importance of putting yourself in the moment while shadowboxing, and SM reports that shadowboxing (especially outside) is a meditative practice. Another important insight from the first-person reports provided by Muay Thai professionals is that mentally visualizing and simulating interaction with others (in underlined sections) is another important component of their shadowboxing. For example, JLP reports that visualizing possible interactions with others is the main reason that they shadowbox, MH reports the importance of visualizing an opponent and simulating how their interactions might play out during a competition, and OT reports the importance of mentally simulating possible attacks from opponents as well as defensive techniques and counterattacks while shadowboxing. Finally, a third important insight from the first-person reports provided by Muay Thai professionals is that shadowboxing is often a component part of a larger system of training that involves a continuous fine-tuning of technical mastery through reiterated physical training and film analysis. For example, as BJ reports, "I'll film my shadowboxing and review the video, film the shadowboxing then review the video, so that's a really slow and long process but I tend to find that I get good results from that". We can therefore see from this collection of firstperson reports provided by Muay Thai champions that shadowboxing is often highly meditative and conducive for flow experience, often involves visualization and mentally simulating interaction with others, and forms an important part of a larger training system that often involves film analysis as well as other forms of physical training (drills, pad work, bag work, technical sparring, etc.).

Discussion
The results from this study are interesting and significant since this is the first empirical study to report that the practice of Muay Thai shadowboxing contributes to the psychological well-being of professional Muay Thai practitioners (n = 14). Further, results from this study show that although shadowboxing contributes to all elements of psychological well-being in professional Muay Thai practitioners (all composite scores are above 8 and the dotted line in Fig. 1), shadowboxing contributes most strongly to engagement or flow experience (1st), followed by positive emotions (2nd), accomplishment (3rd), meaning or purpose in life (4th), and finally, social relationships (5th). Although shadowboxing contributed to social 1 3 relationships less than it contributed to other elements of psychological well-being, notice that professional Muay Thai practitioners (n = 14) nonetheless still rated shadowboxing as significantly contributing to their social relationships. Interestingly enough, results from this study on professional martial artists suggests that even when professional martial artists are engaged in individual training like shadowboxing, this individual training often mentally includes interacting with partners and significantly contributes to the social relationship (R) element of their psychological well-being (11.54 ± 2.36, CI 10.17-12.90; Fig. 1). This is a particularly interesting result, since the use of mental simulation to create social contexts that promote psychological well-being is a topic that has not yet been rigorously explored in the psychological literature. This study is also the first to investigate whether shadowboxing contributes to the psychological well-being of professional Muay Thai practitioners differently based on factors such as their gender, fight experience, and training location. Results from this study reveal that although shadowboxing contributes positively to the psychological well-being of all the professional martial artists involved in this study, shadowboxing did not contribute to the psychological well-being of everyone in precisely the same way. Rather, men found that shadowboxing contributed most to their engagement or flow experience (Fig. 2) whereas women found that it contributed most to their positive emotions (Fig. 3), more experienced practitioners found that it contributed most to their positive emotions (Fig. 4) whereas less experienced practitioners found that it contributed most to their accomplishment (Fig. 5), and practitioners training in Thailand found that it contributed most to their accomplishment (Fig. 6) whereas practitioners training outside of Thailand found that it contributed most to their positive emotions (Fig. 7). As mentioned in Sect. 2 of this article, shadowboxing (as the individual rehearsal of technical forms) is an important component of training across all striking-based martial art systems since rehearsal of relevant striking techniques is central to mastering any striking system [2], and this study is the first to provide data from professional Muay Thai practitioners suggesting that shadowboxing generally contributes to the overall psychological well-being of martial artists while also providing different psychological benefits for individuals of different kinds and in different training contexts. This initial exploratory study suggests that shadowboxing may even contribute to psychological well-being differently for the same individual over time, since shadowboxing impacts people differently based on their training and experience (Figs. 4 and 5).
Furthermore, the free responses provided by the professional Muay Thai practitioners in this study also gives psychologists a unique opportunity to gain insight into the mental state of elite martial artists engaged in their professional craft. Several important points about the free responses are worth highlighting. First, notice that shadowboxing is often highly technical, for example, martial artists visualize and mentally simulate different movement patterns for attacking, defending, faking and feinting, exploring angles and setups against opponents, and perfecting particular strikes. The professional martial artists in this study also discussed how they often filmed their shadowboxing sessions so that they could analyze their own work and reflect on what to improve upon in future sessions. The process of (shadowboxing) practice and (film) analysis is then reiterated repeatedly to improve mastery of martial arts techniques. Second, notice that shadowboxing is often described as "meditative" and occurring "with fluidity and flow of the mind and body" and "without overthinking". These reports on flow experience from professional Muay Thai practitioners are highly consistent with previous research on flow experience carried out by Csikszentmihalyi [7] and Dietrich [13]. Previous research by Ulrich et al. [32] also found that experimentally induced flow experience involved decreased activation in the amygdala and medial prefrontal cortex and increased activation in the inferior frontal gyrus and putamen, so an interesting avenue for future research would be to employ fNIRS and other portable neuroimaging techniques to investigate whether self-reports of flow while shadowboxing among martial artists correlate with decreased activation in the amygdala and medial prefrontal cortex and increased activation in the inferior frontal gyrus and putamen [13,32].

Limitations
There are necessarily limitations to every study, and in this section I discuss three limitations of the present research on shadowboxing and psychological well-being. Although a notable strength of the present research is that it provides original insight about the training practices and psychological well-being of a rarely studied population in the psychological literature-professional Muay Thai practitioners-this focus on a specialized population entails that the results of this study remain limited to this specialized population and do not necessarily generalize to other populations. It would therefore be valuable for future research to investigate how shadowboxing impacts the psychological well-being of amateur Muay Thai practitioners, as well as amateurs and professionals practicing other martial arts that utilize shadowboxing such as Boxing, Kickboxing, Karate, Taekwondo, Kung Fu, Krav Maga, and Capoeira. Despite this limitation on the generalizability of the present results, it is nonetheless clear that a focused study on professional Nak Muays is still important since it can provide unique insight into the training practices and psychological well-being of the most elite champions in this increasingly popular martial art. Currently there are no published studies on the mental visualization and psychological well-being of elite Muay Thai champions, so this initial study utilizing the PERMA framework fills an important gap in the extant literature and takes a modest step forward in motivating future research.
A second limitation concerns the sample size of Nak Muays included in the present study. Although a notable strength of the present research is that it provides original insight about the training practices and psychological well-being of some of the world's most elite Muay Thai champions, this focus on elite Muay Thai professionals rather than the general public entails that the sample size in this kind of study will necessarily be smaller than that focused on amateurs or the general public. Consider for example that although it is easy to recruit hundreds of participants from college classes and by using crowdsourcing methods such as Amazon's Mechanical Turk, this is not likewise possible with certain specific and specialized populations such as Muay Thai champions, free climbers that have completed grade 9c climbs, and other professionals that are the very best in the world at their craft. The number of elite professionals and decorated champions in many fields will necessarily be smaller and more limited compared to the general population, so sample sizes of studies that focus on elite professionals and decorated champions in many fields will also be comparatively smaller. Yet despite this limitation on the sample size of elite Nak Muays in the present study, it is nonetheless clear that a study focusing specifically on this group is still important since it can provide new insight into the training practices and psychological well-being of elite (rather than amateur) Muay Thai fighters. Currently there remains a lack of psychological research focusing on top performing professionals in martial arts and other sports, so this study fills another important gap in the literature and contributes to future research on elite martial artists.
Finally, a third limitation of the present study is the usage of the 23-item questionnaire and open-ended question methodology. Although a notable strength of the present research is that it provides initial insight into the psychological well-being of professional Muay Thai practitioners based on the PERMA framework, psychological well-being in this study was assessed by means of the commonly utilized self-report methodology in social and positive psychology [11,12,[27][28][29]. Accordingly, future research should build upon the initial results presented in this study by utilizing supplementary research methods including longitudinal studies and neuroimaging studies to investigate the influence of shadowboxing on the psychological well-being of martial artists. For example, future neuroscience research can use the results from the present study to investigate whether self-reports of flow while shadowboxing correlate with decreased activation in the amygdala and medial prefrontal cortex and increased activation in the inferior frontal gyrus and putamen since previous experimental research has established these brain areas as involved in the experience of flow [13,32]. Despite the methodological limitations of the present research, it is nonetheless clear that research on martial artists using self-report methods still offers one useful approach for understanding the practices and perspectives of professional martial artists.

Conclusion
Does martial arts practice contribute to psychological well-being in professional martial artists? If so, what are the specific ways that martial arts practice accomplishes this? It has been a long-standing and widely held belief that martial arts practice can contribute to psychological well-being, however, there has been a lack of empirical research in the psychological literature focused on investigating the details of this hypothesis. The purpose of this research was therefore to investigate the impact of a paradigmatic martial arts practice-shadowboxing-on the psychological well-being of Muay Thai professionals. Throughout this article several important contributions to the literature on martial arts and psychological well-being have been made, including (1) this article provided qualitative first-person reports from professional Muay Thai practitioners (n = 14) about their use of visualization and mental imagery and their experience of flow while shadowboxing, (2) this article provided quantitative data from professional Muay Thai practitioners (n = 14) that reveals how Muay Thai training influences the five elements of their psychological well-being including positive emotions, engagement, relationships, meaning, and accomplishment, (3) this article discussed how shadowboxing differentially impacts the psychological well-being of professional Muay Thai practitioners (n = 14) based on their experience, gender, and training location, and (4) this article discussed limitations of the present study and offered suggestions for future research. As it has been revealed through empirical research presented in this article, martial arts practice (shadowboxing) provides an opportunity for individuals to experience improved psychological well-being in at least five distinct ways, by contributing to their positive emotions, engagement or flow experience, social relationships, meaning or purpose in life, and accomplishment. Shadowboxing specifically is a non-contact form of martial arts training that is used across many different martial arts disciplines, and a form of martial arts training that can offer a flexible means for individuals to tap into a positive psychological resource as required. By better understanding how each martial art and practice provides a unique profile of psychological costs and benefits to practitioners, researchers can offer valuable insight into the psychological effects of martial arts training and even help to more effectively match individuals to optimal martial arts training programs.
Author contributions The author is responsible for all contributions. The author read and approved the final manuscript.

Data availability
The datasets generated and analyzed during the current study are available from the corresponding author upon approval of the request.

Declarations
Ethics approval and consent to participate The present research had ethics approval and participants provided informed consent. All procedures performed in this study were in accordance with the ethical standards of the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Consent for publication
The participants have consented to the use of their interview data for publication.

Competing interests The authors declare no competing interests.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/.