1. Intergenerational Theory and Exercise Programs
1.1. Intergenerational Program Theory
Several theories have been used for elaborating the importance of intergenerational activities, and highlighting focal points of their components, which explain older adults’ social, physical, psychological health throughout their lifespans. Seven related intergenerational theories were identified from studies that have been utilized for intergenerational activities such as arts, exercise, and recreational physical activity programs regarding improving health benefits for both generations
Transtheoretical Model (TTM)—
TTM refers to six stages of changes that individuals move through in terms of starting new behaviors or participating in activities. The six stages include precontemplation, contemplation, determination, action, relapse, and maintenance. Each stage has different spans depending on individuals’ cognitive, psychological levels 
According to contact theory, prejudice arises from generalizations and misrepresentations about a group of people based on inaccurate or insufficient information. The primary concept is that when one learns more about a group of individuals, prejudice may be lessened 
Social Capital Theory—Social capital theory maintains that social relationships have the power to influence individuals’ resources, which enables the development and accumulation of human capital. Social capital theory examines how social relationships can positively impact on individual and organization levels beyond the original context of its making. The great value of social capital is in its potential to shift and facilitate other types of capital value for both individuals and organizations. It is only beneficial when social capital is mobilized, and as a form of system, it grows on itself.
Situated and Contextualized Learning Theory—
Situated and contextualized learning theory posits that individuals who acquire professional skills through learning within situational contexts will acquire membership in a community of practice. Situated learning provides opportunities to experience problem-solving and hands-on experience for practitioners. Lave and Wenger 
argue that situated learning theory enables individuals to focus on the forms of social engagement instead of being concerned with what cognitive processes and conceptual structures are required.
Human Development Theory—Erikson argued that personality development occurs in a predetermined order shown by eight stages of psychosocial development, from infancy to adulthood. Challenges individuals might experience during these stages may cause positive or negative outcomes for the development of personality. The psychosocial and educational benefits of connection between older and younger individuals are emphasized in the components of intergenerational activities.
Personality Theory— Many scientists have stressed the significance of unconscious instinct in personality development and formation. Erik believed that the social element is critical for the development of personality, and it forms over the course of the entire lifespan. Some studies emphasized the importance of others in interpersonal relationships and in the construction of personality.
Whole Person Wellness Model (WPWM)—WPWM refers to the combination of multiple aspects of health-related beliefs and meaningful activities for the individual. The WPWM consists of six dimensions, which include intellectual, social, emotional, vocational, spiritual, and physical. The objective of the WPWM is that individuals find balance among six elements of daily life activities. The main objective of the model is to seek an element of life activities that contributes to enhancing functioning and quality of life.
1.2. Intergenerational Exercise or Physical Activity Program
A total number of 13 studies that cover a range of applications were selected as intergenerational physical activity/exercise programs. These programs were chosen based on the type and duration of interventions, as well as the engagement of both generations in physical activity at the same time. The age of older adult participants ranged from 50 to 96, the age of young generations ranged between 2 and 7, and young adults were 18 to 30 years old. Two studies used Mini-Mental State Examination (MMSE) 
and Physical Activity Readiness Questionnaires (PARQ) 
to determine sample eligibility. Ten out of thirteen studies included only older adults who could voluntarily participate in physical activity without physical and psychological limitations. Nine out of thirteen studies were conducted in community-based institutions such as community centers 
, universities 
, or leisure/recreational centers 
while only two studies included older adults residing in facilities 
The 13 proposed intergenerational activity programs varied depending on the duration, types, outcomes, and characteristics of participation. Seven programs were short-term interventions and lasted between four weeks and 3 months, and long-term interventions lasted 5 years. Although it was challenging to compare varied physical activity in many aspects, it was possible to identify some program features that were applied to older adults. These were sorted into three different categories: physical function improvement, psychological health benefits, and social and emotional development. For example, Minghetti et al. 
focused on physical functions such as balance, lower-limb strength, and cardiovascular health after receiving the dynamic balance exercise, while Choi and Sohng 
compared loneliness and depression levels of both generations following the intergenerational exchange program.
A variety of self-reported and proxy measures were implicated across the studies. Eleven studies applied self-reported measures that detect perceptions of psychological wellbeing, self-efficacy, depression, and the level of physical activity. Three studies that measured physical functions such as gait speed, gross motor skills, and balance were conducted by health professionals or staff in institutions. Only one study presented contradictory results. Mosor et al. 
reported no significant changes in older generations’ self-efficacy and activity engagement, while the younger generation showed higher engagement and longer duration of attention and listening skills following the intervention. Most interventions demonstrated positive outcomes of interventions among elderly groups.
There are several benefits to both physical and social health throughout participation in intergenerational programs. The first and most important is that intergenerational activities are beneficial for enhancing social health because they offer a sense of mutual links between two generations, as evidenced by precise theory and practice. Louise Douse et al. 
found that older adults who engaged in the activity had increased social integration and positive emotions, and Minghetti et al. 
and Choi and Sohng 
reported that older adults had enhanced psychological health. Positive factors resulting from mutual participation are also essential for maintaining continual physical activity 
The second is that intergenerational activities that incorporated the learning of communication skills and decision-making processes are beneficial. Participants in the program, as Kim 
mentioned, learn how to share their thoughts and feelings in a natural setting, which varies from conventional one-sided communication programs in that it gives a variety of opportunities for communication. In this regard, the intergenerational taekwondo program may be considered a good example because it allows partners to set goals and adapt and supplement each other’s posture.
The final is that, if the literature’s impression is correct, intergenerational activity programs can help improve cognitive capacities. Researchers identified publications that support the idea of using activities to improve memory and attention span. Both generations demonstrated enhanced attention and listening, as well as emotional expression, according to Morsor et al. 
. The results of the studies showed that continual intergenerational activities have a good impact on the participants’ cognitive characteristics.
2. Development of Intergenerational Taekwondo Program
2.1. Taekwondo Culture
Taekwondo, a traditional form of Korean martial arts, literally translates to “the way of feet and hands,” and its origins began in the Korean peninsula about two thousand years ago. As with all other disciplines, it is essential for the Taekwondo trainers to be familiar with its five tenets. Although many scholars argue that Taekwondo tenets and principles should be reestablished as they solely focus on spiritual aspects, 
and there are different principles based on types of training 
, nevertheless, General Choi Hong-hee’s five tenets of Taekwondo are still maintained as the principles that encompass the spirit, culture, and concept of Taekwondo, and they are still being followed by many trainees around the world. The five tenets of Taekwondo are “Courtesy”, “Integrity”, “Perseverance”, “Self-Control”, and “Indomitable spirit”.
Some scholars assert that the national representative martial arts have great value in cultivating core values that are required of citizens 
. Ryu 
mentioned that in Japan, the noble spirit was sublimed into the universal spirit of Japan in terms of the “honor and character-building” of Samurai, and its concepts include righteousness, courtesy, loyalty, and self-control. Moreover, it is mandatory to learn these tenets through participating in martial arts with regular school curriculums. Moreover, Lee et al. 
argued that practitioners learn different aspects of values according to the belt system in Taekwondo, which include “fairness”, “perseverance”, “harmony”, and “satisfaction”. In this respect, Taekwondo can play a significant role in cultivating significant values throughout Taekwondo training.
Among these principles, some scholars captured the significant culture of mutual respect in Taekwondo. According to Lim 
, children (mean age 12) who participated in Taekwondo for 6 months increased greeting, language, and public etiquette. In addition, the study showed that participants improved more on etiquette as they learned for longer periods. In addition, Kim and Yeo 
argued that training Taekwondo is a process of learning normative attitude and morality, which are important for the role of individuals as members of society. This highlights the “courtesy” among the five tenets of Taekwondo.
For older adults, however, Taekwondo’s intrinsic value leads to continued engagement, resulting in values such as mutual respect, improved health perception, and improved quality of life. For example, Yang 
demonstrated significant associations between Taekwondo participation and quality of life and perceived health among older adults. In this regard, according to Stebbins 
, “unique ethos” refers to the existence of differentiating ideas, values, feelings, or guiding beliefs that contribute to the creation of a distinct social environment and the establishment of a social network. Taekwondo’s unique culture encourages both older and younger generations to engage in the activity in a continuous and beneficial manner in this respect.
2.2. Intergenerational Taekwondo Program
Two theories were applied that were used in previous intergenerational studies 
. Choi and Sohng 
employed the Contact Theory to reduce stereotypes of aging and develop health by engaging older adults and younger generations in intergenerational physical activity programs. A study reported that interventions using five components in Contact Theory (support from authority, common goal, opportunity for friendship, cooperation, and equal group status) were more useful compared to non-theory-driven interventions 
. Choi and Sohng 
used a community-based intergenerational exchange program on older adults to improve older adults’ health-related quality of life, loneliness, depression, and walking speed. They utilized five strategies in the intervention, where a single component counts for each stage. For example, “common goal” refers to establishing a detailed goal of making traditional artwork planned for each session, and “equal group status” indicates engaging in a part of a traditional play that does not have a distinctive role in the activities. In proposed Intergenerational TKD Program, both generations share goals for each week’s activity, such as learning high blocking, basic stances, which can be a part of common goals in this theory. In addition, for the part of self-defense, both generations teach each other and conduct what they have learned from the class, which is the “equal group status” component of the theory.
2.3. Lessons Learned: Recommendations for Instructors and Health Care Services
As much of the above empirical evidence demonstrated, there are significant health benefits from participating in intergenerational activities for both younger generations and older adults. There are some recommendations to encourage participation and improve the retention rate of continuous participation. Kim 
mentioned that intergenerational activities provide mutual responsibilities that largely impact older adults’ engagement and participation. However, there are no ample studies that suggest the key elements for sustainable performance in intergenerational physical activities. Thus, the current study proposes a few strategies for instructors and health care services that could help both generations engage in the intergeneration Taekwondo programs more effectively and successfully.
First, establishing common goals. As Choi and Sohng 
noted, establishing common goals based on their needs and capability is a key component of making strong bonds between partners. Taekwondo has learning goals corresponding to the color of the trainee’s belt, such as low block and front kick. These characteristics may serve as effective motivators for trainees to participate in the activity. In order to set up goals for both generations, instructors facilitate a small session focused on socializing and creating rapport before starting the program. It is important to emphasize training-related concepts that both generations can apply within the program and achieve together. For example, this includes the two agreeing on the importance of continuous physical activity and expressing their willingness to participate in the program.
Secondly, accommodating differences in ability. Some studies asserted that the lack of interest in participation in programs due to different physical functions between generations was one of the important factors affecting continuing participation 
. When working with both generations, instructors may need to accommodate differences in abilities such as strength, flexibilities, or body coordination. While some Taekwondo movements help to improve overall health and change the level of physical function over the life course, students may be more interested in improving techniques and fun aspects. Instructors may need to consider accommodating differences in abilities for both generations.
Thirdly, offering incentives is an effective means to encourage participants to engage in physical activity programs. Many studies found that offering incentives increased participants’ physical activity at multiple levels 
. According to Capps and Harkey 
, approximately 70% of people were more engaged in physical activity when financial incentives were provided by team-based participation rates. A wide variety of incentives helps participants to maintain participation rates over a long period. The Taekwondo belt system may be used as an effective means of motivating participants when they engage in activity with their partner.
Lastly, encouraging both generations to help one another as often as possible. Kim 
mentioned that in the intergenerational exercise program, participants were more engaged in physical activities and utilized fine and gross motor skills while they helped to reach goals together. Taekwondo movement requires a sense of balance and intensive physical coordination. Physical function could be improved while guiding participants to cooperate to perform standing or blocking movements during the training.