Intellectual disability (ID) and autism spectrum disorders (ASD) are neurodevelopmental disorders that affect daily living due to impaired adaptive and intellectual functions (Matson et al., 2008; Totsika et al., 2010). ASD and ID improve as the child grows older, but some entail impairments throughout life. Both ASD and ID are affected by heredity and males account for a higher percentage than females. Most research studies on ASD have shown prevalence figures using data from child cohorts. There has been a steady rise in the prevalence of ASD in children, with an estimated 5% of child subjects from studies conducted from the mid-1990s onward (Baird et al., 2006).

Until recently, no epidemiologic studies in adults, including ID, have been done. However, Brugha et al. (2011) looked into ASD in adults based on an adult psychiatric morbidity survey from the United Kingdom. From their study, prevalence rates were confirmed to be approximately 1%, but showed a higher prevalence rate in men (1.8%) than in women (0.2%). There was a higher likelihood for people with ASD and ID to be poorly educated, unmarried, and economically deprived compared to the general population (Howlin and Moss, 2012). In other words, adults who are mentally retarded are psychologically and socially vulnerable. The severity of both ID and ASD was determined by social awareness and communication. Generally, ASD is classified as mild, moderate, and severe, while the severity of ID is divided into four stages. Pedersen et al. (2017) reported that people who have ASD tend to exhibit a greater deficiency in nonverbal social behavior, which includes body language and the understanding of social cues. Matson and Dempsey (2008) found that subjects with ID displayed less repetitive behaviors. When compared to subjects with ID, those with ASD were reported to be more likely to self-isolate and to avoid eye contact. Several researchers reported a high likelihood of accompanying or overlapping ASD and ID (Matson and Shoemaker, 2009; Wilkins and Matson, 2009). Higashida et al. (2019) speculated that people with ID may go unnoticed in regards to co-occurring ASD. Actually, people with both ASD and ID have different needs compared to those with only either ASD or ID (Carminati et al., 2007; Gilchrist et al., 2001).

As such, ASD and ID share clinical characteristics which could result in confusion during diagnosis (Pedersen et al., 2017). It is possible that people with ASD that exhibit symptoms of ID may inadvertently be codiagnosed, which could result in receiving treatment for a nonexistent condition. Likewise, there is also the chance that people with ID may be misdiagnosed to have ASD and wrongly receive treatment for a condition they do not have. Clearly distinguishing the differences between ASD and ID will allow for the prescription of the appropriate treatments (Matson and Shoemaker, 2009).

Various treatment methods from several studies have been shown to improve symptoms (Bahrami et al., 2012). A growing body of evidence provides added support that regular physical activity has positive effects, such as improved respiratory function (Khalili and Elkins, 2009), reduced depression and anxiety, an enhanced sense of well-being, and better performance at work (Croce and Horvat, 1992). Several studies point to the importance of maintaining health and physical activity for people with ID and similar conditions (Chanias et al., 1998; Jansen et al., 2004). Among the outcome measures often used in early intervention programs are changes in the intelligence quotient (IQ). A lower IQ indicates a poorer prognosis for early intensive plans (Ben Itzchak et al., 2008; Matson and Smith, 2008). Verschuren et al. (2016) recently reported that engaging in physical activity can improve body image and help with treatment. Physical activity provides children with developmental disabilities with opportunities for physical development, reduces stress and anxiety, and improves muscle functions that helps for improved safety.

It is difficult to clearly distinguish between symptoms in individuals with ASD or ID. Although, major advances have been made in regards to the diagnosis, causes, and treatment for children with such conditions, there is a lack of research on the prognosis, results, and effective interventions for adults (Howlin and Moss, 2012). Even in Korea, physical activity programs for adults with ASD or ID were provided by various institutions, but no detailed program was provided depending on the type of disability. In addition, most play and exercise programs related to the disability were focused only on children, but programs that take into account the characteristics of adults were not provided. Therefore, this study aimed to provide an exercise program for each type of disability after analyzing the exercise program performed by an adult with ASD or ID in a developmental disability center. In other words, this study analyzed the differences in gross motor function (GMF) and health fitness in participants who took part in the same exercise program for one year among adults with ASD or ID.

This study analyzed the differences in GMF and health fitness in participants who took part in the same exercise program for a year among adults with ID or ASD. From the results of this study, no significant differences existed in GMF and health fitness between ASDG and IDG. In other words, a year-long exercise program did not provide a difference in disability type. The result showed that exercise programs could provide similar results, even with other disorder types with similar symptoms. In fact, this study was a retrospective study comparing variables between two groups with postvalue only after a year of exercise without prevalue. Therefore, it was not known whether health fitness and GMF increased or decreased.

Many researchers have reported that adults with mental retardation have lesser adaptive, cognitive, and social skills. Individuals with developmental disability also have more limited physical abilities compared to those who do not. Moreover, they are often accompanied by stereotype and challenging behavior such as depression, anxiety, and schizophrenia (Downs et al., 2008; Holden and Gitlesen, 2008; Lee et al., 2008; Lifshitz et al., 2008; Matson et al., 2005; McGillivray et al., 2008; Myrbakk and von Tetzchner, 2008; Thirion-Marissiaux and Nader-Grosbois, 2008; Yalon-Chamovitz and Weiss, 2008; Zayac and Johnston, 2008). All of these problems could be problematic for patients, their family, and even society. Specifically, individuals with developmental disability, on average, score 25% less on developmental tests than those without (Wood et al., 2000). In other words, there is no physical fitness test for the disabled and only exercise programs are provided. According to several previous studies, there are many reports that people with disabilities who have good physical fitness or enjoy sports have increased psychological stability and improved sociality. However, as described above, if the program was provided after the physical examination was performed, it may provide better results. In other words, a lot of researchers reported that a physical activity or an exercise program provided to adults with mental retardation has been reported to promote psychological health as well as physical health of persons with disabilities and play a role in society (Chanias et al., 1998; Croce and Horvat, 1992; Jansen et al., 2004; Rimmer, 1999; Verschuren et al., 2016). A review on studies involving the mental health and physical fitness of both able and disabled populations showed that physical activity led to improved psychological states in children with ID (Folkins and Sime, 1981). Gabler-Halle et al. (1993) found that aerobic exercise led to many improvements in psychological variables such as behavior, self-concept, and intellectual functioning.

Especially, a variety of programs are offered to help children with mental retardation grow into members of society. Among them are physical activity programs that could improve the health of children with disabilities, promote psychological stability, and increase the chances of social adjustment (Ahn and Fedewa, 2011; Janssen and LeBlanc, 2010; Latorre Román et al., 2015). The effects of physical activity in children with developmental disabilities include improved physical development and muscle function necessary to protect the body (Verschuren et al., 2016). Body fat distribution and physical fitness in childhood are highly correlated with cardiovascular health in adulthood. Bürgi et al. (2011) indicated that preschoolers who are physically active tend to have improved aerobic capacity and heart function. These findings show that childhood fitness levels have important long-term effects on health. (Ortega et al., 2008; Ortega et al., 2015). For adults with ASD or ID, physical activity not only provides available movement, but also improves physical function and mental pleasure. In other words, since physical activity itself is learning and living, it is essential for the education of adults with mental disabilities.

Lower levels of muscular strength and cardiovascular fitness and higher levels of obesity were found in individuals with ID compared to those without. (Pitetti and Yarmer, 2002; Pitetti et al., 2001). For people with ID, Frey et al. (2008) showed that physical fitness performance is significantly lower, while Frey et al. (2008) reported less physical activity than those without ID (Van den Berg-Emons et al., 1998). Similarly, a meta-analysis was conducted by Chanias et al. (1998) to analyze the effects of physical activity on fitness levels in people with ID. Data was gathered from 21 studies yielding an effect size of 100. Significant effects were shown in areas of cardiovascular and muscular endurance, moderate effects for muscular strength, less notable effects for flexibility, and insignificant effects for body composition. In addition, they reported that program type influenced strength and program frequency influenced flexibility.

In conclusion, no significant differences were found in the GMF and health fitness between ASDG and IDG in this study. In other words, a year-long exercise program did not provide a difference in disability type, but the BMR of ASDG was higher tendency than that of IDG. The result showed that exercise programs could provide similar results, even with other disorder types with similar symptoms. Specifically, this study includes some limitations as follows. First, the experiment was conducted by selecting a special education institute, as such, it was difficult to generalize the research results to all adults with disabilities. Second, the adults were not able to control the physical other activities and eating methods. Revising the standards of reporting relevant data related to samples and exercise prescription components would be beneficial for future research studies.