Intellectual disability (ID) is a common developmental disorder that affects an estimated 4.6 million Americans (9,10); although, prevalence studies tend to underestimate the number of persons with ID (10). ID is defined as a disability that occurs before 18 years of age, and where individuals experience significant limitation in intellectual functioning and adaptive behaviors (1). ID is not curable, and the focus of treatment lies in the normalization of behavior with intervention starting as early as possible (9). Individuals with ID are able to lead satisfying, meaningful, and healthy lives with support to enhance physical, social, emotional, and cognitive functioning. Today, persons with ID are encouraged to be part of a community and to develop daily living, social situation, and workplace skills. This article will provide considerations for exercise programming for individuals with ID.
EPIDEMIOLOGY AND ETIOLOGY OF INTELLECTUAL DISABILITY
Major differences between persons with ID and developmental disabilities (DDs) are: age of onset, severity of limitations, and the fact that the DD definition does not refer to an IQ requirement. It is estimated that approximately 50% of individuals with ID will also meet the definition for DD (1).
Individuals with ID are considered to be at high risk for a sedentary lifestyle and commonly perform poorly on fitness tests such as peak V[Combining Dot Above]O2 and maximal strength (4). A recent study used the Centers for Disease Control and Prevention's National Health Interview Survey data to examine disability prevalence among adults in the United States based on body mass index (BMI) (3). The findings showed that more than 40% of the obese adults in the sample had at least 1 disability. Disability prevalence increased among respondents as their BMI increased. The findings also illustrated that movement difficulty was substantially higher among those who were obese compared with those of normal weight. Obese adults also reported higher prevalence of social and work limitations compared with those of a normal weight. The study demonstrated some differences between men and women; yet, the causes for these differences were unclear. Knowing that a large percentage of people with obesity have a disability and understanding the type of disability will help exercise professionals design, implement, and evaluate physical activity training programs for persons with ID (3,5).
Body composition, muscular strength, muscular endurance, and flexibility are common factors associated with low fitness performance for individuals with ID (2). Many individuals with ID also have a wide range of comorbidities such as epilepsy, autism, cerebral palsy, hypertension, and hyperthyroidism. For example, individuals with Down Syndrome have a higher prevalence of muscle weakness and low bone mineral density, and more than 50% are born with heart defects such as atrioventricular and ventricular septal defect (1,2,7,11). Overweight and obesity are common health problems for individuals with ID due to their often very sedentary lifestyle and can increase the risk for other comorbidities.
A meta-analysis by Bartlo and Klein indicates that regular physical activity is vital for adult individuals with ID. Of the 11 clinical studies that included a variety of physical activity modes, the findings revealed moderate to strong evidence that physical activity positively affected balance, muscle strength, and quality of life in individuals with ID (4). In a 13-year follow-up study, researchers found that adults with ID have higher health risks and lower fitness levels associated with aging than adults without ID (8). In fact, only about one-third of adults with ID are active enough to receive health benefits (12).
The benefits of regular cardiorespiratory exercise for individuals with ID include reduced risk of cardiovascular disease, type 2 diabetes, arthritis, hypertension, depression, and obesity (2,4,7,8). In addition to the cardiorespiratory exercise training, resistance training should be implemented. Resistance training is safe and effective for individuals with ID as a method to increase muscular strength, endurance, range of motion, and balance when performed under proper professional supervision (6). Overall, physical fitness relates to better self-efficacy when performing activities of daily living, which can lead to improved well being and quality of life among persons with ID (4,6). Elmahgoub et al. (7) reported that adolescents with ID who performed combined endurance and resistance training received a positive effect on indices of obesity, physical fitness, and lipid profile. Other benefits of resistance training include greater muscle mass, bone mineral density, and improvements in glucose metabolism (2,4,5).
EXERCISE SAFETY AND PRECAUTIONS
It is also important for the fitness professional to be aware that many individuals with ID take prescription medications that could affect the response to exercise and performance. Common health conditions for which medication is prescribed for this population include seizure disorders, hypertension, high cholesterol, and depression (9). It is recommended to obtain a list of medications that are being taken by the client and become informed about possible contraindications to exercise and side effects. For referencing medications, visit http://www.nlm.nih.gov/medlineplus/druginformation.html. Considering the unique combination of medical conditions that individuals with ID may have, it is recommended that the fitness professional becomes well informed of their clients by speaking with their personal and health care providers regarding medical conditions and medications before designing and implementing exercise training.
Often, individuals with ID have concurrent conditions that may complicate participation in exercise. Factors such as impaired depth perception, unstable joints and gait, and difficulties in understanding instructions, all contribute to increased risk of falls or injury. Individuals using wheelchairs may encounter overuse injuries in the wrists, elbows, and shoulders, and can also benefit from a balanced cardiorespiratory and resistance training program. Others may have movement, and balance issues that can be improved with neuromotor exercise that is designed to improve motor skills. Improvement of balance, agility, coordination, and gait helps improve physical functioning and may help to prevent falls among persons with ID (4,8).
EXERCISE PROGRAM GOALS
Regular physical activity is beneficial for individuals with ID and should follow the 2008 Physical Activity Guidelines for Americans issued by the U.S. Department of Health and Human Services (13). These guidelines suggest adults perform a minimum of 150 minutes a week of moderate-intensity aerobic physical activity, moderate- or high-intensity muscle strengthening activities on 2 or more days a week, and exercises to increase flexibility and balance. See Table 1 for specific exercise program goals.
Individuals with ID can benefit from physical activity programs but are currently underserved regarding physical activity programs offerings. The ability to perform movements through a full range of motion without undue discomfort and fatigue, maintain normal weight, and participate in meaningful leisure activities are important for quality of life. Proper program progression and adaptations to exercises and equipment will need to be taken into consideration during physical activity planning and execution. It is important that fitness professionals understand individuals' medical conditions, intellectual, and social abilities, as well as their required systems of support and use this knowledge to design and adapt physical activities according to the needs of each individual. Medical clearance from a physician to participate in an exercise program is recommended due to the varied medical conditions associated with ID. Additionally, exercise professionals should use a multidimensional approach to assess the needed accommodations to appropriately support persons with ID. Bodde et al. (5) have developed a physical activity education curriculum for adults with ID that exercise professionals may find helpful as they design, implement, and evaluate physical activity interventions with this population. The One-on-One Column accompanying this article will address how to set up a safe and effective exercise program for individuals with ID.
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