Physical Disabilities
The most common physical disabilities include cerebral palsy, spina bifida, amputations, and SCI. Many individuals who use wheelchairs resulting from a SCI have a series of health impairments that include orthostatic hypotension. autonomic dysreflexia, pressure sores, spasticity, and poor thermoregulation. Some individuals have an incomplete injury in which the spinal cord is only partially severed or damaged, while others have a complete injury in which the spinal cord is completely severed or damaged. Several research questions that must be addressed concerning persons with SCI include the following: a) Do persons with SCI have a high enough functional capacity to perform routine transfers, negotiate architectural barriers such as ramps and curb-cuts, or perform activities of daily living (i.e., dressing and bathing)? b) Is there a difference in the incidence of heart disease between active individuals with SCI compared with those who are inactive? c) Do persons with T7 to T12 lesions elicit different cardiovascular responses to maximal exercise testing compared with persons with TI to T6 lesions?

While exercise scientists have made tremendous strides in studying the performance levels of persons with SCI, there has been less interest in studying persons with cerebral palsy and spina bifida. Research questions pertaining to individuals with these conditions include: a) What are the exercise capacities of individuals with cerebral palsy and spina bifida? b) What are the best techniques for measuring the fitness levels of individuals with these conditions? c) Do persons with cerebral palsy have a higher metabolic rate than nondisabled persons as a result of their spasticity?

Neuromuscular Disorders
Neuromuscular disorders are physical disabilities that are a major challenge to researchers in exercise science. Many conditions such as multiple sclerosis, amyotrophic lateral sclerosis (ALS), postpolio syndrome, myasthenia gravis, Parkinson's disease, and muscular dystrophy, have a progressive/generative component, which implies that the condition will worsen over time regardless of the treatment. Because of the potential hazards of "doing more harm than good," many investigators have been apprehensive about studying this group of individuals with disabilities. Despite this concern, there has been a growing interest in studying the exercise responses of persons with multiple sclerosis. Less research has been conducted on other neuromuscular conditions. Important questions that need to be addressed include: a) How much exercise is considered safe for this population? b) What are the recommended training modalities for persons with neuromuscular diseases? c) Can exercise slow the progression of a degenerative disease?

Respiratory Disorders
The major physically disabling conditions that are listed under COPD include asthma, chronic bronchitis, and emphysema. One of the most common diseases is exercise-induced asthma (EIA). There is a growing body of research being conducted by exercise scientists on EIA, but there is still very little exercise science literature on emphysema and bronchitis. There is also very limited information on a hereditary respiratory diseases known as cystic fibrosis. Important research questions include: a) Could exercise improve the health of individuals with EIA to a point where absenteeism from work or school is mitigated? b) What exercise modalities result in the least amount of dyspnea while maintaining oxygen saturation higher than 85% in persons with emphysema? c) What is the recommended frequency, intensity, and duration of exercise for persons with different types of COPD?

Metabolic Disorders
The primary disorders under this heading include obesity and diabetes. There is a substantial amount of research in exercise science on both of these conditions. However, many questions still remain, particularly the most elusive one: How much of obesity can be attributed to genetic and environmental conditions? A possible twist to studying this research question would be to track populations of individuals with disabilities, such as those with intellectual disability or mental illness, who often live in different settings during their lifetime (i.e., group home, supported living facility, foster home, intermediate care facility) where food and physical activity may be more or less accessible. Other research questions include: a) What are the most effective weight loss strategies for persons with physical and cognitive disabilities? B) Can exercise reduced the dosage of daily insulin needed in persons with Type I diabetes? c) Do persons with disabilities have a higher incidence of obesity or diabetes?

Mental Disabilities
Intellectual disability, mental illness, autism, and traumatic brain injury (TBI) are the most common forms of mental disability. There is some research in the literature on physical activity and persons with intellectual disability and mental illness; however, there is very little information on physical activity and autism and TBI. Research questions include: a) What is the exercise capacity of persons with autism and TBI? b) Do persons with autism and TBI have a similar fitness profile compared with the general population? c) Can accurate physiological data be obtained on persons with autism or TBI?

Aging-Related Disorders
The fastest-growing segment of the population in the United States is in persons over the age of 65 years. As the population grows older, the number of disorders associated with aging will likely increase. Some of these disorders include Parkinson's disease, stroke, Alzheimer's disease, arthritis, fibromyalgia, depression, and osteoporosis. Although there is a growing volume of research on exercise and aging, many research questions in this area still need to be addressed. Some of the more important ones include: a) What are the safest training modalities for the frail elderly? b) Can exercise started in the later years (after 65) increase lifespan and lower the disease rates? c) Can exercise reduce restlessness in persons with Alzheimer's disease? d) To what extent can exercise reduce depression in the elderly?