Each year, approximately 1.4 million people sustain a traumatic brain injury (TBI) in the United States. Of these, approximately 235,000 require hospitalization. The vast majority of these injuries seen in hospitals are classified as closed head injuries, wherein the skull is not actually penetrated. The nature of the injury sustained in vehicular accidents (e.g., blunt impact, acceleration-deceleration) often results in multi-focal lesions and diffuse brain damage, with a variety of physical, cognitive, and neurobehavioral impairments.

The Brain Injury Association (www.biausa.org) defines TBI as coming from two sources:

1. Open head injuries are caused by bullets or other penetrating objects.
2. Closed head injuries, which are the most common, are usually caused by a rapid movement of the head during which the brain is whipped back and forth, bouncing off the inside of the skull. The stress of this rapid movement pulls apart and stretches nerve fibers or axons, breaking connections between different parts of the brain. It can also cause brain contusions, especially in the frontal parts of the brain, which help control behavior and emotions.

Brain injury is the leading cause of death and disability in children and adolescents. In the United States, approximately half a million children sustain brain injuries each year and 200,000 of them will require hospitalization. In 2006, the Centers for Disease Control and Prevention estimated that 6.02 million people in the United States are living with a permanent disability due to traumatic brain injury. About half of all traumatic brain injuries are transportation-related. The other half are caused by falls, assaults, and other means.

The location of the injury in the brain will determine what functions will be impaired and to what extent. These include cognitive, behavioral, emotional, and psychosocial impairments. These impairments present a special challenge in developing a fitness program for a person with disability due to acquired brain injury.