Brain Concussion: A nonspecific term used to describe transient alterations or loss of consciousness following closed head injuries. The duration of UNCONSCIOUSNESS generally lasts a few seconds, but may persist for several hours. Concussions may be classified as mild, intermediate, and severe. Prolonged periods of unconsciousness (often defined as greater than 6 hours in duration) may be referred to as post-traumatic coma (COMA, POST-HEAD INJURY). (From Rowland, Merritt's Textbook of Neurology, 9th ed, p418)Athletic Injuries: Injuries incurred during participation in competitive or non-competitive sports.Hockey: A game in which two parties of players provided with curved or hooked sticks seek to drive a ball or puck through opposite goals. This applies to either ice hockey or field hockey.Football: A competitive team sport played on a rectangular field. This is the American or Canadian version of the game and also includes the form known as rugby. It does not include non-North American football (= SOCCER).Post-Concussion Syndrome: The organic and psychogenic disturbances observed after closed head injuries (HEAD INJURIES, CLOSED). Post-concussion syndrome includes subjective physical complaints (i.e. headache, dizziness), cognitive, emotional, and behavioral changes. These disturbances can be chronic, permanent, or late emerging.Head Protective Devices: Personal devices for protection of heads from impact, penetration from falling and flying objects, and from limited electric shock and burn.Brain Injuries: Acute and chronic (see also BRAIN INJURIES, CHRONIC) injuries to the brain, including the cerebral hemispheres, CEREBELLUM, and BRAIN STEM. Clinical manifestations depend on the nature of injury. Diffuse trauma to the brain is frequently associated with DIFFUSE AXONAL INJURY or COMA, POST-TRAUMATIC. Localized injuries may be associated with NEUROBEHAVIORAL MANIFESTATIONS; HEMIPARESIS, or other focal neurologic deficits.Mouth Protectors: Devices or pieces of equipment placed in or around the mouth or attached to instruments to protect the external or internal tissues of the mouth and the teeth.Athletes: Individuals who have developed skills, physical stamina and strength or participants in SPORTS or other physical activities.Sports Medicine: The field of medicine concerned with physical fitness and the diagnosis and treatment of injuries sustained in exercise and sports activities.Unconsciousness: Loss of the ability to maintain awareness of self and environment combined with markedly reduced responsiveness to environmental stimuli. (From Adams et al., Principles of Neurology, 6th ed, pp344-5)Sports Equipment: Equipment required for engaging in a sport (such as balls, bats, rackets, skis, skates, ropes, weights) and devices for the protection of athletes during their performance (such as masks, gloves, mouth pieces).Head Injuries, Closed: Traumatic injuries to the cranium where the integrity of the skull is not compromised and no bone fragments or other objects penetrate the skull and dura mater. This frequently results in mechanical injury being transmitted to intracranial structures which may produce traumatic brain injuries, hemorrhage, or cranial nerve injury. (From Rowland, Merritt's Textbook of Neurology, 9th ed, p417)Boxing: A two-person sport in which the fists are skillfully used to attack and defend.Brain Injury, Chronic: Conditions characterized by persistent brain damage or dysfunction as sequelae of cranial trauma. This disorder may result from DIFFUSE AXONAL INJURY; INTRACRANIAL HEMORRHAGES; BRAIN EDEMA; and other conditions. Clinical features may include DEMENTIA; focal neurologic deficits; PERSISTENT VEGETATIVE STATE; AKINETIC MUTISM; or COMA.Brain Chemistry: Changes in the amounts of various chemicals (neurotransmitters, receptors, enzymes, and other metabolites) specific to the area of the central nervous system contained within the head. These are monitored over time, during sensory stimulation, or under different disease states.Trauma Severity Indices: Systems for assessing, classifying, and coding injuries. These systems are used in medical records, surveillance systems, and state and national registries to aid in the collection and reporting of trauma.Brain Neoplasms: Neoplasms of the intracranial components of the central nervous system, including the cerebral hemispheres, basal ganglia, hypothalamus, thalamus, brain stem, and cerebellum. Brain neoplasms are subdivided into primary (originating from brain tissue) and secondary (i.e., metastatic) forms. Primary neoplasms are subdivided into benign and malignant forms. In general, brain tumors may also be classified by age of onset, histologic type, or presenting location in the brain.Craniocerebral Trauma: Traumatic injuries involving the cranium and intracranial structures (i.e., BRAIN; CRANIAL NERVES; MENINGES; and other structures). Injuries may be classified by whether or not the skull is penetrated (i.e., penetrating vs. nonpenetrating) or whether there is an associated hemorrhage.Neuropsychological Tests: Tests designed to assess neurological function associated with certain behaviors. They are used in diagnosing brain dysfunction or damage and central nervous system disorders or injury.Soccer: A game in which a round inflated ball is advanced by kicking or propelling with any part of the body except the hands or arms. The object of the game is to place the ball in opposite goals.Acceleration: An increase in the rate of speed.Brain Mapping: Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.Martial Arts: Activities in which participants learn self-defense mainly through the use of hand-to-hand combat. Judo involves throwing an opponent to the ground while karate (which includes kung fu and tae kwon do) involves kicking and punching an opponent.Diagnosis, Computer-Assisted: Application of computer programs designed to assist the physician in solving a diagnostic problem.Research Report: Detailed account or statement or formal record of data resulting from empirical inquiry.Dizziness: An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness.Wrestling: A sport consisting of hand-to-hand combat between two unarmed contestants seeking to pin or press each other's shoulders to the ground.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Cognition Disorders: Disturbances in mental processes related to learning, thinking, reasoning, and judgment.Neck Injuries: General or unspecified injuries to the neck. It includes injuries to the skin, muscles, and other soft tissues of the neck.