A concussion is a traumatic brain injury (TBI) that temporarily disrupts normal brain function. It results from a blow to the head or a sudden, forceful jolt that causes the brain to move rapidly inside the skull. This mechanical force triggers chemical and functional changes within the brain tissue. Continuing to play sports while concussed is dangerous and can lead to immediate, life-altering, or fatal consequences.
The Immediate Life Threat
The most catastrophic risk of sustaining a second head injury before the first has healed is Second Impact Syndrome (SIS). SIS occurs when a person, still symptomatic from a first concussion, receives a second blow to the head or body. The second impact does not need to be forceful; even a minor jolt can trigger the syndrome.
The mechanism involves a rapid loss of the brain’s ability to regulate its blood flow (cerebral autoregulation). This failure leads to massive, uncontrolled swelling of the brain tissue (cerebral edema). The rapidly increasing pressure within the skull can cause brain herniation, where brain tissue is forced through openings in the skull structure.
Neurological collapse can occur within minutes of the second impact, leading to a swift deterioration of consciousness, respiratory failure, and death. The mortality rate for SIS, when diffuse cerebral swelling occurs, is estimated to be at least 50%. For those who survive, the outcome is often severe, permanent disability.
Hindering Brain Recovery
Even if Second Impact Syndrome (SIS) is avoided, playing sports while concussed exacerbates symptoms and significantly delays recovery. A concussed brain enters a state of metabolic crisis, characterized by mitochondrial dysfunction. Neurons struggle to produce sufficient energy, making the brain highly vulnerable and susceptible to further damage.
Physical exertion, which requires increased cerebral blood flow and energy, prevents the injured brain from restoring its delicate chemical and energetic balance. This activity essentially draws energy away from the healing process, delaying the normalization of brain metabolism. Consequently, athletes who return to play too early often experience a worsening of existing symptoms, such as persistent headaches, dizziness, fatigue, and cognitive fog.
Clinical and metabolic recovery times may differ, as brain function can remain altered even after symptoms have cleared. Forcing the brain to perform complex cognitive and physical tasks during this vulnerable period prolongs the time until full recovery is achieved, sometimes extending the typical recovery window of a few weeks into months.
Chronic Neurological Health Concerns
Beyond delayed acute recovery, returning to play while concussed or sustaining multiple head impacts over time raises concerns about long-term neurological health. One outcome is Post-Concussion Syndrome (PCS), a condition diagnosed when concussion symptoms persist for weeks, months, or even years after the initial injury. Symptoms of PCS can include enduring difficulties with memory, concentration, mood, and sleep.
Repetitive head trauma is also the established risk factor for Chronic Traumatic Encephalopathy (CTE), a progressive neurodegenerative disease. CTE is associated with the accumulation of an abnormal protein, tau, in the brain tissue.
Unlike PCS, CTE symptoms do not typically present until years after the trauma-producing activity has ceased. The definitive diagnosis of CTE can only be made post-mortem through a brain tissue biopsy. Preventing repeated injury is the only known measure to mitigate the risk of developing these chronic conditions.
Mandatory Immediate Action Steps
Upon any suspicion of a concussion, the athlete must be immediately removed from play for the day. The principle of “If in doubt, sit them out” must be strictly followed, as symptoms can be delayed and may not appear until hours later. Sideline personnel are not expected to diagnose the injury, but rather to recognize the signs and symptoms and remove the athlete from the environment.
Following removal, the individual must be evaluated by a qualified healthcare professional experienced in concussion management. This evaluation is not a task for a coach, parent, or teammate.
If certain “red flag” symptoms are present, such as repeated vomiting, a worsening headache, or a seizure, emergency medical services should be activated immediately. The athlete should not return to any physical activity until they are medically cleared and have successfully completed a supervised, gradual return-to-play protocol. Adherence to this medical guidance is mandatory to ensure the brain has fully recovered and to prevent the devastating consequences of re-injury.