What is Concussion?

Concussion, also known as mild Traumatic Brain Injury, is caused by a single impact to the head, which creates abnormally strong rotational forces to the brain (rotational brain injury), causing damage to brain nerve cells and shearing. Concussion is the most frequent form of brain injury and can be potentially career-ending and life-changing for every player in sport.

What are the symptoms of a Concussion?

Concussion produces symptoms that an individual is aware of (e.g. headache, dizziness) or signs that another person can see (e.g. balance disturbances).

Symptoms of concussion include:

  • Headache

  • Dizziness

  • Confusion

  • Visual Problems

  • Nausea or Vomiting

  • Fatigue

  • Drowsiness

  • Pressure in the head

  • Light or noise sensitivity

How Long do Concussions Last?

Changes in white matter, brain connections and blood flow can persist a year or more after a concussion. Returning to play too soon can increase the risk of sustaining further injury and subsequent symptoms, requiring a prolonged period of recovery. Repetitive concussions can lead to long-term progressive symptoms of brain injury due to Chronic Traumatic Encephalopathy (CTE).

A concussion can last from hours to days and depends on each individual case. Early recognition is key. Initially, there is a need for 24-48 hours of rest, followed by gradual resumption of everyday activity, and then a graduated return to cognitive and physical activity. For more serious symptoms, the period of rest should be extended and a reduction in physical activity recommended.

While the more serious concussions can last anywhere from weeks to months, it is vitally important to confidently know the signs of a concussion and to contact your healthcare professional for the correct guidance and advice.

There are risks in returning to play too soon after a concussion. Another impact has the potential to be fatal – Second Impact Syndrome, although this is rare, and most common among children and youth players.

How Frequent is Concussion in Sport?

It is suggested up to 90% of concussions go unreported. Estimates from the US, where there is a much greater awareness of brain trauma, records of head injuries and extensive data sets around concussions suggest that around 50% of concussions go unreported to coaches, medical staff or parents.

Every year in English professional rugby, concussion accounts for 28% of all injuries, and in football, as many as 22% of all injuries are head-related and concussions. Putting that into context:

Likely concussion and brain injuries for women in England playing football and rugby is x 13 times greater than the number of women diagnosed with breast cancer in the UK each year.

Likely concussion and brain injuries for men in England playing football and rugby is x 39 times greater than the number of men diagnosed with prostate cancer in the UK each year.

Sub-Concussive Impact

What is a sub-concussive impact? It is an impact that damages brain cell function, but does not produce overt signs or symptoms. Sub-concussions go largely unnoticed.

Are sub-concussive impacts serious? Yes. Repetitive, sub-concussive impacts also cause damage to the brain and lead to damage later in life. The risk and severity of CTE are not caused primarily by single, big hit concussions, but by multiple sub-concussions.

The force to the brain to cause a concussion is 2-4 times greater than for a sub-concussion, but sub-concussions are over 500 times more frequent.

Is a sub-concussive impact only from heading a football? No. They can come from head-to-head, head-to-ball and head-to-ground impacts. In football, only 13% of head impacts come from the ball.

Mechanics of head impact in football

Concussion FAQs

Here you can find answers to some of the more common questions surrounding concussion.

Symptoms of concussion include:

Headache | Dizziness | Confusion | Visual Problems | Nausea or Vomiting | Fatigue | Drowsiness | Pressure in the head | Light or noise sensitivity

A player should be removed from play as soon as they are suspected of having a concussion. Those who continue to play after suffering a concussion are more likely to have a higher number of symptoms and more severe symptoms, compared to those who stopped playing immediately after their injury.

We don’t know any safe threshold tolerance for rotational forces to the brain, or if a certain number of impacts leads to later-life brain degeneration, or if there is a safe threshold of repetitive impacts in a game, season and career. This means every concussion has the potential to be career-ending or life-changing.

No. It’s not the force of the impact to the head in sport, but how the force causes the brain to move inside the skull that is significant to cause damage.

Concussion does not necessarily require a loss of consciousness. A blackout only occurs in approximately less than c.10% of concussion cases.

There is a wide variance in incidences of concussion and sub-concussion across contact sports. It is suggested up to 90% of concussions go unreported.


Concussion and sub-concussion accelerate the progression to negative cognitive, psychiatric, or mental health outcomes. Concussion and sub-concussion can also lead to physical, emotional, and sleep problems.

Research Highlights:

  • There’s a significant association between a history of concussion and lower extremity injury, especially lateral ankle sprain, knee injuries and muscle strains. All athletes of all levels in sport have a greater risk of lower-body injury issues for more than a year following a sport-related concussion. In some cases, this risk is as high as 67%.
  • Those who have a history of three or more concussions have a five-fold increased risk of developing mild cognitive impairment in later life.
  • Those who have lost consciousness due to sustaining a head injury in their 50s or younger can experience exacerbated or accelerated dementia symptoms.