First, every person is different. Many people can take a blow to the head without feeling or showing signs of sustaining a concussion. This is called a sub-concussive blow. In theory, one would think that taking several blows to the head would potentially “add up” to the point that the blows would cause concussion or brain injury. However, this has not been shown to be true.
There is no set number of blows and no exact or collected degree of force from blows over time that has been shown to result in a concussive injury. However we do know if you experience a blow and have shown or felt symptoms of concussion or have been diagnosed with a concussion and you continue to participate, you are at increased risk of permanent brain injury if you were to experience another concussion before you have fully healed and are 100% symptom-free.