Furthermore , while the total number of blows differentiated the groups , the median peak linear acceleration did not. The number of impacts experienced in the week immediately preceding in season reassessment was significantly correlated with changes in fMRI activation in all players. Interestingly, the group with no concussion and no changes on cognitive measures had more collisions per player in each location on the helmet than the concussed group, suggesting that concussion was due to a particularly damaging single or smaller number of blows rather than a lowered concussion Threshold from a cumulative.