Document Type

Theses, Ph.D


Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence


2. ENGINEERING AND TECHNOLOGY, Medical engineering

Publication Details

A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophyof Technological University Dublin


Concussion in sport is very common and often the injury is undetectable using CT and MRI scans. In addition, approximately 50% of concussions areunreported.The project initially investigated the suitability of a skin patch sensor and a head-band sensorfor the measurement of head impacts in unhelmeted sports. It was found that both were unsuitable due to large angular accelerationerrors. Thestudy then collaborated withCAMLab at Stanford University and 25 Mixed Martial Arts (MMA) athletes were fitted CAMLab’s validated instrumented mouthguard. 451 video confirmed impacts were recorded at 19 sparring and 11 competitive MMA events. Five concussions were diagnosed during the competitive events. The most severe impacts were simulated using the Global Human Body Model Consortium head model. The average resultant linear acceleration of the impacts that resulted in a concussion was approximately 20% lower than concussive studies of US football while the resultant average angular acceleration was 34% higher. It ishypothesised that these differences are due to the high energy frontal impacts in US football as opposed to the ‘hook’ style punches in MMA.Large strains in the mid-brain occurred from frontal impacts whereas lateralimpacts resultedin large strains in the corpus callosum. It was found that the average strain in the corpus callosum of the concussed athletes was 0.27 which was 88% higher than that in uninjured fighters. In collaboration with the Genetics department in Trinity College Dublin it was found that the maximum principal strain correlated (R2=0.84) with the volume fraction of blood brain barrierdisruptionpost-fight. In conjunction with Stanford University,it was found that the spectral density of MMA impacts was higher than that in US football.This study is the first known study to measure in vivohead impacts in unhelmeted athletes that have suffered a concussion.