From biomechanics of football heading to brain tissue biophysics

There is growing public concerns and anxieties around the consequences of exposure to impact from football heading. It is partly fuelled by recognition of increased risk of development of neurodegenerative disease in late life of former players. Nearly all the current study on prevalence of dementia in sports, encountering head contact, are based on retrospective clinical data. A basic understanding of science behind the damaging effects from football heading impact is crucial.

In this project, we will investigate the mechanical effects of impact from heading to brain tissue in terms of micro-injury at tissue and cellular levels. Outcomes from this study would aid in evaluating the different strategies to protect the players and informing guidelines from various governing bodies on controlling the associated risks.

The growing concerns regarding long term effects of repeated brain insults from head impact in football, particularly those with no clear or marginal concussion symptom, has applied pressure to football sport’s governing bodies. Last week a new guideline from the Scottish Football Association bans professional footballers in Scotland from heading the ball in training the day before and after a game. Data in sports medicine have demonstrated strong correlation between susceptibility to neurodegenerative disease and exposure to repetitive head impacts. However, there is lack of fundamental scientific understanding on injury mechanisms that encompass the impact mechanics of heading and their cumulative effects on tissue structures and the corresponding biological response to the damage. Particularly, it is still not clear to what extent impact from heading can cause damage, to what type of tissue and how long it will take to fix the damage.

Although brain injury from blast has been investigated intensively, there is still big knowledge gap when translating those understanding on injury mechanisms to situation like impact from football heading. Apart from the difference in scales and loading mechanism, most of the research on blast injury are carried out using animal models. Due to the divergent nature of human factors involved in sports, it is impossible to apply the same scale-up/down approach to investigation of mild traumatic brain injury (mTBI) from heading. The bright side is that mTBI is supposed to be a local and immediate effects of mechanical stress to brain tissue from heading. Hence, fundamentally the nature of the problem is more about mechanics of biological fluids, cell and tissue, and physiological structure effects in response to stress wave from interaction of skull and football.

Stress wave from impact of heading can propagates through various brain tissue structures of different density and materials properties and be reflected at their boundaries. Blood brain barrier (BBB) is a highly selective endothelial barrier that prevents foreign substances ,circulating in the blood, from entering the brain. One of the mechanisms of mTBI proposed is leaking BBB due to shear stress and/or micro-cavitation in capillary structures, attributing to the fluid mechanical response to the stress wave. In vitro models of BBB have been developed and used very intensively in drug screening and testing. The novelty of this project is understanding impact energy dissemination process of heading in the context of micro-injury at tissue and cellular level of BBB. The objectives are: 1) Modification of an existing human skull surrogate to allow accommodation of engineered BBB structures and the corresponding biological practicality; 2) Applying the modified physical models to verify pressure profile of heading at different impact location and velocity; 3) To gain understanding of mechanical response from BBB, simulated cerebrospinal fluid (sCSF) and blood; 4) Investigation of over-pressure and under-pressure effects to the engineered BBB and tissue structures; 5) Identification of impact threshold effects on cavitation of sCSF and blood with and without pre-existing microbubbles.

At the end of project, we should be able to, establish quantitative relationship between the extent of stress wave and the micro-injury and cavitation of brain tissue, and map out the impact “dangerous zone” of ball-head collisions.

Supervisors

Primary supervisor: Dr Yang Liu

Entry requirements for United Kingdom

Successful applicants should have, or expect to achieve, an undergraduate honours degree with a minimum classification of a 2:1, or equivalent in a relevant subject for the PhD topic. A relevant master’s degree and/or experience would also be advantageous.

English language requirements

Applicants must meet the minimum English language requirements. Further details are available on the International website.

How to apply

All applications should be made online. Under programme name, select ‘Mechanical and Manufacturing Engineering’. Please quote reference number: P1SAM23-10 in your application. 

Competition for funded entry is high so please ensure that you submit a CV and the minimum supporting documents by the advert closing date. Failure to do so will mean that your application will not be taken forward for consideration. See studentship assessment criteria.

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