Non-linear temporal contact pressure for quantification of impact severity from association football collisions

Engineering of Sport 15 - Proceedings from the 15th International Conference on the Engineering of Sport (ISEA 2024)

A series of epidemiological cohort studies have indicated elevated risk of later life neurodegenerative disease development and mortality, consequential of a professional football career. It is postulated these increased risks are explained by repetitive heading of the football. Neurodegeneration has been anecdotally observed and diagnosed in players from older “eras of play”, however the ball has changed significantly since, in terms of materials, shell construction and manufacturing assembly methods. Assessing the relative impact severity between balls from different eras is challenging, due to the lack of evidence regarding a damage mechanism specific to likely sub-clinical CTE lesions arising from football heading. Many researchers have attempted to quantify impact severity using metrics such as, or linked to, peak impact force, which notionally causes greater head accelerative magnitudes and increased risk for brain injury through the “brain slosh” mechanism, often deemed responsible for concussion. However, as evidence has emerged suggesting subclinical CTE injuries are independent in type, location and distribution from concussion, it is likely that additional characteristic measures of impact severity may be more appropriate for assessing asymptomatic impact risks. Contact pressure is a largely unexplored metric within the football collision literature, only derived computationally, where non-linear temporal pressures were observed with high peak contact pressures within the first quarter of the contact time, preceding the time at which peak force occured. This study aimed to experimentally measure temporal contact pressure from football impacts, and assess its appropriateness in quantifying and comparing impact severity from football collisions.