Comparison of Frequency and Impact Magnitude of Heading in 1966 and 2018 International Professional Men's Soccer Matches

Abstract

Athletes participating in professional soccer are at an increased risk for long-term neurologic disease due to exposure of repetitive head trauma (MacKay et al., 2019). Recent studies have confirmed cases of dementia and chronic traumatic encephalopathy in retired professional soccer players who played during 1966 (McKee et al., 2014; Hales et al., 2014; Bieniek et al., 2015; Ling et al., 2017; Grinberg et al., 2016). It is suspected that repetitive sub concussive impacts from heading may be a contributing factor to the development of chronic neurological deficits (Matser et al., 1998; Witol & Webbe, 2003). It is unknown if current soccer players are at similar risk of brain trauma. Differences of soccer balls, rules changes, and evolution of the game, may have influenced total frequency and impact magnitude of heading. A comparison of frequency and impact magnitude of heading between 1966 and 2018, highlights the potential risk of chronic neurodegeneration in professional soccer players. Ten 1966 and ten 2018 FIFA World Cup matches were randomly chosen for video analysis. Total frequency of headers were documented for each game. Header exemplar reconstructions were completed in the laboratory using a 1966 Slazenger Challenge and 2018 Telstar 18 ball. A pneumatic linear impactor and projectile launcher were used to hit the ball and impact a Hybrid III head form to measure dynamic head response. A finite element model was then used to determine heading magnitudes as measured by Maximal Principal Strain (MPS). The study revealed there were no significant differences in overall frequency of headers between the 1966 and 2018 games. The year 2018 had significantly higher frequency of headers in the medium MPS category while, 1966 had significantly higher frequency in the high category. There were no significant differences of linear acceleration, angular acceleration, and MPS values when comparing the 2018 dry and 1966 dry ball at the same velocity and location. Current athletes who are heading the 2018 Telstar 18 are sustaining similar frequency and magnitudes of heading as athletes in 1966 under the same velocity and impact locations.