Contact events in rugby linked to reduced blood flow to brain

Repetitive contact events incurred over a single season resulted in professional rugby union players having a reduced ability to regulate blood flow to the brain, which may pave the way for neurodegenerative disease later in life. That’s according to a new study led by the University of South Wales and published in the journal Experimental Physiology.

Previous research in rugby union has predominantly focused on concussion incidence, linking concussion in rugby with neurodegenerative diseases in later life, but the physiological toll of repetitive contact on the field has not been investigated to date. The new study addresses these gaps by highlighting the physiological ‘signatures’ of professional rugby players who are exposed to repetitive contact sustained on the field.

The researchers collected data before, during and after a season that comprised 31 games. Before the season began, they created a profile for each player based on data including molecular (blood-borne), cerebrovascular (blood flow regulation to the brain) and cognitive (memory, attention, concentration) metrics.

During the season, the team determined how many contact events each player was exposed to throughout play. They also mapped concussion incidence in order to determine which match event was most likely to cause concussion. Following conclusion of the season, they reassessed the players’ physiological profiles and mapped these against contact events sustained throughout the season.

The study highlighted that repetitive contact sustained through participation in rugby union causes subtle yet important alterations in a player’s ability to regulate blood flow to the brain over a single season, which may potentially pave the way for neurodegenerative diseases in later life. This decline in blood flow regulation is believed to be related to an increased formation of invisible molecules called free radicals that circulate in the bloodstream. In excess, they prevent blood vessels from opening up as they should, to get oxygen and glucose to the brain due to a shortage of nitric oxide, which causes blood vessels to open.

Additionally, the researchers compared effects on players who were in the position of forward versus back. Compared to backs, forwards were involved in more contact events (such as tackles and collisions) and demonstrated an accelerated decline in their ability to regulate blood flow to the brain.

“We hope that this study will encourage more rugby teams to engage in larger-scale studies of this nature to determine the lifelong implications associated with recurrent contact and concussion in rugby, including the potential links to neurodegeneration in later life,” said Professor Damian Bailey, senior author on the study. “Our ultimate goal is to make the sport safer for the players and minimise the damage they incur through contact.”

Image credit: ©stock.adobe.com/au/Alison Bowden

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