Rugby player who lost career to brain injury nears finish of 100 ultramarathons in 100 days

A former professional rugby player forced to retire after a traumatic brain injury is days away from completing 100 ultramarathons in 100 consecutive days, raising money for brain injury charities along the way.

David "Jacko" Jackson, 44, set off from his home in north Wales in May 2026. His route took him through Scotland and England, and on Saturday 5 September he is due to finish at Caernarfon Castle in north Wales — 100 days after he began, with 700 people having run alongside him at various stages. They ranged in age from eight to their 80s, according to The Guardian.

Each daily run covers 50km — roughly 30 miles. Jackson has gone through seven pairs of shoes.

His rugby career ended abruptly in 2013, when he suffered a traumatic brain injury and a seizure during a training session. For months afterwards he dealt with fatigue, sensitivity to light and cognitive problems. An ultramarathon, for context, is any race longer than a standard 26.2-mile marathon; Jackson is running roughly double that distance every single day.

The original plan was even more demanding. Jackson intended to run two marathons a day — 200 marathons in 100 days, a challenge he branded "Mission in Possible" on his coaching website, The Breath Running Coach. On day 14, in the Lake District, a leg injury forced a rethink. He scaled back to one ultramarathon per day and has held that pace ever since.

He is raising funds for Headway, which supports people living with acquired brain injury, and Head for Change, a charity focused on brain health in sport. Both causes sit close to his own experience.

After recovering from his injury, Jackson retrained as a strength and conditioning coach and developed an interest in breathing techniques and endurance running. His wife, Catherine, has been with him throughout the challenge — acting as his physiotherapist, nutritionist and logistics coordinator.

The story has drawn attention beyond Britain. The Athletic, published by The New York Times, featured Jackson's challenge on 20 August under the headline: "A brain injury changed David Jackson's life. Now he's running 100 ultramarathons in 100 days."

What makes Jackson's effort resonate is the direct line between what ended his rugby career and what he is doing now. The brain injury that forced him out of the sport he loved became the reason he laced up 100 days in a row — and the reason several hundred strangers chose to run a few miles beside him.