Former rugby player David Jackson on brink of 100 ultramarathons in 100 days

The key for David “Jacko” Jackson is to take each stage nice and gently. “It’s not about running fast,” he said. “It’s more like the hare and tortoise story. Slow and steady – and do it again tomorrow.”

So far, so good. Jackson, a former professional rugby player who retired after a traumatic brain injury, is nearing the end of an extraordinary bid to run 100 ultramarathons (50km, or about 30 miles) in 100 consecutive days.

He began from his home in north Wales in May and, if all goes well, will finish back there, at Caernarfon Castle, on Saturday (5 September).

Jackson’s run has taken in Scotland and England, and he has been joined by more than 700 people, aged eight to in their 80s, who have run alongside him. He has used seven pairs of shoes.

“I should be feeling tired now,” said Jackson, 44, when the Guardian caught up with him in south Wales. “But I’m getting excited about getting to the end and, hopefully, making a bit of a difference.”

Jackson is raising money for the brain injury charities Headway and Head for Change, but the idea is also about drawing attention to the issue and hearing people’s experiences.

“All the way through, the highlights have been the people,” he said. “We’ve been to some really cool conversations.

“When you’re running side by side, people tend to share a lot. So many people have things they wanted to talk about. Some were excited because they’ve overcome something, others were in the midst of something really horrible but find running a great way to … keep them sane. People tell you some really, like, deep stuff.”

Jackson’s rugby career ended abruptly in 2013 due to a traumatic brain injury and seizure on the pitch during a training session. For months, he experienced symptoms including fatigue, sensitivity to light and cognitive issues.

When he recovered, he became a strength and conditioning coach and became interested in breathing techniques and then running. “Running is quite rhythmical and your breathing when it’s good is rhythmical. Running is a great way to train better breathing patterns and habits,” he said.

Jackson also became fascinated in the “marathon monks” of Japan, who train for years and run huge distances in search of enlightenment.

He set off on this challenge intending to do two marathons a day, but suffered a leg injury on day 14 in the Lake District. “I’d done 26 marathons in 13 days and the wheels fell off. I was hobbling, crying my eyes out. I was in pain and felt like a letdown.”

His wife, Catherine, who acts as his physio, nutritionist and logistics supremo, encouraged him to keep going. “The mindset was, if I can move, we’ll keep going until I can’t. If we manage to complete that leg, then we’ll try and do the same thing tomorrow. It sounds really cheesy, but it was one step at a time.”

The injury eased and Jackson was able to keep going, though he tweaked the challenge from two marathons a day to one ultramarathon.

The support vehicle is the couple’s camper van, where they prepare many of Jackson’s meals and drinks. Making sure he has enough fluids on board has been vital as he ran through the summer’s heatwaves.

Post-it notes are dotted around the van with inspiration and questioning messages including: “We choose our attitude”, “Is this a reaction or a choice?” and “Greatest ever comeback”.

Catherine Jackson said it had been an adventure. She thought people opened up to Jackson because he was prepared to make himself vulnerable by sharing his story. “Other people seem to follow suit. When he’s low, someone comes along with fresh energy or shares a heartfelt story that he gets locked into and it makes him keep moving.”

The couple have mainly slept in the camper van, but along the way well-wishers have offered them more roomy accommodation, cooked them meals and helped them with washing. “People have been very kind,” Catherine said.

Being away from home for so long has been a challenge. David said: “We’ve unplugged from society. We have no idea what’s going on. Which has been quite nice.”

He has not shaved during the run and has an impressive beard that brings to mind a famous movie runner – Forrest Gump.

“A few people have shouted ‘Run Forrest, run’ at me. It wasn’t intentional. You don’t look at yourself much in the mirror when you’re doing something like this and in any spare moment you’re eating or doing recovery. But the beard has become almost a symbol of how far I’ve run, so it’s staying for now.”