David Jackson began the summer intending to run two marathons every day. A hundred days later, the original plan had changed dramatically, but the former professional rugby player was still moving.
Jackson completed the final stage of his extraordinary running challenge at Caernarfon Castle on Saturday, September 5th, bringing an unbroken sequence of 100 ultramarathons in 100 days to an end.
The performance formed part of a Guinness World Records bid for the most consecutive ultramarathons completed by a man. Jackson moved beyond the previous mark cited by his campaign when he completed his 81st ultramarathon on August 17th, before continuing for another 19 days.
The 44 year old, widely known as Jacko, covered an estimated 5,500km during a journey through England, Scotland and Wales. That is roughly equivalent to travelling from London to New York on foot.
His Mission IN Possible challenge was created to raise money and awareness for Headway UK and Head for Change, two charities supporting people affected by brain injuries.
The Original Plan Lasted 13 Days
Jackson set out on May 29th with an even more punishing target. He intended to cover two full marathons on every one of the 100 days, producing a total of 200 marathons and more than 8,450km.
For the first 13 days, that was exactly what he did. Jackson completed 26 marathons before a leg injury brought the original schedule to a sudden halt in the Lake District.
Rather than abandon the entire project, he changed its terms. From that point onwards, the daily target became one 50km ultramarathon.
It meant accepting that the original distance would not be reached while preserving the central challenge of running beyond marathon distance for 100 consecutive days.
The revised plan still left Jackson facing another 87 ultramarathons, with no scheduled rest day and little opportunity for an injury or illness to settle.
Brain Injury Brought His Rugby Career to an End
The reason behind the challenge reaches back to 2013, when Jackson’s professional rugby career ended following a traumatic brain injury and a seizure during a training session.
The former Nottingham Rugby player subsequently experienced fatigue, sensitivity to light and problems with his cognitive function. Running was not an immediate part of his recovery. It took seven years following the injury before he completed his first marathon.
Long distance running and breathwork later became central to his work as a coach, eventually providing the foundations for Mission IN Possible.
Jackson’s chosen charities reflect his own experience. Headway UK provides services and support to people living with acquired brain injuries, while Head for Change works with former sportspeople and families affected by neurological conditions linked to contact sport.
The challenge was launched with the ambitious aim of raising £1 million for the two organisations.
Hundreds Joined the Journey
Mission IN Possible travelled through 25 locations across Britain, with Jackson generally remaining in each area for four days.
Rather than disappearing along remote roads for the entire distance, he completed much of his running on repeated 5km and 10km loops. This allowed members of the public to join him for anything from a single lap to an entire ultramarathon.
Around 800 people are estimated to have run alongside Jackson during the 100 days. They ranged from experienced endurance athletes to people completing their first organised 5km, with ages stretching from eight into the eighties.
Jackson and his wife Catherine spent much of the summer living in a campervan as the challenge moved between locations. Catherine managed much of the nutrition, physiotherapy and daily logistics needed to get him back to each starting line.
The scale of the undertaking could also be measured in smaller details. Jackson worked through seven pairs of running shoes while the couple relied on assistance from friends, rugby clubs, local runners and strangers throughout the route.
A Guinness World Record Bid Awaiting Verification
Jackson and his campaign presented the 100 day undertaking as a Guinness World Records attempt throughout the summer.
The previous men’s mark cited by the campaign stood at 80 consecutive ultramarathons. Jackson passed that total on August 17th before extending his sequence to 100 at Caernarfon Castle.
Completing the distance does not automatically provide formal Guinness recognition. Route data, witness statements and other supporting evidence must be submitted and assessed before the performance is ratified.
Jackson’s own campaign has acknowledged that verification remains pending. For that reason, his achievement can currently be described as a completed Guinness World Records bid rather than a formally confirmed Guinness World Record.
That qualification does little to reduce the physical scale of what he completed. His opening 13 days contained 26 marathons, followed by almost three further months of daily 50km runs.
The challenge Jackson finished was not precisely the one he announced. Injury removed the possibility of completing 200 marathons, forcing him to choose between stopping and creating a demanding new target while already exhausted.
A hundred consecutive ultramarathons was the answer.
Further information and donations are available through the Mission IN Possible fundraising page.
