'The legs know what they need to know. It’ll be in them or not' - Heather Jackson to defend her Unbound XL title just weeks after finishing the 250-mile Cocodona running race

Heather Jackson is preparing to defend her Unbound XL gravel race title just weeks after completing the grueling 250-mile Cocodona ultramarathon across the Arizona desert. Rather than following the typical pre-race routine of fine-tuning equipment and focusing solely on cycling fitness, Jackson spent nearly 70 hours running with minimal sleep, enduring hallucinations and extreme fatigue. Despite the physical and mental toll, she views Cocodona not as a distraction but as an integral part of her broader ultra-endurance season, which also includes the upcoming Tour Divide bikepacking race. Jackson’s approach to training has evolved significantly since her days as a professional triathlete. She no longer fixates on data or peak freshness for individual events, instead adopting a philosophy centred on building overall durability and resilience across multiple disciplines. Her recent preparation has involved balancing moderate running mileage with endurance cycling, strength training, and hill repeats, focusing on maintaining the ability to endure long hours in the saddle rather than maximising specific fitness metrics. This shift reflects her belief that ultra-endurance success depends on a combination of physical and mental toughness rather than purely aerobic capacity. The former triathlete’s transition from professional racing to ultra-endurance events has been driven by curiosity and a desire for new challenges. While gravel racing initially appealed to her sense of adventure, she found the increasing professionalism and tactical nature of the sport less aligned with her strengths. Instead, she has gravitated towards longer, multi-day events that test sleep deprivation and sustained effort, such as Unbound XL, Cocodona, and Tour Divide. Jackson’s recent performances and evolving goals illustrate her commitment to pushing the boundaries of endurance sport beyond conventional formats. As she approaches the 2025 Unbound XL, Jackson remains realistic about her performance prospects given her recent exertions and ongoing recovery. She emphasises that her legs “know what they need to know” and that the focus in the final week will be on reacclimating to the bike rather than chasing perfection. Whether she repeats her victory or not, Jackson views the race as a valuable part of her broader ultra-endurance journey, with the Tour Divide looming as the ultimate test of her evolving athletic philosophy.