ATHX vs Nuclear Fit: distance, stations, price & difficulty compared (2026-27)

ATHX is a UK-born hybrid fitness competition, co-founded by coach Ollie Marchon, that now runs events across the UK, Europe and the United States. Each ATHX event is a continuous 2.5-hour session across six zones. Every competitor completes the same three workouts: a Strength zone (20 minutes), an Endurance zone (30 minutes) and a MetCon X zone (30 minutes). These are separated by a warm-up zone, a refuel zone and a recovery zone. The workouts and movement standards are published for each season.

Athletes enter as singles or pairs, in an ATHX or a harder ATHX PRO category, and pairs can be same-sex or mixed. Season results lead to the ATHX Finals, held in Lisbon in 2026. The fixed rest periods and clear divisions make ATHX accessible to first-timers, while the strength element suits athletes who lift as well as run and row.

Nuclear Fit is an outdoor hybrid fitness race run by Nuclear Races at its obstacle course site near Brentwood, Essex. Instead of an indoor track, athletes run six 1 km trail loops, each including two 4 ft hurdles, and complete a fitness station after each loop in a central arena called The Core.

The stations use farm-themed equipment: a tyre flip, a farmers urn hug, a plough pull, a milk churn carry, a sandbag duck-and-throw and a squat-and-lift, with separate loads for men and women. Categories include singles, doubles and mixed doubles, plus a three-person relay in which each member completes two runs and two stations, and a Pro wave with longer station distances. Waves start every 10 minutes, chip timing records each run and station split, and there is a 2-hour time limit. It suits runners and gym-goers who want a hybrid race on trails rather than indoors.