In the punishing world of Hong Kong endurance sports, few events command as much respect as the Hong Kong Four Trails Ultra Challenge (HK4TUC), a gruelling 298km (185-mile) test across the city’s major trail networks. While 51-year-old ultra-runner and coach Elliot Froidevaux has conquered the challenge twice, his journey from a 100kg (220lbs) heavy smoker to elite trail runner was no solo effort. Standing next to the Swiss-born, Hong Kong-raised Froidevaux is his older sister, Joanne Nixon, a...