Beijing, April 23 -- On a crisp Sunday morning, the starting gun rang out at an innovation zone on the southeastern outskirts of Beijing. More than 100 humanoid robotic runners clattered across the starting line, their servos humming with a staccato whir.

The novelty had worn thinner than it had been the previous April, when the first annual humanoid robot half marathon drew large crowds. This time, however, the machines had more to prove than just putting on a show.

Over the past year, Chinese robots have wowed global audiences with dynamic feats of speed and agility, including sprinting, martial arts and gala dancing. Once the cheers died down, a key question emerged in the era of embodied intelligence: how can these machines move bey...