By sportswriters Liu Yang and Du Yaning
FUZHOU, March 20 (Xinhua) -- They don't sweat, cramp, or drift into a bad mood.
As humanoid robots begin lining up alongside human runners at marathons across China, the running community is confronting a new question: could these mechanical creations one day replace human pacers?
ROBOTS ENTER THE RACE
In recent years, robots have moved steadily from the lab into real-world settings, including road races, where robotic pacers are appearing with growing frequency.
For now, though, their role leans more toward spectacle than utility. At the 2024 Hangzhou Marathon, a four-legged robotic dog accompanied the fun run and acted as a sweeper in the half marathon, the final pacer responsible for ensuring runners finished within the cutoff time.
A year later, a humanoid robot greeted runners at the finish line of the Great Wall Marathon in Beijing's Huairou District. The 2025 Beijing Yizhuang Half Marathon allowed robots to take part alongside humans, albeit in separate lanes, while next month's 2026 edition plans to go further with humans and robots running together.
"The robots add a sense of novelty and fun," said Jiao Yuansu, who completed the 2026 Xiamen Marathon. "If a robot pacer showed up in front of me, it would give me extra motivation to catch up."
Fellow finisher Sun Kuangsheng noted their appeal for family-oriented events such as parent-child runs.
Organizers and industry figures see the machines as a bridge between cutting-edge technology and public engagement. Jin Da, marketing manager at Unitree Robotics, acknowledged that their current role in sport is largely entertainment-driven.
"They spark curiosity about AI and robotics," he said. His company's robotic dogs have also been deployed as "emergency runners," carrying first-aid kits and supplies to assist distressed participants.
Beneath the novelty, however, lies a more serious proposition: precision. Even elite human pacers are vulnerable to fatigue, dehydration, and simple error. A robot, in theory, is not.
"Set the pace, and it could be accurate to the second," said Dai Shiyu, a veteran pacer who guided runners to a 2:45 finish at this year's Xiamen Marathon.
Lin Rong, a marathon organizer in Fujian Province, pointed to the 2024 Putian Marathon, where a robotic dog served as sweeper.
"It was more stable in pacing," she said. "After all, human runners can fail."
Robots could also take on support roles such as mobile medical units, course sweeping, route guidance, and even waste collection, functions planned for the upcoming Beijing Yizhuang Half Marathon.
Researchers including Bai Yufei of Beijing Sport University and Zhao Yilong of the China Institute of Sport Science view the trend as a showcase of China's technological progress, helping demystify advanced innovation for the public.
PATH TO FULLY AUTONOMOUS ROBOTIC PACERS REMAIN BUMPY
At the 1,500-meter race during the 2025 World Humanoid Robot Games in Beijing, one robot veered off course and collided with its human operator. At last year's Beijing Yizhuang Half Marathon, only about 30 percent of participating robots reached the finish line, with times well behind those of human runners.
"Maintaining a steady speed over long distances is a huge challenge for power systems, hardware, and algorithms," Jin said.
The low completion rate and occasional mishaps underline the gap between current capabilities and public expectations.
Wang Guodong, an associate professor at Soochow University and an athletics official, highlighted battery life and navigation in crowded, uneven race environments as major obstacles.
For humans and robots running together, some raised their concerns.
Zhang Hua, an official with the Beijing Municipal Bureau of Sports, think humanoid robots are not mature enough to complete full marathons, particularly in mixed "human and robot" scenarios where safety must be assured.
For now, robot pacers are typically limited to half marathons or deployed as slower sweepers to avoid the congestion of mass starts.
Sun Yanjun, a three-hour pacer at the Xiamen Marathon, pointed to the risks: "On crowded or narrow sections, robots could be knocked over or trip runners."
Their presence also raised questions of fairness.
"Pacing support from robots and human pacers are fundamentally different," Wang said. "If both appear in the same race, it could trigger debates over fairness. As robots become more capable, rules will need to evolve."
REPLACEMENT OR COEXISTENCE
Beyond the technical and regulatory hurdles lies a more human question. Can machines replace pacers who sense a runner's struggle and offer a timely word of encouragement?
In every marathon, the so-called "wall" around the 30-kilometer mark is where races unravel and pacers prove their worth.
"The human element is irreplaceable," Sun said. "We observe runners during that phase, offer advice, and adjust based on conditions. Robots can't do that yet."
Dai added that human pacers provide technical guidance and reassurance that machines cannot replicate.
Chen Lin, a six-hour sweeper at the 2026 Xiamen Marathon, emphasized the emotional intelligence required.
"Beyond maintaining pace, our most important role is to support runners based on their physical and mental state," she said. "Robots can't tell when someone is struggling or about to give up. A marathon tests human willpower, and human pacers bring warmth and sportsmanship."
Most experts see the future not as a takeover, but a partnership.
Jin believes robotic and human pacers will complement each other, serving different needs. Zhao expects both to share the course, each playing to its strengths. Wang sees robots expanding into areas such as course inspection and intelligent medical support, enhancing rather than replacing the human experience.
"There will be robot and human pacers running side by side," Bai said. "That will be a beautiful sight on the course." ■
