Every morning, in schoolyards and public parks, millions of Japanese people bend and stretch following directions recorded over a piano track—a nearly century-old fitness routine known as rajio taisō. These Japanese calisthenics date back to 1927, when the Ministry of Posts and Japan’s public broadcaster, NHK, teamed up to promote national health exercises on the radio. According to the Japanese government, over 25 million people still participate in the three-minute-long choreography at least twice a week, enjoying the communal exercises “not only for their health benefits but also as an activity that brings people together.”

Perhaps surprisingly, synchronized group gymnastics may foster cooperation, improve mental health and make people more sympathetic to one another. Wheth...