It’s early on a summer morning and schoolchildren have gathered for some rhythmic exercise timed to music coming from the radio.

The “rajio taiso” (radio exercise) on NHK dates back to 1928, created by the “kampo” postal insurance system with the help of experts to commemorate the coronation of Emperor Hirohito, known posthumously as Emperor Showa.

Currently, 20 percent of the entire population, or around 27 million people, and 76.4 percent of elementary schools, still do the warmups, according to the National Radio Exercise Federation.

Following are basic questions and answers about the exercise:

What do the exercises entail?

The radio exercise involves easy movements that stimulate blood circulation and improve flexibility, according to the book “Itsudemo, Dokodemo, Daredemo” (“Whenever, Wherever, Whoever”) published by the kampo insurance system.

The warmups entail two parts, each consisting of 13 rhythmic movements. The second part is designed specifically for young people. After the exercise, pulse rates average around 140.

Where are the exercises performed?

The exercises can be done anywhere, at home for instance, provided there is enough space and a radio or TV. Neighbors sometimes get together in parks. Factory workers partake at the workplace. Most elementary school children do the exercises at school on sports day and in their neighborhood park during summer vacation.

Why are the exercises aired in the morning?

According to the National Radio Exercise Federation, morning workouts have an awakening effect. It takes around three hours for someone to fully wake from sleep, but with the radio exercise, which airs at 6:30 a.m. daily, nerve functions are activated and the blood gets circulated to muscles and the brain.

How did the exercises start and what are their origins?

The concept’s roots are in the United States.

Metropolitan Life Insurance Co. sponsored 15-minute radio broadcasts daily for exercise accompanied by piano in the 1920s in six cities, including New York and Washington, according to the kampo book on the history of the workouts.

Around that time, the average Japanese lived until sometime in their 40s, and many died of infectious disease and tuberculosis, which made the insurance business unstable.

Looking for ways to improve the nation’s health, two kampo employees visited the American insurer and brought back examples of the radio exercise to start similar workouts in the mid-1920s.

Did the exercises air during the war?

Yes. In fact, the Imperial Aid Association supported the radio exercises and played a part in promoting them to improve the health of both soldiers on the battlefield and rear-echelon ranks.

But the original version of the radio exercise was banned in 1946 by the Occupation because it appeared too militaristic. NHK subsequently created a new workout regimen, but it did not catch on in the tumultuous early postwar era and the show was canceled in 1947.

When did the exercises resume?

As the economy began to pick up, kampo in 1950 urged NHK to air a new exercise routine.

A year later, the current rajio taiso debuted with the help of the education ministry, health ministry, Japan Gymnastic Association and Japan Recreation Association.

Why do school kids do the exercises every day during summer vacation?

This got started when NHK and kampo began distributing radio exercise stamp cards to spread the activity. Elementary school children collect a stamp each time they exercise. When the card is filled at the end of the holiday period, the children get free prizes, including stationery or snacks.

Are there any qualifications necessary to teach the exercises?

In 2005, the federation started giving official certificates to people who pass a test.

There are three levels based on being able to promote the exercise activity nationwide, at the prefectural level or at the community level. The first two categories require advanced exercise skills.

The test is only conducted in Tokyo, Kobe and Kanazawa, Ishikawa Prefecture.

Are there any countries that have adopted the Japanese radio exercises?

Japanese immigrants in Peru and Brazil are increasingly engaging in the warmups, the kampo book says.

The Weekly FYI appears Tuesdays (Wednesday in some areas). Readers are encouraged to send ideas, questions and opinions to National News Desk