BEIJING — Three Chinese astronauts have been living and working in China's space station core module Tianhe for more than a month. They are scheduled to stay in space for three months.

The astronauts have been exercising, maintaining healthy diets and undergoing regular check-ups to reduce the effects of living in a microgravity environment.

Scientists have found that microgravity weakens both muscle and bone, and the weakening of muscle can accelerate the weakening of bone.

In Tianhe's exercise area, the three astronauts can use a treadmill, spin bike and resistance bands to burn calories and practice strength training.

Li Yinghui, deputy chief designer of China's manned space program astronaut system, said the three astronauts have personalized daily exercise schedules according to their physical conditions.

Li said that they currently undertake moderate-intensity exercises every day, at levels requiring approximately 60 to 80 percent of the astronauts' maximum strength.

The intensity will gradually increase as their time in space progresses, Li noted. "It is only in this way that they can resist the physiological effects of microgravity."

Liu Weibo, deputy chief designer of the astronaut system, said the astronauts will also use a device called a neuromuscular electrical stimulator to stimulate the nerves in their muscles, restoring function and strength and preventing muscle atrophy. Experts on the ground can adjust the device according to the status of the astronauts.

According to Liu, dozens of pieces of medical equipment are available in a checkup cabinet. The astronauts have regular physical checkups every four to five weeks, including ultrasound examinations and complete blood counts.

A healthy diet has also been designed for the astronauts. They can choose from more than 120 variations of high-quality and appetizing space food, including staple foods, non-staples, meat and vegetables.

On June 17, China launched crewed spacecraft Shenzhou-12, sending the three astronauts to its space station core module Tianhe for a three-month mission.