The ball that the old man plays in the square is a fitness ball. Fitness ball is mainly to enhance the toughness, flexibility and coordination of fingers and wrists, which can enhance the strength of fingers, palms and wrists and help prevent the elderly from shaking hands and stiff knuckles and wrists. Stimulating palm acupoints with fitness balls can reflect and adjust the functions of the central nervous system, give play to the functions of the brain to improve intelligence and relieve fatigue, and at the same time, it has the functions of relaxing muscles and tendons, promoting blood circulation, strengthening bones and muscles, and strengthening internal organs.