Female: 1 1- 13 years old.

It is a period of sudden increase in height, with an average annual height of 4 cm. At this stage, stretching exercises such as ball swimming and running help to grow taller.

Male: 15- 17 years old.

Female: 13- 15 years old.

It is a period of rapid muscle growth, and strength exercises such as gymnastics and weight-bearing are helpful to strengthen muscles.

Teenagers' daily fitness exercise is best at 6: 00 am, 9: 00 am and 4: 00 pm.

The average daily exercise time exceeds 1- 1.5 hours.