Children's sports system is characterized by a large amount of organic matter in bones, and the proportion of inorganic salts is 1: 1. Therefore, bones are elastic and plastic, but their hardness is small and they are not easy to fracture, but they are easy to bend and deform. Lower limbs and spine develop late, and excessive training or long duration may cause deformation of spine and flat feet. Children's bones are not completely ossified, so they are easily injured in sports. Before 16 years old, the strength quality of boys grows rapidly with age, so it is best to carry out strength training after muscle development is mature, that is, 16- 18 years old.

The cardiovascular system, cardiac volume and cardiac output of children and adolescents are smaller than those of adults, so the adaptation mainly depends on increasing the heart rate during high-intensity exercise, but this adaptation method can not meet the long-term high-intensity exercise and will lead to hypoxia. During adolescence, the heart develops rapidly, blood pressure rises rapidly, and sometimes "adolescent hypertension" occurs. At this time, if strength training or even static strength training is carried out, dizziness, headache and other symptoms will be aggravated.

Respiratory system, the child's respiratory muscles are weak, the chest is narrow, the alveoli are small, the breathing surface is shallow, and the vital capacity is small. Exercise is mainly maintained by accelerating the breathing frequency, so it is also easy to lack oxygen and fatigue.

Therefore, the appropriate age to start fitness should be 16- 18 years old. If you want to do strength training around 14 years old, don't use too much weight, it is best to use your own weight as resistance, and it is best not to be exhausted, and the total training time should not be too long.

Proper exercise is ok, as long as you don't lift weights, it should not affect your height.

Everyone's development is different Some people 16 years old, so they won't grow up.

Some will grow up. I don't know,

If you are thin, push-ups and sit-ups are better.

Dumbbells and barbells are too heavy for you to lift. It's no good to handle with care.

Don't exercise after smoking, it will affect the development of heart and lung. I study medicine, and many diseases are caused by smoking. .

I wish you the best of health!