How much does it cost to check the bone age in the hospital?

Bone age test costs 20 ~ 30 yuan/person.

Section 1 Growth and Development of Children and Adolescents

In recent 20 years, the average height of countries in the world has increased by 1 cm every 10 years. The human body tends to be taller from generation to generation. According to records, more than 200 years ago, the average height in the United States was 170 cm, and now it has reached 180 cm, an increase of10 cm; In the past 30 years, the average height of Japanese teenagers aged 14 has increased by 8.2 cm. During the 80 years from 185 1 to 193 1 in Sweden, the height of recruits increased from 166.6 cm to 174.438+0 cm, an increase of 7.5 cm. The former Soviet Union measured the bones of soldiers in the18th century and found that the average height of soldiers increased by 20 cm in the past 250 years. In recent 20 years in China, the average height of urban youth aged18-25 has increased by 2.3 cm for men and 2.0/5 cm for women.

First, measure the height

The benefits of measuring height.

It is generally believed that weight changes rapidly, so the increase or decrease of weight is often used as an objective standard to evaluate health. In fact, using height growth to evaluate growth, health and fatigue is as accurate as weight.

In childhood and adolescence, measuring the height of 1 ~ 2 times a year (preferably once every quarter) is one of the important means to grasp the growth and development in time. Normal height growth indicates good growth and development; If the height growth is slow, basically not long, or even stops, it is necessary to analyze the reasons and take corresponding measures to make targeted remedies.

Middle-aged and elderly people often measure their height, which can also evaluate the degree of aging to some extent. Height decreases with age. The peak of normal people is between 20 and 30 years old. From the age of 40, the height decreases by 1 ~ 2 cm with each increase in age. The average height of the male elderly should be reduced by 2.25\\%, and that of the female should be reduced by 2.5%. It has been reported abroad that from the age of 40 to 90, the height of the human body can drop by 7 ~ 9 cm, and even obvious hunchback appears. This physiological change of human body is commonly known as "aging".

Height change in a day is also one of the important methods to evaluate physiological load and fatigue. Personally, it is the highest when you get up in the morning and the lowest before you go to bed at night. This height change is directly related to professional characteristics. Those heavy manual workers and athletes, especially weightlifters, have more obvious height changes in one day. Getting up in the morning is 2 ~ 5 cm higher than before going to bed at night. There are two main reasons for this change: first, the spinal disc is compressed. Intervertebral disc is cartilage tissue, and the elastic nucleus pulposus in the middle has a buffering effect, which makes the spine have certain stretching activities. Due to the load of the spine, the elasticity of intervertebral cartilage is temporarily "weakened" and the spine is shortened. Second, the muscles of the neck, back and chest that maintain the normal physiological curvature of the human spine are gradually tired after a day's load, and the support of the spine is reduced, the curvature is increased, and the height is correspondingly reduced. The physiological increase or decrease of the spine is only a one-day change. After a night's sleep, the muscles got a full rest, and after the fatigue was eliminated, the height recovered.

2. Methods and requirements for height measurement

1) measurement method: the measured person stands barefoot on the bottom plate of the altimeter in a "stand at attention" posture, and the heel, sacrum and scapula are close to the column of the altimeter. The surveyor can stand on the left or right side of the examinee, adjust his head to the level of the lowest point of the upper edge of the tragus and the lower edge of the orbit, and then move the horizontal plate of the altimeter to the top of the examinee's head with proper tightness, so as to measure the birth height.

2) Measurement requirements: Every time you measure your height, you should be barefoot. At the same time (more accurately in the morning), you should use the same altimeter, and your body posture should be the same before and after. The altimeter should be placed on the flat ground, near the wall. It is best to measure the height twice continuously, with an interval of 30 seconds. The results of the two measurements should be roughly the same. The error of the height gauge shall not exceed 0.5 cm.

3. Methods and requirements for measuring upper body length

1) measurement method: the measured person sits on the seat plate of the altimeter, and the pillow on the head, the ridge between the two shoulder blades and the sacrum should be attached to the column of the altimeter. When sitting, the head should be straight, the eyes should be straight, the trunk should be straight, the legs should be close together, the big legs should be kept at a 90-degree angle, the feet should be placed on the ground or the mat of the altimeter, and the arms should naturally fall to the side. The surveyor's position and operation are the same as height measurement.

2) Measurement requirements: The three points of the measured head, namely the occipital part, the ridge part between the two shoulder blades and the sacrum part, should be attached to the column of the altimeter. The rest are the same as height measurement.

4. Methods and requirements for measuring the length of lower limbs

1) measurement method: the measured person stands on a flat ground with his feet shoulder width apart. Measure the vertical distance from the upper edge of the femoral rotor of the left lower limb to the ground, which is the length of the lower limb.

2) Measurement requirements: The surveyor must accurately touch the upper edge of the greater trochanter bone of the subject. When touching, first stick the index finger, middle finger and ring finger on the trochanteric bone of the subject, let the subject bend his knees and lift his thigh, and then swing the straight leg back and forth several times, so that the subject can accurately judge the position of the upper edge of the trochanteric bone (the position where the upper end of the femur rotates with the action). The error of steel tape measure shall not exceed 0.2 cm.

Ordinary families don't have an altimeter, so they can straighten and fix it on the door with a small tape measure, and replace the horizontal plate of the altimeter with a book. According to the operation method, the height can also be accurately measured.

As mentioned earlier, height depends on two factors: heredity and acquired environment. Among these two factors, heredity plays an extremely important role, but the positive role of acquired environmental factors, especially in the two critical periods of growth and height, in ensuring adequate and balanced nutrition and regular physical exercise cannot be underestimated.

Many people want to grow tall, and some young women pay special attention to the height of men when looking for a partner. Once upon a time, there was a joke circulating in the society, comparing young men of medium height to "disabled people". It is not appropriate to emphasize height unilaterally when choosing a spouse. Tall people have advantages, and short people also have advantages. Comparing the two groups, short people are smarter, smarter, healthier and live longer than tall people. Medical experts in China made a survey in Hunan, Hubei, Guangxi, Guizhou and other provinces, and found that most of the people over 90 years old were between 128 ~ 158cm in height and weighed about 40kg. American scholar Marlowe surveyed celebrities and athletes from all walks of life in the United States with the height of 1.73cm as the boundary. As a result, 1% of short people lived nine years longer than tall people. Among 750 men, 15 lived to be over 90 years old, and 13 was short. Of the nine celebrities who lived to be over 90 and succeeded, eight were short-lived. The average life span of a giant over 230 cm is only 39.8 years. Short men lived an average of 80.2 years, while tall men lived an average of 66.6 years.

The trend that human beings are taller from generation to generation will continue. Take China as an example. At present, the average height of men and women in China is 170.3cm and 159cm respectively. It is predicted that in one hundred years, the average height of men in China will exceed 183 cm, and that of women will exceed 169 cm. To this end, some scientists believe that in the future, we may control the sustained growth of mankind as we control the population growth today.

So what is the ideal height? With the development of science and technology, people expect height growth and height control to become a reality. If so, mankind will be happier.

Second, the factors affecting height

The height and weight index not only reflects the growth and development of children and adolescents, but also coincides with the development of various tissues and organs of the body. Height is the length and proportion of longitudinal parts of the human body, which originates from the longitudinal growth of the human body and is greatly influenced by genetic factors. Male is 20 ~ 24 years old, female 19 ~ 23 years old. The long bones and vertebrae of the limbs have ossified and the height has stopped growing.

There are many factors that affect height, such as heredity, nutrition, exercise, environment, living habits, race, endocrine, sexual maturity (menarche age 18 ratio1height 5 cm), distant marriage, medical progress and so on.

1, genetic

Growth and development are influenced by congenital inheritance, acquired nutrition, physical exercise and various living conditions. But among many factors affecting height, heredity is more important. The development of human body from single-celled fertilized eggs to complex multicellular individuals, from young fetuses to strong individuals, is controlled by genetic genes. The heritability of body length is as high as 0.75 ~ 0.92, especially for daughters, which is as high as 0.85 ~ 0.92. In other words, the height of men is 75% ~ 92%, and that of women is 85% ~ 92%, which is influenced by genetic variation. The highest for men is only 25%, and the highest for women is only 15%, which depends on other factors. Prove that heredity plays an extremely important role in children's height. Relatively speaking, weight is less affected by genetic factors, and 63% of men and 42% of women are affected by genetic factors. 37% of men and 58% of women depend on acquired environmental factors. It can be seen that the acquired environment has a great influence on weight.

2. Nutrition

Nutrition is an indispensable material basis for human survival, that is, to maintain normal life, develop the body and engage in activities, especially in the peak period of human growth and development, it is very important to ensure high-quality and sufficient nutrition supply and balance vitamins and minerals (calcium, phosphorus, zinc, etc.). The average height of urban children and adolescents in China is 2 ~ 4 cm higher than that in rural areas. One of the reasons is that urban nutrition is better than rural nutrition. Take protein as an example, the nutrition of height is "piled up" especially by protein. It is known that there are about 20 kinds of amino acids in human body or nature, and the amino acids that make up protein depend on nutrition. Food can provide enough 8 essential amino acids, which is conducive to accelerating the synthesis of protein, thus promoting the growth and development of human tissues and organs, especially the growth and development of bones and epiphyseal cartilage. Taking lysine as an example, Japan divided six pairs of twin babies into two groups. The first group was given normal nutrition, and the second group was given lysine in normal nutrition. After an experiment of 13200 hours, it was found that the second group was 1.7 cm higher and weighed 1 kg than the first group. The experiment on school-age children showed that the height and weight of the experimental group with 0.5 g lysine per meal were significantly higher than those of other school-age children. In some countries, 25 grams of soybean flour and appropriate amounts of calcium, iron and vitamins are added to the lunch bread of children and teenagers. After half a year, these children and adolescents are 2.62kg heavier, 0.9cm taller and 3.4g higher in hemoglobin than those who eat a normal diet. The reason is that protein is not only a "building material" of human body, but also an important substance of enzymes, hormones, hemoglobin, fibronectin and collagen involved in important physiological activities of human body. Similarly, the nutritional status of the mother also restricts the normal development of the fetus to a certain extent. If there is a lack of certain nutrients in the diet, it will cause fetal malformation.

Malnutrition will not only affect the growth and development, but also affect the quantity and quality of brain cells; On the contrary, overnutrition will lead to obesity, which is also harmful to the physical and mental health of children and adolescents.

Step 3 exercise

Among many acquired factors that affect height, the most active and effective factor is exercise. What affects the physical development of children and adolescents is muscle weakness. Doing more exercise is a physiological need for children and adolescents to grow taller. Therefore, sports is an important driving force for the healthy growth of children and adolescents. A large number of survey data at home and abroad prove that compared with children and adolescents of the same age who do not exercise or lack exercise, the chest circumference, vital capacity and grip strength of children and adolescents who insist on exercise are increased by 5-8 cm, 500- 1500 ml and 4.6-5.7 kg respectively, which is helpful for the growth and development of children and adolescents. According to the survey data of a primary school in Liaoning province, students who often participate in school or sports school training are 4 cm taller, weigh 2 kg and have 200 ml more vital capacity than ordinary students. In the extreme night without sunshine, children in the far north of the former Soviet Union are not enthusiastic about activities. Although they are tall and have big skeletons, their physical strength and endurance are poor. Compared with southern children of the same age, the grip strength is 8 kg less, the long jump score is 9 cm less, and the high jump score is 3 cm less. All these prove that physical exercise can not only promote height, but also affect the improvement of physical function and sports ability.

4. Environment

Environment includes natural environment, social environment and psychological environment. The environment also affects the growth and development of human beings to varying degrees. Take the influence of natural environment (the sum of various natural factors around human beings in human ecosystem), climatic conditions and geographical environment on height as an example. Generally speaking, children and adolescents in tropical and temperate regions have earlier sexual maturity and slightly lower physical development level. /kloc-the average height (cm) of 0/7 age group was analyzed by the Institute of Pediatrics of China Academy of Sciences in 1975. The results are as follows: Male, Beijing 168.7, Wuhan 167.8, Guangzhou164.7; Female, Beijing 157.7, Wuhan 157.3, Guangzhou 155.3. According to 1982 "Research on the Body Shape, Physiological Function and Physical Fitness of Children and Adolescents in China", it is proved that children and adolescents aged 7 ~ 17 in Beijing are 2.5 ~ 4.6 cm taller than those of the same age group in Hunan. The above two surveys prove that the height of children and adolescents in China tends to be higher in the north and lower in the south. This trend is not only related to food varieties, but also directly related to climate, geographical location, lighting time and other factors.

Psychological factors will also affect growth and development. Psychological factors can be said to be the sum of emotions, and seven emotions, such as joy, anger, sadness, joy, sadness, fear and shock, are all expressions of emotions. The emotional world is varied, and objective things give the human body a feeling of happiness, cheerfulness, happiness or sadness, pain and disappointment, which directly affects all human activities. Sudden, intense and persistent emotional stimulation will affect the activities of human organs, qi and blood, brain and endocrine system. Sadness, depression, sulking, etc. It is easy for children and adolescents to suffer from various diseases, which will affect their growth and development. Clinical observation has proved that children who are severely stimulated are not only prone to various diseases, but also grow slowly or even stagnate, leading to premature aging. This is the result of bad psychological factors affecting brain and endocrine function. Therefore, to create a good psychological environment for children and adolescents, especially families should give their children warmth, love and care under the premise of active inspiration and guidance, so that they can obtain necessary and normal psychological satisfaction and grow up in full spirit, happiness and health.

5. Living habits

Living habits cover a wide range, such as diet, exercise, hygiene, sleep, work and rest system, combination of work and rest and so on. Improving some living habits also helps to grow taller. According to relevant data, the average height of Japanese nationals increased by 2.23 cm in the 34 years from 1892 to 1926. Mainly because most people used to sit cross-legged. With the progress of the times, sitting cross-legged is gradually replaced by sitting in a chair, which promotes the growth of lower limb bones and is used for education. Body posture also affects height. When the human body enters the second peak period of growth and development (adolescent growth spurt period), the muscle growth rate lags far behind the growth of height, so the muscle fibers are thin, the cross section and volume are small, and the muscle strength is poor. Some children and adolescents don't pay much attention to the correct posture of standing, sitting, walking, reading and writing in their daily lives. They always habitually bow their heads, shoulder their backs, hold their chests and hunch back, which will lead to spinal deformation and affect their height 1 ~ 5 cm.

In addition, medical progress can also promote height. If you take zinc sulfate and lysine preparations, you can stimulate appetite and promote growth and development. The former Soviet Union achieved great success in promoting height through traction surgery. A dwarf named Peter Penkus, whose height is only 130cm, has reached 160cm after three years of treatment by Professor Yili salov. Professor Yi's treatment method is: pierce both ends of the long bones of limbs with a hammer and chisel, penetrate the muscles and bones with a sweater needle, and fix them on a metal frame with a steel wire. Three days later, use a screwdriver to lengthen the metal frame 1mm, and new bone cells will fill this small gap in just 24 hours, and blood vessels, muscles and tendons will also grow. Peter has grown 30 cm in three years, and his calf alone has grown 19 cm. Professor Yi has stretched himself for 300,000 people.

Third, predict height.

Height is the most important index of body shape characteristics, which has attracted worldwide attention. There are many methods to predict height, such as bone age prediction, foot length prediction, parents' height prediction, children's and adolescents' height prediction in the current year, height prediction at the beginning of adolescence, mathematical prediction and so on. This volume of data only briefly introduces the tested and scientifically based forecasting methods at home and abroad.

There are many methods to predict height, which can be roughly divided into two categories. One is to use the current bone age and current height to predict the adult height: the theoretical basis is that the height of each age stage is highly correlated with the adult height, R=0.8. According to the present bone age, how high can you predict?

From 65438-0987-88, China State Sports Commission organized a study on the evaluation standard of China people's bone age, and formulated the CHN method of China people's carpal bone development standard. 1992 was approved as the industry standard of People's Republic of China (PRC) and officially promulgated and implemented.

When shooting X-ray of carpal bone, the fingers of the left hand are separated, the palm is pressed down on the X-ray box, the hand is straight and in line with the forearm, and the X-ray lens is aimed at the third metacarpal bone, about 90 cm away from the back of the hand. X-ray should include not only all the hand and wrist bones, but also the distal radius of 3 ~ 4 cm.

The development degree of radius, metacarpal bone, phalanx and wrist 14 bone was evaluated by CHN method. Add up the grade scores of 14 bones, and then look up the table to evaluate the bone age. After systematic training and repeated practice, the error of CHN method in evaluating films is not great.

Bone age assessed by carpal bone age method is also called biological age, which is a sign of human growth, development, maturity and aging. In childhood and adolescence, biological age is usually regarded as the degree of growth and development. The biological age is roughly the same as the life age calculated according to the date of birth. However, due to the influence of heredity, nutrition, physical exercise, diseases and other factors in the process of growth and development, the development speed may not be completely consistent with the age. Some people develop ahead of time, and their biological age will be greater than their living age. There are also people whose biological age is less than their living age. The speed of development is sometimes uneven. A person's development is backward in a certain period, and after a period of time, it may be normal because of the acceleration of development. Traditionally, the difference between bone age and life span is within 1 year, which is called normal development. The difference between bone age and life age > 1 year is called precocious puberty. The difference between bone age and life span < 1 year is called developmental backwardness (short for late maturity). In the growth and development stage of children and adolescents, it is of great significance to regularly evaluate their development degree for promoting the healthy growth of children and adolescents.

Among various methods for predicting height by bone age, TW2Mark2 method is more accurate by comparison. When forecasting, you need to input the current height and bone age, and girls also need to input whether they have menstruated. Then calculate the adult height with different forecasting formulas for men and women.

The other is to predict adult height according to parents' genetic factors. There are also several forecasting formulas. After comparison, the error of foreign formulas is relatively large. After investigating and counting the height of 182 1 young men and women and their parents 1983 ~ 84, Hubei Institute of Physical Education calculated the prediction formula of birth height, which has a smaller prediction error than that of foreign formulas, and has a good application effect in the selection of athletes and the evaluation of teenagers' physical fitness in China. The height prediction formula is as follows: (unit: cm)

Boy height = 59.699+0.4 19× father height +0.265× mother height.

Girl's height = 43.089+0.306× father's height +0.43 1× mother's height.

The future height predicted by bone age is mainly predicted from the current development level, and the future height predicted by parents' height is predicted from the innate genetic possibility, so the prediction results of the two are completely inconsistent.

It should be noted that because there are many factors affecting height, it is impossible to take all the factors into account in the prediction formula no matter which method is used, and many changing factors such as nutrition, disease and environment of the predicted object cannot be predicted after a certain period of prediction. Therefore, although we are sure that these forecasting methods are scientifically based, the trend reflected by the forecasting results cannot be wrong. However, the error of height prediction is always inevitable.

Fourth, exercise promotes growth and height.

1, two critical periods of human growth

Judging from the law of human growth and development, there are two peaks in the growth and development of height in human life. The first time is from the second trimester to infancy. In the second trimester (4 ~ 6 months), the height of the fetus grows fastest, which is about 27 cm in these three months, accounting for half of the height of the whole fetus, which is the fastest growing stage in a person's life. The growth rate in infancy (from birth to 1 year) slowed down slightly, but it still increased by 20 ~ 25 cm, which was 50% of that at birth. After that, the growth rate slowed down and remained relatively stable until the second peak of growth and development. Women were about 10 years old and men were about 12 years old (puberty). The average height of adolescence increases by 7 ~ 8 cm, and the maximum height can be increased by 10 ~ 12 cm. The annual weight gain value is 4 ~ 7 kg, and the individual weight can reach 8 ~ 10 kg. About three years later, the growth rate slowed down again until the height of women was about 17 years old and that of men was about 22 years old. Because the second growth spurt of girls started earlier than that of boys, the height development curves of men and women crossed for the first time around 10 years old. Before crossing, boys were taller than girls, and after crossing, women surpassed men. At the age of 12, boys began to grow suddenly for the second time, and girls began to slow down, so conversely, men were taller than women and the curves crossed for the second time. Because of the long period of boy's sudden increase and long growth time, most men's body shape indexes are higher than those of women when they reach adulthood.

According to the average value, there are three types of development: early maturity, normal maturity and late maturity Early maturity is characterized by early development, and the peak of sudden increase in height appears early, but the process of sudden increase is often short, so although it appears higher at first, it is not necessarily higher than late maturity in the end. The weight-height ratio of precocious girls is generally higher than that of late-maturing girls, and finally the shoulders are narrow and the pelvis is wide, which tends to be short and fat. The characteristic of late maturity is that although it is short at first, it suddenly increases for a long time and is often higher than early maturity in the end. Late-maturing boys have narrow pelvis, wide shoulders and tall and thin figure. Normal development is somewhere in between.

When we know the general law and peak of height growth, besides supplementing comprehensive and balanced nutrition, especially in protein, pregnant women and fetuses, infants and children and adolescents can be fully recuperated in these two periods (in the second half of pregnancy, fetuses need to supplement calcium when growing bones, so it is advisable to eat more calcium-containing foods, such as soybean milk, tofu, eggs, potatoes, cabbage, carrots, etc. And small fish and shrimp can be eaten with skin after frying. During pregnancy, especially in the second trimester (4 ~ 7 months), the abortion rate is greatly reduced, the pregnancy reaction is eliminated or alleviated, and the mental state is stable. Moderate physical activities should be carried out, such as aerobic exercise, deep breathing, active games, walking, and a small amount of exercise with weak intensity and moderate rhythm. This can not only improve the functions of nervous system, cardiovascular system and respiratory system, regulate gastrointestinal function and human metabolism, but also contribute to fetal development and delivery.

After the baby is born, it is not a bad thing to cry a few times without illness or other external stimuli, but it is good exercise and good for health. Babies crying, stretching their limbs and "dancing" can not only accelerate blood circulation, provide sufficient nutrition and oxygen for the brain, bones and muscles, but also improve cardiopulmonary function and thoracic growth and development. Infants aged 6 ~ 12 months should be properly induced to play, turn over, climb or help them walk according to the situation, which is helpful to physical and mental health and brain development. The nervous system is the earliest, fastest and most mature system in human body. At the age of 6-7, the weight of the brain has reached 90% of that of adults, and it only increased by 10% at the age of 20, weighing about1400g. But at this time, the internal structure and function of brain cells have become complex and highly developed, reaching a very perfect period. Therefore, it is very beneficial to give babies more information to stimulate their brain development and physical and mental health.

The sudden increase of adolescence is a transitional period for children and adolescents to mature, and it is the second peak of growth and development in life. During this period, the shape, physiology, psychology, biochemistry, endocrine and intelligence of the human body will change suddenly, so moderate physical exercise in adolescence, especially full-body stretching exercise, is more helpful for growing taller.

2. Why can exercise grow taller?

There are three main reasons why exercise can promote height.

(1) increases the secretion of growth hormone. There are three endocrine hormones that control height, namely growth hormone secreted by pituitary gland, luteinizing hormone and sex hormone. Among these three hormones, growth hormone is the most effective and necessary substance to ensure the normal growth and development of human body. Experiments show that after 90 minutes of moderate-intensity physical exercise, the secretion of growth hormone in human body is twice that at rest. Good stimulation of exercise can also ensure a deeper sleep. Through EEG, ECG and eye flow monitor, scientists found that the sleep time of children and adolescents is 1 hour, and the secretion of related hormones (growth hormone, luteinizing hormone, sex hormone and prolactin) in the body is extremely strong, especially the secretion of growth hormone reaches its peak, with the content of 20 micrograms per milliliter of blood, which is 5 ~ 7 times that of daytime. Increasing the secretion of growth hormone can promote the normal growth and development of children and adolescents. According to the newspaper, a 23-year-old young woman lost sleep for two months because of illness, and her height increased by nearly 3 cm. If the growth hormone secretion is insufficient, it will seriously affect the growth and development of children and adolescents, and even suffer from dwarfism.

(2) It can increase the proliferation of epiphyseal cartilage. The height of the figure depends on the length of the long bones of the lower limbs and the growth and development of the spine. Anatomically speaking, the long bone of limbs is a tubular bone with cartilage between its two ends and the bone body (in infancy, each bone has a growth point or ossification center), which is called epiphyseal cartilage. People mature from infants, and their height has increased several times, mainly due to the growth of epiphyseal cartilage. When the epiphyseal cartilage ossifies, people no longer grow taller. The growth and development of epiphyseal cartilage is controlled by growth hormone. Insisting on physical exercise can not only increase the secretion of growth hormone, but also promote vigorous metabolism and accelerated blood flow. In a quiet state, it takes 20 ~ 25 seconds for blood to circulate to the whole body, and it is shortened to 8 ~ 9 seconds during exercise. Physical exercise can also increase oxygen uptake by 7 ~ 12 times. 15 ~ 20 years old teenagers, the breathing frequency can be increased from 18 ~ 20 times/min in a quiet state to 30 ~ 40 times/min, and the lung ventilation can be increased to 70 ~ 120 liters. Adequate blood oxygen and accelerated flow rate can provide sufficient raw materials for bone cells.

Proper exercise can not only provide sufficient raw materials for the proliferation of epiphyseal cartilage and give it beneficial "mechanical massage", but also play a good role in changing the shape, structure and function of bones, such as thickening bone density and making bones stronger and stronger; According to different pressure and tension, the arrangement of trabecular bone is more neat and regular; The muscle attachment protrusions on the bone surface are more obvious. These changes can greatly improve the performance of bones in tension, compression, torsion, bending and bending.

(3) More vitamin D and "air vitamin" can be obtained. Mass sports activities are mostly carried out outdoors. Outdoor sunshine and fresh air can make people get more vitamin D and "air vitamins". Physicists have found that sunlight emits seven colors of red, orange, yellow, green, cyan, blue and purple through the prism, and there are many invisible rays besides these seven colors, accounting for about 50 ~ 70% of sunlight. Red light can excite nerves and improve the functions of cardiovascular system, respiratory system and muscle tissue. Yellow light and green light have sedative effects, while blue light and purple light have inhibitory effects. In different seasons, the length and intensity of light are different, so seasons have a great influence on growth and development. Take height and weight as an example. In the four seasons of the year, the height growth is the fastest in spring. Compared with the three months from September to June, the height growth of the former is 2-2.5 times higher. On the contrary, the weight gain is the fastest in autumn, and it is the fastest in 9 ~ 1 1 period all year round. The main reason for the rapid growth of height in spring is that the sun is getting closer and closer to the earth in spring, so the sun contains more infrared rays and ultraviolet rays. Infrared ray has short wave length, strong penetrating power, and contains a lot of heat energy, which can evenly heat human skin, reflexively promote blood vessel expansion, accelerate blood flow, and provide sufficient blood oxygen for epiphyseal cartilage hyperplasia. Ultraviolet light can change a substance called ergosterol in human skin into vitamin D, and vitamin D enters the blood, which can promote the absorption of calcium, phosphorus and other substances in the gastrointestinal tract and provide more bone-building materials for the growth of bone cells.

Doing exercise outdoors and breathing fresh air can get more "air vitamins". The four seasons in the south are evergreen and colorful, and the spring, summer and autumn in the north are colorful. In this natural environment, the number of anions will double. Negative ions are essential "elements" to maintain the normal growth function of human cells, which scientists call "air vitamins". Some people divided the mice into two groups (identical nutrition). Group A was fed in normal air, while Group B was fed in air filtered by cotton. After four weeks, Group A remained unchanged. The prevalence rate in group B is high, and some of them are facing death. The key reason is that the negative ions in the air breathed by group B mice have been completely absorbed by cotton. It can be seen that the increase in the number of negative ions in the human body not only helps children and adolescents grow taller, but also helps to improve the function and health level of the body.

3. What projects contributed to Gao Pei?

The skeletal system of children and adolescents grows rapidly, and the bones contain a large proportion of organic matter and a small proportion of inorganic matter, so the bones are fragile and elastic. The spine of children and adolescents is elastic, but the strength of muscles and ligaments is poor, and the strength of fixed joints is weak. The neural process of children and adolescents is characterized by more excitability than inhibition, and the neurons in the cerebral cortex are poor in working ability and easy to get tired, but they are quick in response, quick in recovery and good in flexibility. During the period of children and adolescents, especially during the sudden increase of adolescence, the height grows rapidly, the thoracic development is relatively backward, the development speed of the heart can't keep up with the growth speed of other parts of the body, the blood supply and oxygen supply are relatively insufficient, and the regulation function of the cardiovascular system is also unstable. In view of the above characteristics of children and adolescents, we should choose those sports with large stretching range, high frequency, strong sense of rhythm and short duration, and try to avoid those endurance and static sports that are too tense, lasting and breathless.

(1) Full-body stretching events: There are many full-body stretching events, such as unarmed exercise, light weapons exercise, aerobics, pull-ups, arm flexion and extension, hanging swing, leg swing, leg press, kicking, cheating and "bridge".

(2) Collaborative projects: These projects include ball games, swimming, skating, skiing, dancing and active games.

(3) Jumping events: These events include standing single, jumping with two legs, jumping with one leg and two legs during marching, striding, leapfrog, vertical jump, standing long jump, standing multi-stage jump, jumping rubber band, skipping rope, supporting jump and jumping over obstacles.

(4) Short-distance events: Short-distance events include 50m, 60m,100m, 200m, 400m, 4x100m relay running and swimming (butterfly, backstroke, breaststroke and freestyle).