What is growth?

Growth literally means “acomplishing length”. According to a dictionary, growth refers to “a stage in the process of growing (for people and animals)”. However, the true meaning of growth involves development of both mind and body. When it comes to the word ‘growth’, a human’s body needs not only its height but also its whole parts to develop. Our body is composed of bones, muscles, connective tissues, nervous systems, and skin tissues.

Increasing height involves the development of all of the above, and the factors that are associated with height growth the most are bones and the muscles around them. There are 206 bones in a human body, and among those, 26 pieces of vertebra and 62 bones of lower limbs are the ones that control growth of height and body. Growing height refers to lengthening the backbone (the vertebra), the femur (bone of lower limbs), the shinbone, and the fibula.

Such processes of lenghtening bones are done by epiphyseal cartilages that exist at the each end of the bones, just like shown in the picture above. Epiphyseal cartilages grow long, thick, and strong at the end of the periosteum by receiving enough blood from growth hormone and other hormones. Through cell division of cartilage cells, osteoblastocytus gets formed and matured; its calcification results in formation and growth of osteocytes, and ultimately, bone growth.

Role of growth hormones ① Gets released from anterior lobe of the pituitary gland during deep sleep. Takes 5*10^-10g in one 1cc of blood. Gets converted into growth factor via liver, and makes bones grow through cell division, proliferation, and accumulation of bone plates. Also stimulates amino acid absorption.
② Stimulates protein formation and makes muscles grow in balanced form.
③ Makes new cells and cures injuries.
④ Decreases weight by dismantling fat accumulated in adipose tissues.

Growth plates

Most bones change into bones from its orignal formation, but joint areas get converted into cartilages.

Growth plates are cartilage plates that get formed into a shallow disk from their original shapes. Height growth depends on how much of growth plates are open.

In most cases, growth plates tend to get closed out when boys become 16 years old and girls become 14 years old. Growth plates are located in all the long parts of our body, including our fingers, toes, elbows, shoulders, ankles, femur, and vertebrae.

During the growth phase, these growth plates grow in size, resulting in lengthening of bones. Disappearance of such growth plates due to cartilages at the end of the bone turning into solid bones is known as the closing of growth plates. Growth plates serve to be the core of growth, and active growth plates could result in children with long legs.

Bone age

Bone age refers to the physical age, and examining bone age results in figuring out when height stops growing.

The reason why people have different time of reaching their height limit is because of the bone age differing from actual age. This is why someone who is smaller than others could become taller if growth gets delayed.

All people have different time phases of reaching height limit, starting to have period, growing beard, or reaching puberty. This is all due to physical age, aka bone age, differing from actual age. If bone age is younger than actual age, reaching height limit gets delayed, but if bone age is older than actual age, reaching height limit can come early.

Considering bone age and current height could result in predicting final height as well.

Height growth and sleep

As the phrase ‘Sleep is the best remedy’ goes, sleeping well is necessary to relieve stress and become healthy.

Proper amount of sleeping is an essential factor of a healthy lifestyle. By sleeping, people could get rid of physical stress and regain energy for daily life by getting rid of bad memories. Enough sleep also promotes health and comfort by affecting tissue recovery, immune system, and mental functions. On the other hand, sleep deprivation leads to increased fatigue, mood swings, and decrease in pain tolerance, resulting in disturbance of normal activities.

In particular, growth hormone, which serves to be the core for growth, gets released actively during sleep periods at nights, especially during deep sleep (3rd and 4th stage of sleep). Therefore, in order to increase growth hormone release, it is necessary to secure enough sleeping time and have deep sleep. Therefore, before going to bed, chlidren should be ensured with delightful and comfortable minds. Also, make sure to turn out the lights in the bedroom and the living room so kids could have deep sleep. Watching television loudly outside while telling children to go to sleep results in children not being able to sleep soundly, so it is recommended for parents to take care of their children to sleep deeply.

Quality of sleepIn terms of the sleeping environment associated with growth, the time of children going to bed is very important, but it is also important to sleep soundly. General sleep health also gets impacted more by the quality of sleep rather than the absolute duration of sleep. This is known as sleep efficiency, which is calculated in percentages. Effective sleep can be ensured when sleep efficiency is increased. Calculation is as follows:

(Time of actual sleep – Amount of time spent lying on the bed) x 100(%)

In general, if the value does not reach 85%, sleep efficiency is considered to be bad. However if the person does not feel too much discomfort during daily life, it won’t be problematic. Yet it is really important to have a regular sleeping cycle and keep track of the time in which sleep starts and the time in which sleep ends.

Growth hormone and height

Growth hormone is a 22kDa single chain polypeptide hormone that gets secreted from anterior pituitary gland, and helps stimulate bone growth through the accumulation of calcium of cartilage cells in growth plates. Growth hormone also enhances absorption of amino acids which are crucial for forming muscles and stimulates protein formation in the intestines, allowing muscles to grow in balance. It is used as growth stimulants in our bodies. It also increases glucose to be made in the liver, allows more fat to be used as energy sources for bodily movements, and stores glucose which is a main energy source of muscle and brain activities.

During the youth period, growth hormones mainly work in lengthening bones and increasing muscle mass. After the age of 25, however, growth hormone does not make people grow taller anymore.

After people become adults, growth hormones focus more on increasing connective tissues and collagen, and increases non-fat weight, resulting in muscular strength increase. It also stimulates dismantling of fat, and increases bone density of the vertebra, preventing adults from getting osteoporosis, becoming shorter, and getting injured.

	(1) Growth hormones tend to reach its maximum during early stages of sleeping. (2) During 7 hours of sleep, 4 sleep cycles show up. Deep sleep is induced during 1st and 2nd sleep cycles. (3) Deeper sleep induces better sleep. Growth hormones get secreted the most during the first 1 to 4 hours of sleep.
	(1) From the onset of exercise, growth hormone secretion gets increased up to 30 minutes after the end of exercise. (2) The level of growth hormone turned out to reach its maximum 30 minutes after the end of exercise. Since the growth hormone secretion reaches its max in 1 to 2 hours after exercise, protein must be consumed within 2 hours of exercise.
	(1) Based on the intensity of exercise, amount of growth hormone gets increased. In the event of a hard exercise, growth hormone can be secreted up to 25 times more than in a resting body. (2) In the event of performing exercise that uses 70% of the total strength on a regular basis, secretion of growth hormones necessary for becoming taller gets increased, and growth plates get to receive proper stimulus as well. Athletes who go through regular training have higher level of growth hormone secretion, and go through stronger stimulation of growth plates, resulting in bone length increase and stimulating protein formation that allows both bones and muscles to grow equally.

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