Secrets of Human Growth: When and Why We Grow the Fastest 0 7

One might think that the peak growth rate occurs during adolescence. But that’s not the case.

Growth is the result of cell division and increase in the epiphyseal plates, the cartilaginous zones of long bones. This process is regulated by hormones: primarily growth hormone (somatotropin), produced by the pituitary gland, thyroid hormones synthesized by the thyroid gland, and sex steroids (androgens and estrogens). It is their activity that determines how quickly and for how long a person grows.

Human Growth Rate at Different Life Stages

The highest growth rate is observed in the first year of life. During this time, an infant can grow almost 30 centimeters — more than double the rate of even the most pronounced growth spurts during adolescence. Moreover, according to scientists, by the age of 18 months, girls are almost 50% of the height of an adult woman!

Then the pace noticeably slows down: from the age of 4 until puberty, a child grows about 5–7 centimeters per year.

The next sharp increase occurs during puberty. Moreover, girls typically experience this earlier than boys: during this time, adolescents can grow 8–10 centimeters a year, and in some cases even more.

However, such growth spurts come at a cost: during rapid growth, bones become weaker and more prone to injury. First, the bones grow, and only then do they mineralize — and this process can take up to nine months. This is why adolescents often suffer from fractures. Additionally, both muscles and tendons require up to nine months to catch up with the growing bones — which can lead to another type of injury, particularly affecting the knees and lower back.

After puberty, the growth plates in the bones close, usually occurring by the ages of 16–18 in girls and 18–21 in boys. From this point on, height growth ceases, and a person no longer gets taller.

Interestingly, in adulthood, a person's height can fluctuate slightly throughout the day. In the morning, a person is usually 1–2 centimeters taller than in the evening — this is due to the intervertebral discs, which can expand overnight and compress during the day under the force of gravity.

Various Factors Affect Growth Rate

First and foremost, these are hormones and genetics. Additionally, it is important what kind of diet a person follows, whether they are getting enough macro- and micronutrients from food, whether they engage in physical activity, their health status, and the conditions in which they live.

What Grows First

Growth is first observed in the extremities — the feet and hands. Then the arms and legs begin to lengthen, while the torso grows last. If a child develops late, sometimes the torso does not catch up with the other body parts — according to scientists, this feature can be an advantage in sports such as ballet or gymnastics, as such children have a linear body shape and longer legs.