During childhood and adolescence, children go through what is known as periods of accelerated growth, popularly known as lugs. The most significant is the first year, when they grow in stature and gain weight in a spectacular way that is never repeated again. After this first year, growth slows down, but throughout their childhood and adolescence they will go through periods in which this growth accelerates significantly. Around these stages, there are urban legends and myths, such as that their bones hurt or with fever they grow.

To tell us what is true and what is not, we spoke with Dr. Toya de la Rua, editor of EnFamilia, the information website for parents of the Spanish Association of Pediatrics (AEP).

When and why do the typical ‘spurts’ occur?

Growth is not linear, so it is normal for children to go through stages of great growth and others in which they grow more slowly. After the rapid growth of the first years, the most significant ‘growth spurt’ is that it occurs in early adolescence, “In childhood it is characteristic that we notice that children around the beginning of adolescence grow a lot, it is the so-called ‘puberty or pubertal stretch’. At that time there is a significant acceleration of growth due to the increase in sex hormones along with an increase in growth hormone as well”Says Doctor de la Rua. Thus, depending on when puberty begins – which depends on many factors, especially genetic ones – it will occur at one age or another. In general, it always takes place earlier in girls, because while puberty usually starts between “10-11 years, in boys it usually appears later, around 12-13 years, once it is puberty started ”.

These stretches are produced by a substantial increase in growth hormone, and also in sex hormones (androgens or estrogens). The combination of the increase in these two types of hormones causes that, at this age, in addition to a strong growth in stature, appear “the typical physical changes of puberty, both from the physical and emotional point of view ”. On a physical level, the most notable are the appearance of the breast bud in girls and, later, menarche (first menstruation). In boys, it will appear a little later, and it manifests itself with increased muscle and testicular volume.

To be able to cope with these changes and this growth, more energy will be required, so also it is normal for your appetite to increase considerably. And it is that, to grow in total between about 25-30 cm. in boys and 23-27 in girls, and gaining between 7-8 kg in girls and 8-9 kg in boys per year, the body needs a lot of extra calories.

It hurt? Do they grow bigger with the fever? What is true is these popular beliefs

Surrounding these lugs there are many beliefs, some more accurate than others. For example, it is believed that when they have a fever they grow larger or that they grow larger at night. Given these beliefs, Dr. Toya de la Rua states that “It has not been shown by any scientific study that sleeping more hours or when they have a fever they grow more, although it is true that both situations influence the production of growth hormone”. And it is that, although it is true that during sleep more growth hormone is produced, this does not mean that by sleeping more they will grow more. This also occurs, as noted in Damn science, during febrile processes, which can increase the secretion of growth hormone. Other specialists, on the other hand, assure that during the fever growth slows down, and the organism has to recover ritual afterwards, hence we notice a small stretch. Not one thing is not completely proven or ruled out.

It is also not true, for example, that girls stop growing when they have their first menstruation, they simply grow more slowly again. According to the web EnFamilia, “When menarche occurs, the growth spurt is almost over, but they continue to grow at a slower rate. Growth after menarche is variable, between 4 and 12 cm, although most girls grow only about 6-7 cm and most of them in the first and second year after the first period ”.

As for those known as growing pains, they also exist, although not as in the bones, as is believed, nor do they have to occur, “During the phases of rapid growth, muscles, bones and tendons grow at different speeds, and this causes the tendons that are inserted into the bone to produce constant traction on the bone and can cause inflammation and pain. It is typical on the knees and heels ”. These pains, in addition, can also appear around 3-5 years, not only during the great pubertal stretch.