Both girls and boys may before puberty (approximately age 6 to 12 years) increase their body height by 4-8 cm per year. During a period the rate of growth in height becomes significantly greater (8-15 cm per year} representing the start of puberty (see figure 1). This period is called the adolescent growth spurt, and the age at which the growth speed peaks is called “peak height velocity" and is abbreviated PHV. There is a variation in the duration of the growth spurt but in most cases it lasts 1-2 years, where after the increase in body height becomes smaller and smaller; and the growth may stop at an age around 16 and 18 years for girls and boys, respectively (see figure 1).

The time of the start of the growth spurt gives information about the maturation of the child. The earlier the more mature the child is. There is a large difference in individual maturation within a given age group. The adolescent growth spurt may start as early as the age of ten or it may not start until the age of sixteen. This is illustrated in another way in figure 2, which shows how many girls in different age groups that have their first menstruation (menarche), which is another sign of maturation.

It is clear that in a majority of girls onset of menarche occurs at an age between 12 and 14 years, but also that some girls have their first menstruation much earlier and some when they are older than 14 years. On average, girls mature about two years earlier than boys. To express the degree of maturation, the term biological age is used rather than the chronological age, which is the child's age from birth. The first sign of puberty in boys is an increase in testicular volume and in girls, onset of menarche and growth of the breasts. The next phase in maturation is the beginning of growth of pubic hair.

In the period of a growth spurt a child may have difficulties to co-ordinate movements, since the changes in body dimensions are so rapid. It is common that the children have problems even with simple tasks that they were able to do previously. Boys have more pronounced difficulties than girls as their increase in body dimensions is greater. There is a common perception of “awkwardness" occurring at this period of adolescence. Is should be noted, however, that less than one-third of adolescent children are heavily affected and for all the effects are transient. Playing soccer on a regular basis does not affect statural growth, the timing or magnitude of peak height velocity, nor skeletal maturation.

For both girls and boys the body mass increases in parallel with increasing body height before puberty and for boys body mass continues to increase during puberty. Girls in puberty produce the hormone oestrogen, which increases the amount of fat and they get a relatively greater body weight in relation to height. After puberty, girls have around twice as much adipose tissue as boys of the same height.

For further reading see ”Aerobic and Anaerobic Training in Soccer”