Puberty is the time of transition from physical and sexual immaturity to maturation. The young girl's body is feminized, and turns into that of a woman. The process takes an average 3 years, usually between the ages of 10 and 13. By the end of puberty, the reproductive organs are functioning, and the girl is capable of having a child.
Adolescence follows puberty, and is perceived as a "catching up" process. Though the girl may be adult in a reproductive sense at 13, she lacks the skills of maturity in other respects. Adolescence is the time of mental, social, and emotional maturation. It can continue until the late teens or early 20s.
By age 10, a girl has reached 83 percent of her adult height. She will make up the last 17 percent in a very short space of time. Rapid growth starts at age 10; it is a sudden increase in height due to speedy skeletal (bone) development. There is more than one spurt of rapid growth spurt during puberty. Each follows a distinct pattern of order:
- The head, feet, and hands begin enlarging to adult size.
- The arm and leg bones then grow longer and stronger.
- The trunk is the last to develop to full female size.
It is not unusual for a girl to grow 1 1/2 inches within 8 weeks. The bones get harder, more solid and less flexible. Under pressure, they fracture rather than break. Skeletal growth stops around age 14, though there can be a slight height increase later. In one study, the most rapid growth was at 12 years, but 10 percent of girls grew their fastest at age 11, and 10 percent at about 13 1/2 years.
In terms of percentage body weight of fat tissue, little girls are plumper than little boys. In the pre-pubertal years, both genders tend to increase their body fat. During rapid growth, this slows down. Yet in girls, there remains a steady increase in the fat content of the body. Fat is mainly deposited on the trunk and female sexual contours: breasts, lower abdomen, hips, and thighs, and not so much on the limbs.
At age 10, a girl has reached 53 percent of her adult weight. There follows a rapid increase in weight, with changes in the ratio of fat cells to muscle and bone. Appetite is hearty; it should be equal to, or larger than, an adult's. This is important as heart weight nearly doubles, lung capacity increases, and muscle and bone develop at a very rapid rate. Some parents worry that their daughter is building fat tissue, but she is building her entire frame. A big weight increase is normal and to be expected, because it is dependent upon the process of puberty. By the time her first period arrives, weight and height increase are almost complete.
Stretch marks occur in 25 percent of girls between ages 12 and 14, usually after the rapid growth in height and weight. They appear as pinkish or purple parallel lines on the upper thighs, buttocks, or breasts. It takes a few months, sometimes a few years, before the colour fades. The stretch marks then turn smaller and white, though they do not entirely vanish.
Acne is more common and the spots are more severe in girls who have coloured stretch marks; the reason why is unclear. Nor is it known if the lost interest in sports makes the condition worse; in rare cases, thin girls get stretch marks too. There has been a constant plug for exercise throughout this book. It benefits women in more ways than any beauty cream or aid can. Exercise is very important at puberty to assist a smooth passage through the rapid growth stage. If a girl dislikes contact sports, encourage dancing, swimming, bicycling, gymnastics, and so on. A word of warning: a girl with an eating disorder can over-exercise as part of her obsessive/compulsive disorder.
From babyhood, girls are more agile than boys, bending to touch toes, and so on. The flexibility of small children depends upon the ratio of length to bulk. Both genders achieve maximum agility between ages 12 and 14. Some girls lose interest in sports at puberty. This is a pity; bones and muscles and emerging adult frame benefit from the stamina, strength, and suppleness which exercises brings. A few girls become preoccupied with their appearance, rather than their physical and mental development.
In terms of speed and timing of reaction, human response to stimulus reaches its peak between ages 10 and 14. Awareness and responsiveness continue to improve, but the capacity to learn complex skills begins to regress after age 15, unless there is continuing training.
Rapid growth at puberty can result in clumsiness for a while. There is a slight loss of symmetry; hands are too large for arms, feet seem too huge and so on. Objects break, and people collide, when this awkward stage arrives. Each accident reinforces a painful sense of clumsiness, of being out of control. Avoid teasing or scolding. Explain what is happening with reassurances that growth will soon even out. Exercise improves co-ordination. Encourage a girl by telling her that young athletes rarely suffer this lack of physical grace.