A new school year is always full of surprises. One of them is seeing how much taller certain classmates have gotten over the summer. What is the science behind growth spurts?

Adolescence isn't the first time that humans grow by leaps and bounds. Babies' bodies change and grow dramatically. Children usually grow at a gradual, steady pace until puberty, when growth occurs in an intense "spurt."

The adolescent growth spurt typically begins in girls around the ages of 10 or 11 and peaks by age 12. Girls typically stop growing by the ages of 15 or 16. In boys, the growth spurt begins at 12 or 13, reaches a peak by age 14, and is typically over by the age of 19. Of course, adolescents don't all develop at exactly the same time. Some develop earlier than their peers, and others mature a bit later.

Within the adolescent "growth spurt," teens and pre-teens experience "mini-spurts" of intense growth. They may experience growing pains; after all, their skeletons are being formed. During a one-year period of intense growth, boys can gain about 4 inches (10.16 centimeters) and girls about 3.5 inches (8.89 centimeters) in height.

The surest sign that you are experiencing a growth spurt is when you suddenly notice you've outgrown your shoes and clothes...again.

• Calculate how much you and two other classmates might grow in a year by filling in the chart below.

Surviving a growth spurt isn't easy. Limbs can grow at different rates, leaving teens uncoordinated, clumsy, and even weak. The clumsiness most likely stems from the body's nervous system trying to adjust to the growth of limbs, muscles, and nerve lengths.

During adolescence, the body grows so fast that connective tissues such as tendons and ligaments become tighter—sometimes becoming very tight. If young athletes don't stretch before and after playing sports, growth-related pain can occur, particularly in the knees and lower legs. Most teen athletes will experience discomfort in these areas until their bones stop growing.

During and immediately after growth spurts, students should avoid training on hard surfaces and monitor the intensity and duration of their workouts. It is also important to stretch regularly and perform low-level strengthening exercises. Heavy weights should be avoided.

Teen athletes who do not stretch or who train on hard surfaces run the risk of sports injuries. A sports injury is characterized by pain that increases slowly over several weeks. A sports doctor can answer questions about such injuries.

To locate a sports doctor, try the following organizations:

• Pediatric Orthopaedic Society of North America
  
  

• American College of Sports Medicine
  
  

• American Association of Orthopaedic Surgeons

A team of U.S. and Canadian scientists recently discovered that it's not just the bodies of teenagers that are growing during puberty—their gray matter is changing as well. Previously, scientists believed that the brain was almost fully developed by the time a child reached the age of 3. New studies show that teens' brains are not completely developed until mid-adolescence. The fiber system that relays information between the brain hemispheres continues to grow while unnecessary cells in other areas shrink.

"The teen-age years are a kind of critical time to optimize the brain," child psychiatrist Jay Giedd of the National Institutes of Health told the Washington Post. "If a person is doing sports or academics or music, those are the abilities that will be hardwired."

Kids 15 years and younger experience the most growth in the middle and back of their brains, the area linked to the ability to learn languages and think abstractly. This finding supports the widespread belief that young children are the most adept at learning languages.

Learn More

• Analyze and compare growth patterns for males and females in the Tangible Math exercise, Spurting Up.

Related Resources

• The book, Adolescents: Continuity, Change, and Diversity, by Nancy J. Cobb, examines the role of development in early adolescence.