The stages of adolescence physical development can be broken down into three distinct phases. The early developmental phase usually encompasses preteens ages 12 to 14 and marks the majority of puberty-related changes. Ages 15 to 17 often mark the middle developmental phase in which many of the physical changes have already taken place. Finally, the late stage of adolescence physical development occurs between the ages of 18 to 21.
In the early stage of adolescence physical development, many and the most drastic physical changes occur as the child begins to mature into adulthood. This stage is often referred to as the onset of puberty. Typical signs that puberty has begun is the growth of pubic hair. The emergence of acne on the face and body of both sexes might also be an outward sign that puberty has begun.
Girls will often start noticing a change in the tissues that make up the breasts during adolescence physical development. Breast development and subtle changes in the vaginal area occur as early as 8 years old to a later onset of 16 years old. Many girls might begin menstruating during this same time period. Additional body hair could begin growing at this time leading to an onset of shaving the legs and arm pit areas of the body. These changes happen due to an increase in hormones produced in the female body called estrogen and progesterone.
Boys can often begin puberty later than girls at approximately 11 years old to a later onset of 17 years old. The male voice can begin to deepen during this time and might even make an uncontrollable high-pitched sound while transitioning into the adult tone. Increased muscle tone in the arms and legs begins to replace fat stores from childhood. Many boys begin to notice growth to the male genitals and increased facial and body hair growth. An increase of the testosterone hormone is produced in the male body during this time accounting for the onset of these changes.
The middle and late stages of adolescence physical development are noted by a refinement of the physical changes that occurred in the early stage of development. Fat continues to be deposited in the breast and hip regions of girls. Boys can continue to grow taller and voices begin to stabilize. Overall, hormones reach more even levels with less fluctuations and emotional tolerance of the physical changes can lead to a more self-confident individual.