In this context, “growth” primarily refers to an increase in linear height, which occurs due to the lengthening of bones. While various developmental processes continue into the mid-twenties for males, significant linear height growth typically concludes much earlier than age 25 for most individuals.
The Biological Basis of Height Growth
Height growth is driven by the lengthening of long bones, such as those in the arms and legs. This lengthening occurs at specialized areas near the ends of these bones called epiphyseal plates, commonly known as growth plates. Growth plates are composed of cartilage cells that divide and expand, pushing bone ends apart.
As new cartilage is produced, it is replaced by new bone tissue, a process called ossification. This continuous cartilage production and bone formation enable bones to grow longer. This process is influenced by several hormones, primarily Growth Hormone (GH) and sex hormones like testosterone.
Growth Hormone, produced by the pituitary gland, stimulates the proliferation of cartilage cells in the growth plates and promotes the synthesis of insulin-like growth factor-1 (IGF-1), which further mediates bone growth. As puberty progresses, rising levels of sex hormones, particularly testosterone in males, also contribute significantly to the pubertal growth spurt by influencing the growth plates. However, these same sex hormones eventually signal the growth plates to mature and close.
When Male Growth Typically Ends
Significant linear height growth for most males concludes in the late teens or early twenties, well before age 25. This cessation of growth is marked by epiphyseal closure, or growth plate fusion. During this process, cartilage in the growth plates hardens into solid bone, fusing the long bones to their main shafts.
Once fused, no further bone lengthening or height can be gained. For boys, growth plates generally close by the time they turn 16-17 on average, though this can vary, with some individuals completing the process earlier or later. While some sources indicate that virtually all growth plates are closed in males by age 19, minor growth might occasionally continue into the early twenties in rare instances.
Factors Influencing Growth and Late Development
An individual’s height is largely determined by genetics, accounting for approximately 80% of adult stature. Genetics influence the timing and extent of growth. Environmental factors also play a role, with nutrition contributing to achieving one’s full genetic height potential.
Adequate intake of protein, vitamins, and minerals is important for proper bone development and overall growth. Insufficient nutrition can hinder growth and prevent an individual from reaching their potential height. Factors such as chronic illness can also impact a child’s growth trajectory.
Some males experience what is known as “constitutional delay of growth and puberty,” where their pubertal development and growth spurt occur later than average. These “late bloomers” may appear shorter than their peers for a period, but they typically reach an adult height within their genetic potential, albeit at a later age. Their growth plates still undergo fusion, just on a delayed timeline.