The idea that playing basketball or engaging in activities that involve jumping can directly increase a person’s height is a popular belief, often repeated in gyms and playgrounds. This assumption suggests that the physical strain or stretching associated with the sport somehow forces the body to grow taller. To understand whether this is true, it is necessary to look past anecdotal evidence and examine the biological processes that govern human growth. Height is not a simple characteristic that can be manipulated by physical activity alone; rather, it is a complex biological trait determined by several interwoven factors.
The Primary Role of Genetics in Determining Height
The single biggest factor dictating a person’s final adult height is their genetic makeup, which is estimated to account for about 80% of an individual’s stature. Height is considered a polygenic trait, meaning it is influenced not by a single “height gene” but by the cumulative effect of thousands of gene variants. These inherited variants establish a specific potential height range that a person’s body is programmed to reach.
Vertical height gain occurs primarily through the lengthening of the long bones in the legs and arms. This elongation takes place at specialized areas of cartilage called growth plates, or epiphyseal plates, located near the ends of these bones. Cells within the growth plate continuously divide and turn into new bone tissue, which pushes the bone outward and causes the limb to grow longer.
Growth plates remain active until the end of puberty, when a surge in sex hormones, such as estrogen and testosterone, signals them to harden completely into solid bone. This process is known as epiphyseal fusion or growth plate closure. Once the growth plates have fused, the long bones can no longer lengthen, and the individual’s final adult height is set permanently. For most people, this closure occurs in late adolescence, typically between ages 16 and 18 for females and 18 and 20 for males, after which no amount of jumping or stretching can add inches to their height.
How Physical Activity Influences Growth
While genetics sets the ultimate ceiling for height, environmental factors like nutrition and physical activity play a role in ensuring that a person reaches their full genetic potential. Exercise, especially during the growth years, stimulates the production of Human Growth Hormone (HGH) from the pituitary gland. This hormone is fundamental to triggering cell reproduction and regeneration in bones and tissues, promoting overall healthy growth.
The temporary increase in HGH caused by physical exertion helps facilitate the normal process of growth at the still-open growth plates. However, this hormonal boost does not allow a person to grow beyond their inherited genetic potential; it supports the healthy development of bone and cartilage.
High-impact activities like jumping, which is central to basketball, also have beneficial effects on the skeletal system by increasing mechanical stress on the bones. This stress is a powerful stimulus for increasing bone mineral density and overall bone strength. This makes the skeleton more robust, but it does not cause the bones to grow longer than the length determined by the epiphyseal plates. The notion that jumping “stretches” the spine or legs to add inches is biologically inaccurate; the lengthening process is cellular and hormonal, not mechanical.
Correlation Versus Causation in Professional Sports
The belief that basketball makes people taller often arises from observing the extraordinary height of professional players. However, this observation confuses correlation with causation, a phenomenon best explained by selection bias.
Individuals who are naturally taller possess a significant, inherent advantage in the sport, making them more effective at rebounding, blocking shots, and shooting over defenders. This advantage leads coaches, scouts, and teams to disproportionately select taller athletes from a very young age. Consequently, the population of professional players is not representative of the general population; it is a highly selected group of already tall individuals.
The average height of a male NBA player is approximately 6 feet 7 inches, a height that is far outside the general male population average. The common height of professional players is the reason they are successful in basketball, not the other way around.