The belief that certain forms of exercise can permanently reduce a person’s height is a misconception rooted in a misunderstanding of human physiology. The vast majority of physical activity, including resistance training, does not cause lasting height reduction. This concern often confuses temporary, reversible changes in the spine with permanent structural alterations in the skeleton.
The Biological Basis of Adult Height
An individual’s final adult height is predominantly set by genetics, which accounts for up to 80 to 90% of a person’s potential stature. This genetic blueprint is expressed through the growth plates, also known as epiphyseal plates, which are areas of specialized cartilage located near the ends of long bones in children and adolescents.
These plates contain chondrocytes, cartilage-producing cells that multiply and enlarge, gradually pushing the ends of the bones further apart to lengthen the skeleton. Linear growth continues until the end of adolescence when hormonal changes cause the cartilage in the growth plates to fully harden into solid bone, a process called epiphyseal fusion. Once these plates fuse, the long bones can no longer lengthen, and a person’s final height becomes fixed for life.
Exercise and Growth Plates: Debunking the Stunting Myth
A persistent myth suggests that exercises like weightlifting or gymnastics can stunt the growth of children and teenagers by damaging their growth plates. Scientific evidence does not support this claim; properly performed exercise is generally beneficial for skeletal development. Resistance training, when supervised and conducted with age-appropriate loads and correct technique, promotes bone health.
The mechanical stress from muscular contraction and weight-bearing activity stimulates bone cells, leading to increased bone density and strength. Physical activity also encourages the release of growth hormone and insulin-like growth factor I (IGF-I), which positively influence skeletal development. The only risk to growth plates comes from acute, traumatic injuries caused by poor form, excessive loads, or accidents, which can happen in any sport.
Understanding Temporary Spinal Compression
While exercise does not cause permanent height loss, it can cause a temporary reduction in stature that fuels the myth. This phenomenon, known as spinal shrinkage, is a short-term, reversible change usually measuring between one to two centimeters. It occurs after prolonged periods of standing, running, or intense weight-bearing exercise, such as heavy squats or overhead presses.
The spine is composed of vertebrae separated by intervertebral discs, which act as shock absorbers. These discs are largely made of water and cartilage, and they slowly lose fluid throughout the day due to the constant downward force of gravity and body weight. Intense exercise, especially with axial loading, accelerates this fluid loss and temporarily compresses the discs. This momentary height reduction is quickly reversed during non-weight-bearing activities, as the discs fully rehydrate and expand while the person rests and sleeps overnight.
Factors That Truly Impede Skeletal Growth
If exercise is not the cause of reduced potential height, other factors impede skeletal growth during childhood and adolescence. Chronic severe malnutrition is a major global contributor, particularly a deficiency in protein and total caloric intake needed to fuel the high energy demands of bone growth. Without sufficient nutrients, the body cannot produce the materials necessary for the growth plates to function optimally.
Chronic sleep deprivation also interferes with the mechanisms of growth. The majority of human growth hormone (hGH) is released in pulses during the deepest stages of sleep. Consistent lack of sleep can suppress hGH production, negatively affecting the rate of linear growth over time. Additionally, certain hormonal disorders, such as untreated growth hormone deficiency, and chronic diseases can suppress the body’s ability to grow.