A depth jump is a specific, high-intensity plyometric exercise designed to increase the explosive power of the lower body. It involves dropping off an elevated surface, like a box, and immediately performing a maximal vertical jump upon landing. This movement subjects the legs to significant impact forces, often multiple times the athlete’s body weight. For parents and coaches of young athletes, this intense loading raises a common concern: whether such high-impact training could damage the long bones and negatively affect the athlete’s final adult height. This article explores the scientific evidence regarding the risk of stunting growth.
Understanding Growth Plates and Skeletal Vulnerability
The concern about stunted growth is rooted in the unique anatomy of a young, developing skeleton. Growth plates, also known as epiphyseal plates, are areas of cartilage located near the ends of the long bones. These plates are the site where new bone tissue is produced, determining the future length and shape of the bone until skeletal maturity is reached.
These cartilaginous plates are significantly softer and weaker than the surrounding mature bone, ligaments, and tendons. This relative weakness makes the growth plate the most vulnerable point in a young athlete’s skeletal structure. High-impact activities, including depth jumps, generate compressive and shear forces that, if excessive or repetitive, can cause an epiphyseal fracture or a stress injury.
An acute fracture or chronic overuse injury to a growth plate can lead to a premature closing or a partial growth arrest. This disruption is the mechanism that could result in a slight shortening or angular deformity of the affected limb. The vulnerability is especially pronounced during periods of rapid growth, as the bones are lengthening quickly while supporting muscles and tendons adapt more slowly.
The Evidence: Do Depth Jumps Stunt Growth?
The notion that depth jumps, or plyometric training in general, will stunt a child’s growth is largely a misconception. Scientific consensus confirms that properly structured and supervised plyometric training does not negatively affect a young athlete’s stature. In fact, moderate mechanical loading is beneficial for bone health and development.
Controlled, age-appropriate jumping and landing exercises increase bone mineral density and overall bone strength in youth. The body adapts to stress, and the forces involved in a well-executed depth jump can stimulate the skeletal system positively. The actual risk is not from the exercise itself, but from poor execution, excessive volume, or starting the exercise before the athlete is physically prepared.
Rare instances of growth disturbance are linked to severe, traumatic injury to the growth plate, or chronic overuse from poorly programmed training. This acute trauma risk is comparable to forces experienced in many organized sports, such as landing after a basketball rebound or a volleyball spike. Therefore, the issue is not the movement pattern of a depth jump but the uncontrolled application of high-magnitude force.
Safe Implementation of Youth Plyometric Training
Since safety depends entirely on the application, a progressive approach is necessary for young athletes. Before attempting a depth jump, the athlete must demonstrate a strong foundation of baseline strength and the ability to control their body weight during landing. They should first master less intense plyometrics, such as simple jumping and landing drills, to develop proper mechanics.
Correct landing technique, which involves absorbing the force by bending at the hips, knees, and ankles, is non-negotiable for injury prevention. For depth jumps, a low box height (often between 12 to 18 inches) is typically used for initial training to keep landing forces manageable. The focus should be on minimizing the ground contact time before the immediate jump, ensuring a rapid, explosive rebound.
Depth jumps are highly intense and should be performed in low volumes, generally limited to a few sets of three to five repetitions. Training must be overseen by a qualified coach who can provide real-time feedback and ensure the athlete is not fatigued, as technique breaks down with tiredness. Gradual progression in height and volume, along with adequate rest and recovery, is the safe pathway to harnessing the power benefits of this exercise.