Youth has a variety of meanings in the world of sport. As a description of the relative physical maturity of an athlete, youth represents the progression from childhood to adulthood. A youth is an adolescent whose body is continuing to grow into its adult state. A youth possesses all of the physical attributes of an adult, but not yet fully formed. A youth is also someone whose emotional development is not complete; it is not uncommon for athletes to reach their adult musculoskeletal development in advance of the completion of corresponding emotional growth.
Youth is usually associated with the biological process known as puberty, which begins at different times for both males and females. The general commencement of puberty for females in North America is age 10; for males, puberty often begins at age 12 or 13. In the three to four years that follow the onset of puberty, the human body undergoes its most rapid growth, second only to the growth rate experienced in a newborn child. It is the rapidity of physical growth that necessitates a specific consideration of the injuries commonly sustained in youth sports.
All youth athletes who participate in sport are exposed to the same physical forces and the same general types of injury as are adult athletes. The mechanics of the execution of the various maneuvers in any sport do not particularly change when the sport is played at a younger age; given the smaller athletes, there are often lesser amounts of mass making contact with one another, resulting in lesser forces in sports where contact is either desired or incidental. The risk of injury to a youth athlete in both contact sports and non-contact sports will usually stem from one of three causes—poor technique, often a function of substandard coaching, growth-related weaknesses in the youth musculoskeletal structure, and overuse or repetitive strain.
During adolescence, the bones, skeletal muscles, and connective tissues continue to grow. The most prominent aspect of this phase is the presence of growth plates near the epiphysis, the end of the long bones of the body, including the femur (thigh), the tibia and fibula (shin), and the humerus (upper arm). The growth plate is a softer, cartilage-like region of growing bone cells; at maturity, the growth plate will entirely ossify, or harden, into a permanent and seamless component of the entire bone. The growth plate is at elevated risk of injury during contact sport, as it is more prone to fracture if it receives significant trauma. A damaged growth plate that is not repaired may disturb future growth in the limb.
A related condition common to young athletes is Osgood-Schlatter disease (OSD), which is a condition where the patellar tendon, which attaches the kneecap to the tibia, is growing at a different rate than the bone structure. OSD becomes painful to athletes who are engaged in repetitive motions such as running. The condition is usually treated with rest; OSD will ultimately be outgrown by the athlete.
Concussion is an injury caused by the receipt and absorption of a blow to the head, often causing damage to both the skull and the surface of the brain. A concussion can cause pain, dizziness, and nausea, and an athlete who has sustained a concussion should have a through neurological examination prior to the resumption of a contact sport. Concussions are often the result of both poor coaching technique in contact sports such as American football and ice hockey, where the player is improperly instructed to position their body with the head leading the body on contact with an opponent.
A further coaching-related athletic injury among youths is the wide range of problems associated with overuse and repetitive strains placed on the not yet mature bodies of the athlete. In sports such as track running, distance running, and figure skating, where the legs of the athlete are subjected to continual stress, the athlete's training program must be carefully constructed to avoid the excess training volumes and intensities that lead to stress fractures; over 60% of stress fractures sustained by young athletes occur in the lower leg, commonly in the tibia (shin) between 1 in to 3 in (3-10 cm) above the ankle. Although not strictly a physical injury, these circumstances are also ripe to produce the debilitating mental state referred to as burn out, when the young athlete loses interest in training due to the combination of physical and mental overload.
The most common of the unavoidable athletic injuries in youths is the buckle or greenstick bone fracture. These fractures most often result when the young athlete puts out a hand to avoid a fall, with the impact radiating into the small carpal bones of the wrist; the bone, not yet fully formed or as dense as it will be in adulthood, does not fracture completely, but bends under the forces on impact. Most buckle fractures will heal through immobilization, by splint or cast. A common carpal bone to sustain fracture is the scaphoid (navicular) bone, located below the thumb joint in the wrist.
Throwing sports place significant forces on all of the muscle and skeletal structures involved in generating the forces necessary to throw the desired object. The most common and the most significant of these injuries with respect to the long-term health of the athlete are those caused to either the throwing shoulder or the elbow of young baseball pitchers. The development of a curve ball, a pitch that requires a vigorous overhand shoulder motion, accompanied by a forceful twisting of the elbow, places particular stress on the rotator cuff, the four muscles that are positioned on the top of the shoulder, providing strength and stability to the joint; the elbow motion creates powerful forces in very small tissues, the ulnar cruciate ligament, and the epicondyle tissues that encapsulate the elbow joint. The repetitive stress of throwing these pitches often leads to the development of strains or tears in one or more of the shoulder and elbow joints.
A common and dangerous injury to young athletes is environmental in nature. In outdoor sports played in warm weather, young athletes are exposed to heightened risk of the development of one of the progressive heath illnesses, heat cramps, heat exhaustion, or heat stroke. As young athletes may not possess the maturity to abide by a self-directed hydration plan, no warm weather youth sports should ever be undertaken without both ample and appropriate fluids, as well as heat-combative first aid materials.