Coaching Young Athletes
In the first two years children grow about 5 inches (13 cm). Growth then continues at a steady rate of 2.5 inches (6 cm) per year until about the age of 11 in girls and 13 in boys, when the pubertal growth spurt begins.
The pubertal growth spurt lasts about 2 years and is accompanied by sexual development (growth of pubic hair, development of sex organs, deepening of the voice in boys, and beginning of menstruation in girls). Normal growth stops when the growing ends of the bones fuse.
This usually occurs between the ages of 12 and 15 for girls, and 14 and 17 for boys. This growth rate is an important factor in the Long Term Athlete Development (LTAD) of a child.
Bones develop from a cartilage growth plate, called epiphysial plates, at each end of the bone shaft. These growth plates divide the calcified head of the bone (epiphysis) and the calcified shaft (diaphysis). The bone lengthens as cartilage is calcified into bone. At the same time, cartilage continues to grow on the epiphysial border, so the epiphysial plates retain a constant width of cartilage throughout. Growth ends when the plate eventually calcifies.
Muscle mass increases steadily until puberty, at which point boys show faster muscle growth.
The hormonal changes at puberty also affect body composition in terms of fat.
• At birth, both boys and girls have around 10 to 12% body fat
• Pre-puberty, both girls and boys still have a similar 16-18% body fat
• Post-puberty, girls have around 25% body fat due to high serum oestrogen, which causes the hips to widen and extra fat to be stored in the same area.
• Post-puberty, boys have 12 to 14% body fat
Most athletic females, post-puberty, tend to keep body fat at around 18%. Any lower than 12% body fat for females can be considered unhealthy in terms of maintaining bone density and disrupting hormone levels, which may increase the risk of stress fractures.
At Ultra Athletics the Coaches ensure female athletes are aware that until they are 19, they will steadily gain in muscle and so will naturally be gaining weight and that by eating the right kinds of foods is the way to avoid unwanted weight gain.
Potential growth related injuries
The change in female body shape during the growth spurt has its particular injury risks. The hips widen, placing the femur at a greater inward angle. During running or walking, this increased femur angle leads to greater inward rotation at the knee and foot. This rotation can result in an injury called chrondomalacia patella, which occurs when the knee-cap does not run smoothly over the knee joint and pain is caused at the front of the knee.
Appropriate preventive training to avoid chrondomalacia patella would be to strengthen the vastus medialis muscle, the lower abdominals, obliques (side of stomach), hip abductor and hip external rotator muscles.
Traction injuries are another type of injury associated with bone growth. They are caused by repetitive loading while the tendon is sensitive to stress as the bones and tendons are fusing. Traction injuries occur at different sites at different stages of growth.
• 10 to 13 years of age - at the heel (Sever's disease)
• 12 to 16 years of age - at the knee (Osgood Schlatter's disease)
• late adolescence - lower back and iliac pain
The only cure for these traction injuries is rest.
Exercise will neither stunt nor promote growth in terms of height but it does thicken the bones by increasing mineral deposits (Wilmore & Costill, 1994).
Growing bones are sensitive to stress so repetitive loading should be avoided. The epiphysial plate is susceptible to injury and therefore a fracture to the epiphysial plate prior to full growth could be a serious injury as it could disrupt bone growth.
A more common kind of epiphysial plate injury, and the one coaches must take care not to cause, is called epiphysitis. This is a repetitive-strain injury that occurs when excess loads are placed on the tendons that attach to the epiphysis, causing an inflammatory response. In extreme cases, this type of injury can result in a separation of the epiphysis from the epiphysial plate.
Use of steroids
Anabolic steroid use in young athletes can STUNT GROWTH by causing premature calcification of the epiphysial plate (Strauss & Yesalis 1991).
Strength improvements are possible but should be done very carefully. At Ultra athletics coaches ensure:
• young athletes are properly taught (skill development)
• young athletes undertake a well controlled progressive program (planning)
• young athlete's joints are not subject to repetitive stresses (injury prevention)
Strength can be developed with circuit training programs where the young athlete's body weight is used as the load.
Aerobic and anaerobic development:
The aerobic ability of young athletes can be developed so it makes aerobic training worthwhile, since it will improve their performance.
Anaerobic training is of limited use to young athletes as they possess little anaerobic capacity and is perhaps best left until the young athlete reaches adolescence.
The development of sport specific skills along with agility, balance and co-ordination are important areas that Ultra Athletics coaches focus on when coaching young athletes.
Long Term Athlete Development (LTAD) is a sports development framework that matches training needs to a child's growth and development. In athletics a novice athlete will go through the following stages of development:
• Fundamentals - developing agility, balance, coordination
• Foundation - developing run, jump, and throw skills
• Event Group - developing the athletic event skills associated with the Sprints, Endurance, Jumping or Throwing
• Event - develop the skills specfic to one athletic event