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Profile of a young athlete

Brian Mackenzie explores the physical development of young athletes and what we need to take into consideration when coaching them.

Young athletes are physically developing, from early childhood to late adolescence. This means they have different capabilities for, and adaptations to exercise, and for this reason, young athlete training programs should not be just scaled-down versions of adult training programs. The fastest rate of growth occurs in the first two years. The growth rate then slows until the adolescent spurt when the growth rate increases again. The adolescent spurt lasts approximately two years and takes place, on average, at 10 to 12 years for girls and 12 to 14 for boys. The growth rate then decreases until the full height is reached. 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 to 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% (Wilmore & Costill, 1994). 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. Coaches need to make female athletes aware that until they are 19, they will steadily gain muscle and so will naturally be gaining weight and that eating the right kinds of foods is the way to avoid unwanted weight gain.

Potential growth-related injuries

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 on the diaphysial border, thus lengthening the shaft. 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. The changes in the female body shape during the growth spurt have particular injury risks. The hips widen, placing the femur at a greater inward angle. During running or walking, this increased femur angle leads to a greater inward rotation at the knee and foot. This rotation can result in an injury called chondromalacia patella, which occurs when the kneecap does not run smoothly over the knee joint and pain is caused at the front of the knee. Appropriate preventive training to avoid chondromalacia 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 does not stunt or 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 before 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 excessive 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. The most common epiphysitis, called Little Leaguer's Elbow, occurs mostly in the USA among young baseball pitchers.


Strength increases with age because of body growth and the development of the neuromuscular system. From research Weltman et al. (1986) carried out on the effects of resistance training on young athletes, it would appear that strength improvements are possible. If coaches are to place young athletes on strength training programs, then they must ensure that the young athletes:

  • are properly taught (skill development)
  • undertake a well-controlled progressive program (planning)
  • joints are not subject to repetitive stresses (injury prevention)

Code of conduct for coaches working with young athletes

As coaches of young athletes, we need to ensure that every child or young person who takes part in athletics should be able to participate in a fun and safe environment and be protected from neglect and physical, sexual, and emotional abuse. To ensure that forms of abuse are prevented and to help safeguard coaches who work with young athletes, the following guidelines should be considered:

  • Always be publicly open when working with children. Avoid situations where you and an individual child are completely unobserved
  • If a performer needs to be touched, it should be provided openly, and the performer should be asked first. Care is required, as it is difficult to maintain hand positions when providing manual support if the child is continually moving. Some parents are becoming increasingly sensitive about touching children, and their views should always be carefully considered
  • Where possible, parents should take responsibility for their children in changing rooms. If groups are to be supervised in changing rooms, always ensure that adults work in pairs.
  • Where mixed teams compete away from home at least one male adult and one female adult should always accompany them
  • Coaches must respect the rights and dignity and worth of all and treat everyone with equality
  • Coaches must place the well-being and safety of the performer above the development of performance. They should follow all guidelines laid down by the sport's national governing body and be adequately insured
  • Coaches should hold current athletics leadership or coaching qualification
  • Coaches must ensure that the activities, which they direct or advocate, are appropriate to the age, maturity, and ability of the performer
  • Coaches should always promote the positive aspects of their sport (e.g. fair play) and never condone rule violations or the use of prohibited substances
  • Coaches must consistently display high standards of personal behaviour and appearance
  • Coaches should never overtly criticise athletes or use sarcasm where it may cause the child to lose self-esteem or confidence

It is recommended that you contact the national governing body for your sport to obtain a copy of their codes of contact for coaches working with young athletes.

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 a little anaerobic capacity. Training for aerobic and anaerobic endurance is best left until the young athlete reaches adolescence. The development of sport-specific skills, along with agility and coordination are essential areas to focus on when coaching young athletes.

Article Reference

This article first appeared in:

  • MACKENZIE, B. (2003) Profile of a young athlete. Brian Mackenzie's Successful Coaching, (ISSN 1745-7513/ 4 / August), p. 1-2

Page Reference

If you quote information from this page in your work, then the reference for this page is:

  • MACKENZIE, B. (2003) Profile of a young athlete [WWW] Available from: [Accessed

About the Author

Brian Mackenzie is a British Athletics level 4 performance coach and a coach tutor/assessor. He has been coaching sprint, middle distance, and combined event athletes for the past 30+ years, and has 45+ years of experience as an endurance athlete.