The child and young athlete: early specialization, growth-phase injuries, and safe sport

Short answer

The body of a child and young athlete differs from an adult's: the growth plates and the bone–tendon junctions are relatively vulnerable. For this reason two principles stand out: (1) Locking onto a single sport at an early age (early specialization) increases the risk of overuse injury and burnout, and is not necessary for long-term success — multi-sport participation is recommended. (2) Increasing load gradually and giving adequate rest during growth phases reduces injury.

During the growth phase, load-related problems at the bone–tendon junction (apophysis) — Osgood-Schlatter at the front of the knee, Sever at the heel — are common. Though popularly called "growing pains," these are not classic growing pains but load-related traction apophysitis; they are usually benign and respond well to conservative treatment. Strength training in children, with qualified supervision and correct technique, is safe and beneficial — the aim is not heavy lifting but technical and neuromuscular development.

Early specialization: why be cautious?

In most sports there is no evidence that children specializing in a single sport at an early age provides long-term benefit; on the contrary, it increases the risk of overuse injury and burnout. The recommendation of expert organizations:

Multi-sport (more than one) participation until puberty; delaying specialization to late adolescence.
Regular rest periods during the year from the main sport, and 1–2 full rest days per week.

Early multi-sport participation does not hinder later elite success; it even supports general athletic development.

Growth-phase injuries (apophysitis)

As the child grows, the bone can lengthen faster than the tendon; this causes pain at the bone–tendon junctions (apophyses):

Osgood-Schlatter: pain and swelling at the prominence below the kneecap (top of the shin bone); worsens with jumping/running.
Sever disease: pain at the back of the heel, commonly seen in running children.
"Little League" elbow/shoulder: an overload picture seen in the throwing arm in throwing sports.

These are usually benign, self-limiting and resolve with load management + stretching/strengthening; but if not managed, they can lead to months of lost play.

Load and rest management

A rough guide: the total weekly hours of organized training should not exceed the child's age (for example, 12 years → under about 12 hours per week). In children who train more hours than their age, the risk of serious overuse injury rises markedly.
The growth-spurt period (about 10–13 years in girls, 12–15 in boys) is the window most open to injury; load increases should be handled more carefully in this period.
Increase load gradually (avoid sudden jumps), and give 1–2 full rest days per week.

Note: rules like "hours equal to age" are practical rough frameworks, not strict, precise thresholds. The real measure is the child's pain, performance, sleep, and willingness.

⚠ See a physician in these situations: localized pain at a specific bone point, limping, night/rest pain, marked one-sided swelling or fever; also, in a young athlete, energy insufficiency, weight loss, and menstrual irregularity. These may point to a bone stress injury or low energy availability in sport (RED-S) — pictures that should not be neglected.

Is strength training safe in children?

Yes — with qualified supervision and correct technique it is safe and beneficial. The aim is not to lift maximal weight; it is technique, neuromuscular control, and general strength development. Most reported injuries arise from unsupervised free-weight use — that is, the risk is essentially due to a lack of supervision. With appropriate supervision, children and adolescents benefit safely from strength work.

For clinicians

Early-specialization recommendations (AOSSM/AAP/AMSSM) rest on strong consensus, but the evidence is mostly observational/consensus-based; early-peak sports (gymnastics, figure skating) may be exceptions. Chronological age does not reflect biological maturity; recommendations are population averages. Apophysitis is a clinical diagnosis; atypical/one-sided night pain, systemic findings, or trauma require imaging/differential diagnosis. Resistance training in children is considered safe by the AAP and NSCA (supervision, priority of technique, appropriate progression).

Frequently asked questions

Should my child focus on a single sport, or be multi-sport?

Multi-sport (more than one) participation at an early age is recommended. It has been shown that locking onto a single sport early is not necessary for long-term success and, on the contrary, increases the risk of overuse injury and burnout. Delaying specialization to late adolescence is safer.

My child's shin below the knee (or heel) hurts; is it serious?

Growth-phase pains in these areas (Osgood-Schlatter, Sever) are common and usually benign; they resolve with load management and stretching/strengthening. However, if there is night pain, marked one-sided swelling, fever, or trauma, a physician should be seen.

Can children lift weights, will it stunt their growth?

With qualified supervision and correct technique, strength training in children is safe; there is no evidence that it stops growth. The aim is not heavy lifting but technique and general strength development. Most injuries arise from unsupervised weight use.

How much training per week is too much?

As a rough rule, the weekly hours of organized training should not exceed the child's age. More than that increases the risk of overuse. But the real measure is the child's pain, fatigue, and willingness; 1–2 full rest days per week are important.

Why do more injuries happen during the growth phase?

During rapid growth, the bone can lengthen faster than the muscles and tendons; this temporarily makes the bone–tendon junctions more vulnerable. Keeping load gradual and paying attention to rest in this window reduces injury.

Scientific references

Author's own work:
Yüksel O, Demir Benli M. Frequency of iron deficiency and iron deficiency anemia in children presenting for preparticipation evaluation. Turkish Journal of Sports Medicine 2015;50(1):1-9.
Other references:
LaPrade RF ve ark. AOSSM early sport specialization consensus statement. Orthop J Sports Med 2016;4(4).
Brenner JS ve ark. (AAP) Sports specialization and intensive training in young athletes. Pediatrics 2016;138(3).
Stricker PR ve ark. (AAP) Resistance training for children and adolescents. Pediatrics 2020;145(6):e20201011.
DiFiori JP ve ark. Overuse injuries and burnout in youth sports: position statement (AMSSM). Br J Sports Med 2014;48:287-88.

This information is for general guidance only; it does not replace an examination, a diagnosis, or your physician's individual advice. Please consult a physician for your symptoms. About the author: Doç. Dr. Oğuz Yüksel — Academic Profile.