The demand-capacity model
Almost every overuse injury in youth sport can be explained with one idea: the tissue was asked to do more than it could currently tolerate. Injury risk rises either when demand goes up quickly, or when capacity goes down - and during adolescence, both can happen at once.
That framing is useful because it points at solutions. You can lower demand by adjusting the weekly schedule, and you can raise capacity through strength and impact training. Most successful youth injury programmes do both.
Why capacity drops during growth
- Growth plates at tendon attachments are mechanically weaker than mature bone.
- Bone lengthens ahead of muscle and tendon adaptation, raising passive tension.
- Relative strength, strength per kilogram of body mass, often dips as mass increases.
- Coordination and landing control temporarily deteriorate as limb proportions change.
- Sleep and energy intake frequently fall short of what a growing, training body needs.
Why demand spikes
The demand side is usually structural rather than individual. A young athlete moves up an age group, joins a second team, starts pre-season after six weeks off, or hits a run of three fixtures a week. Each coach sees a reasonable amount of work. Nobody sees the total.
The commonly cited warning sign is weekly organised sport hours exceeding the athlete's age in years, a 12-year-old doing more than 12 hours a week. Equally important is the rate of change: an increase of more than about 30% in weekly load from one week to the next is where risk climbs.
The role of specialisation
Playing one sport year-round concentrates the same movement pattern on the same tissue with no break. A young footballer who also swims in winter loads their body differently for a few months; the one who plays football twelve months a year does not. Diversified participation through to mid-adolescence is consistently associated with fewer overuse injuries.
What reduces risk
- Two short strength sessions a week, maintained year-round rather than started when pain appears.
- Neuromuscular warm-ups that include hopping, landing and change-of-direction work.
- One genuine rest day per week and one to two months off the main sport per year.
- Holding weekly volume steady through an active growth spurt rather than progressing it.
- Tracking height monthly and soreness weekly to spot the vulnerable window early.
- Prioritising sleep, the biggest single recovery variable in adolescence.
The reframe that helps most
Growth-related injury is not a sign your child is fragile, badly coached or doing something wrong. It is a signal that this week's demand is ahead of this month's capacity. Once families see it that way, the conversation shifts from 'should they stop?' to 'what should we adjust, and what should we build?', which is the conversation that gets athletes back fastest.