How to coach cadete football: puberty, load management and injury prevention

At cadete, the coach's biggest challenge is not tactical, it is biological. Players are 14 or 15 on paper, but their maturational age can differ by two or three years inside the same dressing room. One is 1.80 m and already shaving; another, born the same year, has not started growing yet.

That spread conditions everything: how much load each one tolerates, injury risk, how many minutes they can play and even what you can demand of them technically. Coaching everyone the same way — the most common mistake — overloads the one who is growing and frustrates the one lagging behind.

It is the flip side of the alevín age (U-12), where the body is still homogeneous and the focus was technical. At cadete, with the jump already made to 11-a-side (size 5 ball and full offside, as the grassroots categories by age guide sets out), the number one priority becomes not breaking the player during the growth spurt.

Peak height velocity (PHV) is the moment in puberty when the body grows fastest: a boy can gain 8 to 10 cm in a single year. In male footballers it arrives around age 14 on average — a study of 170 academy players placed it at 14.4 years (Bult et al., 2018) — right in the middle of the cadete bracket.

The problem is that bones grow before tendons and muscles do. For months the player has longer levers but the same motor control as before: he becomes temporarily more uncoordinated, loses striking accuracy and trips over his own body. It is not that he "got worse"; he is rebuilding his body map.

For the coach this means two things. One: lower the fine technical demands during the spurt and be patient. Two: the same spurt that disrupts coordination is the one that spikes injury risk, so the PHV window is also the window of maximum caution with load.

Two cadete players born the same year can be up to 2 or 3 years apart in biological age: in the Dutch study cited above, the spread within a single team reached 3.1 years. One has already passed PHV and has an almost adult body; another has not started and still has a child's build.

This creates a perception trap. The early maturer runs faster, hits harder and wins duels: he looks like the better player. The late maturer, smaller and less powerful, has to solve with technique and game reading — and is often the one hiding the most real talent. Confusing maturity with talent makes clubs release exactly the players with the most upside.

Professional academies use bio-banding: grouping players by maturity rather than birth year alone (Science for Sport). At a modest club you cannot reorganise the leagues, but you can factor it in when assigning tasks, duels and minutes: do not systematically pit the one who has not grown against the one who is already built like a wall.

Managing load at cadete is, above all, about individualising. A kid's total load is not just what he does with you: it adds up club training, the weekend match, PE at school, the regional select team if he gets called up and playground football. A cadete can rack up six or seven sessions a week with nobody keeping count.

Practical rules that work without expensive kit:

No technology needed: a two-minute chat at the start of the session ("how are the knees?, did you sleep?, did you have an exam or a school match?") gives more useful information than any GPS.

During the growth spurt the weak point is not the muscle but the growth cartilage (the physis and the apophyses), more fragile than the tendon pulling on it. Hence the two signature cadete injuries, both from repetitive traction:

Both are traction apophysitis: the bone grows fast, the tendon stays tight and pulls on the cartilage until it inflames (OrthoInfo, AAOS). You do not "play through pain": if a cadete limps or clutches his knee when he jumps, you reduce load, you do not tell him to push on.

The figure that demands attention: the late maturer is the most exposed to overuse injuries around PHV. In a follow-up of academy players, late maturers suffered 3.97 overuse injuries per 1,000 hours in the PHV year, against 1.56 for early maturers (van der Sluis et al., 2015). Prioritise preventive warm-ups, mobility and volume control for them.

A cadete session runs around 90 minutes and, unlike alevín, includes a formal preventive block. Four parts:

The preventive warm-up stops being optional at cadete: FIFA 11+ style programmes — strength, balance and eccentric control of hamstrings and quadriceps — reduce injuries in adolescents and do not steal useful time, because they also warm the players up for the session.

Adjust the demand inside the same drill: give the one in full spurt more technical volume and less jumping and maximal sprinting; for the one who has passed it, ramp up power load progressively. To vary tasks by level, the logic in grassroots football drills by age still applies.

Cadete is one of the big academy filters, and that is where the costliest mistake happens: releasing the small kid for not performing today. Because the early maturer dominates physically, he hogs minutes and praise; the late maturer is let go just when his body has not yet played its cards.

Evidence and experience agree: many late maturers, once they complete their development a year or two later, overtake the early maturer because they had to learn to play with their head and their feet, not their body. Releasing them at 14 mortgages the team of the future.

What you can do even if you do not run club policy: