The mechanism
During a growth spurt, long bones lengthen at the physis faster than the surrounding muscle-tendon units can lengthen and remodel. The result is a temporary rise in passive tension across the joints, most obviously in the calf-heel complex and the quadriceps-patellar tendon chain.
At the same time, the apophyses (the growth cartilage where tendons attach to bone) are mechanically weaker than mature bone-tendon junctions. Repetitive traction from sprinting, jumping and kicking therefore concentrates stress exactly where the tissue is least tolerant. This is why Sever's disease, Osgood–Schlatter and Sinding-Larsen–Johansson appear where they do, at the ages they do.
The maturity window that matters
Peak height velocity typically occurs around 11–12 years in girls and 13–14 years in boys, with wide individual variation. Chronological age is a poor guide, two 13-year-olds can be four years apart in biological maturity.
Prospective cohort studies in academy football and other youth sport consistently show growth-plate injury incidence rising in the period surrounding peak height velocity, then falling again as maturation completes.
Practical monitoring
- Measure standing height monthly, barefoot, same time of day. A jump above roughly 0.5 cm per month signals an active growth phase.
- Track morning stiffness and post-session soreness on a simple 0–10 scale.
- Note kit changes, outgrowing boots in a season is a growth-spurt marker in itself.
- During active growth, hold weekly training volume steady rather than progressing it.
What to change during a spurt
- Cap high-impact volume (sprint distance, jump count) rather than cutting sport entirely.
- Keep or add strength work - it is protective, not a risk.
- Add regular calf, quadriceps and hamstring length work, but do not rely on stretching alone.
- Build in one genuine rest day and one low-impact day each week.