During the adolescent growth spurt, bones can grow faster than muscles and tendons adapt, and coordination can temporarily dip. It is also a period with higher risk of certain overuse injuries.
Points widely discussed in youth sport science:
The peak growth spurt typically comes around ages 11-13 in girls and 13-15 in boys, but timing varies widely
Growth-related problems such as Osgood-Schlatter (below the knee) and Sever’s (heel) are common in this phase
Measuring height regularly, for example every three months, helps spot rapid growth
Temporarily reducing high-impact volume, while keeping strength, technique and enjoyment, is a common strategy
A sensible adjustment during rapid growth: fewer sprints and jumps per week, more technical and strength work at moderate loads, and attention to flexibility as muscles may feel tighter.
Explain this to the athlete, too. A temporary drop in coordination or performance can be confusing and discouraging if they do not know why.