What are flexibility and mobility?
Flexibility is a muscle’s capacity to lengthen; mobility is the controlled range of motion a joint can reach with this flexibility together with muscle control. The two are related but not the same thing: a child may be flexible, but if they cannot control that range of motion, their mobility is limited. In sporting development the real goal is not just “how flexible” but “how well can they control that range”.
Adequate flexibility and mobility allow movements to be done correctly and efficiently, support posture and can be protective against certain injury types. But “the more flexibility the better” is not correct; uncontrolled excessive flexibility can also create problems for joint stability. Balance and control are essential.
Correct stretching in the warm-up
The most common mistake with stretching is doing long-held static (held-in-a-fixed-position) stretching before training. Research shows that long static stretching at the start of a warm-up can temporarily reduce strength and performance. Instead, dynamic movements are preferred in the warm-up — leg swings, controlled lunges, hip openers, trunk rotations; these both warm the body and prepare the joints for the movements the sport demands.
Static stretching and flexibility-developing work, meanwhile, are left more to after training or to separate flexibility sessions. This work should be done in a controlled, gentle and pain-free way. The aim is not to push limits but to develop range of motion gradually and safely.
Flexibility during the growth spurt
During the growth-spurt (circa-PHV) period, flexibility can temporarily decrease; because the bones lengthen faster than the muscles and tendons, which causes the muscles to become relatively “tighter”. In this period some children may feel stiffer and struggle with movements that require flexibility. This is normal and temporary.
What matters in this period is not trying to “fix” flexibility with forced and painful stretching; because the rapidly lengthening tissues are already sensitive. Instead, focusing on gentle, controlled mobility work and movement quality is safer. As the spurt passes, flexibility usually rebalances. Excessively forced stretching, especially in this period, can do more harm than good.
Balance by sport and by child
Different sports have different flexibility needs; while sports such as gymnastics or dance require high flexibility, for most sports a “sufficient and controlled” range of motion is ideal. What matters is developing a balanced flexibility-stability profile suited to the demands of the sport the child does. Excessive passive flexibility, without control, is not protective.
In children, flexibility work, like everything else, should be play- and quality-focused; instead of dull and painful stretching routines, activities that explore movement and develop control are more sustainable. If there is a clear restriction, pain or asymmetry related to flexibility, this should be assessed with a specialist (coach, physiotherapist or doctor). In conclusion, flexibility and mobility are a component of a balanced movement profile, alongside other parts of development such as strength and coordination; what makes them valuable is not exaggerating them on their own but combining them with control.