Why hypermobility and growth spurts collide
Two things are happening at once in a hypermobile teenager. Their joints move further than average, so the muscles around each joint have to do more of the stabilising work that ligaments would normally help with. And during a growth spurt, bones lengthen faster than muscles and tendons adapt, while the growth plates at the knee, heel and hip go through a period of being less tolerant of repeated pulling and impact.
Either one of those on its own is manageable. Together they mean the same training week that was fine six months ago can now irritate a growth plate or overload a tendon. This is why so many hypermobile young athletes first develop knee or heel pain somewhere between 10 and 14.
The injuries that show up most often
In hypermobile children the injuries are rarely dramatic one-off events. They are the slow-building, load-related growth conditions, often in more than one place at once or one after another.
- Osgood-Schlatter disease, pain on the bony bump below the kneecap, often worse in children whose knees hyperextend when they run and land.
- Sever's disease, heel pain that tracks growth spurts and busy fixture lists, common in hypermobile ankles and flat, flexible feet.
- Sinding-Larsen-Johansson syndrome, pain at the lower tip of the kneecap, the less well-known sibling of Osgood-Schlatter.
- Adolescent patellofemoral pain, a diffuse ache around the kneecap on stairs, hills and after sitting, strongly linked to hip strength and landing control.
- Recurrent ankle sprains, because a very mobile ankle relies almost entirely on calf strength and balance to stay stable.
Why hypermobile children feel tight
Parents are often puzzled that a child who can put their palms flat on the floor complains of tight hamstrings and calves. The tightness is real, but it is usually the muscles working overtime to hold unstable joints steady, not a true loss of flexibility. Stretching harder into an already large range gives brief relief and rarely changes anything.
The more useful question is not how far the joint moves, but how strong and controlled it is in the positions sport demands.
Key recommendations for parents
1
Prioritise strength over stretching
Two or three short strength sessions a week, slow and controlled through a full range, build the stability hypermobile joints lack. Split squats, calf raises, hamstring bridges and side planks cover most of it.
2
Count the whole week, not just one sport
School PE, club training, matches, dance and playground running all add up. Symptoms in hypermobile children usually track total weekly volume, so look at the whole picture before deciding what to trim.
3
Reduce impact before removing sport
During a flare-up, cut the highest-impact volume first (extra running sessions, back-to-back match days) while keeping some sport in. Complete rest rarely helps and makes the return harder.
4
Watch the landing, not just the running
Knees that collapse inwards or lock back into hyperextension on landing put far more stress through growth plates. Simple hop-and-stick landing practice is one of the most protective habits a hypermobile child can build.
5
Expect flare-ups during growth spurts
If your child has shot up in the last six months, a niggle is more likely to be load-related than bad luck. Adjust the week early rather than waiting for pain to force the issue.
The five things that make the biggest difference for a hypermobile young athlete.
What good management looks like
The approach that works for hypermobile children with growth-related pain is the same staged one used for the conditions themselves: settle the irritated tissue by trimming the provoking load, build strength and control progressively, then return to full sport in steps rather than all at once.
Our free condition guides walk through exactly what this looks like week by week for Osgood-Schlatter, Sever's disease, Sinding-Larsen-Johansson and patellofemoral pain, and the 6-week recovery frameworks turn it into a structured plan you can follow at home.
When to get an assessment
For the majority of hypermobile young athletes, though, the outlook is genuinely good. Range plus strength is a powerful combination, and the children who learn to control their flexibility early often become the most robust athletes in their squad.
See a professional if
Pain is present in several joints at once, joints repeatedly give way or sprain, your child is limping or avoiding activities they used to enjoy, pain disturbs sleep most nights, or there is swelling, locking or a joint that looks different from the other side. Widespread pain with fatigue, dizziness on standing or gut symptoms also deserves a GP visit, as a smaller group of hypermobile children need a broader assessment.