Teen Athletes: Check Training Load First to Protect Growth Plates

If your kid has shot up in height this term and now their school team practice, club team training, and weekend private lessons are all stacking on top of each other, this is a good moment to take a hard look at total training load. When a knee hurts, a lot of parents search for Osgood-Schlatter care; when a heel hurts, they search for Sever's disease care, and each time they find a management plan for that one spot. But if pain keeps rotating between different areas, or the sore spot changes from season to season, the real issue may sit one level above any single diagnosis. It's the total volume of training actually piling up in a given week.

During growth spurts, bone length grows faster than the muscles, tendons, and the still-immature apophyses (growth plates) at the ends of those bones can keep up with. During this window, the tibial tuberosity at the knee, the calcaneal apophysis at the heel, the vertebral growth plates in the spine, and several traction apophyses around the hip all become relatively vulnerable at the same time. The problem is that school PE, school team training, club team training, and private lessons are usually managed separately, so no single adult ends up with an accurate picture of how much load-bearing activity a kid is actually doing in a week.

From here, we'll walk through how to size up and adjust training load for the whole week as a number, rather than treating one body part at a time. That means calculating an appropriate training-hour ceiling for age, catching sudden spikes in training volume before they cause trouble, practical ways to add up total volume when a kid is juggling multiple programs, and a warm-up routine built to protect growth plates.

Why Growth Plates Get Especially Vulnerable: Growth Spurts and Training Load

During the pubertal growth spurt, often called the period of peak height velocity (PHV), a kid can grow 8 to 12 centimeters in a single year. The problem is that muscles and tendons don't stretch out at the same pace bones lengthen. When bone length shoots ahead, the muscle-tendon units attached to that bone end up relatively short and stiff, and that added tension gets transmitted as repetitive traction stress to the still-unossified apophyses at the bone ends: the tibial tuberosity, the calcaneus, the vertebral growth plates, several traction apophyses around the hip, and more. That's the underlying reason conditions with different names but a similar mechanism, like Osgood-Schlatter disease, Sever's disease, and Sinding-Larsen-Johansson syndrome, tend to cluster in the same developmental window.

What you miss by watching only one spot

It's not unusual, in practice, to see a kid get treated for knee pain this season under an Osgood-Schlatter management plan and have their training intensity reduced, only to come back the next season with heel pain diagnosed as Sever's disease. That's less about two unrelated conditions and more about the same underlying cause, excessive traction load during a growth spurt, surfacing as a symptom wherever the weakest spot happens to be at that moment. Pain resolving in one location doesn't mean the underlying training-load problem has actually been solved.

What the research shows about injuries clustering around specific windows

Van der Sluis and colleagues, in a study published in 2014 in the International Journal of Sports Medicine, followed 69 talented youth soccer players for three years, analyzing the relationship between growth velocity and the timing of injury onset. They found that overuse injury rates were markedly higher during roughly the one-year window surrounding peak height velocity than at other times, and during that window, pain was reported sporadically across multiple sites, not just the knee and ankle. That said, the study only looked at male players at a Dutch soccer academy, and it estimated individual growth velocity by working backward from height measurements using the Mirwald equation, which can diverge from actual bone age, so that's a real limitation. Even so, the implication is clear: around a growth spurt, protecting one single body part isn't enough. The training load across that entire window needs to come down.

How to tell if your kid is in a growth spurt right now

A precise answer requires a bone-age assessment, but you can get a reasonable read at home with a few simple checks. Measure height every three months and watch for growth that's noticeably faster than before (say, more than 2cm in three months), and pay attention to whether shoe size has jumped suddenly in the last six months, or pants and sleeves keep coming up short. If two or more of these three signs overlap, your kid is likely in a growth spurt, and it's a good time to apply the training-hour ceilings covered below more conservatively.

Remember That Boys and Girls Hit the Growth Spurt at Different Times

Girls typically hit peak height velocity around ages 10 to 12, while boys typically hit it around ages 12 to 14, so even within the same grade at school, kids can be as much as 2 to 3 years apart in when they actually enter a growth spurt. That means applying the same age-equals-hours ceiling to two kids of the same age can mean very different loads on their growth plates, depending on whether one has already passed through the spurt and the other is just entering it. Rather than going by grade or age alone, check the height, shoe-size, and clothing-length signals described above for each individual kid, and apply the ceiling more conservatively for whichever one is currently in a growth spurt.

Managing Training Load by the Numbers: Age Ceilings, Load Ratios, and Play-to-Training Ratios

Deciding how much training is safe by gut feeling tends to slide toward one of two extremes: keep piling it on as long as there's no pain, or shut everything down the moment pain shows up once. Neither works well over the long run. The three benchmarks below can all be checked with numbers, which cuts down on emotional decision-making.

Benchmark 1: The age-equals-hours rule

Jayanthi and colleagues published a case-control study in 2015 in the American Journal of Sports Medicine analyzing training characteristics and injury in 1,190 athletes aged 6 to 18. They found that athletes whose weekly training hours exceeded their age in years had a significantly higher risk of serious overuse injury (roughly a two-fold odds ratio), and risk also climbed when organized sports time exceeded twice the amount of free-play time. Based on this, the authors recommend keeping weekly training hours at or below age in years, and keeping the ratio of organized sport time to free play at 2-to-1 or lower. That said, this was a retrospective design comparing patients who visited a sports medicine clinic against controls, so generalizing it directly to the broader community of youth athletes calls for some caution. Even with that caveat, it's a simple, memorable benchmark, which is why it's so widely used as a first checkpoint in practice.

For example, a 13-year-old's starting point would be keeping organized training (school team plus club team plus private lessons combined, not counting school PE) under 13 hours a week. On top of that, you'd need at least 6 to 7 hours a week of genuinely unstructured free play to hit that 2-to-1 ratio.

Benchmark 2: Catching spikes with the acute:chronic workload ratio (ACWR)

The age rule alone can manage total volume for a kid who trains at a fairly consistent level week to week, but it won't catch a sudden spike in a specific week, say, a school-break camp, an intensive push right before a competition, or the start of a new season. That's where the acute:chronic workload ratio comes in. Here's how it's calculated.

• Acute load: total training hours in the past week
• Chronic load: average weekly training hours over the past 4 weeks
• Load ratio: acute load ÷ chronic load

Say a kid's 4-week average has been 8 hours a week, and this week they trained 14 hours at a camp. The load ratio comes out to 14÷8, or 1.75. Generally, 0.8 to 1.3 is considered a safe range, and anything above 1.5 is treated as a warning zone where injury risk climbs over the following 1 to 2 weeks. Since this concept was originally established using adult elite sport data, there's ongoing academic debate about whether it applies as-is to adolescents, especially those with open growth plates, and methodological critiques keep surfacing about how results shift depending on sample size or calculation method (simple moving average versus exponentially weighted moving average). Even so, using it as an early-warning trigger for sudden change, rather than treating the exact number as gospel, is plenty useful in practice.

Benchmark 3: Extra caution during season transitions

Whenever a new season starts, or a kid moves up to a new school with a different training environment, both benchmarks above should be applied more conservatively than usual. Concretely, that means starting a new training program at 70% of target hours for the first two weeks, then ramping up to 100% over the following two weeks. If age-equals-hours is already being exceeded going into that window, managing the load ratio on top of it becomes pointless, so the two benchmarks always need to be checked together.

3 Warm-Up and Conditioning Moves to Protect Growth Plates

Bringing down total training volume isn't enough on its own. A short routine before and after training needs to keep flexibility and stability up in the areas taking traction stress. The three moves below cover the knee, heel, and spine/hip, the areas that tend to become vulnerable together during a growth spurt.

1. Standing Quad Stretch — Protecting the Tibial Tuberosity

Starting Position

Stand tall with one hand against a wall or the back of a chair for support. Bend the knee of the leg you're stretching and grab that ankle with the same-side hand. Keep both knees close together and keep your hips squared forward.

Movement Phase

① Slowly pull the held ankle toward your glutes until you feel a pull along the front of the thigh → ② Tuck your pelvis slightly under (posterior tilt), which brings the stretch into the front of the hip as well as the thigh → ③ Hold at that point.

Breathing

Don't hold your breath during the pull. While holding the position, breathe in slowly through the nose and out through the mouth for 3 to 4 breaths.

Sets and Frequency

Hold 20 to 30 seconds per side, 3 sets. Do it both before and after training, 5 to 6 days a week.

Common Mistakes and Fixes

The most common mistake is bending forward at the waist while pulling the ankle in, which shifts the stretch sensation from the front of the thigh into the low back instead. Keep the torso upright and practice creating the pull using only the posterior pelvic tilt. If balance feels shaky, bend the opposite leg (the one supporting you against the wall) slightly for more stability.

Stop Signal

If the sensation at the front of the knee shifts from a stretch to a sharp, stabbing pain, or if you feel pain that mimics pressing directly on the tibial tuberosity, ease off the angle right away, and if the pain persists, skip this move for the day.

2. Wall Calf and Achilles Stretch — Protecting the Calcaneal Apophysis

Starting Position

Stand facing a wall and place both hands on it at shoulder height. Step the leg you're stretching back one step, keep the heel fully planted on the floor, and keep that knee straight. Bend the front knee and shift your weight forward.

Movement Phase

① With the back heel staying planted, slowly shift your hips toward the wall → ② Stop at the point where you feel a pull in the upper calf of the back leg → ③ Bend that back knee slightly and repeat the same shift; the stretch will move down into the lower calf (soleus).

Breathing

Exhale as you shift your hips forward, then keep breathing normally while holding the stretch.

Sets and Frequency

20 to 30 seconds with the knee straight, then 20 to 30 seconds with the knee bent, 2 sets each. After training, 5 to 6 days a week.

Common Mistakes and Fixes

The single most common mistake is letting the back heel lift off the floor while pulling into the stretch. Once the heel lifts, the pull shifts away from the Achilles and into the sole of the foot, and you miss the actual target area. Having a mirror or a parent check that the heel stays flat helps a lot in the early going.

Stop Signal

If pain that feels like direct pressure on the back of the heel (the calcaneal apophysis) or pain that causes a limp when walking shows up during the stretch, stop immediately, and if Sever's disease is suspected, prioritize ice and rest over this stretch.

3. Dead Bug Core and Hip Stabilization — Distributing Traction Load Across the Spine and Hip

Starting Position

Lie on your back and lift both knees to a 90-degree bend (tabletop position). Reach both arms straight up over the shoulders. Gently draw the belly button in so the natural curve of the low back doesn't arch excessively off the floor.

Movement Phase

① Extend one arm overhead and the opposite leg toward the floor at the same time → ② Lower only until just before the heel touches the floor, stopping at the point where the low-back curve would otherwise flatten out → ③ Return to the starting position and repeat on the other side.

Breathing

Exhale as you extend the arm and leg, inhale as you return to the starting position.

Sets and Frequency

8 to 10 reps per side, alternating, 2 sets, 3 to 4 days a week.

Common Mistakes and Fixes

The most common mistake is lowering the leg too far, which lets the low back lift off the floor. Slide a hand gently under the low back first and practice lowering the leg only as far as that light pressure holds, then gradually lower it further as it gets more comfortable.

Stop Signal

If you feel a sharp or shooting pain in the low back or down a leg, stop immediately, and if that keeps happening, a spinal evaluation may be needed before continuing with this exercise.

8-Week Training Load Progression: From Season Start to Full Intensity

Using the table below as a benchmark at the start of a new season or whenever a training program changes helps avoid a sudden spike in load. It treats the target training hours calculated from the age-equals-hours rule as 100%, then ramps up in stages.

If the load ratio climbs above 1.5 on any given week while following this table, don't move on to the next stage; hold at the current stage for one more week and pay closer attention to the warm-up routine and pain log instead. It's common to see this table skipped right after exam periods, when training resumes all at once, or right before a competition, when extra intensive sessions get added in, and those are exactly the moments when injuries tend to cluster.

Juggling Multiple Teams: Adding Up the Hidden Training Load

This is the piece that gets missed most often in real consultations. School team coaches usually only know about school training, club coaches only know about club training, and private lesson trainers only know about their own session time, which means the parent is often the only person who can actually see how much total training time a kid puts in during a week.

Items commonly left out of the total

• Regular school PE class (2-3 hours a week, frequently omitted from the age-equals-hours calculation)
• Extra warm-up or cool-down time a kid adds on their own before or after formal training
• Informal soccer or basketball with friends after school that looks like free play but is actually vigorous sport activity
• Multiple matches during a competition week, including qualifiers and finals (the games themselves count as training load)
• Short, intensive programs during school breaks, like camps or training trips

The most practical thing a parent can do

Just keeping a simple log of training time by day and by program for the week can make a real difference in how well this gets managed. Jotting down the type and duration of training each day in a phone notes app or calendar app is enough, and totaling it up after 4 weeks lets you calculate the acute:chronic load ratio by hand. At the start of a school term or a new season, sharing this log with both the school coach and the club coach, and asking them to coordinate so that one side dials back intensity during a week the other is dialing it up, is the ideal setup. In practice, that kind of coordination doesn't always happen, but even just having the parent aware of the total volume makes it possible to catch warning signs sooner.

A case that shows why adding it all up matters

Say a 13-year-old middle schooler on a volleyball team trains 8 hours a week with the school team, 4 hours a week with a club team, and 2 hours a week in private lessons. None of those numbers looks excessive on its own, but added together, that's 14 hours a week, already past the age-equals-hours ceiling of 13. In a case like this, rather than dropping one program entirely, a more realistic approach is adjusting private lessons to every other week during the school term, or splitting club training into technique-focused sessions and conditioning-focused sessions so the days with heavy physical load don't stack on top of each other.

What Gets Missed Most During School Breaks and Season Transitions

During the school term, school team and club team schedules are reasonably predictable, but that changes once a break starts. School team training often drops off while club teams ramp up with break camps or training trips, and parents can easily read that as things loosening up compared to the school term, which makes it tempting to add a new private lesson or extra training session on top. In practice, camps and training trips are often high-intensity, all-day schedules, so total training volume during a break frequently ends up higher than during the term, not lower. Before a break starts, work out the full schedule for that period (number of camp days, hours per day), and during that window, check whether the acute:chronic load ratio is spiking within the existing schedule before adding anything new, rather than layering another private lesson on top.

Stop Signals and When Medical Care Is Needed

Signs that call for stopping training and seeing a doctor right away (red flags)

• Pain that doesn't go away with rest, especially pain that wakes a kid up at night
• Pain showing up in multiple joints at once rather than staying confined to one spot
• Sudden, severe pain that makes it hard to bear weight (possible avulsion fracture)
• Swelling or warmth accompanied by a whole-body fever (needs to rule out an infectious cause)
• Height growth velocity slowing down noticeably over the past 3 months, or a new-onset leg length discrepancy
• Weight loss, accumulating fatigue, or worsening sleep quality showing up alongside pain (possible overtraining syndrome)

When adjusting training load itself needs extra caution (precautions and contraindications)

• A prior avulsion fracture or growth plate fracture without a return-to-play clearance from the treating physician — don't apply the progression table above as-is; follow the individualized prescription instead
• A period with clear acute inflammation (swelling, warmth) — ice and relative rest come first here, not increasing training volume
• An underlying condition affecting growth and metabolism, like diabetes or a thyroid disorder — training-hour benchmarks need to be adjusted together with the treating pediatric endocrinologist
• Recovering from an acute injury within the past 6 months (fracture, ligament tear, etc.) — a site-specific rehab protocol takes priority over this overall load-management approach

This guide covers general training-load management principles and doesn't substitute for an individual diagnosis or prescription. If any of the items above apply, talk to a pediatric orthopedist or sports medicine physician before applying the progression table above.

Why communication between home, school, and the club team decides whether this works

Youth athletes often juggle school PE, school team training, club team training, and private lessons at the same time, so a recommendation to cut back training in one setting frequently never reaches the others, and the actual total load stays unchanged. When a diagnosis or a load-ratio warning comes up, it's worth sharing that with both the school PE teacher and the club coach so the cumulative load across the whole day can be managed together. This kind of communication gap is one of the most common reasons management plans fail, and it's worth remembering that the parent is usually the only person positioned to see the full picture.

Records Worth Bringing to a Doctor's Visit

If a red flag shows up and it's time to see a doctor, bringing along the weekly training log and self-reported pain scores kept up to that point makes the visit far more efficient. It cuts down on the time a doctor spends verbally reconstructing when the pain started, which training session it got worse after, and how training volume has shifted over the past 4 weeks. For a kid juggling multiple teams especially, without that log, even a parent often struggles to come up with an accurate answer on the spot, so a habit of keeping records ends up directly affecting the quality of the medical visit itself.