Training Teenage Athletes: Growth Plate Safety and How to Program for Development

A parent tells a 13-year-old to stay out of the weight room until the growth plates close. The evidence runs the other way. Supervised strength training has one of the lowest injury rates of anything a young athlete does; what takes teenagers out of sport is the growth spurt itself, too many hours of one sport, and short nights. Here is what a growth plate is, when it closes, what hurts it, and how to write the week around it.

What a growth plate is, and when it closes

Three places in a growing skeleton hold growth cartilage: the physis near each end of a long bone, where the bone lengthens; the apophysis, the bump where a big tendon anchors; and the cartilage lining the joints. Cartilage is pre-bone. It is weaker than the tendon and ligament attached to it (NSCA position stand, 2009).

They do not all close at once. In an MRI study of 958 healthy 14- to 21-year-olds the plates fused heel first, then ankle, knee, and the wrist last, and every girl had closed plates at every site by 19 and every boy by 21, girls finishing about two years ahead (growth plate closure MRI study). Most close earlier. A 16-year-old boy who still looks 14 is probably training on open plates at the knee.

Peak height velocity is the fastest year of growth. It begins around 11.6-12.1 years in girls and 13.8-14.1 in boys, and boys grow a mean of 10 cm that year, girls 8 cm (PHV scoping review, 2025). In the Saskatchewan bone accrual study, 26% of adult total-body bone mineral was laid down in the two years around peak bone accrual, and the most active quarter of children carried 9% (boys) and 17% (girls) more bone than the least active quarter a year past that peak (Bailey et al., 1999). Load in those years is how the skeleton gets built. Withholding it has a cost too, and the account gets read back decades later: bone density loss and how training protects it covers the far end of the same story.

Does lifting stunt growth? What the evidence says

No study has shown it. The American Academy of Pediatrics' 2020 clinical report puts it plainly: well-run resistance training programs have no apparent negative effect on linear growth or physeal health (Stricker et al., 2020). The NSCA went back to the 1970s and 80s case reports that started the myth and found improper technique, maximal lifts or no qualified adult in the room, and no injury to growth cartilage in any prospective youth resistance training study (NSCA, 2009). The rates agree. Rugby produced 0.8 injuries per 100 participant hours in one retrospective comparison of adolescents, resistance training 0.012 and competitive weightlifting 0.0013 (NSCA, 2009), and two prospective supervised youth programs logged 0.053 and 0.055 per 100 participant hours (Myers et al., 2017). The weight-room injuries in emergency-department data come mostly from unsupervised home gym equipment (Stricker et al., 2020). Dropped plates, not squats.

Growth plate fractures themselves are common. Physeal injuries account for roughly 30% of all bony injuries in children, and a complication such as early closure follows 2-14% of them (StatPearls, physeal injuries). They come from tackles and bad landings. The barbell is not where the numbers are.

The injuries that do hit growing athletes

Apophysitis is the growing athlete's version of tendinopathy, a tendon pulling on an attachment point that has not finished turning to bone, and it flares during growth, when bone lengthens faster than the muscle-tendon unit attached to it (AAFP, 2019). Three sites account for most of it.

• Osgood-Schlatter (below the kneecap). Prevalence 9.8% among 12- to 15-year-olds, 11.4% in boys and 8.3% in girls, with onset tracking the spurt, 10-15 in boys and 8-13 in girls. It can grind on for up to two years until the apophysis fuses (StatPearls), and what running does to knees has the load-management side of a sore knee.
• Sever's (back of the heel). Most common at 8-12 (AAFP, 2019). Across 612 players in a German soccer academy, 22 cases turned up, mean age 11.8, and cases cost an average of about two months of football, with a spread wide enough that some were back in a fortnight and some lost half a year (academy study, 2022).
• Medial epicondyle apophysitis ("Little League elbow"). 20-40% of school-aged pitchers (AAFP, 2019).

Sprinters and kickers have a rarer and more serious cousin. The avulsion fracture, where an explosive contraction pulls the apophysis off the pelvis or hip, is a risk the AAP flags as raised until closer to skeletal maturity (Stricker et al., 2020). That one is an acute injury, not a load problem: a sudden pop with sharp pain in a sprint or kick means stop, no weight through the leg, and a same-day clinician. The apophysitis cluster above is a load problem. Cut the jumping and sprinting volume, keep the athlete lifting, work calf and quad length, and treat sharp pain at a bony point as a stop sign.

The growth spurt is the risk window, not the barbell

Twenty-six academy soccer players were followed for three years around their growth spurt. Traumatic injuries went from 0.81 per player per year before peak height velocity to 1.41 in the year of it, days lost from 7.3 to 15.7, and after the spurt overuse injuries rose the same way, 0.81 to 1.41 (van der Sluis et al., 2014). One caution. In a clinic sample of 1,190 young athletes, growth rate itself was not linked to injury, 4.8 cm a year in both the injured and uninjured groups; hours were (Jayanthi et al., 2015). The spurt raises vulnerability. The schedule decides whether it gets exposed. For girls the same window is when ACL risk starts to climb, and the landing and single-leg control work that answers it is in ACL and hip injury prevention for female athletes.

Part of the mechanism is coordination. Adolescent awkwardness, a temporary decline in motor control, shows up about six months before peak height velocity, as limb lengths change faster than the nervous system updates its map of the body (PHV scoping review, 2025). A kid who squatted cleanly in October can look lost in March with 6 cm of new femur. It passes. The mistake is adding load or new plyometric drills while it happens, so measure height every three months, and when the chart jumps, hold loads, cut jumps and sprints, and re-teach the main lifts lighter.

Programming by stage: the reference table

Read it by stage, not by age. Before the spurt is the skill window: light loads, clean reps, variety; the spurt year is the hold: same movements, no new maxes, less jumping; after the spurt the athlete trains more like an adult, with loads climbing toward 80% and power work loaded. The age bands are approximate. The height chart overrides them.

Sets, reps, progression and frequency follow the NSCA youth guidelines (NSCA, 2009) and the AAP's Resistance Training Roadmap (Stricker et al., 2020); the hours rule, days off and months off are the AAP's specialization report (Brenner et al., 2016); the sleep bands are the American Academy of Sleep Medicine consensus (AASM, 2016).

Weight-room rules for a growing athlete

• Clear it with a doctor first if there is any history. A healthy teenager does not need a physical to pick up a dumbbell, but the AAP wants a medical opinion before starting resistance training in a young athlete with high blood pressure, a seizure disorder, a heart condition, or past chemotherapy (Stricker et al., 2020). Ask the question once, at the start, rather than finding out in week six.
• Somebody qualified is in the room, every session. The 2014 international consensus ties the safety record to supervised, technique-first programs (Lloyd et al., 2014).
• No true max attempts. The AAP says a 1RM test can be run safely under qualified supervision, and nobody needs one, so take a set of 6-8 that stops two reps short and let a 1RM calculator estimate the number the percentages hang off. It will read low, which is the direction you want.
• Two reps in the tank, always. Grinding reps is where technique goes. It is where the old case reports came from. An RPE calculator turns "how hard was that" into a load adjustment, and the training to failure guide covers why the last rep is not worth it for anyone.
• Light loads for longer than feels necessary. The AAP roadmap keeps early work at or under about 60% of estimated 1RM until technique holds under fatigue, then adds 5-10% at a time (Stricker et al., 2020). Prepubertal strength gains are mostly neural, more motor units recruited rather than bigger muscles (Myers et al., 2017). Light loads deliver the adaptation on offer at that age.
• Big movements first, both sides equally. Squat, hinge, push, pull, carry, then single-leg work, after a 5-10 minute dynamic warm-up (NSCA, 2009). A warm-up set calculator ramps to the working weight without cold heavy sets, and a training volume calculator keeps weekly sets inside what school sport already asks of the same legs.

Hours, sports and sleep: the load outside the gym

Volume outside the weight room is where most teenage athletes get hurt. In the 1,190-athlete clinic study, more hours of organized sport per week than age in years doubled the odds of a serious overuse injury (odds ratio 2.07), an organized-to-free-play ratio above 2:1 raised them 1.87 times, and single-sport specialization was an independent risk factor on its own (odds ratio 1.36) (Jayanthi et al., 2015). A 13-year-old on a club team, a school team and a strength program should total fewer than 13 hours. The strength hours count.

The AAP's specialization report reads like a schedule: multiple sports at least until puberty, specialization delayed to 15 or 16 for most sports, 1-2 full days off a week, and 3 months a year away from the main sport in 1-month blocks (Brenner et al., 2016). Then sleep. Among 112 middle- and high-school athletes, mean age 15, those sleeping under 8 hours a night were 1.7 times as likely to have been injured (Milewski et al., 2014), and the consensus band for 13- to 18-year-olds is 8-10 hours (AASM, 2016); the sleep and training guide has the practical end. A 6 a.m. practice on 6 hours of sleep is the highest-risk session of the week.

Fuel sits next to sleep. A teenager laying down a quarter of their adult skeleton has an energy bill most parents underestimate. Under-fueling here costs bone that does not come back, so read RED-S and low energy availability if weight is dropping, periods have stopped or the athlete is always tired.

Red flags that end the session and start a clinician visit: pain at a bony point that does not warm up, a limp, night pain, a hot swollen bump below the kneecap, or a sudden pop in the hip during a sprint or kick. Once cleared, returning to training after injury has the ramp back.

How Movement Rebels fits

A Movement Rebels account is for athletes 16 and up, with a parent or guardian's consent under 18, which covers the 16- or 17-year-old boy still growing on open plates at the knee. For a younger athlete, the parent or coach works from the table. The app comes later.

For the older teenager, the calendar, the lifting log, the morning check-in and the coach sit in one app. The coach sees the Garmin or Apple Health sync from Tuesday's match and Thursday's intervals, the lifts logged on Wednesday, and the morning readiness check-in where sleep came in at 6 hours and soreness at 8 out of 10. Write "17, still growing, Osgood-Schlatter in the left knee, maximum two gym sessions a week" in the Notes for your coach field and the Sunday weekly plan is written around it, and when Friday's plyometric session lands on a short night the morning brief flags it and one message in chat moves it to Saturday. A resting heart rate climbing across the week is read as a load or fueling signal. Named before the session, not after.

Start with two things this week, the ones that tell you when to hold and when to push: the height mark on the doorframe, measured every three months, and the hours count on the fridge.