Why Do Young Athletes Get Injured? What the Research Says

Most injuries in young athletes are not bad luck. Research points to four causes parents can control: training load that rises too fast, too many weekly hours for the athlete's age, the adolescent growth spurt, and specializing in one sport too early. Each one has published numbers behind it, and each one has a fix.

Some injuries can't be prevented. A collision, a fall or a bad landing can happen to any athlete. Those are acute injuries. This article is about overuse injuries: stress fractures, tendon pain, growth plate irritation and muscle strains that build up from repeated stress without enough recovery.

They are common. In a survey of high school athletes, more than 80 percent reported at least one sports injury. In a three-year study of nearly 1,200 young athletes, close to 40 percent were injured during the study period.

I coached 14 years of NCAA Division I track and field before starting private coaching in the DFW area in 2020. The research below matches what I see in athletes who come to me from schools and clubs across the metroplex.

1. Training load that rises too fast

The body adapts to the load it is used to. Injury risk rises when the load suddenly jumps above that level, not simply when the load is high.

A 2017 study of adolescent elite athletes in Sweden, led by Philip von Rosen, found exactly this pattern. The strongest injury risk factor in the study was a combination: athletes who increased their training volume and intensity while sleeping less at the same time had more than double the injury risk of athletes whose training and sleep stayed stable.

That combination describes the start of almost every season. Practices get longer and harder at the same time school starts and bedtimes slip.

Research on professional athletes, led by sports scientist Tim Gabbett, points the same way. Athletes who built a high workload gradually were more resistant to injury than athletes who trained lightly, as long as they avoided sudden spikes. That work was done in adults, and a 2022 review of youth soccer found too few studies to confirm the exact numbers apply to young athletes. The principle is consistent across the research: a gradual build protects the athlete, and a sudden jump puts them at risk.

In youth sports, the spikes are predictable. They happen:

• At the start of a season, when an athlete goes from weeks of light activity into full practices.
• When an athlete joins a new program, and the coach runs a standard workout without asking what the athlete has been doing.
• When programs overlap, such as the first week a club season and a school season run at the same time.

Sprinting raises the stakes. High-speed running is one of the most common triggers for hamstring strains, and a sudden increase in running volume is a well-known cause of shin pain and bone stress injuries.

What to do: Expect the first two to three weeks of any new season or program to build up gradually. Ask any new coach what they know about your athlete's recent training before the first hard session. And protect sleep hardest exactly when training gets harder.

2. Too many hours for their age

The best-known rule in youth sports medicine comes from Dr. Neeru Jayanthi, a sports medicine physician who has studied youth training for over a decade: an athlete should not train more hours per week in organized sports than their age in years.

His research found that:

• Athletes who trained more hours per week than their age in a single sport were 70 percent more likely to have a serious overuse injury than other injury types.
• Athletes with serious injuries averaged 13 hours a week of organized sports. Uninjured athletes averaged 9.4 hours.
• Athletes were more likely to be injured when organized sports took up more than twice the time they spent in unstructured free play, like pickup games.

For older teens, the American Medical Society for Sports Medicine sets an upper limit: adolescents who train more than 16 hours a week in organized sports may be at increased risk of injury, and younger children should train less. A survey of high school athletes backs this up, finding that more hours of sport per year was linked to more injuries.

The American Academy of Pediatrics adds two guidelines on rest:

• One to two days off per week from the athlete's main sport.
• One month away from the main sport at least three times a year.

Sleep may matter as much as hours

Training only works if the athlete recovers from it, and sleep is where most recovery happens. Two studies of adolescent athletes found almost the same result:

• Milewski, 2014: In 112 middle and high school athletes, those who averaged fewer than 8 hours of sleep a night were 1.7 times more likely to be injured than those who slept 8 hours or more.
• von Rosen, 2017: In adolescent elite athletes, sleeping more than 8 hours on weeknights cut the odds of injury by 61 percent. Meeting recommended nutrition cut it by 64 percent.

In Milewski's study, sleep and grade in school were the two factors that predicted injury. Weekly training hours, the number of sports played, private coaching and strength training did not. A later systematic review of the research confirmed the link: chronic lack of sleep is associated with more sports injuries in adolescents.

An athlete who practices late, finishes homework at 11 PM and gets up at 6 AM for school is losing recovery every night of the week.

For how I build recovery into training at Tier1Athlete, read why recovery beats grinding.

3. The growth spurt

Between roughly ages 11 and 15, most athletes go through a period of rapid growth called peak height velocity. It is one of the highest-risk windows for injury in a young athlete's career, and most parents have never heard of it.

The cause is a mismatch. Bone, muscle and tendon grow at different rates. For a few months, tendons pull hard on growth plates that are weaker than the bone around them, and the athlete's coordination is adjusting to longer limbs.

The research is consistent:

• A 2024 review in the British Journal of Sports Medicine examined 30 studies of youth athletes. Growth-related injuries peaked during the growth spurt, and athletes whose height and legs grew faster had more injuries and lost more time to them.
• Speed of growth matters, not just timing. In a study of 124 academy soccer players, those growing fastest during their growth spurt had 2.6 to 3.3 times the injury burden of players growing at an average or slow rate, and up to 4 times the burden from growth-related injuries. The researchers recommended tracking growth regularly to identify athletes at risk.
• Another study that followed talented youth players through their growth spurt found days missed to injury roughly doubled in the year of fastest growth, from about 7 days to almost 16 days per player.
• Research summarized by FIFA found athletes at the highest risk when they were between 88 and 92 percent of their predicted adult height and growing quickly.

Two growth-related conditions are especially common in sprinters, jumpers and hurdlers, because they're caused by repeated running and jumping:

• Osgood-Schlatter disease: pain and a tender bump just below the kneecap, where the patellar tendon attaches to the shin bone.
• Sever's disease: pain at the back of the heel, where the Achilles tendon attaches to the heel bone's growth plate.

What to do: Measure your athlete's height every one to three months and write it down. If they've grown quickly since the last measurement, that is the time to reduce jumping and sprinting volume, not add to it. Knee or heel pain in an athlete aged 10 to 15 should be checked by a doctor rather than trained through.

4. Specializing in one sport too early

Many families believe that focusing on one sport early is the path to a college scholarship. The research says otherwise.

Researchers at the University of Wisconsin define a highly specialized athlete as one who meets all three of these:

1. Has a single primary sport.
2. Trains in it more than eight months a year.
3. Has quit other sports to focus on it, or has never played another.

What the research shows:

• A meta-analysis in Pediatrics (2018) pooled studies of athletes 18 and under. Highly specialized athletes had 1.81 times the risk of an overuse injury compared with athletes who played a variety of sports. Risk rose step by step: moderately specialized athletes were at higher risk than low, and highly specialized were higher still.
• Middle schoolers are especially vulnerable. In a study that followed middle school athletes through a school year, highly specialized athletes had nearly four times the odds of an overuse injury. Specialization did not raise their risk of acute injuries. It is a repetitive-stress problem.
• The eight-month mark matters. In a study of 302 high school athletes, those who trained in one sport for more than eight months a year were more likely to report knee and hip injuries.
• Earlier specialization, more injury. In Jayanthi's study of nearly 1,200 young athletes, injured athletes had started specializing before age 12 on average.

Researchers still debate how much of this risk comes from specialization itself and how much comes from the extra training hours specialized athletes usually log. Either way, the practical answer for parents is the same.

Specializing early also doesn't deliver what families expect. Research from the same Wisconsin group found that most athletes who reached NCAA Division I were not highly specialized in high school, even though most youth athletes believe specializing improves their chances. The American Academy of Pediatrics reports that for most sports, athletes who play several sports and specialize later are more likely to reach elite levels.

This matters for speed athletes. Sprinting is the same repeated movement on the same tissues every session. An athlete who sprints year-round with no other sport and no planned breaks gets no variety in the stress their body takes.

What to do: Keep your athlete under eight months a year in any one sport. Until about age 15, keep at least one other sport or activity in their year. After that, if they commit to one sport, protect the time off described in section 2.

Pain or soreness? How to tell

Soreness is normal. Pain is a warning. Soreness is a general ache in a muscle a day or two after hard training, and it eases as the athlete warms up.

Stop training and get it checked if the pain:

• Is sharp, or in one specific spot, especially on a bone.
• Gets worse during a session instead of better.
• Changes how the athlete runs, jumps or lands.
• Is still there the next morning.
• Sits below the kneecap or at the back of the heel in an athlete going through a growth spurt.

The American Academy of Pediatrics is clear that young athletes should never be encouraged to train through pain like this.

The numbers in one place

Most families I work with are within these limits for any single program. The problem is the total. School practice, club practice, private training and games are each reasonable on their own, and nobody is adding them up. Keep a simple weekly log of every session and share it with each coach your athlete trains with.

A note on the research: most of these studies come from team sports such as soccer, and many rely on athletes reporting their own training and injuries. They show strong associations, not guaranteed outcomes. This article is for education and isn't medical advice. If your athlete has pain that isn't improving, see a sports medicine physician.

References

Training load

• von Rosen P, Frohm A, Kottorp A, Fridén C, Heijne A. Multiple factors explain injury risk in adolescent elite athletes: applying a biopsychosocial perspective. Scandinavian Journal of Medicine & Science in Sports, 2017;27(12):2059–69. Record
• Hulin BT, Gabbett TJ, et al. The acute:chronic workload ratio predicts injury: high chronic workload may decrease injury risk in elite rugby league players. British Journal of Sports Medicine, 2016. Abstract
• Rico-González M, et al. Acute:chronic workload ratio and training monotony variations over the season in youth soccer players: a systematic review. International Journal of Sports Science & Coaching, 2022. Record

Training hours and sleep

• Jayanthi NA, et al. Sports-specialized intensive training and the risk of injury in young athletes: a clinical case-control study. American Journal of Sports Medicine, 2015;43(4):794–801. Summary: Emory News
• Jayanthi NA, et al. Intense, specialized training in young athletes linked to serious overuse injuries. American Medical Society for Sports Medicine, 2013. Newswise
• Rose MS, Emery CA, Meeuwisse WH. Sociodemographic predictors of sport injury in adolescents. Medicine & Science in Sports & Exercise, 2008;40(3):444–50. Cited in: AMSSM Play.Stay.Thrive toolkit
• Kahlenberg CA, et al. Incidence of injury based on sports participation in high school athletes. Abstract
• Milewski MD, et al. Chronic lack of sleep is associated with increased sports injuries in adolescent athletes. Journal of Pediatric Orthopaedics, 2014;34(2):129–33.
• von Rosen P, et al. Too little sleep and an unhealthy diet could increase the risk of sustaining a new injury in adolescent elite athletes. Scandinavian Journal of Medicine & Science in Sports, 2017;27(11):1364–71. Abstract
• Gao B, Dwivedi S, Milewski MD, Cruz AI. Chronic lack of sleep is associated with increased sports injury in adolescents: a systematic review and meta-analysis. PMC

Growth and maturation

• Associations between growth, maturation and injury in youth athletes engaged in elite pathways: a scoping review. British Journal of Sports Medicine, 2024;58(17):1001. PMC
• Monasterio X, et al. Peak height velocity affects injury burden in circa-PHV soccer players. International Journal of Sports Medicine, 2023. Abstract
• van der Sluis A, et al. Sport injuries aligned to peak height velocity in talented pubertal soccer players. International Journal of Sports Medicine, 2014. Abstract
• Johnson DM, Williams S, Bradley B, Cumming SP. Can we reduce injury risk during the adolescent growth spurt? 2021. FIFA Training Centre summary

Sport specialization

• Bell DR, Post EG, Biese K, Bay C, Valovich McLeod T. Sport specialization and risk of overuse injuries: a systematic review with meta-analysis. Pediatrics, 2018;142(3):e20180657. Abstract
• Bell DR, et al. Sport specialization is a risk factor for overuse, but not acute, lower extremity injuries: a prospective study. Orthopaedic Journal of Sports Medicine, 2019. Abstract
• Bell DR, Post EG, Trigsted SM, et al. Prevalence of sport specialization in high school athletics: a 1-year observational study. American Journal of Sports Medicine, 2016. Summary: University of Wisconsin News
• Youth sport specialization and risk of injury: a general review. Clinical Journal of Sport Medicine, 2023;33(6):652–57. Abstract
• Brenner JS, et al. Sports specialization and intensive training in young athletes. Pediatrics, 2016. Summary: MDedge
• American Academy of Pediatrics and allied medical groups, consolidated youth sports recommendations. Aspen Institute