Protecting the Youth Tennis Shoulder: What Parents, Coaches, and Players Should Know

If your child has gone from school tennis to lessons, tournaments and extra serving practice in the space of a season, or you have been handed a chart of test results and told where they should be, this is worth ten minutes of your time. Most youth tennis shoulder injuries build quietly, across months, while everyone is watching the scoreboard.

Here is the finding that should shape how you read any of those numbers. A 2025 review pooled 45 studies covering 8,008 competitive youth tennis players and 17 different physical tests. Only four of those 45 studies measured the shoulder at all — and the data for girls were thinner still.

The good news? You do not need population averages to look after a young shoulder. Tracking your own player over time tells you more than any chart, and it is something a parent or coach can genuinely do.

At Rooted Motion Physical Therapy, we believe young athletes deserve advice that admits what is not yet known. Here is what the evidence supports.

Are Young Players Just Smaller Adults?

No, and this is where a lot of well-meant training goes wrong. Your child is learning skills while their body changes underneath them. Growth alters limb length, coordination, strength and the way they move, and it does not arrive on a schedule that suits your tournament calendar.

The fastest phase of the growth spurt comes at roughly age 12 in girls and 14 in boys. During that stretch, rapid change in body size may temporarily upset coordination, although the strength gained through maturing generally more than makes up for it. So a temporary dip in movement quality during a growth spurt is not necessarily a training failure — and it is not necessarily a reason to train harder either.

Age groups complicate this further. Juniors compete within a two-year band, which can mean substantial differences in maturity between opponents of the same nominal age. One study found 85 percent of British youth elite tennis players were born in the first half of the year. Some of what looks like talent at twelve is a birthday.

What Did the 8,008-Player Review Actually Find?

The broad pattern: performance improved with age, boys generally scored higher, and the dominant side outperformed the other. In the jump test, no difference between boys and girls appeared until the under-14 group. In the 20-metre sprint, boys were consistently faster at every age, with the largest gap — about 14 percent — at under-16.

The authors are careful about how far this can be pushed. Many results varied widely between studies, largely because testing methods differed — different instruments, different numbers of attempts, different rest periods. They state directly that figures drawn from a single study may not hold up elsewhere, and data for players under 8 to 10 were largely missing altogether.

Imagine a Pencil Mark on the Doorframe

Nobody measures their child against the national average height. They mark the doorframe, and next spring they mark it again. The number on the frame is meaningless to anyone else and tells you everything you need to know.

The key idea: your player’s own trend is the doorframe. It is more reliable than any chart, it costs nothing but consistency, and it is the one measurement that is genuinely about your child rather than about eight thousand other people’s.

Why Track Your Own Player Instead?

Because a comparison against a broad average carries all of that uncertainty, and a comparison against your own child last spring does not.

Repeated testing of the same player shows whether strength is improving, whether movement is changing, or whether a recent growth spurt has altered things. It also sidesteps the problem that the average was assembled from studies using different methods. The one rule that makes it work: measure the same way every time.

Is a Lopsided Shoulder a Problem?

Usually not by itself. Tennis naturally creates differences between the two shoulders. More outward rotation and less inward rotation can simply be the sport shaping the body, thought to come from repeated loading as the arm slows down after a stroke.

The questions that matter are whether your player’s movement is becoming progressively restricted, whether the total is being lost, whether pain is developing, and whether any of it is affecting how they play.

The review does cite findings worth holding in mind. A side-to-side difference of 18 degrees or more in inward rotation has been linked to higher injury risk in overhead throwing athletes. In one study of 42 tennis players aged 14, 46 percent already had a loss of more than 13 degrees. In another, of 67 players aged 7 to 13, gains in outward rotation did not fully make up for what was lost inward, so total movement on the dominant side was reduced.

Two things follow. Loss of movement is worth tracking. And the review is explicit that it remains unclear whether these changes are needed for performance or whether they cause injury — so no single number should be treated as a verdict, especially in girls, where the normal ranges barely exist.

What Is Worth Keeping an Eye On?

• How far the shoulder rotates inward and outward, and the total of the two.

• Rotator cuff strength and how long it lasts.

• Shoulder blade control.

• Trunk and hip strength.

• Leg power, measured with a simple jump test.

• Speed and the ability to change direction.

• Where the player is in their growth.

• Serving volume and tournament density.

• Pain, and how well they recover between sessions.

• Recent changes in technique or equipment.

Not every player needs formal testing in every category. The goal is to find what matters for that athlete and then measure it consistently.

Why Do Load Spikes Matter So Much?

Because a young player can go from school tennis to private lessons, tournaments, strength training and extra serving practice within the same week — usually because several adults are each adding a perfectly reasonable amount.

Nobody is watching the total. So the total is what parents and coaches should watch. Pain after play, persistent fatigue, a loss of serve speed, growing stiffness or declining mechanics should prompt an adjustment rather than a push.

Should Young Players Lift Weights?

Age-appropriate strength training supports a durable shoulder. The goal is not maximum lifting. It is controlled strength through the cuff, the shoulder blade, the trunk and the legs that supports tennis movement. For the shoulder specifically the review recommends a combination of stretching, movement work and strengthening, started early in a player’s career rather than after symptoms arrive.

There is a performance argument alongside the durability one. Junior players have been found to have better speed and agility than senior professionals but less strength and power — and the largest measured gap between elite and sub-elite players sits in leg power, endurance and agility. The physical base is the part that is usually missing.

What Should Parents Avoid?

Two things, mainly. Do not use pain as the only signal that something is wrong — performance decline and repeated fatigue often appear first, and a young athlete may not volunteer either.

And do not assume every difference between the two arms needs correcting. Some asymmetry is normal in tennis, and the evidence that any particular amount causes injury in young players is not yet strong. The best decisions come from symptoms, trends and a proper evaluation rather than from a number on a chart.

The Rooted Motion Difference

Care is one-on-one, at home or courtside, and built around a young athlete who is still growing. Here is what you can expect:

• A baseline your player can be measured against later, taken the same way each time.

• Attention to where they are in their growth, not just their age group.

• A look at total weekly load across every coach and program involved.

• Age-appropriate strengthening for the shoulder, trunk and legs.

• Honest discussion of what the evidence supports and what it does not.

• Convenient concierge mobile physical therapy delivered where you are.

Because youth development is not just about winning at fourteen — it is about still playing at twenty-four.

Ready to Build a Player Who Lasts?

If your young player is adding hours, entering more tournaments, or moving through a growth spurt, that is the moment a baseline is worth having. It is much easier to notice a change when you know where they started.

Ready to move better and live rooted? Contact Rooted Motion Physical Therapy to schedule a one-on-one evaluation and begin a personalized youth tennis plan.

Research Used for This Article

1. Axman S, Stausholm MB, Volk NR, Ferrauti A, Magnusson SP, Couppe C. Physical Performance Tests in 8008 Competitive Youth Tennis Players — A Systematic Review and Meta-Analysis of Normative Values. European Journal of Sport Science. 2025;25(9):e70023. DOI

2. Tooth C, Gofflot A, Schwartz C, et al. Risk Factors of Overuse Shoulder Injuries in Overhead Athletes: A Systematic Review. Sports Health. 2020;12(5):478-487. DOI

3. Hoppe MW, Brochhagen J, Tischer T, et al. Risk factors and prevention strategies for shoulder injuries in overhead sports: an updated systematic review. Journal of Experimental Orthopaedics. 2022;9(1):78. DOI

4. Cools AM, Johansson FR, Borms D, Maenhout A. Prevention of shoulder injuries in overhead athletes: a science-based approach. Brazilian Journal of Physical Therapy. 2015;19(5):331-339. DOI

Educational disclaimer: This article is for general education and is not a substitute for an individualized evaluation. Seek prompt medical care after a traumatic injury or dislocation, for a sudden major loss of strength, or for new numbness, tingling or weakness in the arm.