By BK, Athletic Hitting Development
Complete Hitters Are Built… It’s Earned!
Key takeaways
- A study that followed 30 young players for three seasons found hip-shoulder separation grew with age.
- Players at U12–U13 showed significantly more separation than U11 players. Younger hitters tend not to have it yet.
- A 10-year-old without much separation isn’t “wrong.” He’s probably on schedule.
- Build the athletic position first, coach separation patiently and judge progress over seasons, not weeks.
Your 10-year-old doesn’t have hip-shoulder separation. Good. Neither do most 10-year-olds.
Hip-shoulder separation develops with age, and most hitters under 11 don’t have much of it yet. Build the athletic position first, then coach separation patiently and judge progress over seasons, not weeks.
Train it: Swing Structure & Mechanics Masterclass →That isn’t a flaw. It’s a stage. Here’s what the research says about when it shows up.
1. What the study found
Tsutsui and colleagues did something most swing studies don’t. They followed the same 30 youth players, ages 6 to 12 at the start, across three seasons, from U8 up through U13. They measured how far apart the upper trunk and pelvis got during the swing.
Separation grew with age. The U12–U13 players showed significantly more separation at foot contact and in the pre-swing than the U11 players, with effect sizes up to 0.79. That’s a meaningful jump, not a rounding error.
The takeaway is simple: younger hitters tend to lack hip-shoulder separation. Many of them develop it around 12 or 13, as they grow and get stronger.
2. What separation is, and why it matters
Separation is the gap between where the hips are pointing and where the shoulders are pointing. The hips start forward while the shoulders stay closed for a moment. That stretch through the middle of the body is part of how good hitters store and release energy.
It lives in two of our 4 Pillars. It’s a Swing piece, tied to our Mechanically Advantaged Angles (MAA): setup posture, the back-elbow load, a launch above the ball, bat lag and an athletic front side. And it’s a Strength & Explosiveness piece. A body that isn’t strong or mobile enough yet can’t hold that stretch, no matter how many times you tell it to.
You can’t cue a body into something it isn’t ready to do.
IT GROWS WITH THE HITTER.
BEPATIENT.
- Start athletic.
- Stay athletic.
- Finish athletic.
- Let separation come with age and strength.
ON SCHEDULE IS NOT WRONG.
3. Athletic position comes first
Losing the athletic position is the #1 swing flaw I see, at every age. If a young hitter can’t start athletic, stay athletic and finish athletic, separation won’t matter. He has nothing stable to separate from.
So for 8-to-11-year-olds, the job isn’t chasing a big hip-shoulder gap. It’s:
- A good setup. Hip hinge, a little spine tilt, weight in the middle of the feet.
- A simple load. Pull back the bow with the back elbow without swaying off the back leg.
- A stable landing. Front foot down, head quiet, body still in balance.
- A balanced finish. Can he hold it for a two-count?
Fix the earliest breakdown first. If the setup is off, separation is the last thing to worry about.
4. How to build it, patiently
When a hitter is ready, usually closer to 12 or 13, separation can be coached. Here’s a simple progression:
- Feel the stretchBat across the shoulders, feet in a stance. Turn the belt buckle toward the pitcher while the chest stays home. Hold one second. Then let it go.
- Step and holdStride, land, and keep the shoulders closed for a beat after the front foot is down. Then swing.
- Moving ballSame feel on front toss. If it disappears on a moving ball, slow down and go back a step.
- Film itOne swing from the front each week. Compare month to month, not swing to swing.
- Build the engineAge-appropriate strength and mobility work, so the body can hold what you’re asking for.
5. For parents of 8–13-year-olds
Your hitter is going to hear a lot of swing words. Some of them will come from the dugout. Some from the internet. And somebody is going to tell your 10-year-old his swing is wrong because his hips and shoulders turn together.
Don’t buy it. The research says that’s normal for his age. Don’t label it. Don’t chase it with 20 cues. Build an athletic hitter with a sound setup and a balanced finish, keep him strong and moving well, and let separation show up when his body is ready.
Want a plan by age? Our 12U hitter development plan lays it out. Or start with the free SwingChecker™. It takes about 3 minutes and shows you the first priority.
Quick answers
At what age do hitters develop hip-shoulder separation?
In one study that followed 30 youth players for three seasons, U12–U13 players showed significantly more separation than U11 players. Younger hitters tended to lack it.
Should I teach my 9-year-old hip-shoulder separation?
Teach the athletic position first: setup, load, stable landing and balanced finish. You can introduce the feel, but don’t expect it to stick until the body is ready.
Is my kid’s swing wrong if his hips and shoulders turn together?
Not at 10. The research shows separation grows with age, so a young hitter without much of it is likely right on schedule.
Does strength training help separation?
This study didn’t test strength training. In my experience, a body has to be strong and mobile enough to hold that stretch, so age-appropriate strength work is part of the plan.
What is hip-shoulder separation in hitting?
It’s the gap between the hips starting to rotate and the shoulders following. That stretch through the torso helps create bat speed, and it tends to grow as young hitters get older and stronger.
Research: Tsutsui et al., “Longitudinal changes in youth baseball batting based on body rotation and separation,” BMC Sports Science, Medicine and Rehabilitation (2023). This was a small group of 30 youth baseball players, summarized here from the published abstract; it tracks how separation changes with age but doesn’t test how to coach it.
Don’t collect drills. Build a complete hitter.
Complete Hitters Are Built… It’s Earned!
This article is part of the AHD guide Baseball Swing Mechanics. Start there for the full picture and every related article.
