Windows of Trainability in Baseball Development
In today’s article, I want to clearly explain why we bring certain age groups into the gym for weight training and why we intentionally hold others back. Also you will learn how parents mess up sports for their kids.
When it comes to developing baseball players, I think in terms of windows of trainability. These are specific time periods in an athlete’s life when certain qualities can be developed more effectively than others. If you miss the window, it becomes much harder, and sometimes impossible, to fully get that quality back later.
This framework was taught to me early on by Tom House, one of my mentors, and it completely changed the way I look at youth development. Once you see development through this lens, a lot of common youth training mistakes become obvious.
For simplicity, I break development into four major windows: ages 9–14, 15–19, 20–26, and 26 and beyond. Each window has a primary focus, and forcing the wrong stimulus at the wrong time often does more harm than good.
The age group I personally specialize in training is 17–24, because this is where strength development, skill acquisition, and long-term career trajectory intersect most clearly.
Window 1
Ages 9–14 are focused on neurological development, stability, and flexibility. This is the most butchered window in all of youth training.
At this age, parents and coaches often prioritize results, competition, and sport-specific skill development before the body is physically or neurologically ready. The goal here is not strength and it is not specialization.
Neurological development at this stage is about learning how to move the body well:
• learning basic mechanics
• understanding movement patterns
• developing coordination and spatial awareness
• learning how to compete and understand the game
From a training standpoint, the focus should be stability and flexibility. Strength will come later. There is some overlap between strength and stability, but for this age group that means:
• bodyweight exercises
• bands
• light weights
• machines used appropriately
What you should not do is overload young athletes with:
• year-round repetition of the same sport
• excessive volume of the same movement patterns
• an emotional environment where the sport feels like work
That is the fastest way to burn a kid out and make them hate the game long-term.
In my ideal world, a 9–14-year-old plays four sports across four seasons. Not because the sports matter, but because the variety matters.
If I had to choose:
• winter: basketball
• spring: baseball
• summer: golf and time off with family
• fall: tackle football to get tough and learn adversity
But the specific sports do not matter as much as this principle:
• change environments
• change coaches
• change movement demands
• challenge the brain
One important note is not to fill in on extra teams during off-seasons. That is one of the worst things you can do. I do not care how competitive the travel team is or what the social pressure looks like. Specializing early is not what is best for your kid.
Let them sprint more than you think they need to.
Let them play.
Let them move.
Window 2
Ages 15–19 are about fundamental strength development. This window is about strength, plain and simple.
In high school, the players who get recruited are the biggest, strongest, and fastest, period.
This is the time to get on a legitimate training model. You should still practice your sport and develop skill, but the standard during this window should be how strong and how fast can I possibly get right now.
If you get that right, the sport tends to take care of itself.
One good habit leads to another here. If you are lifting and sprinting consistently:
• you will naturally start eating better
• you will want to recover better
• you will want to practice more intentionally
In my experience, 90 percent of skill flaws clean themselves up once an athlete is strong enough to actually get into the right positions. You cannot coach your way around physical limitations forever.
Window 3
Ages 20–26 are about skill acquisition and longevity. At this point, you are likely in college baseball or professional baseball. You have built a foundation of strength, and now skill becomes the primary driver.
Your income or future income is directly tied to:
• how well you can throw a quality slider
• how well you can hit a fastball
• how well you can execute under pressure
That is where your energy needs to go.
Training does not disappear, but it becomes supportive:
• stay healthy
• stay fresh
• maintain strength and power
• understand your own body
By now, you should know what you need and what you do not. The foundation is built and the game is the focus.
Window 4
Ages 26 and beyond are about fast-twitch retention and cognitive edge. We begin losing fast-twitch muscle fibers around age 28 and that decline continues for the rest of our lives.
https://pubmed.ncbi.nlm.nih.gov/7493202/
For athletes in this stage, the question is no longer are you good enough. If you are still playing professionally at 26, you are.
The goal now is staying fast.
Training should emphasize:
• fast-twitch output
• speed and power
• reaction and cognitive function
This is where experience becomes the greatest weapon. Baseball is a young man’s game physically, but older players dominate when they stay fast and sharpen what is upstairs.
Think about athletes who aged well:
• Tom Brady
• Matthew Stafford
• Nolan Ryan
They did not get worse with age. They got smarter and their bodies stayed fast enough to let their experience take over.
If you can preserve speed and power, the older athlete often becomes the most dangerous one in the room.
How to Use This Framework
If you are a parent, coach, or athlete trying to decide what training is appropriate for your child, this framework should be your filter.
Instead of asking “what program is best,” the better question is “what window are they in right now?”
Training decisions should be based on age, physical development, emotional maturity, and long-term goals, not what other kids are doing or what looks impressive on social media. The biggest mistakes in youth development come from applying adult training concepts to kids who are not ready for them.
If you are unsure what your child should be focusing on right now, this article is designed to give you clarity and help you avoid costly long-term mistakes.
Who This Is For
This approach applies to parents searching for answers like:
• what age should kids start lifting weights
• how should my child train for baseball
• is my kid training too much
• should my child specialize in one sport
• how do I prevent burnout and injury in youth athletes
If you are asking those questions, the answer is not more work. It is better timing.
Call to Action
If you want help applying this correctly to your athlete, especially in the 17–24 age range where development decisions have the biggest impact on college and professional opportunities, reach out.
The goal is not to do more.The goal is to do the right things at the right time.
