A plain-language guide to physical development for youth baseball and softball. Built on published position statements and research, honest about where the evidence is strong and where it is thin, and clear about which calls are ours.
Train the athlete before the sport. From about 6 to 13, build a strong, coordinated, multi-sport mover: bodyweight strength, jumping, sprinting, throwing, catching, rotating, and playing more than one sport. After the growth spurt, load can go up, with form leading and a qualified coach watching. Readiness beats birthday at every step.
Four stages from 6 to 18. The stage names come from the Sport for Life LTAD framework (Balyi), a coaching consensus model, not tested science. Ages are guides, not gates, and they run about a year or two earlier for girls. Tap a stage to see what to build and what to avoid.
Under 6: the job is free play and lots of it. Sport for Life calls that stage Active Start. This guide picks up at 6. After 18: college and pro training is individualized, periodized, and coached, and it is outside what we cover.
These do not change from 6 to 18. Only the dose changes.
Maturity, not a birthday, sets the program. Progress on what the athlete can control with clean form. Earlier is not better. Ready is better.
In a 2019 national survey of youth-sports parents (Aspen Institute and Utah State University), the most common reason given for a child quitting a sport was that it was not fun anymore. Variety and play keep them coming back.
Our default for volunteer-led teams. Master bodyweight patterns before adding external weight. Squat, hinge, push, pull, brace, land, carry. Clean reps first, load later.
Youth resistance training is relatively safe and beneficial when the program is properly designed and supervised by qualified adults. The guidance is to begin with relatively light loads, focus on correct technique, and increase resistance gradually (NSCA 2009; International Consensus 2014). It does not say kids must master bodyweight before touching any load.
Most volunteer teams do not have a qualified strength coach at practice. So on these pages the default is bodyweight first, no dynamic lifts under load, and no max-effort lifting. External load waits for two things: readiness (maturity and clean form, not a birthday) and a qualified coach watching. That is our conservative call, not a research finding. With a qualified coach, the research supports more.
A big part of development is keeping the athlete healthy. These three deserve your attention.
During the fastest growth phase (Peak Height Velocity), bones can outpace muscles and tendons for a while. Many kids go through a clumsy patch, and overuse complaints at the knee (Osgood-Schlatter) and heel (Sever's) become more common in this window (Bergeron et al., 2015). Signs: a sudden height jump, recent shoe-size change, new complaints of knee or heel pain. Our response: lower the jumping and high-impact (plyometric) volume, lean into mobility and clean technique, and never push through joint pain. The position statements allow supervised strength training through puberty; we hold back because most volunteer teams lack a qualified strength coach.
Highly specialized young athletes show higher rates of overuse injury in clinical studies (Jayanthi and colleagues, mostly case-control and retrospective designs), and a 2022 meta-analysis (Güllich, Macnamara and Hambrick) found that world-class adult athletes typically played more sports and specialized later than near-elite peers. Specialization is one associated risk factor among several, not a proven single cause of burnout. Still, the direction of the evidence, and groups like the AAP (Brenner, 2016) and AOSSM, support sampling through the early teens and delaying year-round single-sport play.
Female athletes mature earlier and carry a higher ACL injury risk than males in the same sports. Any athlete can be under-fueled during growth (known as RED-S; Mountjoy et al., 2018). Neuromuscular warm-up programs that teach soft, aligned landings (PEP, FIFA 11+) cut ACL injury rates by roughly half in meta-analyses (Webster and Hewett, 2018), mostly in soccer, basketball, and handball. We think they are worth making standard from late childhood on. Enough food, sleep, and managed load protect both performance and long-term health.
This guide is about athletic development: strength, power, speed, movement. It does not cover throwing or pitching programs. Throwing volume is the highest-risk variable for a young arm and has to be coordinated with the athlete's actual team and game schedule by someone qualified, watching that specific athlete. We keep it separate on purpose.
Most recommendations here trace to recognized position statements and peer-reviewed research. Where a rule is our own conservative choice, it is labeled as ours. Every title below is a link.
A caution we take seriously: the popular "windows of trainability" idea from early LTAD writing is contested in the research (Ford et al., 2011). We treat stages as a planning framework, not a biological law. Anything on these pages without a source behind it gets cut.
Educational resource only. Not medical advice. This guide explains general principles of youth athletic development. They are not a personalized training prescription and do not replace a qualified strength coach, athletic trainer, or physician who can see your athlete. Around a growth spurt or with any pain, check with a professional first.