Is Training Safe for Kids? The 180-Year-Old Myth Holding Them Back
Every major sports medicine body says resistance training for kids is safe and necessary. So why are we still afraid of it?
If you grew up the way I did, you did resistance training every single day — you just never called it that.
You jumped off snowbanks. You jumped off docks. You bucked hay bales in the summer. You wore your backpack wrong and walked to school with it loaded down. You carried your little brother on your back. You climbed trees and you jumped out of them.
Nobody worried about any of it. But put a 15-pound dumbbell in that same kid’s hand inside a gym, and suddenly everyone gets nervous.
Why?
Where the fear comes from
The myth that weight training stunts kids’ growth goes all the way back to 1842.
That year, England’s Children’s Employment Commission noticed that kids working in coal mines were shorter than other kids. They blamed the heavy loads — the rationale being that carrying coal compresses the skeleton. So they recommended children be kept unburdened until they were physically mature.
It was a clean story. It was emotional. And it was wrong.
As historian Peter Kirby later showed in the Economic History Review, those kids were short for completely different reasons. The smaller kids were selected to work the narrow coal seams in the first place. They were starved. They never saw daylight, so they had rickets. Their fathers were dying in mining accidents at horrific rates, and the resulting childhood anxiety suppressed their growth hormone.
Other inspectors at the time wrote the opposite — that the boys working in the mines had “a development of the muscles of the chest, back and arms which could not have been surpassed in the athletes who won the laurel wreaths at the Grecian games.” Nobody remembers that quote. They remember the stunted-growth story, because it had teeth.
That myth has now outlived two centuries of real science.
What the science actually says
Every major certifying body in the world has now weighed in on resistance training for kids. The list is unanimous:
- National Strength and Conditioning Association (1985, revised 1996): even heavy resistance training is safe and effective for youth.
- American Academy of Pediatrics (2001): provides the foundational definition of resistance training and supports its use in youth.
- President’s Council on Physical Fitness and Sports (2007): recommends strength training as a better option than aerobic activity for overweight youth.
- Canadian Society for Exercise Physiology (2008): there is no minimum age for resistance training, and Olympic-style lifting and plyometrics can enhance strength, power, coordination, and balance.
And it gets better. A force-plate study with 70 kids in grades four through six measured the load on their joints during 12 different jumps. Dropping off a 20-inch box: 4.7 times their body weight at impact. A jumping jack: 3.7 times. A jumping lunge: 2.1 times.
Translation: a 50-pound kid playing hopscotch on the sidewalk is loading their joints the equivalent of holding 100 pounds and doing a split jerk.
The researchers weren’t trying to find out how dangerous those jumps were. They were trying to find out which one built the most bone. The load wasn’t a risk. It was the point.
Why kids aren’t miniature adults
Here’s the part most parents miss.
When an adult gets stronger, we associate it with bigger muscles. Bigger biceps, bigger quads, more mass. That’s not how it works for kids.
A child can make dramatic strength gains without putting on any muscle at all. Because what’s actually getting stronger is the wiring — the central nervous system, the connection between brain and muscle, the recruitment and timing of motor units. The plumbing isn’t changing. The electrical is.
Every time a kid squats, presses, or jumps, they’re rewriting code inside their own nervous system. That code stays with them for life.
The two jobs of a coach
When a kid walks into my gym, I have two jobs.
First — make them better at their sport.
Second, and equally important — don’t make any existing problems worse.
Most kids walking into a gym today already have issues. They sit too much. They’re hunched over phones. Their hip flexors are short. Their glutes don’t fire. When you ask them to squat, half of them tip onto their toes or fall backwards. If I throw a barbell on that kid and load them up, I’m just baking those problems in deeper.
How a good coach progresses a kid
Same order every time:
- Mechanics. Can the kid do the movement correctly with no load?
- Consistency. Can they do it correctly ten times in a row, twenty times, fifty times — without thinking about it?
- Coordination. Can they string movements together without their form falling apart?
- Strength. Now we add load. Compound movements only — squat, deadlift, press, carry. No machines.
- Power. Now we make it faster. Cleans, jumps, throws.
- Speed and plyometrics. Sprinting, single-leg work, sport-specific patterns.
That progression might take six weeks for a 14-year-old who already moves well. It might take two years for a five-year-old. There’s no rush. Nobody’s going to an NFL camp at age nine.
What to look for in a program
- A coach who watches your kid’s movement before adding any weight. If the first session involves a barbell, walk out.
- Small groups or one-on-one — not a free-for-all.
- A coach who talks about technique, not PRs. If they brag about your kid’s weight on the bar before they brag about your kid’s squat depth, that’s a red flag.
- A kid who wants to come back. Fun matters. If the kid hates it, the program isn’t working — no matter how good the science is.
The bottom line
The myth that training stunts kids’ growth is 180 years old. It was wrong when it started, and it’s still wrong now. Every credible scientific body has said so. The only thing standing between your kid and a lifetime of stronger bones, better movement, and a more confident body is the right coach.
If you’ve got a kid in the Sault and you want them training with us at Catalyst, come down. We’ll show you exactly how we do it.
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