Children Running

[twirlytwit]

Me and my DH, both active but quite unfit, are just venturing out on a few runs. My son (3.5 years) wants to join us and has gone with DH a few times, quite happily covering a distance of approx 1 mile.
Although DH thinks I'm using this as an excuse to take it easy, I don't want to go any further than this with my son at his young age as I have no idea if running regularly is good for him?
We encourage activity in all sorts of ways, he loves biking, swimming, walking and general running around and physical play. Obviously an active healthy lifestyle is a good thing but I can't help but compare to my basic knowledge of puppies for example, who shouldn't cover long distances over concerns about joint and muscle development.
We're not seriously training and happy to keep it fun, especially when he chooses to join in. I'd just like some weight to my argument that we should limit what son does in terms of distance to prevent injury..otherwise my husband would be quite happy to 'build him up'. Would welcome the opinions of anyone more informed on the subject, thanks.

Kid that age in a nomad family might trek 20 miles a day, whether they liked it or not. He sounds tougher than you guys, but why would you want to rely on how far a 3 yr old can reliably run? 1 mile is good, keep it fun.

Overuse injuries are possible. Riding a bike with wrong gears (too big, so what you might find on a cheap bike for age 6-14) can encourage development of something called Osgood Schlatter's disease, a knee injury.

too early at that age.
I sometimes go running with my 9yo, a mile round the block but a 3 yo should run and tumble in a park/garden with plenty of rest in between. imo.
nomads walk long distances, they would not run long distance if they could avoid.

He's certainly got more energy than us! Just wanted to make sure it wouldn't be damaging him physically. We don't have to rely on his distance, happy to go further on solo runs and follow his lead when he wants to join in.
Felt like it's on that fine line between positive encouragement and being a 'pushy parent' though. Also agree that 3 year olds aren't normally found running anywhere other than in the park/garden. As long as son is happy and wants to join in than that's fine.. However sometimes DH forgets he's only 3!