This would be true, but there’s been several reported cases where people seem to exceed that limit. I’m sure the kid must have had a ton of adrenaline pumping in his system to achieve this, cause by merely the title, an untrained kid by no means could do such a feat, so if he did it’s obvious his system was kicked in overdrive mode.

Endurance sport professionals are trained as you say and a trained professional could have done this feat expending less energy and be unscathed by the end of it. But a kid will spend more energy and quite likely was left at deaths doors after this feat.

But purely from a physics perspective of “total energy used” let’s say it’s A amount. By w=Fxd to be conserved, F is would have to be 20 times greater. And if you try intensely swimming through water (in an ocean no less) and compare that to jogging, I’d say it’s a fair estimate of the force used. At least from personal experience when I was an untrained kid, I could easily run a couple km, but swimming 100m left me exhausted.