Comments about ‘Dos, don'ts of child exercise’

I am an exercise physiologist and personal trainer also.
While nothing is concrete, one can also make the case for training kids the way they play in the real world - short burst of exertion followed by short periods of rest. This is akin to interval training. All kids are different of course and bring unique needs to the table that must be addressed. For prepubescent kids, I'd focus not on heart rate but rather on asking kids how they feel on a scale from zero to 10 where zero is very very easy and 10 is super duper hard.
Joe Cannon, MS, CSCS, NSCA-CPT