"If I Could Bottle That Energy..."

I don't know if any of you had grandparents that would say "If I had could bottle your energy, I'd sell it and make a million dollars," as you were tearing around their house with your cousins when you were little, but it was a common refrain in my family. I noticed that they would say it less and less as I got older, and a study in The Journal of Pediatrics may point to why.
Eiholzer et al published a paper to be released in the November issue examining the metabolism and energy expenditure of young boys who play ice hockey. The boys were compared to their teenage hockey playing counterparts in areas like daily energy expenditure, sleep, spontaneous physical activity, and amount of energy they spent training. It turns out that the activity level (specifically the spontaneous physical activity level, like taking off running in the parking lot or beating up your brother, I suppose) of young boys doesn't seem to suffer one bit if they get less sleep. This is completely different than what the researchers found with the teenagers and from what previous studies on overtraining and sleep deficiency have found with adults. It actually seems to defy the principles of physics and common sense. How can you keep up that level of maddening 8 year-old craziness if you don't get enough sleep?
In their conclusion Eiholzer and colleagues offer a possible theory why. The write that the findings suggest an important point- "child-specific control of physical activity" may be the answer. Now I have to admit I don't exactly know what "child-specific control" means, so I Googled for it. No luck, except the article's abstract was returned to me in three search results. So, I've gone to the source, Dr. Eiholzer himself, and asked the following:
(by "child-specific control")... Does this mean that the level of control is related to the age group somehow, or that the prepubescent boys have more choice in their physical activities and therefore perform more of them? Does this suggest that parents who control their children's activity levels rather than allowing the children to choose them hamper the effect somehow? Furthermore, are the controls of sporting activity by the coaches any more or less regimented in this club? How should a coach of young athletes use this information to increase or decrease the amount of practice time or activity level (or spontaneous activites) within practice to the best effect?
The one question I probably should have asked... "How do you bottle that stuff?"
Reference:
Eiholzer U, Meinhardt U, Rousson V, Petròa R, Schlumpfa M, Fusch G, Fusch C, Gasser T, Gutzwiller F (2008). "Association between Short Sleeping Hours and Physical Activity in Boys Playing Ice Hockey." The Journal of Pediatrics 153 (5) pp 640-645.