Yes, maybe the discussion is getting too technical, but there is an interesting paper that was published in Nature in 1997 about learning foreign languages. Now I explain why I consider that important also for training.
It was shown that people learning other languages before 12 (more or less) have a single brain region for generating complex speech, while people learning foreign languages after 12 have two brain regions for generating complex speech http://www.nytimes.com/1997/07/15/science/when-an-adult-adds-a-language-it-s-one-brain-two-systems.html.
Now, I wonder if it happens the same also with motor skills. Of course, having a single brain region gives advantage, but the implications are also that maybe the way of learning after a certain age has to be appropriate for the different modifications happening in the brain.
At the end, a good part of the adaptions that training stimulates, especially the neural part, consist in learning.