Some time ago I stumbled across this interesting column. The conclusion is:
Of course, not every mental activity can or should be performed while walking, but this new research reinforces anecdotal evidence and other research findings that suggest being too tightly chained to our desks is bad for our minds as well as our physical health. Science shows we often have creative breakthrough when our minds are disengaged from the problem we’re wrestling with, hence the common experience of getting great ideas while relaxing in the shower.
Getting up for a walk or a jog is another way to achieve this sort of head space–after all, it worked for Einstein and Charles Darwin
It seems to me a strong reinforcement of the importance of pomodoro technique. I make use of this technique quite often, and – al least in my case – I find that its usefulness is strongly linked to the necessity to break your activity after at most 25 minutes. In fact I find it difficult to stop my task(s) and I end up getting too tired and not productive.