Depends what you mean by windsprint.  My research tells me that intervals between 20 seconds and 45 seconds or so are best for fat loss and muscle retention.  I´ve put this into practice and it worked well for me.  
It´s commonly called interval training.  The point is to get your heart rate at a base level of 60% of max(a brisk walk does it for me) and then move it to around 85% through a windsprint interval(running very fast if you´re using running as a medium).  From what I understand, after the windsprint you have to allow your heart rate to get back to 60% for the training to be effictive.
I just started this again yesterday after a power cycle and it took me around 5 minutes to get back down to 60% after the interval, which is quite long for me.  The point is, start slow.  It may not feel like a lot of work but it is hard on your body.  Also helps to avoid shin splint, if that´s a problem for you.