I've read in more than one place in the last few months that it's better to run strides on slightly downhill terrain? I think the argument being strides are about form & efficiency at high speed and doing them on a downhill grade helps you run fast without stressing the body but you still get all the physiological effects of running that fast speed. What are the boards thoughts on this? And if this is so how much better is to do it on a downhill grade vs flat?