I've no doubt that exercise is good for us, in fact i think it should be the 1st thing out of the Doc's mouth.
The 25 ft times walk thingy has akways been wierd for me. I can walk very quickly for short periods, totally straight and balanced.
When i try or have to walk slowly ( as in a crowded sidewalk), I can't keep my balance at all. So I think I skew those studies.
Be kinder than necessary, for everyone you meet is fighting some kind of battle..