We are talking about getting stunned mate. I kind of think of being stunned as something that is over very quickly i.e. a few milliseconds and then you are able to fight as normal. When the legs go, I call that being hurt. This tends to last a while and you are not able to fight as normal till recovered. Others may have different names for these sensations?
Ya, I can't say i've felt the heavy legs feeling, but I definitely have gone from sober to HAMMERED and back to sober again within a matter of seconds. Ha ha, that's how I like to describe it.