question: Can t stand up for more than 5 minutes; it feels like I will be falling down if I persist. I am 88 years old and in perfect physical condition; all tests (MRIs, blood etc) normal. I used to be quite active 5 months ago with my garden and then in a matter of a few months I am experiencing a weakness when standing. The only surgery I have had is knee surgery. They tell me I may have neurological issues?