Hello, My husband is experiencing ongoing weakness in both thighs, starting 6 weeks ago and finds walking, especially on the flat, more of an effort. he is 71 with no health problems..active over the years, an avid tramper... and seems to be able to walk hills with no great problem. Says there is no pain just stiffness and weakness. walking like a duck now. is Dr thinks it is just ageing. I wonder if there is something else going on. What do you think?