With aging the joints and ligaments become thickened and may narrow the space for the nerves within the spinal canal and if a disc is also bulging that restricts the space more.. Walking pulls on the spinal nerves via the sciatic nerve with each forward step, producing a grabbing sensation of weakness and numbness causing a person to stop and rest a while before going on.
This intermittent “grabbing” (claudication) due to spinal stenosis is called SINC (Syndrome of Intermittent Neurogenic Claudication). Bending forward while walking can open the space within the spinal canal by stretching and thinning the thickened ligaments and people with SINC often must bend over while walking. Some find they can walk better in a grocery store by bending over the market basket.
If the “grabbing” is due to insufficiently increased blood supply to the legs while walking, it is called Vascular Claudication or Vascular Insufficiency. Those persons have a similar walk-rest-walk pattern but bending over doesn’t help and they often have impaired pulses in their feet. See Spinal Stenosis.