Brian , the Wikipedia reference-linkMRI information is irrelevant.
Nerve conduction tests and their results , are , for the most part, sometimes an indicator of nerve "entrapments " or focal irritations and compressions related to injury. Their results , by themselves , bear very little relationship to the kind of commonly observed spinal Wikipedia reference-linkfacet joint somatic referred events of which I speak.
Compromise , to L5S1, will most often occur , without injury , without nerve compression , and without pathological breakdown of any kind. The most common occasions giving rise to distal pain and other symptoms are those related to protective behaviour and a cascade of normal but irritating responses associated with an automatic response to threat.
These can be and are routinely turned off by continuous mobilisation to facet joints. By doing so the normal unprotected behaviour of the spine is restored, giving immediate and lasting ( in most cases ) relief from referred pain such as to your calf.