Cement

How many are/were running on cement (concrete?)?

We have lots of runners around here who run the cement trails. Yet we have parallel dirt/gravel paths, plus some wonderful "cross-country" dirt and gravel running areas. I find that even when I walk on cement for any length of time, my knee and hip start hurting, yet if I do the same distance on dirt or gravel I have no pain.

Even asphalt is better than cement (concrete?), IMHO, as it has an uneven surface, and is softer and gives a little.