In reply to davidwright:
I am not sure it is that simple David.
Bannister ran in simple leather slippers. A cursory google for X-Country trainers yields a much higher level of sophistication including:
- Forefoot and heel cushioning - which MUST affect your gait,
- Mesh upper - Needed to stop shod feet overheating and blistering,
- Support for the forefoot, mid and rearfoot - which again MUST affect your gait,
- Padding around the heel and ankle - for comfort.
Also, closed toed shoes are believed to inhibit formation of the arches of the foot -
http://www.jbjs.org.uk/cgi/reprint/74-B/4/525
Specifically, going barefoot on varying terrain facilitates the formation of arches.
If barefooting was a problem then you'd see evidence in indigenous tribes and the fossil records.