Would normal road work help to tighten flat feet?

Any exercise will help, but pebbles, shingle, uneven ground, would be better

Pebbles are fab, our beaches around here are in the main pebbles, so letting ten off lead and run about helps. I also do pebble training which entails on lead and me walking them up and the te beach to the shoreline and number of times..  I don't know if it helps as not ever had a dog with poor feet, lol. 

My dobe friends say giving Vitamin C will help with feet and pasterns.  Don't know how true it is, but vit C can't do any harm in normal doses.

I would be interested to see a photo of tight paws, and paws which require tightening if anyone could oblige? :)