firewalker job3 - I think the sore calves is not so much from impact as from you use way more of your muscles in many more ways barefoot. The leg makes so many tiny little adjustments that shoes smooth out.

The proprioceptors (give us a sense of where we are in space) are abundant in the foot, ankle and lower leg and getting these working better (running barefott being one way) increases balance and co-ordination and function of the whole body, especially the lower legs and feet etc...

When i worked on that whole area I could be running, completely roll an ankle and keep going without a second thought or any damage. The lower leg, ankle, foot was much stronger and more competent etc

We generally over use our eyes to gage or location in space and with our artificial flat ground and hard shoes we loose a lot of natural abilities of balance and performance. (closed eye balance exercises can be very benefitial - if I had room I would often shadow box with my eyes closed - specifically helping with balance and awareness relating to fighting)

The more the body uses the lower leg/foot proprioceptors the more naturally functioning the body is and the less energy the nervous system puts to balance cause the balance has been trained better and the more energy the nervous system can put to striking etc

To kick explosively the body integrates and synchronizes everything and it will limit movement to the weakest link. When it can worry less about the lower legs etc and balance cause they are returned to normal natural functioning ability and or trained well it doesn't use as much energy and focus to organize and more power can be put into the kick.

That's my opinion and experience anyway.

In warm up I use to knee and teep stepping onto a bosu ball or balance board (I do stuff like that for warm up so I am not taking time from training or conditioning...

Watch Avatar and I think us humans, in the right environment and lifestyle, have much of those natural abilities.

This isn't magic training stuff. Its about normal body function and how we are designed in my opinion