This will not, of course, settle the agelong debate of whether to walk toe first or heel first in tango. Still, I found it interesting that there has recently been published research on the efficiency of the human walk, specifically investigating walking heel first versus walking toe first. If you are striving for the most efficient walk, their conclusion might be worth noting:
> > When human subjects walked with their heels slightly elevated in a ‘low-digitigrade’[toe first] posture, COT [cost of transport] increased by 53% above that of normal plantigrade [heel first] walking. > > > > Cunningham, C. B., Schilling, N., Anders, C. andCarrier, D. R. (2010). [The influence of foot posture onthe cost of transport in humans](http://jeb.biologists.org/cgi/content/full/213/5/790?ijkey=ce57e4d265e26213e5a9717dc550495b1e75a6c9). J. Exp. Biol. 213, 790-797 > >
The researchers were wondering why we are not walking and running toe first like many other animals and wanted to test the hypothesis that walking heel first is more efficient. They did experiments with different walks and runs on a treadmill where they could measure the oxygen consumption of their subjects at normal walking speed. They also did experiments with running subjects, where this difference does not exist.
In short, the reasons for the increased efficiency of walking heel first are (p. 796):
lower collisional losses of the body as a whole
increased recovery of kinetic and potential energy
lower ground reaction force moments specifically at the ankle joint.
Not very surprising, maybe, to anyone who has tried both ways, but now you’ve got the reference :-)
Their paper says nothing about style, of course…
Illustration taken from the original paper.