Jay Honeck wrote:

With the four of us pushing, we were able to break Atlas free and push
him back about four feet -- enough so that I could clear the tire.
Start up was normal, and, as expected, back-taxiing on the soft, snowy
grass took considerably more power than normal. I utiliized the
"Sylvania Swing" (accelerating *away* from the direction of departure
and swinging it around while applying full throttle -- a short-field
technique that we learned at Sylvania Field in Wisconsin that can buy
you an extra several hundred feet of runway) to get off the short
field, and used classic soft-field technique to get the nose wheel out
of the snow. The cold air and Atlas' 235 horsepower did the rest, and
we climbed strongly in the cold, clear air.

How does this buy you an extra several hundred feet of runway?

Matt