The Australian Wing Three Quarter, David Campese, made the Goose Step famous and perfected its use making it a trademark attacking ploy.
The purpose of the movement is to change the speed of the attacking player therefore disrupting the timing of the defensive players.
It was used by Campese very effectively once he broke the first line of defence and found himself in open territory being chased by the cover defenders.
What he was trying to do was to change the pace of his run while still maintaining the opportunity to continue at full pace.
In effect what he did was change his normal sprint stride while not changing the cadence of his stride thus minimising the disruption to his ability to maintain top pace.
Continue to run at full pace
Wait until the cover defenders are also at full pace
Wait until the defenders are no less that 8 metres away from you
Straighten both legs
Lean back into the stride
Kick the legs out fully straightened
Lean forward into your stride and continue accelerating
Hold the ball in the arm away from the defender.