Players will jump from side to side, jumping as high as the can while also tucking their knees up.
Once the player lands, they will want to jump again as quick as possible.
The player will continue this exercise for 45 seconds.
World Rugby has reportedly conceded Aaron Smith's disallowed try in the World Cup final should have stood.
"It is not only useful for staff who are experienced but a valuable tool for those subject staff who have to take teams."
The variety of sessions across sports - sometimes we steal session ideas from one sport and use them with another.