Remove all locks. Body placed in push-up position with toes placed on the treads. The treads are in the back third of the guide rails.
Extended legs are pulled toward upper body, position is held for a moment and slowly pushed back to starting position.
Legs always remain fully extended during the exercise!
The shoulder area is strongly stressed during this exercise, don’t drop your belly.
The slower the exercise is performed, the more intense and effective it is.
For a bigger challenge: Place your hands on an unstable surface, e.g. a ball.