Spider-Man Pushup

Instructions

1. 
   Begin on all fours placing your hands on the floor slightly wider than shoulder-width apart. Your body should form a straight line from your ankles to your shoulders. Squeeze your abs as tight as possible and keep them contracted for the entire exercise.
2. 
   As you lower into the pushup, pull one knee up and towards the elbow of the same side. Pause, then push your body back up and return the lifted leg back to the starting position. Alternate sides.