Set-up: Lie flat on your back on a mat, with head and shoulders elevated slightly. Touch your hands to the front of your head. Lift your feet off the ground and bend your knees to 90 degrees
Lift: Bring the left elbow and right knee together in one movement, then lower and repeat on the opposite side.
Emphasis: Brace through the core throughout the entire movement. Do not come too far off the floor.
Repetitions: When both arms and legs have met once, this counts as one repetition.
Instructions and effects for the Bicycles exercise 
