You go to the gym with a friend and they tell you they want…
You go to the gym with a friend and they tell you they want to work their core. Because you are so smart, you know there are 4 primary muscles that make up our core musculature. When your friend is doing normal crunches, they are primarily working the 6-pack muscle known as the (transverse abdominis, rectus abdominis, rectus femoris, biceps femoris) . When they are doing bicycle crunches in which they are crossing their RIGHT elbow to the LEFT knee, they are working the right (internal or external) oblique and the left oblique.