But anyone who's ever taken a group fitness class knows that they are a deceptively difficult exercise. A plank is an isometric ... which is a muscle group many women overlook.

Jennifer Lopez is known as much for her sculpted physique as she is for her music, movie roles and romantic partners.

The plank is a brilliant bodyweight exercise for building a rock-solid core to help stabilise and protect the spine. However, it’s not the easiest move to master, as it requires a decent level ...