Paying attention to the body plane that an exercise is performed in will allow you to analyze your own form and prevent injury. The body has three anatomical planes, which are used to describe motions the body may perform. Each movement the body performs is said to be occurring within a single plane, or in a combination of the planes.
The Anatomic Plane of a Biceps Curl
Biceps curls are performed in the sagittal plane. In reference to the human body, the sagittal plane is a vertical plane that runs from front to back, dividing the body into right and left portions. The sagittal plane motion of a biceps curl divides your arm in half. The motion is performed by bending your arms at your elbows, until your forearms are vertical, keeping your shoulders and upper arms in place.
Tips for Keeping Your Motion in the Sagittal Plane
While performing a biceps curl, you can ensure that your motion stays within the sagittal plane by keeping your elbows pressed into your sides and your shoulders still. Keep your core muscles contracted to avoid rocking, jerking and swinging motions of your torso. Finally, by keeping your wrists straight, the weight will be carried by your biceps brachii muscle, rather than your forearm.
Other Biceps Exercises in the Sagittal Plane
There are variations of the biceps curl that are also within the sagittal plane. For example, the hammer curl, which involves holding the dumbbell in a different position, yet maintains the same motion as a bicep curl. Other biceps exercises staying within the sagittal plane are barbell curls, chinups and cable curls.
Other Anatomic Planes
The other anatomic planes of the body are the transverse and frontal. The transverse plane divides your body into upper and lower halves. Exercises within the transverse plane would be twisting exercises, such as oblique sit ups. The frontal plane divides your body into a front and back side. Lateral arm raises are performed in the frontal plane.