When we describe how we move in fitness, we divide the body into three planes. One imaginary plane splits us into right and left halves, one splits us into front and back halves, and one splits us into top and bottom halves, as if we were the hapless assistant in a magician’s show. The three planes are called, respectively, the sagittal, the frontal, and the transverse.
When we swing a leg back and forth in the hip socket or raise an arm in front of us in a “Halt!” kind of way, we are moving parallel to the sagittal plane. This is the plane that most of us feel most comfortable in because that’s how we walk and run and so on.
The frontal plane, confusingly, is the plane we are moving parallel to when we shuffle side to side or do jumping jacks. Practicing this kind of movement helps with sports like basketball and tennis and with everyday actions like getting in and out of cars. Work in the frontal plane can also help us practice motions that keep us from spraining our ankles as we strengthen the muscles on the inside and outside of our legs.
The transverse plane is for twisting. Think about golf swings and racquet sports, salsa dancing, and getting out of bed in the morning. We sometimes don’t like working with transverse plane exercises because they tend to require a little more balance control and thus more core work.
Working in all three planes, separately or together, is what helps us prepare for whatever life throws at us.