When most people perform lower body/leg exercises (if they perform them at all), they usually choose squats, leg presses or maybe even deadlifts. While these are all great compound movements that hit all the major joints and muscles of the lower body, they are all performed in the sagittal plane. They are also all performed with the feet planted on the floor or on a stable surface with no movement or change of position.
Rarely will someone incorporate lower body exercises that require a change in foot position or a direction change. If they do, it's usually with lunges which are almost always performed again, in the sagittal plane.
If we take a look at how we move in everyday situations, this is not really how we use our lower body or legs. Basically our legs serve two main functions; 1) they support our torso and upper body keeping us upright and 2) they move us around.
As we go about our daily lives we use a lot of multidirectional movement patterns; forwards, backwards, sideways, crossovers and combinations. We perform these movement patterns both on flat and on elevated surfaces. If we now take it one step further (no pun intended) and look at sports related movements, these are way more dynamic and varied.
It is extremely important to incorporate a variety of lower body exercises that include movements in all three planes (sagittal, front & transverse) and require changes of foot placement and direction into your training program.
So what are some good examples of these types of movements?
Let's start with the lunge for example. A lunge by definition is a sudden movement forward, usually accompanied by a thrust of ones rapier, taken from days of old when people were more preoccupied with sword fights than working out. In essence, a lunge requires a change of position of the feet and sometimes also a change of direction. They can be performed in all three planes; sagittal for forward or reverse lunges, frontal for side lunges and transverse for crossover lunges (these can also be thought of as a combo of sagittal and frontal plane movements).
Next there's the step up. A step up is exactly as is sounds, you are stepping up onto a higher surface, something we do everyday as we climb stairs. Step ups can be performed to all different heights as well as in a few different directions or movement patterns.
By adding just these two movements, along with varying the planes and the surfaces or heights to the existing staples of squats, leg presses and deadlifts, you can really expand your lower body training and positively affect results.