By Gerard Bochese
When people think of training their legs in the gym they always look for the leg extension machine, the leg curl machine, and the leg press machine. The reason “in the gym” is such an appropriate line in the preceding sentence is because only on these machines in a gym would your lower body ever perform these types of movement patterns.
In real life your legs do not function as they do on these machines. These machines all isolate a body part and were designed with a body-building mentality. They are, therefore, only really good for building bigger muscles (hypertrophy) and can actually set us up for injury if they’re the only equipment we use to train the legs.
Having said that, it’s fine to mix in these machines with a lower body regimen that includes much more functional exercises such as squats, lunges, and step-ups. Remember, the nervous system stores movement patterns and therefore we do not want to store incorrect or non-functional movement patterns that will be useless to us in our everyday activities.
Let’s examine how the legs function in a real-life setting and compare it to the leg extension, leg curl, and leg press machines (we will call them the “gym 3”)
When we use our legs in real life (standing, climbing stairs, skiing, playing basketball, going for a run) our feet are in contact with the ground. On the gym 3 the feet are either dangling in space or on a platform above your head or directly in front of you. These exercises do not allow you to use ground reaction forces that you encounter everyday.
In real life we must deal with gravity at all times. This means that the direction of force and weight on your legs goes from your head down toward the ground. When you are carrying things (groceries, children, heavy lumber, backpacks, etc) the force is that much greater. On the gym 3 the weight is located at the bottom at your feet. Therefore, the normal forces of gravity and the body mechanics and postures needed for a downward force are not being taken into consideration.
When we use our legs in real life our hips and knees almost always flex and extend (bend) together. We don’t isolate bending only the knee or only the hips. Think of squatting down to pick something up, getting into a car, climbing stairs, walking, and running. On the leg extension and leg curl (not the leg press) we isolate the knee joint from the hip joint. Once again, we are not training proper movement patterns that we will need to call on in everyday activities. This could potentially set us up for injury because we train the muscle in a way that they will not be used and thus, even though the muscles look strong, they will be functionally weak.
One of the most important functions of our lower body is locomotion. When we walk, run, or go down stairs, we are forced to decelerate our body weight at some point then accelerate our body weight forward. Basically, the function of the lower body during locomotion is to stop the ankle, knee and hip from bending during foot contact so that we don’t fall to the ground. Once the foot is placed on the ground the next action of the lower body is to extend the ankle, knee, and hip to create forward movement. Machine training does not train this necessary stabilization and deceleration component, nor does it train the acceleration component in a functional way (ground contact) or with correct movement patterns.
It is, therefore, essential to train the lower body with functional movements such as squats and lunges. These exercises will not only create a more efficient and dynamically strong lower body but will certainly create the great looking muscles most people are going for.