Unilateral Exercise
Single arm and leg exercises are often programmed as a means of isolating particular body parts or to train athleticism specific to a given sport. These rationales serve as reasonable points in the world of fitness and do hold some degree of merit. I will often encourage clients to perform these types of activities when they see me for pain as they limit interference with the rehab-ish exercises I prescribe along with them. They are also truer to the way we seem to prefer to move versus the traditional movements we see in the gym.
Let’s consider walking as a primary movement strategy for most people. One leg strikes the ground as the other is leaving the ground. Forces transfer from one side of our body to another, each side assisting in propulsion of the other. During a more common activity, like a barbell back squat, both feet are glued to the floor symmetrically. Forces from the barbell and the equal force from the ground squish us together into one big piece, limiting side to side transfer. This is an awesome arrangement for getting muscles to grow bigger and stronger. The tradeoff is movement variability and adaptability.
During unilateral activities, like a lunge per se, we mimic the mechanics involved in walking more effectively. The lead leg is absorbing most of the force from the ground, while the trailing leg is pushing off. This asymmetry might, in fact, create a rotational element through the entire body. That rotation could be what keeps tissues healthier and more adaptable over the long-term. It might be a more efficient way of moving and makes greater use of the elastic mechanisms that store and release energy.
We all have individual aspirations in the gym, a lot of them consist of moving well and staying healthy. Symmetrical activities have a time and a place, they make us feel strong. Offsetting those activities with ones that restore foundational mechanics may play to our advantage in the long run. They could reduce focal stressors and promote a more uniform distribution of forces throughout the system.
Austin Ulrich, Physical Therapist
