The homunculus discussed in this article will pertain to the somatosensory cortex. It is located just posterior to the frontal lobe within the parietal lobe. The structure is termed the postcentral gyrus and was discovered by brain surface stimulation performed by a former Princeton University football player named Wilder Penfield.

The basic premise behind this area of the brain is that the majority of the brain tissue is devoted to the most sensory rich areas of the body—the hands, feet, and facial structures. So how can we use this to optimize training? This question has rarely been asked because motor neurons overshadow their forgotten sensory counterparts. It is often forgotten that the perception of your body to turn on more motor units is part of the foundation for moving big weights.

The Hands

The hands are enormous on the sensory homunculus and for good reason. They are at the ends of our upper extremities and used to explore and perceive our environment. For moving heavy weight, they can be one of the best tools to get the job done. The harder an athlete squeezes the bar, the more motor units are signaled to turn on. The hands feel the increased white-knuckling pressure and are prepared to lift a heavy load. More motor units are turning on because your brain is signaling this output. The sensory input is part of what is signaling your brain to create this driving motor mechanism. This is a synergist loop of events. The sensory neurons tell the brain what to do, the brain conveys the message to the motor neurons, and then the sensory neurons gain additional feedback and make adjustments accordingly through this same loop.

Now, I’m not trying to disregard the innate abilities of the motor neurons. When you tell your hands to create maximum grip tension, you are “outputting” contraction to your muscles. However, think of the sensory neurons as your fine-tuning dial that is constantly surveying the quantity and quality of how the body is performing. Sensory neurons are simply converting external stimuli from the environment into internal stimuli. The point being—the two work as a team and are not easily separated.

Great pressure generated in the hands yields great stability in the shoulders. Try this with a client who has a winging scapula. Have them ball up their fingers in a tight fist and squeeze and observe their scapula suction to their rib cage like a vacuum. I remember reading awhile back that Dan John claimed that the baseball players he trained no longer had shoulder problems when they started doing heavy carries. It’s interesting to consider that when his athletes fatigued they could feel their hands sliding off the handle and would instinctively tighten their grip as a correction. The carry is self-limiting for shoulder stability because when you lose grip and thus shoulder stability, you lose the weight. Without perception, there is no correction.

The Feet

Although not as large as the hands on the sensory homunculus, the feet still have a large portion of brain tissue devoted to them relative to their physical size. Most people’s thighs are physically bigger than their feet (I hope), but the opposite is true on the sensory homunculus.

Homunculus Robbery

The feet can be used in much of the same way as the hands to create pressure to signal more muscle recruitment. While the hands squeeze, the feet push. As more of the surface of the foot is driven into the floor, more motor units are signaled to turn on based on the perception of increased pressure. You’ve just manufactured your own high stability environment.

When you squat/deadlift, consciously push hard into the floor to prime the nervous system for the task. If you’re having trouble with single-leg work, do the same. A foot partially in contact with the floor doesn’t fair well for stability with a couple hundred pound body above.

It’s reasonable to assume that the Vibram wearers that instantly become pain-free just immediately restore perception. A perfect example of less is more. Although their knee may have hurt, their brain previously didn’t understand that they could use their feet to help stabilize. I would think the dynamic and neurological rich foot is a little better at stabilizing than a hinge joint with slight rotation capabilities.

The Eyes

This one is simple. The body follows the eyes. When you are at the bottom of a squat, you should be looking up to obtain a desirable vestibular effect. The eyes provide sensory feedback as to where they want the body to go—which is hopefully up.

I am not suggesting to lift your head/chin in the upward direction as you will lose stability, but to only look up with your eyes. The eyes supply the sensory input that automatically creates a neuromuscular output. No thinking needed. The topic of why you should keep your chin tucked will be expanded upon in a future article.

The Mouth

This is a fairly overlooked area that has the potential to yield more total body stability. The mouth is incredibly oversized as illustrated on the sensory homunculus. A large proportion of the postcentral gyrus is devoted to such a physically small structure.

If we can figure out how to tap into this potential, this could mean a greater degree of lifting stability. Try this out for me, throw a quick jab or hook. Notice that your mouth remains closed. Now do the same thing with your mouth open. Notice the stability difference. It is reflexive to close your mouth during a punch to pressurize your abdomen for a brief moment.

So how do we use this for training? I’m not quite sure yet. Obviously, you should be pressurizing your abdomen with air before big lifts with your mouth closed, but there is more to the mouth than lips closed. I have begun toying around with a mouth guard to allow me to clinch my teeth hard without damage. With the mouth closed and the teeth clinched hard, you are creating a perception that the ensuing task will need maximum motor recruitment. A clenched jaw stimulates a stable cranium. A stable cranium stimulates a stable spine. A stable spine reduces energy leak and maximizes lower to upper body force transfer while minimizing risk of injury.

The tongue could also come into play by firmly pushing it against the anterior portion of the palate. However, this technique may be unsuccessful because it could turn into a game of “turn this muscle on” as opposed to the more instinctive behavior of tight lips and a clenched jaw. Further expansion of this topic is definitely warranted.

Conclusion

I think creating perception is overlooked and underappreciated. Pressure on our feet, hands, and in our mouth matters. No one is yet to figure out how to consciously tap into the huge motor recruitment it takes for a mother (who is completely untrained) to lift a car that her child is under. Who knows, maybe it is safer that we don’t know how. But the possibility is still out there because people have done extraordinary things when a life or death situation demands it.

You’re not optimizing your performance or safety if you are benching with loose hands, letting the bar roll down your fingers during a set of RDLs, and flopping on the edges of your feet during single-leg work. Stability is the name of the game to effectively utilize strength. Use your brains incredible perceptual capacity to your advantage. Strength limitation is often not a lack of muscle tissue. Train your brain to take the governor off of your engine.

Give your body an environmental reason and it will give you a result.