Amazing Proprioception — Football ( Soccer)
Nope. Never really played the sport except ineptly, in disorganized pickup games. But as someone who lost a bunch of proprioception on one side of my body, I’ve lately been appreciating how remarkable is the brain’s processing of proprioception in football players (Italian: calcio, US: soccer). And sure, there’s even more of a demand for great proprioception in gymnasts, for example. But most of us have never had first-hand experience with gymnastics, while many of us have at least dabbled with football, many more having played the sport more or less seriously.
Proprioception (Kinesthesia)
Although I’ve discussed this sensory function of the brain in prior posts, let’s try a simple explanation using everyday examples like keyboarding or swimming. Let’s start by asking the question, how are these sophisticated movements accomplished by the brain. An essential part of the answer is by processing and using proprioceptive information. In general, this is sensory information about the detailed dynamic positions and movements of our bodies with respect to gravity (the earth) and the positions of our head, arms, shoulders, legs, hands, feet, and fingers/toes in reference to the body’s midline. And in reference to one another: arms to head, hands to wrists and to each other, legs to each other, fingers to each of the other fingers of the same hand, etc.
A simple example is keyboarding — on both computer keyboards or piano keyboards. It’s essential that each finger on each of our hands knows where the other fingers are located relative to itself; and relative to the wrist and the other hand as movements occur and evolve. This is necessary to avoid fingers stumbling over one another and punching keys in the wrong order as the keyboarder types or plays a demanding piano part. Skilled qwerty keyboarders (who were once called touch-typists) do this with minimal sensory input from vision. One-handed plodders like me need more visual input. But we all need proprioception so that our hands and fingers know where they all are in space as they clack away. Every skilled movement from keyboarding to the backstroke to skillfully dribbling a football requires that the brain receives this information from muscle and joint stretch receptors (and often, from the vestibular apparatus in the inner ear).
Motor Programs
Amazingly, if the system is functioning correctly, this is mostly an automatic and subconscious process that the brain learns for diverse body, head, and limb movements as each movement is learned. This learning is partly stored in our cerebellums as a so-called motor (movement) program. This is a brain algorithm that automatically specifies the sequences and timing of muscle contractions required for the movement. But it feeds this information to other parts of the brain and spinal cord, which are responsible for actualizing the movement by signalling muscles. Part of that actualization — of putting a motor program into action — requires that the brain has proprioceptive information.
At its most basic level, this encompasses stretch information from your muscles and joints. It says this to your brain: “muscle A is contracted by this amount, muscle B is relaxed at normal relaxed length, Muscle C is stretched by this amount. This information changes from moment to moment as a skilled movement continues. Proprioception keeps track of these changes. The brain uses that information in the context of the particular motor program to keep the muscle contractions (or relaxations) happening smoothly as the movement continues. It’s sometimes described as a sixth sense.
Overview of the Proprioceptive System Components
All of these movements require that we use our muscles, so what may not be so obvious is why proprioception is called a sixth sense. I should reiterate that the balance systems also are important to proprioception, for instance the balance info coming from our inner ear vestibular system. And vision is often a component of this body and body part orientation information. But these are related topics beyond this discussion.
A movement starts via the contraction (shortening) of a sequence of usually several muscles with others relaxing. For instance, in throwing a ball, muscles in my back must contract to draw my arm backward, while muscles in my arm contract to close my fingers around the ball to hold it while my arm draws back. Chest muscles must relax to allow this to happen, these muscles stretched during the movement. Subsequently, the chest muscles contract to help draw the throwing arm forward, with other back muscles relaxing so as to not oppose that arm motion. At the same time various hip and leg muscles contract to maintain my balance and shift my weight while other hip and leg muscles must relax to avoid resisting the movements. And at the appropriate time during the arm’s forward motion, I must relax the fingers in order to release the ball.
Most important to proprioception is that all these muscle contractions and stretched relaxations are monitored by stretch receptors within the muscles themselves and within the joints that are moved by the muscle actions. Then, of course, this information is relayed to the brain. The stretch receptors inside our muscles are formally called muscle spindles, and there is an entire population of nerve cells in the spinal cord that talks to them. These nerve cells set the sensitivity of the stretch receptors. And that’s also part of the brain’s elegant proprioception system, which is understood in some detail that I’m choosing to avoid in this broader overview.
Two Football Kicks That Require Amazing Proprioception
A player running toward the goal receives an airborne pass from a teammate. In full stride s(he) leaps into the air, adjusts body, arms, and legs with respect to the ball and strikes or volleys the airborne ball before it hits the ground, driving it into the goal.
Not only must the player’s brain know the relative positions of all limbs, s(he) must have a body sense of his /her position in space with respect to the ground and his/her momentum with respect to the ball. And after jumping into the air with that computed relationship, instantly adjust the body’s angle to the ball at its last moment of arrival, so that the striking leg propels the ball toward the goal rather than erratically.
But that player is still in a normal relationship to gravity, with head above the rest of the body and body upright with respect to the earth. An even greater proprioceptive challenge is to volley the football with these relationships turned upside down.
Here’s a video collection of volleyed goals (10 minutes of them, but a great example in the first 25 seconds) https://www.youtube.com/watch?v=GqAmfI4NMaQ
Overhead Kick
The upside-down display of the marvels of proprioception in footballers is the overhead or bicycle kick. The ball is struck in the air (volleyed) by a player whose body position is upside down with respect to gravity and who’s often oriented with his/her back to the goal. So both upside down to the earth and backwards to the goal. Finally, after the ball is struck, the player’s body must hit the turf in a manner that prevents injury. This is an amazing display of body and limb control, as shown in this image of the legendary Brazilian footballer, Pelé.
Short Video: The Polish footballer Robert Lewandowski displaying this amazing talent in November 2021, playing for Bayern Munich. https://www.youtube.com/watch?v=feKIdqzLo7w
A longer video replete with overhead kicks/goals. https://www.youtube.com/watch?v=UMcJAXwWaf0
The Automaticity of Proprioception
Because all these processes are automatically in operation in your nervous system and muscles, it’s easy to overlook proprioception. Folks who lose some of it through brain or spinal cord injury can hardly ignore what’s lost. For example, a once competent and dexterous hand becomes capable only of coarse movements like gripping a handle, but can no longer perform finer movements like keyboarding. A body that was formerly equally adept at lateral movements to position itself to hit a tennis ball loses some of that ability on one side. Perhaps that’s why I’m so impressed by what some of the top footballers can do with their bodies. It’s certainly given me a greater appreciation of football than I had before I lost some of my own proprioception.
