Posts Tagged Human Movement

Symmetry in Motion

THE BODY SEEKS SYMMETRY

“Learning coordination is a matter of training the nervous system and not a question of training the muscles. The transition from totally uncoordinated muscular effort to skill of the highest perfection is a process of developing the connections in the nervous system” Bruce Lee (1975)

Symmetry is possibly one of the most important of actions that occur within the human body, once we really understand the benefits of this natural heritable process of movement it will enable an individual to move efficiently and effectively. I intend to explore how symmetry works and where it can be found. There are body responses that do not require symmetry to ensure their speed and effectiveness, what I am referring to here is the inbuilt startle reflexes that the body uses to protect itself against impending danger, pain and other types of stimulus.

An object that is symmetrical has the property of being symmetrical about a vertical plane, however we also have other various types of symmetry. Radial symmetry is symmetrical around a central axis. When an organism is radially symmetrical, you could cut from one side of the organism through the centre horizontally to the other side, this cut would produce two equal halves. Bilateral symmetry occurs along the vertical plane (sagital) and is created by a reflection of images on either side of a centre line. There are five basic types of symmetry at work in the human body, “symmetry of movement”, “symmetry of postures”, “symmetry of muscle strength activation”, “symmetry of control systems”, and “symmetry of features”. My intention is to explore movement in more detail and provide some evidence as to why this type of movement within the human body is so important, I will also take a look at postures and muscle strength activation as this also has an effect on the efficiency of movement and the biomechanics that drive the human body.

Human movement originates from a communication system between our neuromuscular proprioception senses and the sensory input and output region within the brain, Neural-Muscular Programming (NMP) along with Fixed Action Patterns and startle reflex, all play their part and will be discussed in detail later. The region in the brain that is responsible for controlling the movement of humans is the primary motor cortex, located in the posterior portion of the frontal lobe. The Primary Motor Cortex works in association with other motor areas including pre-motor cortex, the supplementary motor area, posterior parietal cortex, and several sub cortical brain regions, to plan and execute movement. The primary motor cortex sends axons down the spinal cord to synapse onto the interneuron circuitry of the spinal cord and also directly onto the alpha motor neurons in the spinal cord which connect to the muscles. The primary motor cortex contains a rough map of the body, with different body parts controlled by partially overlapping regions of cortex arranged from the toe (at the top of the cerebral hemisphere) to mouth (at the bottom) along a fold in the cortex called the central sulcus. Each cerebral hemisphere contains a map that controls mainly the opposite side of the body. Later I will discuss early research into the mapping of the motor cortex in primates, which led to evidence that the brain is indeed plastic in every account. Within the primary motor cortex there is a representation of the various different body parts of humans. The arrangements of these representations are called a motor homunculus, Latin for little person. All the human body is represented on this map, including the extremities, parts of the torso, all areas of the head down to the tips of the fingers, and these, along with fixed action patterns like raising the arm up to grasp an object, all have their place in the homunculus. The arm and hand motor area is in comparison to the leg, larger in its occupied land-space, and occupies the part of perceptual gyros between the leg and face area. The area that represents the hand and some face parts are larger than any other, with more neurons being assigned to activate and receive incoming stimuli from these areas.

Research has shown that after amputation for example; the area previously assigned to the limb that has been amputated shifts to take up sensory input from another area. The assignment of large areas of the motor cortex to various body actions help us understand why humans have such dexterity in their arms, hands and fingers. Remember the research into taxi drivers in London; their amygdala had grown in size, reassigning more neurons to the activity of remembering the complex road system in London. Using both arms together for a dedicated activity and matching the pattern of movement would over a long period of time produce the same results, larger areas dedicated to such movement, indicating that bilateral symmetry takes up more land space within the primary motor cortex and that the brain is plastic and able to reassign more neurons to a particular activity. In most cases, symmetry comes naturally without having to consciously think about it. It’s when we take it out of our subconscious thought process and apply it to conscious thought that we are able to make extraordinary improvements in the way we move. It has a direct effect on speed, power, alignment principles and many more areas within the combative and martial art arena. An important aspect about adapting new or existing pathways of muscle movement is to know why the human body moves in a particular manner.

Understanding this movement is the first step towards more efficient and effective movement, once you have taken new improvements on board and adaptation has occurred, your neuromuscular pathways will start to embed the specific movements, working towards being able to assign them back to the domain from where they came from, your subconscious. Here you will access them without conscious thought and your speed and power will increase substantially. For this process to work at its best we need to be able to really understand what is happening, why we do certain movements and what works and what does not. Symmetry training of specific movements has a significant effect on the recovery of limb movement after injury Joseph Zeni. Jr (2013) and his associates of the university of Dalaware conducted an analysis on a longitudinal basis and researched the feasibility and effectiveness of an outpatient rehabilitation protocol that included movement symmetry biofeedback on functional and biomechanical outcomes after Total Knee Arthroplasty (TKA).

This involves a surgical procedure in which damaged parts of the knee joint are replaced with artificial parts, muscles and ligaments around the knee are separated to expose the inside of the joint. The ends of the thigh bone (femur) and the shin bone (tibia) are removed as is often the underside of the kneecap (patella). The artificial parts are then cemented into place. The new knee typically has a metal shell on the end of the femur, and the same metal or plastic trough onto the tibia, and sometimes a plastic button in the kneecap. This surgery has resulted in patients experiencing a loss of strength in the recovering knee that has resulted in movement that is abnormal and even after rehabilitation of the operated knee, problems have persisted, resulting in an asymmetrical increase in load onto the knee that has not been operated on. The method used by Zeni and his colleagues to assess the feasibility of symmetry movement training, was to use biomechanical and functional metrics to assess participants 2 to 3 weeks prior to TKA, then again on being discharged from outpatient physical therapy and finally 6 months after surgery. They assessed 9 men and 2 women all of whom underwent 6 to 8 weeks of outpatient physical therapy that included specialized symmetry training. They compared the 6-month outcomes with a control group that were matched by age, body mass index and sex, 9 men and 2 women, these patients received the normal 6 to 8 weeks of physical therapy but not the specialized symmetry training. Their results were significant, out of the 11 patients that received the specialised symmetry training, 9 demonstrated clinically meaningful improvements that exceeded the minimal detectable change for all performance-based functional tests at the 6-month period after surgery. These patients had greater knee extension during mid-stance walking; the knee movements were more symmetrical, biphasic and were more representative of a normal knee movement than the patients that did not have the specialised symmetry training. They concluded that the additional symmetry training post-operation was safe and viable to regaining normal symmetrical movement. What this study provides is evidence that the body seeks symmetry in movement and that specialised training can produce clinically better movement after damage.

If that is the case, then it stands to reason that when designing movement that is combat based. specialised symmetry training should be an important consideration. It is vitally important that the correct body mechanics are adhered to; teaching movement that is un-natural is one of the key mistakes when efficiency and effectiveness are required. In a great many martial/combative classes today the words “we will teach you what comes naturally”, are all too often heard, the question to your instructor should be; what is natural movement and how do we know it’s natural? Observe a newborn child a few days old, when a parent places their finger onto the baby’s palm, you see the baby grasp the finger tightly. Be careful though, because the baby cannot control this reflex. If you place a rattle in your baby’s hand, for example, they may let go unexpectedly and drop it on their head. A baby’s grip is so strong; you may be able to pull them up when they are gripping both your fingers.

Further information can be found in my book Volitional Attention Training.

References

Zeni, J, Jr. Abujaber, S. Flowers, P. Pozzi, F. Snyder-Macker, L. (2013) Biofeedback to promote movement symmetry after total knee arthroplasty: A feasibility study. Published: Journal of Orthopaedic & Sports Physical Therapy, 2013, Volume: 43 Issue: 10 Pages: 715-726 doi:10.2519/jospt.2013.4657

 

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