How We Move

Using the neuromusculoskeletal structure, the human body is capable of a phenomenal range of movement, stability, strength and alert stillness. How do these systems work together to achieve this?

Movement is so natural to us, so ingrained and such a habit, that we rarely stop to think about how we do it. The funny thing is, that is what nature intended. If we did need to have to think about little motion that our body goes through, even just to take one step forward, our brain would be so overwhelmed having to compute and make sense of it all that we would neverget anything else done!

Just like all habits, the sequencing and nature of of how we move must be learnt. This process occurs early on in life, as we learn first to crawl and then finally to stand up and walk around unaided. For the vast majority of us, we have mastered the art of walking (also termed gait) by the age of 2. Once it has been learned, there becomes no further need to think about it. After having spent several intensive months learning instinctively how to manage it, we now need to get on learning about the rest of the world and life, and we rely on our learnt habit of walking to achieve this.

So, in order to really understand how we move, we must stop and think about it, and break it down into distinct units. By doing this we can begin to understand how the natural forces of gravity and ground reaction forces are transformed into graceful balanced motion. The details of human motion are complex and we are still ignorant of many of the inter-relationships between the three systems that control it - neurological, muscular and skeletal. What we can do, however, is provide a basic grounding in the fundamental principles of human motion, enabling those with a deeper interest to search out greater detail elsewhere.

Question 1 - Where does movement start?
Well, not an easy one to begin with. Neurology probably has the upper hand here, as it is our intention to move that comes from external or internal stimuli (running for a bus, reaching for a cup out of the cupboard), which is registered and managed by the brain.

Question 2 - How does the idea for motion get translated into actual motion?
The brain computes the action that is required from the internal or external stimuli and sends the necessary signals to the muscular and skeletal systems to carry out the required motion. In the case of the running for the bus, the required motion is to place one foot in front of the other in rapid succession in order to get ourselves from where we are (point A) to where we need to be (point B).

Question 3 - How does motion take place?
The placement of one foot in front of the other generates a sequence of whole body motion called the gait cycle. With the feet in contact with the ground, the whole body becomes a closed kinetic chain, meaning that motion within one part of the body will cause motion in all other parts. Whilst it is the brain that sends the signal to commence motion, it is the feet, in their unique position in contact with the ground surface,which must act out this requirement. Through the motions of pronation and supination, the foot directs the rest of the body through the gait cycle, a sequence of motion that interacts with the forces of gravity and ground reaction forces to move us in our intended direction.

Question 4 - How do we know we have completed our intention?
There is a feedback loop within all body systems, and the neuromusuloskeletal system is no exception. Just as our the muscular and skeletal systems act out the instructions from the neurological system, they also send update reports to let the brain know where it is up to. Armed with this information, the brain compares it with the initial instruction, considers the information from external and internal stimuli then issues new instructions or amendments in order to complete the exercise. Based on external stimuli from our visual senses, such amended instructions might include to move slightly to the left to avoid other people walking toward you or to stop running because the bus has left the stop.

This all sounds sensible, but what we must remember is that this all takes place at lightening speed, with data being processed by the brain from all these and other stimuli thousands of times every second. Our bodies really are amazing!